nazri

LEMBAGA LEBUHRAYA MALAYSIA

DOCUMENTATION OF STONE MASTIC ASPHALT (SMA) WORK

IN PLUS THIRD LANE WIDENING PROJECT: RAWANG-BUKIT BERUNTUNG

(PACKAGE 3A)

BAHAGIAN PASUKAN PROJEKLEMBAGA LEBUHRAYA MALAYSIA

MEI 2008

DOCUMENTATION OF STONE MASTIC ASPHALT (SMA) WORK

IN PLUS THIRD LANE WIDENING PROJECT:

RAWANG-BUKIT BERUNTUNG (PACKAGE 3A)

LLM/D/T/1-08

ACKNOWLEDGEMENT

A journey is easier when you travel together. This SMA Report is the result of two and half years of work experiences during the implementation of SMA surfacing in Third Lane Widening Projects between Rawang to Bukit Beruntung Stretch whereby it have been accompanied and supported by many people. It is a pleasant aspect that we have now the opportunity to express our gratitude for all of them.

First of all we would like to express our deep and sincere gratitude to the committee members; En. Md. Zarulazam Bin Md. Eusofe (MHA), En. Nazri Bin Saad (MHA), Cik Norfadzlina Binti Amzah (PEB), En. Kenny Lim (OPUS), En. Hamdan Bin Ghazali (OPUS), Ir. Kim Ewe Beng (Minconsult), Major (R) Ir. Azmi Bin Yusof (Minconsult), En. Lee Chee Mun (Minconsult), En. Mohd Fauzi Bin Moh. Sakroni (UEM), En. Johari Azizi (UEM), En. Azmi Bin Yusop (UEM) and En. Mohamad Bin Abu Bakar (PATI), for their commitment and patience throughout the process of preparation of this report. Your experience and wide knowledge have been a great value for the present report.

We would also like to extend our sincere gratitude to En. Sazali Bin Harun, Project Director I, MHA for his valuable advice and essential assistance in reviewing the report of this committee. His kind support and guidance have been of great value throughout the process.

This committee also would like to thank Yang Berusaha Ir. Ismail Bin Md. Salleh, Deputy Director General (Planning & Developement), MHA for his contributions and constructive ideas that have made this report possible. This report was his brainchild to enable the working experience of SMA to be documented, implemented and then referred to by the future generation.

Finally, we would like to thank Yang Berbahagia Dato’ Ir. Haji Mohammad Razali Bin Othman, Director General of Malaysia Highway Authority, PLUS Expressways Berhad, OPUS International (M) Bhd, Minconsult Sdn. Bhd, UEM Builders Berhad, PATI for their approval and support in documenting the SMA experience in the Third Lane Widening Project of The North- South Expressway.

It is a pleasure to thank the many people who made this report possible.

THANK YOU8 January 2008

iDOCUMENTATION OF STONE MASTIC ASPHALT (SMA) WORKIN PLUS THIRD LANE WIDENING PROJECT: RAWANG-BUKIT BERUNTUNG (PACKAGE 3A)

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TABLE OF CONTENTS

ACKNOWLEDGEMENT 2

TABLE OF CONTENTS 3-6

CHAPTER 1: INTRODUCTION

1.1 OVERVIEW

1.1.1 Background 7

1.1.2 Widening of the Existing Carriageway 8

1.1.3 Final Layer Surfacing 8-9

1.2 OBJECTIVE 10

CHAPTER 2: LITERATURE REVIEW OF STONE MASTIC ASPHALT

2.1 CONCEPT AND HISTORY

2.1.1 General 11

2.1.2 History and Development 11

2.1.3 Concept of Stone Mastic Asphalt 12

2.1.4 Stone Mastic Asphalt in Malaysia 13-14

2.1.5 Paper 1: SMA IN THE UK 15-23

2.1.6 Paper 2: TECHNICAL NOTE 16: SMA 24-25

2.1.7 Paper 3: COST COMPARISON BETWEEN SMA & ACWC25-31

CHAPTER 3: DESIGN OF STONE MASTIC ASPHALT

3.1 DESIGN 32

3.2 MATERIALS

3.2.1 Coarse Aggregate (>2.36mm) 33

3.2.2 Fine Aggregate (≤ 2.36mm) 33

3.2.3 Filler 333.2.4 Binder 33

iiDOCUMENTATION OF STONE MASTIC ASPHALT (SMA) WORKIN PLUS THIRD LANE WIDENING PROJECT: RAWANG-BUKIT BERUNTUNG (PACKAGE 3A)

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3.2.5 Fiber Additive 34

3.3 DESIGN MIXTURES

3.3.1 Proposed Design Mixture 34

3.3.2 Laboratory Design Mixture 34

3.3.3 Job Standard Mixture 34

3.3.4 Job Mixture (Plant Mixture) 35-38

3.4 COST ASSESSMENT 38

3.5 ADVANTAGES & DISADVANTAGES OF SMA

3.5.1 Advantages of SMA 38-39

3.5.2 Disadvantages of SMA 39

CHAPTER 4: QUALITY ASSURANCE & QUALITY CONTROL OF STONE MASTIC ASPHALT

4.1 QA & QC

4.1.1 Transporting, Laying and Compaction 40-41

4.1.2 Sampling & Testing 41-42

4.1.3 Frequency of Samplings and Testing 42-43

4.2 TESTING

4.2.1 Temperature 43

4.2.2 Rolling Pattern 43

4.2.3 Batching Plant Monitoring 44

4.2.4 CSL Lab Monitoring 44

4.2.5 Checklists and Forms 44

4.2.6 Samples of the Test Results 44

iiiDOCUMENTATION OF STONE MASTIC ASPHALT (SMA) WORKIN PLUS THIRD LANE WIDENING PROJECT: RAWANG-BUKIT BERUNTUNG (PACKAGE 3A)

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4.3 TESTING EQUIPMENT FOR SMA IN LABORATORY 44-48

4.4 SEQUENCE OF WORKS FOR OVERLAYING SMA

4.4.1 Sequence 1 48

4.4.2 Sequence 2 48

4.5 REPORTS ON THE PLANT TRIAL & TRIAL LAY OF SMA

4.5.1 SMA Plant Trials & Trial Lays From Matang Pagar Quarry 48

4.5.2 SMA Plant Trials & Trial Lays FromKajang Rocks Innopave Premix 48

CHAPTER 5: IMPLEMENTATION OF STONE MASTIC ASPHALT5.1 PRODUCTION OF SMA

5.1.1 Physical Properties of Aggregates 49-50

5.1.2 Laboratory Mix Design 51-52

5.1.3 SMA PRODUCTION

5.1.3.1 Plant – General 52-53

5.1.3.2 Flow Chart of SMA Production 53-55

5.2 LAYING WORK OF SMA

5.2.1 Introduction 56

5.2.2 Machinery, Equipment & Material 57-58

5.2.3 Overlaying Works 58-70

CHAPTER 6: ISSUES ENCOUNTERED

6.1 Site Problems Encountered & Recommended Solutions 71-73

CHAPTER 7: CONCLUSIONS & RECOMMENDATIONS

7.1 Conclusions 74-76

7.2 Recommendations 76

APPENDICES 77-118

ivDOCUMENTATION OF STONE MASTIC ASPHALT (SMA) WORKIN PLUS THIRD LANE WIDENING PROJECT: RAWANG-BUKIT BERUNTUNG (PACKAGE 3A)

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CHAPTER 1: INTRODUCTION

1.1 OVERVIEW

1.1.1 Background

The North-South Expressway linking all major cities on the West Coast of Peninsular Malaysia comprises of 848km long expressway with 4 and 6 lane divided highway. Under the Third Supplemental Agreement between the Government of Malaysia and PLUS Berhad, the highway is operated and concession by PLUS Expressways Berhad (PLUS) under the authority of Malaysian Highway Authority (MHA).

The NSE was constructed in phases over a period of seven years, completed and opened to traffic in 1994 has reduce the congestion and traveling time experienced by expressway users, especially during festive seasons and long holidays.

The significant increase of traffic volume from year to year over the past 14 years of NSE operations has resulted heavy congestion at some stretches of the expressway especially during festive seasons and long holidays.

Therefore, widening works from 2 lane to 3 lane which involve stretches between Seremban to Ayer Keroh and Rawang to Slim River are necessary to improve the capacity of the expressway and hence the Level of Service (LOS) as well as to cater the increase traffic volume. The Third Lane Widening works are divided into packages as follows:

i) Seremban to Senawang (7km)ii) Senawang to Pedas Linggi (20km)iii) Pedas Linggi to Ayer Keroh (40km)iv) Rawang to Bukit Beruntung (21km)v) Bukit Beruntung to Tanjung Malim (24km)vi) Tanjung Malim to Slim River (28km)

The existing pavement structure for Seremban to Ayer Keroh is all Flexible Composite Pavement (FCP) whilst for Rawang to Slim River is Continously Reinforced Concrete Pavement (CRCP) at mainline and flexible pavement at Emergency Lane.

1.1.2 Widening of the Existing Carriageway

Proposed carriageway widening involves adding a new main lane (third lane) and a new emergency lane on the outer side of the existing slow lane which is FCP, plus a surfacing layer of Asphaltic Concrete Wearing Course (ACWC) or Stone Mastic Asphalt (SMA) on top of the existing mainline.

Since the existing pavement structure at Rawang to Slim River is CRCP, the rationale of FCP structure was designed for the new third lane widening are as follows:

i) Construction site involving live traffic hence constraint to lane width, working corridor and operating hour. As such, FCP construction is more practical compare to CRCP due to traffic and operational constraint.

ii) Special machine must be used for construction of CRCP. One lane will be closed permanently during concreting stage which left only one lane available for traveling. It is not practical since the construction site involving live traffic.

1DOCUMENTATION OF STONE MASTIC ASPHALT (SMA) WORKIN PLUS THIRD LANE WIDENING PROJECT: RAWANG-BUKIT BERUNTUNG (PACKAGE 3A)

50mm ACWC

Reinforcement Membrane

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iii) Widening the existing CRCP with FCP was carried out in other developed country such as United States of America, United Kingdom and other Europe country.

1.1.3 Final Layer Surfacing

ACWC is the most commonly used surfacing material in Malaysia. The material is readily available from quarries throughout Malaysia.

Unlike ACWC, SMA is uncommon surfacing material used in Malaysia comprises of dense, gap-graded bituminous mixture with high content of stone, filler and bitumen, modified with a suitable binder carrier such as cellulose fiber. It has a high proportion of coarse aggregates which interlock to form a stone-on-stone skeleton to resist permanent deformation. The stone skeleton is filled with mastic of bitumen and filler to which fibers are added to provide adequate stability of bitumen during transport and placement.

Due to the limitation of local experience on SMA production and construction in Malaysia, SMA surfacing will only be implemented in Rawang to Bukit Beruntung stretch whilst Bukit Beruntung to Slim River stretch will be used ACWC surfacing. The comparison between typical existing pavement structure and typical proposed widening structure for Rawang to Bukit Beruntung stretch are as shown below:

Existing Pavement Structure

Proposed Widening Pavement Structure


230mm CRCP

330mm Wet Mix

150mm CBM3

150mm Granular Sub-base Type 1

200-300mm Granular Sub-base Type 2

Existing Slow Lane - CRCP Existing Shoulder

230mm CRCP 230mm DBM + ACBC

150mm CBM3


200mm CBM4


40mm SMA

200-300mm Granular Sub-base Type 2

230mm CBM2 + ACBC

40mm ACWC

Existing Slow Lane - CRCP Proposed Widening

New Emergency LaneNew Third Lane

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1.2 OBJECTIVE

As SMA is the new surfacing material used in Malaysia, the Malaysian Highway Authority (MHA) had decided to form a committee to monitor and oversee the implementation of SMA in term of technical as well as during the construction stage.

The committee members which comprises of representative from MHA, PLUS, OPUS, Minconsult, Ace Vector, UEM, and also PATI will record their experience on SMA throughout the implementation of Third Lane Widening Project between Rawang to Bukit Beruntung to share this experience and can be use by other parties in the future.


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CHAPTER 2: LITERATURE REVIEW OF STONE MASTIC ASPHALT

2.1 CONCEPT AND HISTORY

2.1.1 General

Stone mastic asphalt (SMA) is a very high stone content, gap-graded mixture with high binder content. A continuous coarse aggregate skeleton carries the traffic load giving good deformation resistance. A bitumen-rich mastic mortar binds the aggregate together, resulting in both toughness and excellent durability. The projection or the aggregate presents a very uniform ‘negatively textured’ surface profile, combining low noise generation with good skid resistance.

2.1.2 History and Development

Stone mastic asphalt was developed in he late 1960s in Germany. At that time studded tyres were widely used in winter and the resulting wear was the critical factor determining the life of surface courses. The materials than available were asphalt concrete and gussasphalt. Asphalt concrete was found to be prone to rapid wear. The binder content was relatively low and the binder tended to harden at the surface. The mortar then abraded under the studs, soon resulting in the material unraveling. Attempts to overcome this problem by increasing binder contents resulted in instability and rutting by deformation as opposed to stud wear. Gussasphalt, on the other hand, performed very well, but it was expensive to produced, slow andd labor intensive to lay, with the hand or mechanical addition of chippings or ‘Splitt’ to the poured gussasphalt on site. German asphalt companies responded to this situation by developing proprietary formulations of plant mixed stone filled mastic asphalt.

Over the years the materials and techniques were progressively refined using feedback from successful (and unsuccessful) highway projects. The various Contractors’ proprietary products were grouped together under the generic name ‘Splittmastixasphalt (SMA)’ and were standardized in 1984 into the German Federal Department of Transportation Supplemental Pavement ZTV Asphalt – StB94.

Through the eighties, the use of stone mastic asphalt has spread to many countries with variants adopted in Sweden, Denmark, Finland, Netherlands, Belgium, France, Switzerland and Japan. In the early 1990s, trials were conducted in the United States.

2.1.3 Concept of Stone Mastic Asphalt

Stone mastic asphalt is based around a stone skeleton of inter-locking crushed rock coarse aggregate. This skeleton comprises largely single-sized stone of a size appropriate to the laying thickness and required surface texture. The single-sized nature of the aggregate skeleton leaves a relatively high void content between the aggregate particles. This void space is partly filled with a binder rich mastic mortar. The mortar comprises crushed rock fine aggregate, filler, bitumen or modified bitumen and a stabilizing additive, namely cellulose fiber. The mortar itself is void less and has flow characteristics.

The mixture is so designed so that, when fully compacted, the voids in the aggregate skeleton exceed the volume of the mastic by 3-5%. The structure of the material is then such that the traffic load is carried out almost exclusively through the interlocking aggregate skeleton. The rich mortar acts to bind the skeleton together and to make the layer impervious.

The composition of the mortar is very important in determining the performance of stone mastic asphalt. Very high binder content is essential to ensure durability and laying characteristics.


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Sufficiently high binder contents cannot be achieved using unmodified or unstabilized bitumens: drainage of bitumen or mortar would occur during transport and laying. Therefore stone mastic asphalt mixtures use a fiber stabilizer mixed with the binder in the mortar to keep it homogeneous and prevent binder drainage.

SMA has a high proportion of coarse aggregate that interlocks to form a stone on stone skeleton to resist permanent deformation and rutting. There are no precise design guidelines for SMA mixes. The essential features, which are the coarse aggregate skeleton and mastic composition, and the consequent surface texture and mixture stability, are largely determined by the selection of aggregate grading and the type and proportion of filler and binder. Typical SMA composition consists of 70-80% coarse aggregate, 8-12% filler, 6-7% binder and 0.3% fibre.

SMA is mixed and batched in the same batch plant as that used with conventional hot mix. The primary difference in placing SMA, compared to the conventional dense graded asphalt is in the compaction procedures. Multi-tried rollers are not used due to the possible working of the binder-rich material to the surface of the asphalt and consequent flushing and pick-up. The preferred method of compaction is to use heavy, non-vibrating, steel-wheeled rollers. Vibrating rollers are not recommended in order to avoid fracture of the coarse aggregate particles, or drawing of binder to the surface of the mix.

SMA is normally placed with a minimum layer thickness of 2.5 to 3 times the nominal maximum aggregate particle size.

2.1.4 Stone Mastic Asphalt in Malaysia

SMA technology has been introduced to Malaysia since the 1990’s. Since then, several trial lay projects had been initiated for the purpose of evaluating the mix on local road condition. However the acceptability of SMA was quite discouraging among the local road authorities. This setback was probably due to the misconception on the high initial cost of SMA. But lately, the scenario is changing now. The many advantages of SMA greatly out weighed the initial high cost of producing SMA. Now some premix plants have started to produce SMA while many are contemplating to start soon.

Malaysian Highway Authority has initiated a large scale overlaying of SMA for the Third Lane Widening Project Packages 3A and 3B from Rawang to Tanjung Malim, a distance of 45 kilometers & Package 4 from Tanjung Malim to Slim River, a distance of 28 kilometers. The SMA works was later reduced to only in Package 3A1 from Km 423.96 to Km 444.96, a distance of 11.36 kilometers both bounds. For Packages 3B and 4, ACWC 20 was used as the wearing course replacing SMA due to the limited numbers of SMA suppliers. PLUS is also beginning to use SMA as the wearing course replacing ACWC for most of the new Plus Heavy Repair (PHR) projects in Malaysia.The composition of the materials in SMA mix for PLUS’s project consisted of fine and coarse aggregates, and the filler used was ordinary Portland cement. Fibre used was bitumen pre-coated palletized cellulose fibre, type Viatop 66 or Viatop Premium, imported from Germany. The bitumen used was SBS Polymer Modified Bitumen, which shall meet at least the requirements of PG76 Superpave Specifications.

The existing pavement at most of the locations in Package 3A1 was constructed with continuously reinforced concrete pavement, CRCP for short for the fast and slow lanes. The existing emergency lane was overlaid with ACWC wearing course.

The third lane widening project consisted of removing the existing emergency lane and constructing a new slow lane with a new emergency lane. The existing fast and slow lanes, together with the newly constructed slow and emergency lanes were then regulated with bituminous materials, such as ACWC


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10 or ACWC 14, if required, and overlaid with a layer of SMA on the fast, middle and slow lanes. For the new emergency lane, ACWC 20 was used instead of SMA as the wearing course.

On the existing CRCP’s surface, there was a groove joint separating the CRCP’s fast lane and the middle lane in the longitudinal direction. Prior to the overlay of SMA, the above groove joint and the longitudinal joint between CRCP’s middle lane and the new bituminous slow lane were sprayed with a layer of PMB tack coat, immediately followed by a layer of the reinforcement membrane. The PMB tack coat was sprayed using a special calibrated distributor spray bar machine mounted onto a truck and the temperature of the PMB was 160°C during the discharge.

The reinforcement membrane, also known as paving fabric, which consist of mechanically bonded continuous glass filament non-woven, was then laid using a special mechanical custom made rig capable of providing a smooth installation with minimum wrinkling or folding. The laid reinforcement membrane was immediately compacted using a pneumatic tyred roller or the wheels of the premix lorry to ensure that it would bond to the existing CRCP layer. Any movement on the joint would be restricted by the reinforcement membrane, and thus would prevent any movement or crack on the CRCP from reflecting up to the SMA layer above.

Then Neomed tack coat was sprayed on the existing CRCP’s fast lane, CRCP’s middle lane, new bituminous slow lane and the new emergency lane prior to carrying out the overlay works. Neomed tack coat is an elastomeric modified bitumen emulsion. It is a Stress Absorbing Membrane Interlayer (SAMI) which is cohesive and elastic. When applied to the surface to be overlaid, the Neomed entered the pores and cracks of the pavement, sealing them. It would permeate the voids of the lower part of the wearing course, making it water proof. This distribution allowed for full bonding between the binder course and the wearing course without the risk of slippage.

A conventional paving machine was used to lay the SMA. The compacted thickness of SMA was 40mm. Compaction was carried out using two non-vibrating steel-wheeled rollers, with the bigger and heavier roller of 10-ton following closely behind the paving machine. This big roller was the main roller used to carry out compaction to achieve the required density. The smaller roller of 6-ton was used to carry out the finishing compaction to remove any blemish and irregularity.

At the completion of the SMA overlay and before opening to the traffic, surface regularity tests were carried out to determine whether or not the newly laid SMA comply with the requirements of the Specifications. The surface regularity tests consist of the rolling straight edge test and the 3-meter straight edge test. The rolling straight edge test determines the surface regularity in the longitudinal direction, whereas the 3-meter straight edge determines the surface regularity in the transverse direction.

Other tests carried out on the finished surface of completed SMA wearing course were micro texture and macro texture tests and the Falling Weight Deflectometer test (FWD).


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2.1.5 Paper 1: SMA IN THE UK

SCI LECTURE PAPERS SERIESSTONE MASTIC ASPHALT IN THE UKJTG RichardsonTarmac Quarry Products Ltd, Millfields Road, Ettingshall,Wolverhampton, West Midlands WV4 6JP, UKTelephone +44 (0)1902 353522Fax +44 (0)1902 491674

© 1999 Society of Chemical Industry. All rights reservedISSN 1353-114XLPS 0100/98

Key words SMA, deformation, texture, hot rolled asphalt, friction, proprietary

Paper presented at the symposium on Stone Mastic Asphalt and Thin Surfacings, organisedjointly by the Construction Materials Group of the Society of Chemical Industry and the Instituteof Asphalt Technology at the Society of Chemical Industry, 14/15 Belgrave Square, London on19th June 1997 and 9th October 1997.

AbstractDevelopment of Stone Mastic Asphalt (SMA) began in the 1960s in Germany and offered a moreattractive solution than chipped Gussaphalt for the reduction of wear caused by studded tyres. Theexcellent resistance of the product to deformation was recognised and developments continued,leading to the publication of a German Standard Specification and to similar developments in anumber of other countries in Europe, the Far East and the USA.

Typical applications include heavily trafficked roads, airport taxiways, bridge deck surfacing,container storage areas and bus stops. The surface texture of the installed product is greater thanthat of dense graded asphalt concrete but usually less than that currently considered suitable forhigh speed roads in the UK. The material has been re-designed, however, to provide high surfacetexture and evaluation of skid resistance is a matter of ongoing study.

The use of SMA is rapidly gaining the support of highway engineers in the UK and is, inparticular, an intriguing, alternative solution to chipped hot rolled asphalt in many situations.

This paper examines the case for continued use of SMA in the UK.

IntroductionDevelopment of Stone Mastic Asphalt (SMA) began in the 1960s in Germany and offered a moreattractive solution than chipped Gussasphalt (a type of mastic asphalt) for the reduction of wear caused by studded tyres. The excellent resistance of the product to deformation by heavy traffic athigh temperatures was recognised and developments continued, leading to the publication of aGerman Standard Specification1 and to similar developments in a number of other countries inContinental Europe, the Far East and the USA.

Interest in the product has also been generated in the United Kingdom (UK) and a study tour wasmade by a DOT/BACMI/RBA collaborative research group to Germany in 1993. Ademonstration of SMA quickly followed at the Transport Research Laboratory (TRL) test trackand a report of an evaluation of the product was subsequently published in 1994.2 The reportincluded a draft specification for SMA wearing course that had been prepared by the HighwaysAgency for application to trunk roads on a trial basis.


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The scope for producing and marketing the product in the UK for different roads and other pavedareas in both public and private sectors was examined by a number of asphalt suppliers at the time.Although the product was viewed as essentially a heavy duty material, its general application wasconsidered by one or two suppliers to be potentially immense and the suppliers proceeded topromote it actively. A major incentive was the possibility of its use as an alternative solution tochipped hot rolled asphalt (HRA)3 where this was to be laid in difficult situations.

HRA is a high grade asphalt product with a wide range of applications and is the most commontype of surfacing in the UK for major roads. In terms of both durability and surface friction, therehas been none better than HRA. However, because of the need to apply coated chippings to thesurface as a separate but concurrent operation during laying, the process necessarily takes up moreroom across the width of the road leading to greater traffic congestion and so, higher road usercosts and where specified, high chipping spread rates applied to achieve high texture depth4 canlead to subsequent loss of chippings after the road is opened to traffic.

Largely due to the endeavours of the few zealous contractors and the good judgement of variousclients and engineers around the country, SMA began to gain rapidly in popularity from about1995.

The productSMA is a dense, gap-graded bituminous mixture with high contents of stone, filler and bitumen,modified with a suitable binder carrier such as cellulose fibre. The essential elements of mixturedesign comprise the formation of an interlocking stone skeleton that provides high resistance todeformation and the filling of the skeleton voids with a rich bituminous mortar to provide highdurability. The conventional structure is illustrated in Figure 1 and compared with those of PorousAsphalt5 and textured thin wearing course,6 both of which also have high contents of aggregatecoated with relatively thick binder films. In very general terms, however, shifting from PorousAsphalt to thin wearing course and on to SMA, the air voids content and surface texture arereduced, but each material still has a relatively quiet surface compared with that of chipped HRA.

Typical applications in mainland Europe have included heavily trafficked roads, airport taxiwaysand runways, bridge deck surfacing, container storage areas and bus stops. The surface texture ofthe installed product in Germany, for example, has traditionally been greater than that of densegraded asphalt concrete but less but less than that currently considered suitable for high speedroads in the UK (4). Development of SMA in this country, however, has focused a lot on producinghigh texture without impairment of the other desirable properties of the material.


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The main benefits may be described as follows:high resistance to rutting (7)

high resistance to crackinghigh durabilitywear and ravelling resistanceinsensitivity to watergood skid resistancelow surface noisesuperior surface finishThe principal attraction of the material, though, is the unique combination of deformationresistance and durability.

Joint DOT/BACMI/RBA study tourThe aim of the study tour made to Germany in 1993 by a collaborative research group comprisingthe Highways Agency of the Department of Transport (DOT), BACMI (now known as QuarryProducts Association) and the Refined Bitumen Association (RBA) was to gain a betterappreciation of the use of SMA in Germany. The itinerary included visits to the State of Baden-Wuttemberg and the Schellerberg Research Institute at Rotwiell, and inspections of an asphaltmanufacturing plant, laying site and trafficked surfaces. Details of the tour are reportedelsewhere,2 but some of the salient points are described here.

Up until the 1980s, the wearing course on German roads was generally continuously gradedasphalt concrete. A relatively low content of hard grade bitumen became necessary to resistdeformation by increasing traffic. As a result, cracking also became a common mode of failure.The development of SMA as an alternative surfacing hastened and a national specification waspublished in 1984.1 It was reported subsequently that failure of the surfacing was rarelyattributable to the breakdown of the SMA wearing course, but that the rutting that had occurred todate was more likely due to deformation of the basecourse underneath. Consequently, SMA canalso be specified for use as a basecourse.

Despite the high binder content and high mixing temperature (up to 180°C when using 65penetration grade bitumen), the discharged material does not slump in the wagon body and isdevoid of any obvious segregation. This is largely due to the high capacity of the added cellulosefibre for carrying bitumen. SMA can be laid as thin as 20mm, but 40mm is commonly thepreferred thickness to benefit more from the influence of the stone structure on performance.Compacted thicknesses corresponding to 2.5 to 5.0 times the nominal size of aggregate are alsorecommended. A very consistent and uniform surface appearance is produced at the paver screedand very little displacement of the material can be observed during rolling. Due to the high bindervolume in the mixture, the compacted surface has initially a relatively thick binder film coating. Toavoid vehicle skidding during service in the first winter period, uncoated grit is commonly spreadand compacted into the surface at the time of construction. The surface appearance afterconsiderable trafficking is quite reminiscent of a worn “Delugrip” high friction dense asphalt,8

which was introduced in the UK on experimental sections in the mid 1970s.

TRL DemonstrationA demonstration of SMA was organised at the TRL immediately following the study tour. Themain interest of the research group was the possible application on trunk roads. It was thought atthe time that the optimum composition of the material for this case may lie somewhere between thatof Porous Asphalt and that of SMA to obtain the right balance between high texture or porosityand high durability. Trial sections of thickness varying from 40mm down to less than 20mm werelaid. The corresponding aggregate nominal sizes varied from 14mm down to 6mm and the bitumengrade varied from 50 to 100 penetration.2


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The conclusions of the trials were that SMA should be a durable and rut-resistant material with acapacity for generating less tyre noise. It was also observed that there was scope for adjusting thesurface texture to quite high values by raising the stone content even higher.

Application of SMA in the UKMotorways and trunk roads account for 4.7% of the UK road network.9 That leaves 351,700 kmof other types of Public Sector road in addition to various types of paved areas in the PrivateSector. For reasons of expediency, many of the earliest examples of SMA installations fall intothe latter categories. Mixtures used for applications for which high texture depth was not anessential requirement were based closely on the requirements of German Standard Specifications.Some typical data for these early materials are given in Table 1. The low wheel tracking rateprovided confirmation of good deformation resistance. A surface giving a tracking rate of less

than 2mm/h would normally be considered good.10 Subsequent testing on similar materials atthe higher temperature of 60°C indicates that the rate is in general not markedly affected by thishigh temperature. The stiffness modulus may be considered to be comparable with that for HRA.

Table 1. Test results at the time of construction for early SMA in the UKIndirect tensile stiffness modulus (20°C), MPa 2100Wheel tracking rate (45°C), mm/h 0.55Texture depth (sand patch), mm 1.0

Typical applications have included industrial sites; residential, town and country roads; and bypasses.In addition, some proprietary versions11 have been installed as surfacing to motor racingtracks, tunnel toll plaza and access roads, airfield taxiways and runways.In order that the material may be used as a surfacing on the trunk road network, it has beennecessary to re-design it to suit the particular requirements.4 Figure 2 illustrates the shift inaggregate grading away from the more traditional German type to one that will satisfy the hightexture depth requirements in the UK (minimum average of 1.5mm by sand patch) that areconsidered to be necessary to minimise loss of skid resistance at high vehicle speeds ie >90km/h.Despite the coarser grading, some typical test data that are given in Table 2 indicate that otherdesirable properties are not impaired.12.5km of the A1 in East Lothian have been upgraded to dual carriageway standard and this wasthe first section of trunk road in Scotland to include SMA wearing course. The project was adesign and build contract and the use of SMA was part of the fully flexible pavement option. Afurther example is 8km of 2-lane dual carriageway that formed part of a design, build, finance andoperate (DBFO) contract to upgrade the A417 and A419 in the South West of England. Aproprietary mixture of SMA12 was used in this case for the wearing course. A similar material hasbeen used to overlay a cracked and seated concrete pavement as part of another DBFO contract torehabilitate a section of the M40 motorway in Oxfordshire.


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Table 2. Test results for SMA used on high category roadsWheel tracking rate @ 45°C, mm/h 0.25–0.9Wheel tracking rate @ 60°C, mm/h 1.3Wheel track depth @ 45°C, mm 1.5–1.8Wheel track depth @ 60°C, mm 3.0Texture depth (sand patch), mm >1.5Indirect tensile stiffness modulus (20°C), MPa 3200Water sensitivity – stiffness ratio 1.0Noise reduction (90 km/h), dB(A)* 3–5*Compared with chipped HRA

Skid resistance measured by the Sideway-force Coefficient Routine Investigation Machine(SCRIM) and the Griptester has also indicated that a level can be achieved that is commensuratewith that which would be expected of the aggregate used in those same site conditions for atraditional surfacing mixture. There is some anecdotal evidence of lower values in the early life ofthe material which can be offset to a certain extent by the application of grit particles onto thesurface during laying. Lower early life skid resistance is also found on traditional road surfaces,however, which rather suggests that gritting should be rarely necessary. Any initial improvementdue to gritting may be expected to be lost after only a few months of trafficking.Gritting trials of SMA surfacing on a trunk road in 1995 demonstrated that the particles tend tocollect in the voids in the surface and so effectively reduce the texture depth! As soon as thesurface is opened to traffic, a high proportion of the grit particles are then picked up by vehicletyres and dispersed to the sides of the road.

Figure 3 shows the change in texture depth that might be expected over the first few months oftrafficking. So, an initial texture depth by the sand patch method of just over 1.5mm may reduceto around 1.1 or 1.2mm within the first twelve months, depending on the traffic density, beforetending to level off during a further period of trafficking. Associated with this behaviour, thechange in surface friction with speed is also of interest. Figure 4 shows the change in grip testnumber for a SMA mixture with an aggregate nominal size of 10mm that was laid on an airfieldrunway and that typically has an initial texture depth of between 1.0 and 1.5mm. The minimumfriction level for the new runway in this case was 0.52 at 65km/h with 0.8 set as a target. Therequired friction level was achieved, but perhaps the more interesting feature shown on the graph isthat the friction on the SMA surface does not appear to be influenced by speed to any great degreeover the range examined. This might suggest that texture depth may not be quite so critical for thistype of material, but further work would be needed to substantiate such a claim.


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Evidence to date also suggests that SMA can tolerate application on a relatively irregular, existingsurface without detriment to the regularity of the final surface. This may well be related to theneed for a smaller surcharge of material for compaction by the paver screed and rollers.

It is traditional practice in the UK to cut the longitudinal joint of dense asphalt wearing courses toproduce a tight, neat finish. Alternatively, joint heaters or paving in echelon may be employed,although these practices are less common. However, it can be argued that a similar treatment is notnecessary for SMA because of its relatively high binder volume and thick binder film coating.There are now a lot of examples in the UK that appear to support this view. More care is needed,though, in the forming of the joint and, in some cases, the traditional method may be preferred toensure a high quality of finish.

The German Standard Specification1 includes mixture design criteria for SMA stipulating an airvoids content in the range 2–4% (3–4% for HGVs/day>1800) when following a prescribed methodof laboratory impact compaction. For UK conditions, however, it is suggested that this range mayonly be appropriate for the design of materials that are intended to be laid in thinner layers, up to,say, 35mm thick. Thicker layers are more prone to densification by traffic that may lead tounacceptable binder migration with consequent loss of texture and, at worst, surface deformation.


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A slightly higher range of design air voids contents would minimise the risk of such an occurrencein this case without impairment of the durability of the product in the field.

ConclusionThere has been increasing concern in the UK over the lack of resistance to rutting of asphaltwearing courses. This has led to a decrease in binder contents that has in turn resulted in a fear ofpossible loss of durability and of resistance to cracking. A dense material has now been madeavailable that imparts to the road surface both high resistance to deformation and high durabilitythrough the design of a coarse graded aggregate structure having the capacity to accommodate arich bituminous mortar by the incorporation of suitable binder carriers.SMA has been re-designed to provide a high surface texture and to meet the requirements ofsurfacing for UK motorways and other trunk roads. In so doing, other desirable properties of

SMA have not been impaired. It has also been found to be a very versatile material and as such,some freedom, but also great care, is required in its design in order to satisfy the demand for its usein a variety of other applications.

The use of SMA is rapidly gaining acceptance in the UK and provides the highway engineer with afurther option in the choice of surfacing materials. In particular, it has become aconvenient alternative to chipped HRA in difficult situations.

NoteThe views expressed by the author in this paper are not necessarily those of Tarmac QuarryProducts.

References1. The German Federal Department of Transportation (1997). Supplemental Technical Specifications and Guidelines for the Construction of Asphalt Pavements, Revised Version 1997. Bonn, Germany.2. Nunn, ME (1994). Evaluation of stone mastic asphalt (SMA): A high stability wearing course material. Department of Transport TRL Project Report 65, Transport Research Laboratory, Crowthorne.3. BS 594: Parts 1 & 2 (1992). Hot rolled asphalt for roads and other paved areas. 1. Specification for constituent materials and asphalt mixtures. 2. Specification for the transport, laying and compaction of rolled asphalt. British Standards Institution, London.4. Department of Transport Manual of Contract Documents for Highway Works. Volume 1(1995). Specification for Highway Works. December 1991 reprinted August 1993 with amendments, HMSO.5. BS 4987: Parts 1 & 2 (1993). Coated macadam for roads and other paved areas. 1. Specification for constituent materials and for mixtures. 2. Specification for transport, laying and compaction. British Standards Institution, London.6. Nicholls, JC, Potter, JF, Carswell, J and Langdale, P (1995). Road trials of thin wearing course materials. Department of Transport TRL Project Report 79, Transport Research Laboratory, Crowthorne.7. Bellin, P (1997). Development, Principles and Long-Term Performance of Stone Mastic Asphalt in Germany. Symposium on Stone Mastic Asphalt and Thin Surfacings. SCI Lecture Papers Series, Society of Chemical Industry, London.8. Lees, G (1978). Skid Resistance of Bituminous and Concrete Surfacings. Developments in Highway Pavement Engineering-1, pp 272-273, Applied Science Publishers, London. 9. British Road Federation (1997). Road Fact 97. British Road Federation, London. 10. Jacobs, FA (1981). Hot rolled asphalt: effect of binder properties on resistance to deformation. Department of the Environment, Department of Transport TRRL Laboratory Report LR 1003, Transport and Road Research Laboratory, Crowthorne.11. Nicholls, JC (1995). Thin Surfacings. Paper presented at the Surface Treatments Seminar at the TRL on 6 December 1995.


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12. Contract Journal (1994). Tarmac unveils Masterpave. Article published in the 17 November 1994 edition of Contract Journal.

2.1.6 Paper 2: TECHNICAL NOTE 16: STONE MASTIC ASPHALT


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2.1.7 Paper 3: COST COMPARISON BETWEEN SMA & ACWC


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CHAPTER 3: DESIGN OF STONE MASTIC ASPHALT

3.1 DESIGN

230mm CONTINUOUSLY REINFORCED CONCRETE PAVEMENT150mm CEMENT BOUND MATERIAL CATEGORY 3

2.5% CROSSFALL ORSUPERELEVATION

PAVED SHOULDER

PROPOSED WIDENING OF RIGID PAVEMENTS

EXISTING FAST LANE

GUARDRAIL

ACWC

40mm SMA

150mm GRANULAR SUBBASE TYPE 2

40mm ACWC

170mm DENSE BITUMEN MACADAM (DBM40)

170mm CEMENT BOUND MATERIAL (CBM2)SAW CUT AND REMOVE OLD CBM FROM SHOULDER SIDE


40mm SMA

200mm CEMENT BOUND MATERIAL (CBM4)100mm GRANULAR SUBBASE TYPE 1


SUBGRADE (minimum soaked CBR 5%)

REINFORCEMENT MEMBRANE

TY PICAL PAVEMENT DETAILS - CUT SECTION

EXISTING CARRIAGEWAY PROPOSED WIDENING

EXISTING SLOW LANE NEW SLOW LANE NEW PAVED SHOULDER


40mm SMA

200mm CEMENT BOUND MATERIAL (CBM4)100mm GRANULAR SUBBASE TYPE 1


TY PICAL PAVEMENT DETAILS - FILL SECTION



40mm SMA


40mm ACWC

GUARDRAILACWC

EXISTING FAST LANE



170mm CEMENT BOUND MATERIAL (CBM2)

170mm DENSE BITUMEN MACADAM (DBM40)60mm ASPHALTIC CONCRETE BASE COURSE230mm CONTINUOUSLY REINFORCED CONCRETE PAVEMENT

150mm CEMENT BOUND MATERIAL CATEGORY 3

PAVED SHOULDER


230mm CONTINUOUSLY REINFORCED CONCRETE PAVEMENT


2.5% CROSSFALL ORSUPERELEVATION

PAVED SHOULDER


EXISTING FAST LANE

GUARDRAIL

ACWC

40mm SMA

150mm GRANULAR SUBBASE TY PE 2

40mm ACWC

170mm DENSE BITUMEN MACADAM (DBM40)

170mm CEMENT BOUND MATERIAL (CBM2)SAW CUT AND REMOVE OLD CBM FROM SHOULDER SIDE


40mm SMA


100mm GRANULAR SUBBASE TY PE 1150mm GRANULAR SUBBASE TY PE 1



TY PICAL PAVEMENT DETAILS - CUT SECTION




40mm SMA

200mm CEMENT BOUND MATERIAL (CBM4)100mm GRANULAR SUBBASE TY PE 1


TY PICAL PAVEMENT DETAILS - FILL SECTION



40mm SMA


40mm ACWC

GUARDRAILACWC

EXISTING FAST LANE




170mm DENSE BITUMEN MACADAM (DBM40)60mm ASPHALTIC CONCRETE BASE COURSE230mm CONTINUOUSLY REINFORCED CONCRETE PAVEMENT


PAVED SHOULDER



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3.2 MATERIALS

3.2.1 Coarse Aggregate (>2.36mm)

Coarse aggregate shall be hard, un-weathered, durable, clean, crushed rock, angular in shape and free from dust and any foreign matter. The aggregates, when tested in accordance to BS812, shall have the following properties:

Aggregate Crushing Value - not more than 25Flakiness Index - not more than 25Water Absorption - not more than 2%Polished Stone Value - not less than 50

In addition, coarse aggregates shall have a weighted average loss of weight by not more than 12% when subjected to Sodium Sulphate Soundness Test (5 cycles) in accordance with ASTM C88.

3.2.2 Fine Aggregate (≤ 2.36mm)

Fine aggregate shall be approved clean crushed rock. It shall consist of hard, non-absorbent sharp grains and free from clay, loam, loosely bonded aggregations and any foreign matter. Fine aggregates shall have a weighted average loss of weight by not more than 12% when subjected to Sodium Sulphate Soundness Test (5 cycles) in accordance with ASTM C88. The water absorption shall not exceed 2% when tested in accordance with BS812.

3.2.3 Filler

Active filler shall be used to improve the adhesion of aggregates. The active filler is 2% by mass of total aggregates and it shall be hydrated lime or Portland cement complying with BS812. Additional filler (on top of the 2%) if necessary to meet the grading requirements may be limestone dust.

3.2.4 Binder

The binder shall be high performance SBS (Styrene-Butadiene-Styrene) polymer modified bitumen, which shall meet or exceed the Superpave PG76 specification.

3.2.5 Fiber Additive

Fibers shall be used to inhibit binder drain off from the SMA mixture. These shall be bitumen pre-coated palletized Cellulose fibers. The fiber content shall be 0.3% by weight of the mixture.

3.3 DESIGN MIXTURES

3.3.1 Proposed Design Mixture

The contractor shall carry out the proposed design mixture in accordance with the Asphalt Institute’s Manual Series (MS-2).The combined aggregate grading shall be within the grading range given in Schedule 1. Binder content shall be selected from the permitted range and then adjusted to suit the combined aggregate grading. Marshall’s specimens shall be made to determine the volumetric properties. Binder drain off test (according to Schellenberg) and Cantabro Abrasion Test (according to ASTM C131) shall be carried out to satisfy the mixture properties.

3.3.2 Laboratory Design Mixture


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The procedures for laboratory design mixture shall also comply with Clause 901, sub-clauses 9-10.

Once the proposed design mixture is approved by the Engineer, it is designated as the Laboratory Design Mixture. Plant trial is allowed to be carried out using the approved laboratory design mixture.

3.3.3 Job Standard Mixture

The Contractor shall carry out the plant trial as per Clause 901, sub-clauses 13-14 with respect to the mixture properties specified in Schedule 1 using the approved Laboratory Design Mixture. A batch plant shall be used to produce SMA mixture. The contractor shall ensure that the produced mixture shall conform to the mix design parameters specified in Schedule 1.

Once the results of the plant trial have satisfied the requirements of the Specifications, it is designated as the Job Standard Mixture. The Contractor shall ensure that the produced mixture shall conform to the mix design parameters specified. The Engineer shall reserve the rights to request a new “Laboratory Design Mixture” and or “Job Standard Mixture” at any stage depending on the extent of the variations.The Contractor shall submit to the Engineer the proposed “Job Standard Mixture” for approval, which shall also include the following information:

Material sources of all ingredients; Percentages of aggregate passing through each specified sieve based on the dry weight of

aggregate as determined by AASHTO T11 and T27; Proposed percentage of each stockpile to be used, average gradation of each stockpile and the

target value for each sieve size. The target values and the combined average gradation from all the stockpiles shall be within the grading range specified in Schedule 1;

Proposed binder content by mass of total mixture and test results to show compliance with the binder properties as per Schedule 1;

Fiber content and type of fiber to be used; Material properties of all ingredients, such as the specific gravity for individual aggregates,

combined aggregates and bitumen shall be submitted. The calculations for the bulk, apparent and effective gravities; and the aggregate properties (as per sub-clauses 2-4) shall be submitted; and

All mixtures properties as specified in Schedule 1 shall be submitted.


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3.3.4 Job Mixture (Plant Mixture)

Compaction trials shall be carried out, as per Clause 901, sub-clause 17, using the approved Job Standard Mixture to establish the rolling pattern as necessary to achieve the specified density and mix design requirements as per Schedule 1.

The trials shall involve qualified personnel who are experienced in the mixing and placement of the SMA and are capable of making any mixture adjustment as necessary in order to satisfy the mix design requirements.

Once the results from the trial lay using the approved Job Standard Mixture have satisfied the requirements of the Specifications, the approved mixture is then designated as the Job Mixture or Plant Mixture.

Schedule 1: Comparison Between ACWC & SMA

PROPERTIES ACWC SMA

Coarse Aggregates (> 2.36mm) Aggregate Crushing Value not more than 25 not more than 25 Flakiness Index not more than 30 not more than 25 Water Absorption not more than 2% not more than 2% Polished Stone Value not less than 49 not less than 50 Weighted Average Loss of Weight i) Sodium Sulphate Soundness Test (ASTM C88) not more than 12% not more than 12%ii) Soundness Value (BS 812: Part 121) greater than 90 - Los Angeles Abrasion Value not more than 35 not more than 35

Fine Aggregates (≤ 2.36 mm) Weighted Average Loss of Weight i) Sodium Sulphate Soundness Test (ASTM C88) not more than 12% not more than 12% Water Absorption not more than 2% not more than 2%

Filler By Mass of the Total Aggregates 2% 2%(Hydrated Lime or Portland Cement)

Binder Penetration Grade 80-100 SBS PMB

Original Binder Brookfield Viscosity at 135°C - Max 3000 cP Loss of Weight for 5 hrs at 163°C Max 0.5 % - Drop in Penetration for 5 hrs. at 163°C Max 20 %

Dynamic Shear at 76°C - Min 1 kPa Penetration, 100g, 5s, 25C, 0.1mm -

PROPERTIES ACWC SMA


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Ring and Ball Softening Point 45°C to 52°C Min. 60 °C Flash Point Min 225 °C Min. 230 °C Solubility in Trichloroethylene Not less than 99.5 % - Ductility at 25°C Min 100 cm -

Rolling Thin Film Oven Mass Loss - Max 1% Dynamic Shear - Min 2.2 kPa Fibre Additive Pallletised Cellulose Fibre - 0.3 % by Weight Grading

BS SIEVE SIZE Schedule 1 - ACWC Schedule 3 - SMA 25 100 - 20 92 to 100 - 19 - 100 14 74 to 94 - 13.2 - 90 to 100 10 62 to 82 - 9.5 - 60 to 90 6.4 - 40 to 60 5 44 to 63 - 4 - 25 to 40 2.36 32 to 48 20 to 32 1.18 21 to 35 - 0.6 13 to 25 - 0.3 7 to 17 8 to 19 0.15 5 to 13 - 0.075 5 to 9 6 to 10 Thickness Minimum Layer thickness 50 mm 40 mm

Temperatures Mixing temperature for combined aggregate 150°C to 170°C 150°C to 180°C Mixing temperature for Bitumen 140°C to 160°C - Laying Not less than 125°C Bet. 135°C to 155°C Rolling Not less than 110°C Bet. 130°C to 150°C Opening to traffic At Ambience Temperature 60°C or lower


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3.4 COST ASSESSMENT

The overall economics of a surfacing material in terms of some whole life costing assessment must be considered. Tonnage for tonnage, stone mastic asphalt will be more expensive than most other asphalt surfacing materials, including ACWC, for the following reasons.

a) high percentage of premium high PSV aggregate;b) high binder content;c) use of stabilizing additives;d) high temperatures;e) lower production rate; andf) extra attention to quality control.

3.5 ADVANTAGES & DISADVANTAGES OF SMA

3.5.1 Advantages of SMA

Stone Mastic Asphalt does offer a considerable range of advantages, including:

a) high resistance to permanent deformation;b) high wear resistance;c) low noise generation;d) good structural contribution;e) excellent resistance to ageing and cracking;f) good low temperature performance;g) toughness and impact resistance;h) ability to be laid thinly;i) improved visibility in wet weather by reducing spray levels;j) an even finish providing a smooth riding surface;k) can be laid with a conventional pavers without problems;l) less traffic disruption during the laying process; andm) long service life, possibly in excess of 20 years.

3.5.2 Disadvantages of SMA

Stone mastic asphalt thus offers a more expensive but longer lasting surface at the same thickness as ACWC. It is however, possible to reduce the initial cost by reducing the thickness without compromising the life expectancy.

The disadvantages of using SMA are:

a) high initial cost such as increased material cost associated with high binder and filler contents, and fiber additive;

b) increased mixing time due to high temperature required and time taken to add extra filler, may result in reduced productivity;

c) initial skid resistance (lack of friction) may be low until the thick binder film is worn off the top of the surface by traffic. In critical situation, a small, clean grit, may need to be applied before opening to traffic.

CHAPTER 4: QUALITY ASSURANCE & QUALITY CONTROL OF STONE MASTIC ASPHALT


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4.1 QA & QC

4.1.1 Transporting, Laying and Compaction

SMA mixture shall be transported, laid and compacted according to Clause 703 of the Specifications, and the following requirements:

SMA shall be transported to site in clean insulated lorries and the mix must be covered with wind-proof blanket to avoid early oxidation and temperature loss. The floor of the lorries shall be free from adherent bituminous materials or other contaminants;

A thin film of vegetable oil, water or liquid soap, or other non-solvent solutions may be used on the interior of the lorries to facilitate discharge of the mix from lorries. However the amount of such liquid shall be kept to a minimum and any excess quantity shall be removed by tipping or brushing;

Time duration from the mixing of SMA to the completion of compaction shall not exceed 3 hours;

The prepared surface to receive the SMA shall be thoroughly cleaned and free from any loose material, dust, tree leaves, any oil, grease and diesel or other contaminations;

A tack coat of Polymer modified Binder (such as Neomed) shall be applied at a rate of 0.2 -0.5litres/m²;

SMA shall be laid using approved pavers and compacted to the specified thickness within 3 hours of the mixing. Laying shall commence from the lower side of the carriageway. Any hand working of the SMA, after it is laid by pavers and before rolling, shall be minimal. Operators shall not be allowed to walk on the un-compacted SMA surface;

Laying of SMA shall not be permitted during rain. After rain, the surface shall be properly dried to the satisfaction of the Engineer before continuing to lay the SMA. Back-casting during the laying shall not be permitted.

Compaction shall commence immediately after the SMA is laid. The best roller combination is at least two smooth steel wheeled rollers of 8-12 ton deadweight to ensure good compaction, one of which should be a tandem roller. The first roller shall follow the pavers as closely as possible. The rolling temperature shall be between 130-150°C;

Pneumatic tyred rollers are not generally recommended because of the risk of mortar flushing to the surface. High frequency and low amplitude vibratory rollers can only be used under critical situations;

Rolling procedures shall be adjusted to achieve the specified density and air void content. Rollers shall move at a uniform speed not to exceed 5km/h with the drive roller nearest to the pavers;

Rolling shall continue until all the rolling marks are removed and the density achieved before the material is cooled to 120°C;

Care shall be taken to prevent adhesion of the mixture to the wheels of the rollers. Excessive amount of water shall not be used for this purpose;

The pavement shall be compacted to at least 98% of the Marshall density; Rolling shall cease once the specified density is achieved. Over compaction shall be avoided,

as it is likely to cause surface bleeding; Traffic shall not run on the newly compacted surface until the asphalt layer has cooled to

60°C temperature or lower; and In restricted areas where the rollers can not reach, compaction shall be carried out using

smaller size mechanical equipments and/or smaller vibratory rollers.


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4.1.2 Sampling & Testing

Sampling and testing shall be carried out as per Clause 901, sub-clauses 15 and 18 of the Specifications (See Appendix A on the flow chart for SMA works).

In order to ensure the good quality of works at the work site, the sampling and testing at the batching plant, at CSL Laboratory in Tanjung Malim and also at the locations on site, the following types of sampling and testing shall be carried out:

a) Batching Planti. Marshall’s properties, sieve analysis, bitumen content and density tests

ii. Binder drain-off test iii. Cantabro Abrasion Loss test

b) CSL Laboratoryi. Marshall’s properties, sieve analysis, bitumen content and density tests

ii. Binder drain-off test iii. Cantabro Abrasion Loss test

c) Work Site. i. Samplings for Marshall’s properties test ii. Samplings for grading and bitumen content

iii. Checking of temperature of mix before and during laying and before compaction

d) Monitoring of the rolling pattern

e) Coring for compressive strength testing

f) Surface regularity tests – Rolling and 3 m transverse straight edge tests

g) Microtexture and macrotexture tests

h) Falling Weight Deflectometer test


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4.1.3 Frequency of Samplings and Testing

During the SMA overlay work, a series of checks are made for the following parameter. Temperature, quality of mixing, compaction density and finish surface requirement.

Apart from the above, series of quality control test are carried out to ensure the work meet the specification requirement. Loose sample are taken immediately during laying of SMA for laboratory test, while core sample from the compacted layer.

The followings are the frequency of sampling and testing:

a) Grading and bitumen content: First 2 hour and at every two hourly interval thereafter.

b) Marshall’s properties: Twice a day.

c) Compressive strength: After 24 hours.

d) Cantabro Abrasion Loss: Twice a day.

e) Binder drain off at 170°C: Twice a day.

f) Surface Regularity Tests: Before opening to traffic (Clause 701.12).

g) Micro & Macrotexture Tests: Before opening to traffic (Clause 901.25).

h) Falling Weight Deflectometer: Latest 6 months after laying (Clause 707).

ITEMTYPES OF TESTING

FREQUENCY OF TESTING

COMPLIANCE TO SPECIFICATIONS

1 Grading1st 2 hours and at two hourly

SCHEDULE 1

2Bitumen Content

intervals thereafterApproved Design Mixture Bitumen Content ± 0.3% (5.7% to 7.0%)

3Marshall's Properties

Twice a day

i) Stability: Not less than 620 kg ii) Flow: 2 mm to 4mmiii) Stiffness: Not less than 350 kg/mmiv) Void parameters; VTM = 3% & 5% VMA ≥ 17%

4Compressive Strength

2 cores for every 1000m² laid

i) Thickness: ± 5mm ii) Strength: 98% to 100% Marshall Density

5Surface Regularity Test

CLAUSE 701.12 Table 7/2

4mm (20 nos.) & 7mm (2 nos.) for 300m. No irregularity >10mm shall be permitted.

6Falling Weight Deflectometer

CLAUSE 707 Min. 20 points per lane

50m nominal spacing and staggered bet. adjacent lanes. Contact pressure ~700 kPa.

7Cantabro Abrasion Loss

Twice a day Maximum 5% for average of 3 samples.

8Binder Drain Off @ 170˚C

Twice a day Maximum 0.3% by weight

Table 1


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4.2 TESTING

4.2.1 Temperature

i) Mixing temperature: Between 150°C and 180°C

ii) Laying temperature: Between 135°C and 155°C

iii) Compaction temperature: Between 130° and 150°C

4.2.2 Rolling Pattern

The rolling pattern shall be determined during the trial compaction. The number of passes is that the number of times that each point on the surface of the layer being compacted has been traversed by the compaction plant. The number of passes required with each type of compactor s a function of the mass of the machine.

4.2.3 Batching Plant Monitoring

The batching plant shall do its own samplings and testing as part of the quality control to ensure that the mix supplied to the work site meets the requirements of the Specifications. Every morning the plant QA/QC shall carry out samplings and testing for sieve analysis, bitumen content and moisture content, and to make adjustments to the mixture to ensure compliance with the Specification‘s requirements. Consultant and Contractor personnel are required to visit and monitor the plant regularly.

4.2.4 CSL Lab Monitoring

The CSL laboratory shall carry out the samplings and testing to ensure that the mix supplied to the work site meets the requirements of the Specifications. All the results shall be made known to the Consultant and Contractor so that action can be taken without delay, especially for results that are in non compliance to the Specifications.

4.2.5 Checklists and Forms

Samples of the checklists before, during and after the laying of SMA and ACWC and all the test forms for SMA are attached in Appendix B.

4.2.6 Samples of the Test Results

Samples of the test results for SMA works are attached in Appendix C.


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4.3 TESTING EQUIPMENT FOR SMA IN LABORATORY

The equipment used for testing is shown as below:


Portable Skid Resistance Tester for measurement of micro-texture

Proving Ring Apparatus for measurement of Marshall Properties

Oven for heating of Marshall Specimens

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Sieve Analysis for determining the grading

Bitumen Extraction for measurement of Bitumen Content

Drop Hammer for compaction of Marshall Specimens

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Coring Machine for coring of Marshall Specimens

Sand Patch Equipment for determining macro-texture

Rolling Straight Edge Equipment for determining surface texture

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4.4 SEQUENCE OF WORKS FOR OVERLAYING SMA

4.4.1 Sequence 1

There are two sequences for carrying out the overlay for SMA. The first sequence is to divert traffic onto the new slow and emergency lanes in order to work on the fast and middle lane (See Appendix D for Method 1 – Sequence of Works).

4.4.2 Sequence 2

The second sequence is to carry out an island traffic diversion scheme whereby only one lane is made available for working each time (See Appendix E for Method 2 – Sequence of Works).

4.5 REPORTS ON THE PLANT TRIAL & TRIAL LAY OF SMA

4.5.1 SMA Plant Trials & Trial Lays From Matang Pagar Quarry

Three plant trials and trail lays were carried out (see Appendix F).

4.5.2 SMA Plant Trials & Trial Lays From Kajang Rocks Innopave Premix

The first plant trial and trail lay were on November 19, 2007 (see Appendix G).


Los Angeles Abrasion Equipment for determining Cantabro Abrasion

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CHAPTER 5: IMPLEMENTATION OF STONE MASTIC ASPHALT

5.1 PRODUCTION OF SMA

SMA offer considerable advantages and if laid properly and carefully it gives a higher stability as it is stone to stone contact with the Gap-Grade principle. Its flexible results from the relatively high binder content.

Thus polymer Modified Bitumen Shell Cariphate PG76 which is Styrene Butadiene Styrene (SBS) and fibre addictive Viatop 66 are used to stabilize the mixture to prevent binder drain off.

The aggregates used for the production is from our Matang Pagar Quarry which situated at Sungai Buloh, Selangor. The physical and mechanical properties are within specification requirements. Ordinary Portland cement is used as filler is sourced from Negeri Sembilan cement Industries Sdn Bhd (CIMA)

5.1.1 Physical Properties of Aggregates

a) Average Summarized Percentage Passing of Aggregate & Filler The average percentage passing of each individual aggregates were summarized are as shown below:

Type of Aggregates

14mm Agg 10mm Agg Quarry Dust Filler Cement

SourceMatang Pagar

Quarry, Sg. Buloh

Matang Pagar Quarry,

Sg. Buloh

Matang Pagar Quarry,

Sg. BulohAPMC

B.S.Sieve % Passing % Passing % Passing % Passing

20mm 100 100 100 100

14mm 95.06 100 100 100

10mm 40.47 95.76 100 100

6.3mm 4.87 39.32 91.38 100

3.35mm 1.87 11.9 73.87 100

2.36mm 1.7 6.66 57.23 100

0.300mm 0 0 24.63 100

0.075mm 0 0 10.91 98.3

Table 2


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b) Summarized Results of Specific Gravity & Water Absorption

Specific gravity and water absorption were determined in accordance with BS812:

Type of Aggregates

Bulk Specific Gravity

( Saturated Surface Dry )

Apparent Specific Gravity

Water Absorption %

14 mm 2.626 2.645 0.441

10 mm 2.620 2.642 0.505

Quarry Dust 2.638 2.662 0.565

Filler Cement (Absolute)

- 3.06 -

Table 3

c) Summarized Physical & Mechanical Properties of Aggregates

Physical and mechanical properties of 14mm coarse aggregate:

Type of Test ResultsProject

Specification Requirement

Recommendation

Aggregates Crushing ValueMS 30: Part 8:1995

24% Not more than 25% -

Aggregates Impact ValueMS 30: Part 10: 1995

23% Not more than 25% -

Flakiness IndexMS 30: Part 5: 1995

16% Not more 21% -

Elongation IndexMS 30: Part 5:1995

24% - -

Ten Percent Fine ValueMS 30: Part 9: 1995

125 kN - -

Los Angeles Abrasion ValueMS 30: Part 11:1995

28% Not more 35% -

Sodium Sulphate SoundnessASTM C88: 1990

0.30%Sodium Sulphate not more than 12%

-

Sulphate ContentBS812:Part 118:1988

<0.01 - -

Polished Stone ValueBS 812 : Part 114 : 1989

51.8 Not less than 50 -

Table 4


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5.1.2 Laboratory Mix Design

a) Blending of aggregates and design mixture composition

To achieve a smooth curve within specification limits, the following source of blended aggregate and the bitumen of Cariphate PG76 is used and the method of mixing and compacting are as below. Details of combined grading and particular size distribution curves are as below:

14mm Agg 47 % by wt of aggregate10mm Agg 10 % by wt of aggregateQuarry Dust 40 % by wt of aggregateFiller - Cement

3 % by wt of aggregate

Bitumen By design SBS shell cariphate PG76 Polymer Modified Bitumen Fibre Additive

0.3 % by wt total mixture – Viatop 66

Mixing Hand mixing methodCompaction 50 blows per side – Automatic Marshall Compactor

b) Composition of design mixture

Details of the composition of the design mixture at various bitumen content:

Wt of Combine

Agg(gm)

%Bitumen

Car. PG76

Wt of Bitumen by Weight of Mixture

(gm)

Wt. of Mixture

(gm)

%Cellulose

Fibre

Wt of Cellulose Fibre by

Weight of Total

Mixture(gm)

Total Weight of Mixture with bitumen and

Cellulose Fibre(gm)

1111.5 5.00 58.5 1170 0.3 11.74 1181.74

1105.7 5.50 64.4 1170 0.3 11.74 1181.74

1099.8 6.00 70.2 1170 0.3 11.74 1181.74

1094.0 6.50 76.1 1170 0.3 11.74 1181.74

1088.1 7.00 81.9 1170 0.3 11.74 1181.74

Table 5


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c) Aggregates combined grading

% Passing

% Passing

% Passing

%Passing

% Used

% Used

% Used

%Used

Total %

Spec Limit

Sieve Size mm

14mmAgg

10mm Agg

Quarry Dust

Filler14mmAgg

10mm Agg

Quarry Dust

Filler

47 10 40 3 100

20 100 100 100 100 47 10 40 3 100 100

14 95.06 100 100 100 44.68 10 40 3 97.6890 – 100

10 40.47 95.76 100 100 19.02 9.58 40 3 71.660 – 90

6.3 4.87 39.32 91.38 100 2.29 3.93 36.55 3 45.7740 – 60

3.35 1.87 11.9 73.87 100 0.88 1.19 29.55 3 34.6225 – 40

2.36 1.7 6.66 57.23 100 0.8 0.67 22.89 3 27.3620 – 32

0.300 0 0 24.63 100 0 0 9.85 3 12.85 8 – 19

0.075 0 0 10.91 98.3 0 0 4.36 2.95 7.31 6 – 12

Table 6

5.1.3 SMA PRODUCTION

5.1.3.1 Plant – General

Probably situated in quarry or siding convenient for supply of the aggregate. These plant are well situated to modern automatic controls, where type of mix can be set up on a central control panel and as many bathes as required then run off automatically.

Batch Plant Method of SMA plant production are as below:

i) The various sizes of aggregates, excluding mineral filler, are fed into the automatic cold feeder hoppers in the approximate correct volumetric proportions. The aggregate is then passed through the drying drum where it is dried and heated to the correct mixing temperature.

ii) From the drying drum the aggregate passes by means of the screens where it is separated into 3 or 4 sizes according to the number of storage bins . The mineral filler/fine material is fed into a separate screw conveyor and stored in a separate storage bin/silo.

iii) The correct quantity from each bin is then weighed accurately into the weigh hopper/weigher and the mineral is also weighed out separately into a separate compartment of the weigher. The batch of aggregate is passed to the mixer box where the correct amount fibre Viatop 66 and Filler cement are added .

iv) Dry mixing is recommended for 10 to15 seconds before bitumen cariphate PG76 is added, this is to ensure homogeneous distribution of the fibres in the mix. Bitumen is weighed out


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accurately into a bitumen weigher and pump is used into the mixing box through a spray bar/pipe exactly the required quantity of bitumen for each batch. Mixing is continued until all the particles are uniformly coated for 25 seconds.

v) The mix is then discharged into lorries/storage hoppers/bin and ready for transportation to the site work.

5.1.3.2 Flow Chart of SMA Production

Please refer to Chart 1

(A ) Stock pileIn order to avoid segregation, stock piles of aggregate at plant are constructed. Truck loads and shovel is placed side by side over entire stock pile area stock built up

( B ) Cold Aggregate FeederAggregates from cold feeder bins 14mm, 10mm and Quarry Dust are fed in exact proportions by computer controlled speed feeders.

( C ) Collecting and Throwing AggregatesThe aggregates of 14mm, 10mm and Quarry Dust which the correct amount proportions are collected from cold feeder bins and transferred to drier drum

( D ) DryingThe throw belt then sends the aggregates into drying drum at high velocity where theaggregates travel parallel with the flame through the combustion zone. Within the drying zone , aggregates are lifted by special bucket flights to dense curtains for effective heat transfer.

( E ) Dust CollectionA certain amount of dust is carried away in the hot gases from the drum drier and it is usual for this to be collected at the baghouse system provides effective cleaning and fed back into plant as part of fine material through the screw conveyor at the correct amount and proportion.( F1 )

( F ) ScreeningFrom the drier drum the aggregates is taken down in enclosed rotating screens drum where it is separated into various size ( 6.0mm, 12.0mm and 22.0mm ) before passing into hot storage bins which individual size of hot aggregates are stored.

( G ) Hot Storage BinsIndividual size of hot aggregates are stored . Which the K1 ( Passing 6.0mm ), K2 ( Retained 6.0mm and Passing 12.0mm ) and K3 ( Retained 12.0mm and Passing 22.0 mm)


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( H ) Filler / FibreThe cement filler and fibre are stored in separately silo and screw conveyor . The cement filler and fibre are fed to filler weigher which correct amount and sequence before fed into pugmil mixer with screw conveyor for mixing process

( I ) Bitumen WeigherFrom the skid tank, bitumen is pumped into bitumen weigher which the correct amount and proportion

( J ) Aggregate WeigherAggregate are weighed which the correct amount and proportions which start from K1, K2 and K3 cumulative .

( K ) Pugmil MixerCorrect amount and proportion of hot aggregate, cement filler and fibre are fed into pugmil mixer. Pre-mixing/dry mix hot aggregate, cement filler and fibre 10-15 seconds. Introduce the binder Cariphate PG76 mixing 30 seconds to ensure homogeneous distribution of the fibre in the mix

( L ) Hot Storage Bins On completion of mixing, the granular and homogeneous mixture is ready for use.


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Chart 1: Flow Chart of SMA Production

(A) Stock Pile

(B) Cold Feeder Bin (C) (D) Drying/Screening Drum

(E) Dust Collection

G) Hot Storage Bin

Fine Material Silo

F1- Fine Material F2 - Cement F3 – Fiber Viatop (I) Bitumen Weigher

(H) Filler, Fine &Fiber Weigher

(K) Pugmil Mixer

(L) Hot Storage Bin

Transportation to Site


PG 76

tank

SCREEN DRIER

DRUM

(J) Agg weigher

F1 F2 F3

(L) Hot storage bin

AG

AG

AG

AG

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5.2 LAYING WORK OF SMA

5.2.1 Introduction

The proposed Third Lane Widening involves adding an extra lane to the existing dual 2-lane of the North-South Expressway (NSE) between Rawang - Tanjung Malim - Slim River.

The existing pavement construction structures comprises of Continuously Reinforced Concrete Pavement (CRCP) on the slow lane and fast lanes, whilst a flexible pavement on the emergency lane. The proposed widening involved adding 3rd lanes and a new emergency lane on the outer side of the existing slow lane. The pavement design involves Flexible Composite Pavement (FCP) structure for the widening and asphaltic surfacing using Stone Mastic Asphalt (SMA) across the full width of carriageway accept the new emergency lane.

This works are documented to explain the methodology adopted for the proper construction and completion the overlay of Stone Mastic Asphalt (SMA) across the full width of carriageway. The brief summary of construction SMA overlay as follows:

SMA OVERLAYPackage KM Ch. Thickness Distance Qty Production

3AKM 444.96

toKM423.96

0to

2100040mm 21km

21000 tone

1000m length/day

@500tone/day

Table 7

All proposed materials and methods referred to in this method statement are in compliance with the contract drawings and specifications and / or written instructions or approval for equivalent materials and the alternative methods.


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5.2.2 Machinery, Equipment & Material

5.2.2.1 Overlay of SMA work requires a set of equipment as follows:

Table 8


No Type Description No of unit1 Paver

(ABG – Titan 273)

The paver should be self propelled equipped with a hopper at the front designed to receive the paving mix from tip-trucks and shall have a mechanical distribution system for spreading the mixture evenly and without segregation over the surface to be paved in front of a screeding and compacting unit which shall be equipped with suitable heating device. The paver shall be capable of laying the bituminous mixture in paving width in the range of 2.5 to 5.0 meters and of finishing the pavement layer to the required grades, levels, dimensions and cross sections subject to compaction by rolling.

1 no

2 Steel wheeled tandem Roller :

Dynapac(6 tone – 1 no &

10 tone 1 no )

Rollers used to compact the hot mix on site after laying by the paver. The steel wheeled tandem roller shall be self propelled and capable of reversed without backlash. The rollers shall be equipped with water tanks, sprinkler system and scrapper blades to keep drum roller wetted and clean during operation. The speed of the rollers should be control to max 5km/h since too fast speed will not get the compaction and too slow create dragging.

2 nos

3 Power Broom Power Broom used to sweep and clean the surface on which material to be laid. The clean surface shall be free from dust and loose material.

1 no

4 PMB/Neomad Distribution

Tanker

To apply PMB/Neomad on dry surface of pavement by using a distributor spray bar machine.

1 no

5 Hand Pressure Sprayer

To apply Neomad on dry surface of pavement by using a hand pressure sprayer shall be used only in locations where the truck cannot reach.

1 no

6 Water Tank Stand by filling water for roller. 1 no

7 Pavement Cutter Pavement cutter to cut back the exposed edge to vertical face where longitudinal /transverse joints have to be made in bituminous course

1 no

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5.2.2.2 The material requires for overlay of SMA as follows:

No Type Supplier/Manufacturer

1 Stone Mastic Asphalt (SMA) 14PATI Quarry Matang Pagar, Sg. Buloh

2Reinforcement fabric membrane -Polyfelt PGM-G100/100 (high tensile strength – 100Kn/m membrane)

Polyfelt Geosynthetics

3

Tack coati) Elastor Modified Bitumen Emulsion

Tack coat (Neomad)ii) Polymer Modified Binder(PMB) – PMB

PG76

i) ACP-DMT Sdn Bhdii) Petronas Dagangan Bhd. / Kemaman

Bitumen Company Sdn. Bhd.

4Regulating material ACWC14,ACBC 28,DBM 25&40

i) Black Top Industries Sdn Bhd,Rawangii) Quang Rock Products Sdn. Bhd,Sg Bulohiii) Sg. Long Industries Sdn. Bhd, Kajang

Table 9

5.2.4 Overlaying Works

The overlaying of SMA works require proper planning and the following aspects need to be considered prior to the actual laying works.

i) Traffic management – To provide traffic management scheme - include details on proposed length of the diversion and duration of lane closure. Plastic barriers, temporary post, signages, blinkers and temporary road markings, etc will be placed in accordance to authority/client requirement.

ii) Regulating work – Milling/grooving on the existing CRCP (middle lane and fast lane) for regulating and pave with new premix (ACWC, ACBC, DBM) as per required design. The required design as follows :

Item Type of Proposed Treatment of Existing CRCPType 1 Design Regulating up to 20mm using SMAType 2 Design Regulating 20-50mm using ACWC14Type 3 Design Regulating 50-70mm using ACBC20Type 4 Design Regulating 70-110mm using DBM25 BasecourseType 5 Design Regulating 110-150mm using 60mm ACBC20 and 50-90mm DBM25Type 6 Design Regulating 150-260mm using 60mm ACBC20 and 90-200mm DBM40

Note: 1) Detail design for regulation work to refer drawing ref no. W/RTM/3A/PA/CS/1.1 -Typical cross section for pavement strengthening.

Note: 2) Engineer has accepted one (1) type of material for regulating work.


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The laying of the reinforcement membrane fabric (800mm wide) shall commence immediately after spray the Polymer Modified Binder (PMB) tack coat. Pavement fabric to be used at joint between the existing CRCP and widened area; and Groove at location the CRCP pavement.

Tack coat is necessary to be sprayed on top the surface that will receive the bituminous mix. The specified spray rate of overlay SMA works as follow:

i) For underlying bituminous and concrete surfaces, the rate of spread of Neomad tact coat is 0.3 to 0.6 litres/m².

ii) For underlying surfaces with reinforcement membrane, the rate of spread of polymer modified binder (PMB) is 1.1 to 1.3 litres/m².

A trial lay of about 150m length over a lane width(3.75m) is carried out first to ensure that the mixing, laying and compaction equipment conforms to the requirement as per laboratory design mix and the specifications. Among the aspects considered include rolling pattern required to achieve the specified works density, temperature, joints, tack coating and grading of material.

Figure 1 below shows the typical section for widening of existing rigid pavement details.

Figure 1


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During the actual laying of SMA, the sequence of works shall be as indicated in stages below.

STAGE 1

1. Construct both the new slow lane and the new emergency lane and flush to match to the edge level of the existing CRCP. Plan the regulating and overlaying works (Say 1000m long per day per lane).

2. Prepare TMS such as traffic barriers, cones, temporary post, blinkers, etc. and divert the traffics into the new slow and emergency lane. (Refer to Figure 2).

Figure 23. Preparation work - Set up sensor wire, joint dipping, and demarcation of regulating area.

4. Spray PMB and lay reinforcement membrane along groove line of exiting CRCP.

5. Regulate on the fast lane up to the planned length beside the edge of the reinforcement membrane at middle lane.

6. Regulate on the middle lane up to the planned length to the edge of the reinforcement membrane at middle lane and to match to the edge at the slow lane.

7. Regulate for subsequent layers if any, on the fast lane, with a staggered edge along the longitudinal joints. Regulate for subsequent layers if any, on the middle lane, with a staggered edge along the longitudinal joints. (Refer to Figure 3).

Figure 3

8. Overlay SMA on the fast lane 4.45m width up to the planned length. (Refer to Figure 4).


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Figure 49. Taper the start of overlaying works for the purpose of opening to through traffic.

10. Overlay SMA on the middle lane 2.65m width up to the planned length.

11. Taper the start and end of overlaying works for the purpose of opening to through traffic.

12. Carry out all the necessary coring test on the fast and middle lanes.

13. Carry out rolling straight edge test and the 3-m transverse straight edge test for the final layer only.

14. Carry out permanent line marking works on the completed fast and middle lanes for the

final layer only.

15. Prepare TMS to divert traffic to the fast and middle lanes.

16. Prepare and plan to start regulating and overlaying works on the widened area.

STAGE 2

1. Divert all the traffics into the new fast lane and middle lane.

2. Spray PMB and lay reinforcement membrane along groove line of exiting CRCP.

3. Regulate on the new slow lane up to the planned length beside the edge of the reinforcement membrane at middle lane.

4. Regulate on the emergency up to the planned length.

5. Regulate for subsequent layers if any, on the slow lane, with a staggered edge along the longitudinal joints. Regulate for subsequent layers if any, on the emergency lane, with a staggered edge along the longitudinal joints. (Refer to Figure 5).


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Figure 5

6. Start the overlaying works for SMA on the slow lane 4.5m width up to the planned length. (Refer to Figure 6).

Figure 6

7. Taper the start and end of overlaying works for the purpose of opening to through traffic.

8. Overlay ACWC at emergency lane 3.0m width up to the planned length. (Refer to Figure 7).

Figure 7

9. Carry out all the necessary coring test on the new emergency and slow lanes.

10. Carry out rolling straight edge test and the 3-m transverse straight edge test for the final layer only.

11. Carry out permanent line marking works on the completed slow and emergency lanes for the final layer only.


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12. Carry out verge filling works. If necessary, the work can be carried out an early or later stage.

13. Carry out turfing works. If necessary, the work can be carried out an early or later stage.

14. Prepare the next and adjacent 600m to 1000m or other available areas ready for regulating and overlaying works and repeat the whole process.

The SMA overlay work commenced on 9th August 2007 at Ch 11060 – 10440 SB Fast Lane; 600m length and 4.65m width. Prior commencing overlay work, pavement surface to clean was ‘power broomed’ and clean; free from dust and loose material.PMB tack coat (1000mm width) was sprayed on dry surface at groove joint of CRCP pavement using a distributor spray bar machine at rate of 1.1 to 1.3litres/m2.

The reinforcement membrane fabric (800mm wide) was laid immediately after spraying PMB tack coat. After completed laying of membrane fabric, than the Neomad tact coat at rate of from 0.3 to 0.6 litres/m² was sprayed on CRCP surface. Hand spraying and squeezing was used to apply tack coat locations where the truck cannot reach.

After completed Neomed spraying, the pavement machineries –paver, roller, etc. were mobilized at end chainage. For setting out, required level was determined and string line was setup for paver to pave. Level to control by electronic sensor mounted onto the paver. The sensor would travel along string line on short-skids/reference beam to control the premix level.

The SMA batching plant is located at Matang Pagar, Sg. Buloh, Selangor. The travelling distance between batching plant - Matang Pagar and Bukit Beruntung Interchange approximately 39 km.

SMA materials delivered to the site by tipper trucks. Care should be taken when loading, hauling and unloading of SMA. Tipper trucks were covered with double water proofing protection and proper covering in order to minimize temperature drop. Temperature of SMA was inspected regularly at batching plant, lorries before unloading onto paver, for laying and compacting. The optimal temperature ranges required are as follows:

Temperature(˚C)

During MixingLaying @ Paver

OutDuring Rolling After Rolling Opening to Traffic

150˚CTo

180˚C

135˚CTo

155˚C

130˚CTo

150˚C- ≤ 60˚C

Table 10

Upon, delivery SMA material at site, the tipper truck discharged the hot asphalt into paver hoper with care and not to segregate. Than, paver moved in front to spread the mixture without segregation over the pavement surface. Roller moved closely to compact the newly laid SMA using 10 tonne roller first and then followed by 6 tone roller. Booth rollers of static smooth wheeled steel rollers. The required rolling pattern as follow:

i) Static rolling (6 tonne) - 2 passes using Tandem smooth wheeled steel roller. ii) Static rolling (10 tonne) - 4 passes using Tandem smooth wheeled steel roller.

Rollers to move at uniform speed and continue until all roller marks are eliminated but not after the material have cooled after 120˚C. Paver to keep moving, excessive stopping and starting may lead to


LLM/D/T/1-08

cooling of the mix and results in low temperatures for compaction. Precaution to be taken to prevent adhesion of the mixture to the wheels of roller but excessive amount of water shall not be used for this purpose. The pavement to be compacted to at least 94% of the maximum theoretical density. Rolling shall cease once the specific density has been achieved. Over compaction is likely to cause surface bleeding and shall be avoided.

Traffic shall not run on the newly compacted surface until the pavement has cooled to 60˚C or lower. On completion of laying and compaction of SMA, all the necessary coring test to be carried out to determine the thickness of the compacted layer and the density of the compacted SMA.


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The following photographs illustrate the whole process of SMA overlay.

Photo 1: Spraying of PMB@groove line of existing CRCP.

Photo 2: Laying of reinforcement membrane fabric immediately after spraying PMB.


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Photo 3: Laid reinforcement membrane fabric on top of sprayed PMB.

Photo 4: Checking temperature at lorry


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Photo 5: Laying of SMA.

Photo 6: Checking temperature at paver machine


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Photo 7: Checking temperature at laying SMA

Photo 8: Compaction of laid SMA.


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Photo 9: Traffic shall not run on the newly compacted surface until the pavement has cooled to 60˚C

or lower.


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CHAPTER 6: ISSUES ENCOUNTERED

6.1 Site Problems Encountered & Recommended Solutions

Since SMA was not widely used in Malaysia, to many of the site staff, inclusive of the Contractor’s paving team, this was the first time that they were working with SMA. Naturally, there were many problems encountered during the batching of SMA, during the process of laying and compaction. The problems encountered at the site are as summarized below:-

i) Problem - When the temperature during batching had greatly exceeded the maximum temperature of 180˚C, the characteristic of the fibre will be destroyed, which will lead to binder drainage. This was evidenced in the first trial lay when binder drainage was observed.

Solution – To closely monitor the SMA batching at the plant. A thermo coupler was installed inside the pugmill to record the temperature of the heated aggregates to ensure that the temperature inside the hot bins was within the range specified.

ii) Problem – Spraying of PMB and Neomed Tack Coat. The number of trucks was insufficient to cater to all the three packages. As a result of this, some contractors were only able to get the PMB late in the afternoon. As a result, the SMA works was delayed.

Solution – To increase the number of trucks for spraying PMB and Neomed tack coat. Ideally, each package should be allocated with one PMB and one Neomed truck.

iii) Problem – Membrane soaked in the rain. Due to the late start of the PMB and Neomed spraying, the contractor could not able to cover the membrane with asphalt surfacing before the rain started. As a result, any remainder membrane that was not covered and was soaked was required to be removed and replaced with new membrane.

Solution – To start the overlaying works as early in the morning as possible, weather permitting. By starting early, the contractor could completely cover the membrane with asphalt surfacing before the rain starts to fall, usually at late afternoon and early evening. Another method was to lay the membrane in short and manageable sections to be followed with asphalt surfacing immediately.

iv) Problem – Inconsistent supply of SMA. The supply of SMA was not able to feed the pavers with a continuous laying. Most of the time, the pavers had to wait for at least one hour before the next load arrived. The constant stop and go laying had affected the finishes of the SMA mat. Due to the constant stopping, the screed of the pavers resting on top of the mat had inevitably caused the formation of unsightly lines/depressions in the transverse direction. Too many of these lines would cause failure to the surface regularity tests.

Solution – To increase the number of lorries to transport the SMA materials. In addition, the contractor was also advised to source the SMA from another supplier so that the paving could be continuous. We had also recommended to the contractor to delay and control the start of the laying until at least five or six lorries had arrived at the site before overlaying.

v) Problem – Formation of the longitudinal joints. The longitudinal joints formed were not in line and zigzagged.


LLM/D/T/1-08

Solution – To demarcate the position of the intended longitudinal joint on the surface of CRCP and/or by using a long rope to guide the pavers’ operator so that the longitudinal joint could be formed along the intended position. If all else failed, the contractor was required to cut into the laid pavement in order to form a smooth longitudinal joint.

vi) Problem – Too much water was used by the rollers. Too much water would cool down the SMA too fast which in turn would make it difficult to achieve the required compaction.

Solution – To control the amount of the water coming out from the rollers by installing wetter at the front and back of the rollers. The wetter in the form of sponge or gunny sacks would evenly distribute the water throughout the steel wheels of the rollers, and thus the amount of water could be reduced.

vii) Problem – SMA materials sticking to the steel wheels of the rollers. This problem was encountered during the second trial lay when the contractor was only using oil for the compaction.

Solution – To use water instead of oil for compaction. The amount of water to be used for compaction shall be controlled. Too much water will cause the mat to cool down fast, and too little water will cause the SMA materials to stick to the steel wheels of the rollers.

viii)Problem – Delay in carrying out surface regularity testing on completed SMA overlay. The surface regularity testing shall be carried out as soon as overlay is completed and before opening to traffic. But, at the present moment, the testing was only carried out weeks or months later and after the completed pavement had been opened to traffic.

Solution – To carry out the testing as soon as overlay is completed and before opening to traffic. The contractor was advised to mobilize another team to carry out the tests to avoid delay. The later the tests are carried out, the higher the possibility that it will not comply with the requirements of the Specifications for surface regularity.

CHAPTER 7: CONCLUSIONS & RECOMMENDATIONS

7.1 CONCLUSION

During the initial stage of implementation of the SMA at site, there was a lot of hesitation on the use of SMA since the material was new and the parties involved had little or no experience in handling SMA. We had faced many problems during the initial stage of plant trial and trial mix. It took three plant trials for the contractor to get approval for SMA to be used. We had encountered binder drainage problem whereby the binder was overflowing off the lorry that was transporting the SMA to the site. Then there was the case where the SMA material was sticking to the wheels of the rollers because the contractor had used cooking oil instead of water to lubricate the steel wheels. We had also experienced the case where the mat was overly compacted as we were unsure of the rolling pattern.


LLM/D/T/1-08

We had learned a lot from the mistakes during the plant trails. Finally, when we started to lay SMA on the mainline, we found that laying SMA was indeed much simpler than laying the normal wearing course. The pneumatic tyred roller was not necessary to be used for the compaction of SMA mat. The only rollers used were two smoothed wheels tandem rollers. The mat that came out from the pavers looked solid and rich in bitumen. The first heavier roller was mainly used as the main compacting roller and it followed closely to the pavers. The second lighter roller was used mainly as a finishing roller. It was used to remove any blemishes and roller mark left by the first roller.

There were many reasons why the work progress was slow. Initially there was only one approved plant for SMA, which was PATI’s batching plant in Matang Pagar. Another reason for the slow progress was that the contractor was using the same set of pavers to carry out the laying of SMA and the regulating works. Then there was the problem of insufficient distributors to spray the PMB and Neomed tack coats, and also the delay in getting the supply of the reinforcement membrane.

Later, another source for SMA was approved, which was Kajang Rocks Innopave Pavement, and the contractor had started using another set of pavers to carry out the regulating works concurrently with the set of pavers laying the SMA. With two plants in operation and with the additional set of pavers for each paving team, progress had picked up considerably.

However, we were still facing the problem of the delay in getting consistent supply. The supply could not adequately and consistently feed the paving machines in order to carry out continuous laying. As a result of this, the paving machines had to periodically stop to wait for the lorries to arrive. This situation had inevitably caused the formation of some transverse ridges on the top surface of the SMA mat and also causing numerous transverse joints to be formed. We had tried to solve the problem by delaying the start of the SMA laying until at least five to six lorries had arrived at the site before we would allowed the contractor to start laying. We had also asked the suppliers to increase the number of lorries transporting the SMA to the site. However these measures were only effective during the start of laying. As the day progressed, we observed that the paving machines had to stop laying and to wait for the material to arrive. A permanent solution to this problem is to increase the supply by encouraging more batching plants to produce SMA in order to ensure adequate supply to continuously feed the paving machines with continuous laying.

To summarize, the overall economics of a surfacing material in terms of some whole life costing assessment must be considered. Tonnage for tonnage, stone mastic asphalt will be more expensive than most other asphalt surfacing materials, including ACWC, for the following reasons:

high percentage of premium high PSV aggregate; high binder content; use of stabilizing additives; high temperatures; lower production rate; and extra attention to quality control.

However, SMA does offer a considerable range of advantages, including:

high resistance to permanent deformation; high wear resistance; low noise generation; good structural contribution; excellent resistance to ageing and cracking; good low temperature performance; toughness and impact resistance; ability to be laid thinly;


LLM/D/T/1-08

improved visibility in wet weather by reducing spray levels; an even finish providing a smooth riding surface; can be laid with a conventional pavers without problems; less traffic disruption during the laying process; and long service life, possibly in excess of 20 years.

Stone mastic asphalt thus offers a more expensive but longer lasting surface at the same thickness as ACWC. It is however, possible to reduce the initial cost by reducing the thickness without compromising the life expectancy.

Stone mastic asphalt does have some disadvantages. The disadvantages of using stone mastic asphalt are:

high initial cost such as increased material cost associated with high binder and filler contents, and fiber additive;

increased mixing time due to high temperature required and time taken to add extra filler, may result in reduced productivity;

initial skid resistance (lack of friction) may be low until the thick binder film is worn off the top of the surface by traffic. In critical situation, a small, clean grit, may need to be applied before opening to traffic.


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7.2 RECOMMENDATION

We hereby highly recommend that SMA is to be used to replace ACWC as a surfacing course. Although the initial cost for SMA may be high as compared to ACWC, but the overall advantages greatly outweight the disadvantages. In the long run, using SMA will save on the maintenance cost since the SMA mat will have less deformation, high wear resistance, and excellent resistance to rutting, ageing and cracking. Properly constructed SMA will last from one and a half to two times longer than the lifespan of ACWC. Less maintenance would result in less inconveniences and traffic problems to the public users.

We are of the opinion that the cost of producing SMA will drop if more authorities, Government Departments and the private sectors, such as the Malaysian Highway Authority, Public Works Department and North South Expressway Berhad, encourage the use SMA to replace ACWC. When more and more projects start to use SMA, more suppliers would have to seriously look into the possibility of producing SMA. Eventually the cost of producing SMA will drop.

APPENDIX


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APPENDIX A

FLOW CHART FOR SMA


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FLOW CHART FOR SMA


No

NoNo

YesYes

Approval of MaterialsCoarse Aggregates: ACV (<25), FI (<25), WA (<2%), PSV (>50), Weighted Avg. Loss of Wt. (<12%) and LA Abrasion (≤35)

Fine Aggregates: WA (<2%) and Weighted Avg. Loss of Weight (<12%) Filler: Portland Cement (2% by mass)

SBS Polymer Modified Bitumen: Superpave PG76 Specifications Fibre: Bitumen Pre-coated Palletized Cellulose Fibre (0.3% by weight)

and

Consultant's Approval

Laboratory Design Mixture

Plant Trial & Trial Lay

Job Standard Mixture

Compaction Trial

Actual Production to Site

Plant Mixture

CSL Lab** Grading (S3)

** Bitumen Content (S3)Marshall Properties (S3)

Schellenberg Binder Drain-off Test (S3)Cantabro Abrasion Test (S3)

Site Temperature Checking (S3) Samplings,

Tack Coat & Cores (cl. 901.15 & 18) Surface Regularity Tests (701.8, Table 7/2)

Micro and Macrotexture Tests (cl. 901) Falling Weight Deflectometer Test (cl. 707)

Accept and Incorporate into the Permanent Works

Batching Plant* Grading (S3)

* Bitumen Content (S3) Marshall Properties Tests (S3)

Schellenberg Binder Drain-off Test (S3) Cantabro Abrasion Test (S3)

Contractor's Proposed Design Mixture Proposed Composition

Combined Grading Marshall Specimens / Properties Tests

Schellenberg Binder Drain-off Test Cantabro Abrasion Test

Yes

Yes

Yes

No

No

Reject Reject

* If out of the Specifications, to adjust the grading and bitumen content immediately at the plant. ** If out of the Specifications, to ask contractor to improve on the batching of the mix. If consistently out, to reject and ask for revision of the laboratory design mixture and/or job standard mixture.(S3) is Schedule 3 of the SMA Specifications & cl. is the clause number in the Specifications.

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APPENDIX B

CHECKLISTS & FORMS FOR SMA


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APPENDIX C

SAMPLES OF THE TEST RESULTS FOR SMA


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APPENDIX D

METHOD 1 – SEQUENCES OF SMA’s WORKS


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APPENDIX E

METHOD 2 – SEQUENCES OF SMA’s WORKS


Existing line markings Temporary line markings Plastic barriers filled with water/sand or concrete barriers with blinkers

Fast Lane (FL) Middle Lane (ML) New Slow Lane (SL) Emergency Lane (EL)

3.65 m 3.65 m 3.65 m 3.00 m

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METHOD 2 - SEQUENCE OF CONSTRUCTION.

1. Construct both the new slow lane and the emergency lane to match to the lenel at the edge of the existing CRCP.

2. Plan the regulating and overlaying works on a weekly basis.Plan the estimated length of regulating and overlaying works (Say 600m to 1000m long per day per lane).Draw temporary line markings on the new slow lane, if necessary.Prepare TMS such as traffic barriers, cones, blinkers, etc. along the edges of the present slow lane (middle lane) and the emergency lane on Monday.

Monday.

a. Divert all the traffics onto the middle lane and the new slow lane (See Plan 1).b. Set up sensor wire, joint dipping, etc.c. Mill material used as temporary taper, if any to get a straight vertical edge between old and new premix.d. Regulate on the fast lane up to the planned length to completely covering the reinforcement membrane

400mm on the middle lane.e Regulate subsequent layers if any, on the fast lane up to design level (below SMA layer), with a

staggered edge or key along the longitudinal joints.f. Start the overlaying works for SMA on the fast lane up to the planned length.g. Taper the start and end of overlaying works for the purpose of opening for through traffic on Wednesday.h. Start the removal and relocation of guardrails works at the same time along the median to the required

height.

Tuesday.


Sensor wire

Reinforcement membraneTemporary line markings

Plastic barriers filled with water/sand or concrete barriers with

Fast Lane (FL) Middle Lane (ML) New Slow Lane (SL) Emergency Lane

3.65 m 3.65 m 3.65 m 3.00 m

4.65 m

0.5 m

Regulating LayerSMA

To divert traffic onto ML & SL

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a. Continue with the removal and relocation of guardrails works along the median to the required height to completion.

b. Start and complete the median infill works with ACWC along the median.c. Carry out all the necessary coring test on the fast lane.d. Carry out rolling straight edge test and the 3-m transverse straight edge test for the final layer only.e. Carry out permanent line marking works on the completed fast lane for the final layer, or otherwise with

temporary line marking only. f. Prepare TMS (Island Type) to divert traffic onto the completed fast lane and new slow lane (See Plan 2).

Wednesday.a. Shift barriers from middle lane onto completed fast lane and add cones onto the new slow lane (See Plan 2).b. Divert traffic onto the completed fast lane and the new slow lane.c. Mill material used as temporary taper on the middle lane, if any to get a straight vertical edge.d. Regulate on the middle lane up to the planned length to the edge line of the "to be laid" reinforcement membrane.e. Regulate subsequent layers if any, on the middle lane up to design level (below SMA layer), with a staggered edge or key along the longitudinal joints.f. Start the overlaying works for SMA on the middle lane up to the planned length.g. Taper the start and end of overlaying works for the purpose of opening for through traffic on Thursday.h. Prepare TMS to divert traffic onto the completed fast and middle lanes (See Plan 3).

Thursday.a. Shift barriers from edge of completed fast lane onto edge of completed middle lane.b. Divert traffic into the fast lane and part of the middle lane for half a day (maximum one day), in order to avoid doing the temporary line marking.c. Mill material used as temporary taper, if any to get a straight vertical edge.d. Regulate on the new slow lane up to the planned length.


ACWC median infill

Temporary line markings



3.65 m 3.65 m 3.65 m 3.00 m

0.8 m

0.5 m

SMA

To divert traffic onto ML & SL

Relocated guardrails to new height & positions

Permanent Line Marking

To divert traffic onto FL

Temporary line markings



3.65 m 3.65 m 3.65 m 3.00 m

4.65 m

0.5 m

SMA

To divert traffic onto SL

Relocated guardrails to new height & positions Position of reinforcement membrane

2.95 m

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e. Regulate on the emergency lane up to the planned length.f. Regulate for subsequent layers if any, on the new slow lane, with a staggered edge along the longitudinal joints. If no, start the SMA overlaying works.g. Complete the overlaying works for SMA on the new slow lane and shift the cones/barriers so that the middle lane can be opened to traffic full width.h. Regulate for subsequent layers if any, on the emergency lane, with a staggered edge along the longitudinal joints. If no, start the SMA overlaying works.

Friday to Sunday.a. Start the overlaying works for SMA, if not started on Thursday on the new slow lane up to the planned length so that ML can be opened to traffic full width.b. Taper the start and end of overlaying works for the purpose of opening for through traffic on Monday.c. Start the overlaying works for SMA or up to ACBC layer on the emergency lane up to the planned length.d. Taper the start and end of overlaying works for the purpose of opening for through traffic on Monday.e. Carry out all the necessary coring on the new slow lane and the emergency lane.f. Carry out rolling straight edge test and the 3-m transverse straight edge test. g. Carry out permanent line marking works on the completed new slow lane and the emergency lane, if necessary at a later stage.h. Continue the works through the weekend until the new slow lane and the emergency lane are completed to be opened for traffic on Monday.i Carry out verge filling works. If time's not permitting, verge filling works can be carried out at a later stage.j. Carry out turfing works. If time's not permitting, turfing works can be carried out at a later stage.k Carry out guardrails installation works. If time's not permitting, guardrails works can be carried out at a later stage.l. Prepare the next and adjacent 600m to 1000m or other available areas ready for regulating and overlaying works and repeat the whole work process.


To divert traffic onto FL & part of ML Plastic barriers filled with water/sand or concrete barriers with


3.65 m 3.65 m 3.65 m 3.00 m

4.65 m

0.5 m

SMA


2.95 m 4.05 m 2.85 m

0.05m

To divert traffic onto FL & part of ML Plastic barriers filled with water/sand or concrete barriers with


3.65 m 3.65 m 3.65 m 3.00 m0.5 m

Completed SMA


0.8m

0.05m

Permanent Line Marking

Verge Guardrail Verge Filing works

Turfing

0.8m

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APPENDIX F

Observations on the SMA’s Plant Trial at Matang Pagar Quarry and Trial Lay from Ch 10+470 – Ch 10+620 SB on New Shoulder Carried out on 24 April 2007.

Below is the Consultant’s report on the above trials in a chronological order:-

9.40 am Left Bukit Beruntung’s office.

10.20 am Arrived Matang Pagar Quarry. Weather was cloudy and rain was imminent at both the quarry and the trial lay area. At that time, the batching plant was producing ACWC mix.

10.30 am It was starting to drizzle at the plant. The drizzles continued for 30 minutes. However the sky was still very cloudy.

11.30 am The plant was given the green light to start the batching process for SMA. There were still several lorries waiting for the batching plant to produce ACWC mix. After the last lorry had been loaded with ACWC mix at about 12.40 pm, the preparation for the batching of SMA began around 1.00 pm.

1.30 – 2.20 pm The batching plant encountered several problems. The first problem was that the supply from the storage containing the fiber did not function. Attempt was made to fix the problem, but to no avail. The plant manager decided to introduce the fiber manually into the pug mill through an opening on top of the pug-mill. The amount of fiber to be added manually would be pre weighed according to the proportion of the fiber relative to the overall weight of the mixture. We raised our concern on the suitability of this method since there was a possibility that the fiber would not be thoroughly mixed and blended. We were assured the manual method would work. However, a second problem cropped up. The burner could not be started and thus the mixing temperature of between 150°C and 180°C could not be attained.

At the same time there was a heavy downpour at the trial lay area at around 2.00 pm., which had prompted the contractor to call off the plant trial and trial lay. The rain had finally stopped at 3.15 pm.

2.20 pm A message was conveyed from the site to UEM’s representative at the batching plant to call off the plant trial since it was raining heavily at the trial area. We left the batching plant at around 2.30 pm.

3.00 pm UEM had decided to continue with the plant trial and trial lay since the rain at the trial lay area had stopped. Instruction was given to the plant to start back the production. Instead of producing SMA mix, the operator batched two loads of ACWC 14 due to an over sight on the part of the operator. Both the loads were rejected.

4.00 pm The operator prepared to start the SMA production.

4.30 pm At the batching plant, some new problems were encountered. The burner which was not functioning earlier was repaired and was operational, but the fiber problem had not been rectified. The fiber would have to be introduced into the pug mill manually.


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The first new problem was the conveyor belt transporting raw materials from the cold bins was not functioning. It was repaired ten minutes later. The second new problem was the steel bucket transporting the mix from the pug mill to the top of the loading bay had stalled. The problem was also rectified ten minutes later.

5.00 pm Batching had started. Batching was carried out in batches of 2 tons each cycle. Each cycle took about 1 - 2 minutes to complete.

5.23 pm The first load of SMA left the batching plant. The material’s weight recorded was 22 tons and the temperature was at 180°C.

5.50 - 7.40 pm Heavy rain had started to fall at the trial area at 5.50 pm. The rain stopped at around 7.40 pm. It had rained intermittently for about 2 hours with occasional long periods of heavy rains.

6.12 pm The second load of SMA left the batching plant. The material’s weight recorded was 28 tons and the temperature was at 162°C.

6.45 pm The first load arrived at the trial lay area. An enormous amount of bitumen was seen spilling from the back of the lorry (See photographs attached). The spilling of the bitumen might suggest that either the bitumen content used in the mix was too high, or the addition of fiber manually did not effectively bind the bitumen to prevent the binder from draining off. The temperature recorded from the first load on the lorry was 140°C. The draining off of the binder was still visible when the lorry was leaving the site to unload of the SMA material a few hundred meters away at 7.35 pm, when the mix was rejected due to excessive bitumen loss, low temperature of the mix (~100°C) and the fact that the mix was approaching the 3-hour requirement that the SMA had to be completed. It was noted the next day that on the North bound of the NSE where the lorries were using to transport the mix, there were signs of bitumen spillage along the expressway.

7.10 pm The second load arrived at the site. It was still raining at the time of the arrival

of the second load. The temperature was checked to be at 130°C. There was no visible sign of any bitumen spillage from the lorry. However, the laying of SMA could not be carried out immediately due to rain.

7.45 pm The rain turned into drizzle and it had finally stopped at about 7.50 pm. The temperature was checked to be at 110°C, which was below the laying temperature requirements of 130°C to 150°C.

8.00 pm The contractor was still undecided on whether to proceed on with the laying. The surface was still very wet. Attempts to dry the surface failed when the air compressor machine could not be started and the power broom was not available. Also, the sensor wire used to control the level for laying installed along the edge of the new verge was found to have been disturbed and was loose.

8.10 pm The temperature was again checked with both the special digital infra red thermometer and the usual thermometer. Both readings were found to be at more or less the same, which was at 105°C.


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8.15 pm Since the 3-hour requirement is approaching nearer, the surface was still wet, the sensor wire had yet to be rectified, and the temperature had dipped below the laying temperature requirements, the contractor had finally decided to call off the trial lay at 8.20 pm.

8.20 pm The trial lay was called off.

The following day on 25 April 2007, we observed at the dump site where the rejected material was dumped, we found that for the first load, bitumen drain-off was still visible. For the dumped second load, there was no sign of bitumen drain-off.

In conclusion, there were a lot of factors that had affected the planned trial lays, such as the four problems encountered at the batching plant, the trial lay area were affected by heavy rains twice, the binder drain-off that was encountered in the mix from the first lorry and the breakdown of air compressor machine at the site.

The batching plant QA/QC manager has been informed to investigate on the possible causes of the bitumen drain-off and to improve on the maintenance of the machineries and the equipments at the batching plant. Questions such as whether the manual input of fiber could have affected the effectiveness of the mix and using double-sheeted insulated lorries could have prevented the binder spillage have to be seriously looked into.

Our recommendations and suggestions for carrying out any future plant trials and trial lays are as follow:-

To carry out more plant trials until the batching plant’s personnel have familiarized themselves with the procedure to batch and produce SMA before carrying out the actual production;

To carry out more trial lays off site in order for the operators of the paver and compactors, and all the workers to get familiarized with the laying and compacting of the SMA mix;

To carry out frequent routine preventive maintenance rather than breakdown maintenance at the batching plant in order to avoid any unnecessary interruption to the supply;

To use double-sheeted insulated lorries to transport the mix in order to prevent any bitumen spillage, early oxidation and temperature loss. The lorries used to transport the SMA mix for this trial lay were the normal lorries used to transport other premix materials such as ACWC, ACBC and DBM;

To avoid planning and starting works during imminent adverse weather conditions. Wet weather, for example could expedite the process of temperature loss of the mix;

To plan and start works early in the morning, unless the weather is not permitting. It is not recommended to start works after 1 pm in the afternoon since the process of starting the SMA production to the time it takes for the first lorry to arrive at the work site is between 2 to 2½ hours (The initial start-up time of the mixing at 180°C is about 30 - 40 minutes due to the high temperature required for the mixing, the actual production is 1 - 1½ minutes per batch of 2 tons, which will translate to about 14 minutes to 21 minutes for a 28 tons load and a traveling time from the batching plant to the work site of about 1 to 1½ hours depending on the traffic conditions).

Note: During wet weather, the wet aggregates require a much longer mixing and drying time.


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To have back-up machineries and equipments on stand by at the site or can be easily available in the event of any sudden breakdown and failure of the present machineries and equipments;

In the event of an unavoidable night works, which we do not recommend for a wearing course, flood lights, blinkers and other safety equipments must be adequate and are readily available.

Photo 1: The bitumen spillage from the first lorry.


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Photo 2 & 3: Photographs showing different views of the bitumen spillage from the first lorry.


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Observations on the Contractor Second SMA’s Plant Trial at Matang Pagar Quarry and Trial Lay from Ch 8+030 – Ch 8+110 SB Carried out on 11 May 2007.



8.15 am Arrived Matang Pagar Quarry. Weather was fine at the quarry and at the trial lay area. At the time of arrival, the batching plant was idle. It was later brought to our attention that there was an electrical problem with the plant.

9.50 am The electrical problem was rectified. Preparation was under way to batch SMA. It was a manual mode of batching.

10.30 am First batch. Temperature was 140 °C. Rejected.10.33 am Second batch. Temperature was 160 °C. Rejected.10.38 am Third batch. Temperature was 175 °C. Accepted.10.42 am Fourth batch. Temperature was 170 °C. Accepted.10.45 am Fifth batch. Temperature was 183 °C. Accepted.10.52 am Sixth batch. Temperature was 180 °C. Accepted.10.57 am Seventh batch. Temperature was 180 °C. Accepted.11.00 am Eighth batch. Temperature was 180 °C. Accepted.11.02 am Ninth batch. Temperature was 185 °C. Accepted.11.08 am Tenth batch. Temperature was 183 °C. Accepted.11.11 am Eleventh batch. Temperature was 190 °C. Rejected.11.15 am Twelfth batch. Temperature was 185 °C. Accepted.11.19 am Thirteenth batch. Temperature was 185 °C. Accepted.11.24 am Fourteenth batch. Temperature was 180 °C. Accepted.11.28 am Fifteenth batch. Temperature was 180 °C. Accepted.11.32 am Sixteenth batch. Temperature was 180 °C. Accepted.

11.45 am The SMA mix was loaded onto the lorry. The mix looked fine and there was no sign of bitumen drainage. The temperature recorded on top of the lorry was 180 °C.

12.05 pm After weighing in at 25.26 tons, the lorry left the batching plant.

1.10 pm The lorry arrived at the trial lay area. Earlier, the trial lay area of width 3.00 meters and length 80 meters was sprayed with Neomed tack coat. The trial lay area was located at the exit ramp of Rawang’s Rest and Service Area (RSA). Three sets of the temperatures were taken on top of the lorry. The temperatures recorded were 158°C (at the front of the lorry), 175°C (at the middle of the lorry) and 170°C (at the back of the lorry).

1.20 pm There was a problem with the conveyor belt system of the paving machine. It was fixed 5 minutes later.

1.25 - 2.30 pm The mix was loaded onto the paving machine. The temperature of the mix in the hopper of the paving machine was at 155°C. Paving started. The mix that came out from the screed looked consistent, with a constant un-compacted thickness measured to be at 50mm. The temperature taken at the laid SMA or mat was at 145°C.

The first roller started to compact with no vibration allowed. The steel wheels of both rollers were earlier coated with a layer of cooking oil. No water was


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used during the compaction process. The proposed rolling pattern was 8 passes for both the rollers. After 4 passes of the first roller, the mat was observed to be smooth and dense. There was practically little movement of the mat when the roller traversed on the edge of the laid SMA mix. This roller then began to move forward to follow as closely as possible behind the paving machine. A second roller was used to carry out the finishing compaction of the mat. That was when the problem started.

During the compaction, some of the SMA materials were starting to adhere to the steel wheels of the first roller, which caused the surface of the mat to unravel. As the roller traveled along the mat, some of the materials that were sticking to the steel wheel had fallen onto the surface of the mat. The first roller was taken out to remove the materials sticking to the steel wheels. However, when it traveled on top of the earlier compacted mat, it had caused the surface to unravel too.

In the meantime, the second roller moved up to compact the newly laid mat and to follow as closely as possible to the paving machine. But, the materials began to stick to the steel wheels of the second roller, just like it had happened to the first roller.

Confusion started to set in. Both the rollers were coming in and going out of the mat to the extent that we had lost count of the number of passes. Tenderness of the surface of the mat was observed during the compaction. It was difficult to compact. The mat seemed to be shoved under the roller. Also the aggregates were observed to have been “crushed”, leaving behind whitish residue.

In conclusion, the batching of the SMA mix appeared to be in order. The mix was batched at the allowable temperature range and the consistency of the mix appeared to be acceptable (pending the test results of the mix such as sieve analysis, binder content, Marshall Properties, Schellenberg Binder Drain-off Test and Cantabro Abrasion Test). The mix that arrived at the trial lay area was checked to be within the acceptable range of temperatures, and there was no sign of binder drainage of the SMA mixture.There was no problem encountered with the laying of the SMA mixture. The mixture was easily laid and the mat looked consistent after laying. Initially, there was also no problem associated with the compaction on the mat, until when the SMA materials began sticking to the steel wheels of the rollers.

There were three main problems encountered during the compaction of the mat. The first problem was the SMA materials were sticking to the steel wheels of the rollers. The second problem was that the mix was tender at the later stage of the compaction and the mat was seen to have been ‘shoved’ under the rollers. The third problem was that the aggregates appeared to have been “crushed”, leaving behind whitish residue.The probable causes of the first problem of the materials sticking to the steel wheels of the rollers were:-

• The steel wheels were too dry; and• The roller had started the compaction when the temperature of the mat was still high, which

was around the range of 145°C to 150°C.

The probable causes of the second problem of the tenderness of the mat when being compacted by the rollers were:-

• The mix might have contained excessive filler and /or fine aggregates; and• The mat was excessively over compacted.

The probable causes of the third problem of the aggregates being “crushed” by the rollers were:-


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• The polished stone value (PSV) of the aggregates and the aggregate crushing value (ACV) were not in compliance with the requirements of the Specifications; and

• The mat was excessively over compacted.

We have requested that the contractor sample and send the aggregates to test for the polished stone value and the aggregate crushing value. We have also requested that the Contractor carry out some coring at the trial lay locations. Once the results of these tests together with the sieve analysis, bitumen content, Marshall Properties, Schellenberg Binder Drain-off Test and Cantabro Abrasion tests are obtained, we will then be able to determine the causes of the problems encountered.

Our recommendations and suggestions for carrying out any future plant trials and trial lays are as follow:-

To have frequent technical meetings to discuss on the contractor’s method statement. These meetings should be attended by all relevant parties from the personnel of the batching plant, the Highway Authority, the Client, the Consultants, the Contractors and the subcontractor;

To organize seminars and briefings by experts familiar with SMA for site staff; To provide a portable density tester such as Density Nuclear Gauges which can provide quick

density results in order to prevent over compaction; To organize site visits to other job sites where SMA works are on-going or had been

completed earlier; To carry out more trial lays off site in order for the operators of the paving machine and

compactors, and all the workers to get familiarized with the laying and compacting of the mat. In this case, the over compaction could have resulted in the mat to become tender and the aggregates to be “crushed”; and

To carry out more plant trials until the batching plant’s personnel have familiarized themselves with the procedure to batch and produce SMA before carrying out the actual production. The plant personnel should also carry out more trial lays on their own. They should then give advice to the site team doing the actual overlaying works and the supervision team.


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Photographs from the Second Trial Lay.

Photo 1: Start of Compaction

Photo 2: Compaction of the first roller.


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Photo 3: Sampling for testing by CSL Personnel.

Photo 4: SMA Materials Sticking to the Steel Wheels of the Roller.


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Photo 5: The Surface of the Mat began to Unravel. Signs of Aggregates “Crushing”.

Photo 6: The Mat Showing Signs of “Shoving”. The Mat Moved when Compacted.


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Photo 7: The Roller was Compacting at the Starting Location.

Photo 8: SMA Materials were Sticking to the Steel Wheel of the Second Roller.


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Photo 9: Signs of Aggregates “Crushing” and Tenderness of the Mat.

Photo 10: Signs of “Crushed” Aggregates and Tenderness of the Mat.


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Photo 11: The Mat was “Shoved” from the Center to the Sides when Compacted.

Photo 12: Close-up View on the “Crushed” Aggregates.


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Photo 13: End of Compaction.


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Observations on the Contractor Third SMA’s Plant Trial at Matang Pagar Quarry and Trial Lay from Ch 8+010 – Ch 8+160 SB Carried out on 19 July 2007.

On 17 July 2007, Matang Pagar Quarry carried out an internal plant trial and trial lay at the plant to assess whether the laboratory design mix for SMA could be produced and laid successfully after the two failed attempts to produced and lay SMA. During the plant trial, four batches of the mix were produced. The temperature of the SMA mix was around 180˚C. The laying and the compaction of the mix were carried out without much problem. Water was used on the roller to compact the laid mat.

Samples of the SMA were taken for the Marshall Properties testing. The results of the sieve analysis, bitumen content and the Marshall Properties such as voids in mix aggregates (VMA), voids in total mixture (VTM), stability at 60˚C, flow and stiffness have complied with the requirements of the Specifications. However, the Schellenberg Binder drain off test at 170˚C and the Cantabro Abrasion Loss after 300 revolutions were not carried out. For the Schellenberg test, the lab did not have the 800 ml glass beaker as required and the method of testing was incorrect. For the Cantabro test, the samples are to be sent to an independent lab for testing as the lab did not have the equipment.

The plant has yet to install the thermo coupler inside the hot bins to check on the temperature of the aggregates. As the temperature of the aggregates that determine the temperature of the mix, it is very important that this thermo coupler is installed so that the mix produced will be within the temperature range specified in the Specifications.

We were against the idea of carrying out a plant trial and trial lay at the site without the thermo coupler installed and the facts that two tests were still outstanding. However, the contractor insisted to proceed with the trials and had set the date of the trials on 19 July 2007 at 9.00 am.

Below is the Consultant’s report on the third trials carried out on 19 July 2007 in a chronological order:-


9.25 am Arrived Matang Pagar Quarry. Weather was fine at the quarry and at the trial lay area. At the time of arrival, the batching plant was idle. The plant personnel were awaiting instruction from the contractor to start the batching.

9.44 am We were told the reason of the delay was that the contractor could not get the Neomed tack coat. The contractor wanted to use the normal tack coat to be sprayed on the laying surface. We objected to the use of the normal tack coat and insisted that the contractor to use Neomed or PMB emulsion. We made some calls to Package 4 and Package 3B2 to enquire about the availability of Neomed. We were told that the Neomed tack coat could be obtained from both Packages 3B2 and 4. We then informed the contractor to get the Neomed from either Package 3B2 or Package 4.

12.50 pm We waited at the batching plant until 12.50 pm when the contractor called the plant to start the batching since the Neomed tack coat obtained from Package 4 has arrived at the trial site.

12.50 – 1.35 pm The batching plant carried out a few trial runs without bitumen to get the aggregates to the right temperature of between 180 to 190˚C. The temperatures of each batch were checked and recorded to be at 104˚C, 115˚C, 126˚C, 133˚C and finally at 145˚C. Then the first batch together with PMB bitumen was discarded to remove any leftover of pen 80- 100 bitumen that might be left in


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the pipe line during the production of other mix. The temperature of this discarded mix was recorded at 168˚C.

Finally, the first batch was produced at 1.35 pm. The list below is the summary of the SMA batches:-

1.35 pm First batch. Temperature was 180°C. Accepted.1.38 pm Second batch. Temperature was 188°C. Accepted.1.42 pm Third batch. Temperature was 188°C. Accepted.1.45 pm Fourth batch. Temperature was 190°C. Accepted.1.48 pm Fifth batch. Temperature was 189°C. Accepted.1.52 pm Sixth batch. Temperature was 189°C. Accepted.1.56 pm Seventh batch. Temperature was 185°C. Accepted.2.00 pm Eighth batch. Temperature was 185°C. Accepted.2.03 pm Ninth batch. Temperature was 185°C. Accepted.2.06 pm Tenth batch. Temperature was 185°C. Accepted.2.10 pm Eleventh batch. Temperature was 186°C. Accepted.2.13 pm Twelfth batch. Temperature was 181°C. Accepted.2.17 pm Thirteenth batch. Temperature was 180°C. Accepted.2.21 pm Fourteenth batch. Temperature was 174°C. Accepted.2.25 pm Fifteenth batch. Temperature was 174°C. Accepted.2.29 pm Sixteenth batch. Temperature was 174°C. Accepted.2.34 pm Seventeenth batch. Temperature was 173°C. Accepted.2.38 pm Eighteenth batch. Temperature was 178°C. Accepted.2.42 pm Nineteenth batch. Temperature was 181°C. Accepted.2.46 pm Twentieth batch. Temperature was 186°C. Accepted.2.50 pm Twenty-first batch. Temperature was 185°C. Accepted.2.54 pm Twenty-second batch. Temperature was 190°C. Accepted.2.57 pm Twenty-third batch. Temperature was 188°C. Accepted.3.00 pm Twenty-fourth batch. Temperature was 197˚C. Accepted.

2.20 – 3.10 pm The SMA mix was loaded onto the first lorry. The mix looked fine and there was no sign of bitumen drainage. The temperature recorded on top of the lorry was 180°C. The lorry left the batching plant at 2.35 pm. The weight of the SMA was 24.58 tons.

The SMA mix was loaded onto the second lorry at 3.10 pm. The mix also looked fine and there was no sign of bitumen drainage. The temperature recorded on top of the lorry was 180°C. The second lorry left the batching plant at 3.20 pm. The weight of the SMA was 24.50 tons.

3.50 pm The first lorry arrived at the trial lay area. Earlier, the trial lay area of width 3.65 meters and length 150 meters was sprayed with Neomed tack coat. The trial lay area was located at the exit ramp of Rawang’s Rest and Service Area (RSA). We were not satisfied with the surface preparation. The surface to receive the Neomed tack coat was not properly cleaned, especially along the edges next to the shoulder drain. The Neomed was observed to have sprayed on top of loose sand and earth materials. Attempt to remove the sand and loose materials had worsened the prepared surface from Ch 8 + 060 to Ch 8 + 040.

Finally we asked the contractor to shift the laying 600 mm away from the shoulder drain and stop the laying length at 90 meters at Ch 8 + 060 instead of 150 meters as planned at Ch 8 + 010. Three sets of the temperatures taken on top of the lorry recorded were 160°C, 163˚C and 160˚C.


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4.00 – 5.00 pm The mix was loaded onto the paving machine. The temperature of the mix in the hopper of the paving machine was at 169°C. Paving started at Ch 8 + 160. The mix that came out from the screed looked consistent, with un-compacted thicknesses measured from 50 to 90 mm. However, a line was formed in the middle of the mat indicating that the screeds were out of alignment. After adjustment was made to the screeds, the problem was solved. The temperature taken at the laid SMA was at 150°C before the start of compaction.

The first roller started to compact with no vibration allowed. This time the steel wheels of both rollers were not coated with a layer of cooking oil, instead water was used. The proposed rolling pattern was 3 passes for both the rollers. After a few passes of the first roller which weighed 10 tons, the mat was observed to be smooth and dense. There was practically little movement of the mat when the roller traversed on the edge of the laid SMA mix. This roller then began to move forward to follow as closely as possible behind the paving machine. A second roller of weight 6 tons was used to carry out the finishing compaction of the mat.

The heavier roller was not using a sprayer to wet the steel rollers. Instead it

used a dripper with holes at close distances that allowed the water to drip onto the steel wheels. Some of the holes were blocked and the water that came out from the rollers was dirty probably due to the rusting of the steel container on the tandem. As such the water that dripped out was not consistent, with some areas getting more water than others. There was water droplets observed on the surface of the SMA mat at areas with too much water dripping onto the mat. On the other hand where the holes were blocked, there was some mix that was observed to be sticking to the wheels of the tandem. The roller had to stop occasionally on the mat to rectify the blocked holes of the dripper.


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The second smaller roller did not encounter this problem as it used the sprayer to discharge the water onto the steel rollers, instead of the dripper. Both the rollers were observed to have exceeded the proposed rolling pattern for the number of passes. We highlighted this to the contractor and advised the contractor to monitor and control the rolling pattern.

In the meantime the second lorry arrived at the site at 4.30 pm. The temperature was taken on top of the lorry and was recorded to be 160˚C. The SMA was loaded onto the paving machine and the laying continued up to Ch 8 + 060. Since there was some balance of the mix in the lorry, the contractor was allowed to lay from Ch 8 + 040 to Ch 8 + 020, after skipping the areas with contaminated surfaces from Ch 8 +060 to Ch 8 + 040.

The laying was completed at around 4.45 pm. During the laying, the temperature of the mat was checked to be at 120°C when the compaction was first started. The compaction was finally completed at about 5.00 pm.

In conclusion, the batching of the SMA mix appeared to be in order. The mix was batched at the allowable temperature range and the mix appeared to be consistent. The test results of the mix after the trial lay such as sieve analysis, binder content, Marshall Properties, Schellenberg Binder Drain-off Test and Cantabro Abrasion Test are in compliance with the requirements of the Specifications. The only test results pending are the physical and mechanical properties of the aggregates.

The mix that arrived at the trial lay area was checked to be within the acceptable range of temperatures, and there was no sign of binder drainage of the SMA mixture. There was no problem encountered with the laying of the SMA mixture. The mixture was easily laid and the mat looked consistent after laying. There was also a minor problem with the compaction on the mat when the water did not discharge due to the blocked holes. As a result, some mix was observed to be sticking to the wheels of the rollers.

We would like to highlight some of the matters and problems we observed before and during the trials, which are:-

1. Planning.

The contractor who planned the trials at 9.00 am somehow had forgotten about the Neomed tack coat. This had resulted in the delay in the batching of the mix until 1.00 pm. The contractor was lucky that the weather was fine that day. Otherwise the trials would have to be postponed.

2. Surface preparation.

The surface to receive the SMA mix was not thoroughly cleaned, especially along the edges next to the shoulder drain. Neomed tack coat was observed to have been sprayed on top of loose sand and earth. If SMA was allowed to be laid on top of these areas, it would have caused the mat to fail during the compaction.

3. Water Sprayer for Rollers.

The water sprayer is recommended to be used over dripper for all compactor rollers since the sprayer gives out a uniform spray of water. Unlike dripper, sprayer will not get blocked easily, and thus will give a uniform spray which will eliminate the mix from sticking to the wheels of the rollers.


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4. Rollers Stopping and Standing on Newly Compacted Mat. The rollers were observed to be stopping on the surface of the newly laid and compacted mat,

which was not advisable since depression on the mat could occur if the rollers were left standing for a long period of time.

5. Rolling Pattern.

The proposed number of passes of the compactor rollers was again not followed. The rollers’ operators were seen to go back and forth on the mat with no account of the number of passes. In addition, the big roller was not following closely to the paving machine.

6. Final Finishing Rolling by the Smaller Tandem Roller.

There were no personnel on the contractor side to check the finished surface after the smaller compactor had completed the rolling. We observed that at some areas, the surface was not yet fully compacted. We had to ask the tandem operator to come back to re-compact the mat that was not properly compacted.

Our recommendations and suggestions for carrying out any future SMA laying are as follow:-

To better organize and plan properly for future laying. To ensure that all materials are in order and are readily available; equipment and machineries are adequate and in good working conditions; and manpower are sufficient. To also ensure that the surface to receive the mix is thoroughly cleaned to be free from dust and loose materials and Neomed is uniformly applied.

To provide a portable density tester such as Nuclear Density Gauge that can provide quick density results in order to prevent over compaction. The use of a Nuclear Density Gauge will eliminate the confusion on the number of passes of each roller, and thus will ensure that the newly laid and compacted mat will not be overly or under compacted.

To have the big roller following the paving machine closely. As soon as the mat is laid, it needs to be compacted quickly since the temperature of the mat drops very fast. Before the temperature of the mat drops to below 135°C, it needs to be quickly compacted, failing which the compaction may not be able to achieve the requirements of 98 to 100% of the Marshall Density and the durability of the mat will be compromised. The smaller roller is for final finishing rolling to remove any blemishes and irregularity on the surface of the mat.

Both the rollers are not allowed to stand or stop on top of the newly laid and warm compacted materials. The rollers shall be driven outside the newly laid areas for carrying out repairs and adjustments.

To designate someone to keep track of the number of passes of each roller so that over-compaction can be avoided. The same personnel shall check and inspect the mat during and after compaction so that any area that was not properly compacted could be immediately re-compacted with the smaller roller.

To ensure that all the rollers shall be installed with the water sprayer instead of the water dripper since the sooner will give a much uniform spray and the holes will not be easily blocked. Whichever system is used, the operation shall control and adjust the amount of water


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coming out. Too much water will cause the mat to cool down faster and too little water will cause the mix to stick to the wheels of the rollers. Scrappers for keeping the rollers clean and wetting pads to keep the rollers wet are also recommended to be installed on to the rollers so that the rollers are not stopped every time to remove the mix sticking to the wheels of the rollers.

To replace the short ski or shoe with a long tubular grade or a floating-beam grade on the paving machine. The present short ski or shoe is not effective in averaging out the differences and variations in elevation and grade of the existing pavement surface in the longitudinal direction. We prefer a long tubular grade or a floating-beam grade of minimum length 6 meters long.


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Photographs from the Third Trial Lay on 19 July 2007.

Photo 1: Start of Laying

Photo 2: Temperature of the Mat after Laying and before Compaction.


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Photo 3: Compaction of the Mat from a 10-ton Tandem Roller.

Photo 4: Compaction of the Mat from a 6-ton Tandem Roller.


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Photo 5: Compaction in Progress for Both Rollers.

Photo 6: The Big Roller Was following Closely to the Paving Machine.


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Photo 7: The Big Roller Was Standing on Newly Laid Mat, which is not Advisable.

Photo 8: Final Finished Surface of SMA.


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APPENDIX G

Observations on Package 3A2’s First SMA Plant Trial at Kajang Rocks Innopave Premix and Trial Lay from Ch 15+950 – Ch 15+770 SB on November 19, 2007.



9.25 am Arrived Kajang Rocks Innopave Premix in Kajang .Weather was cloudy with intermittent rain at the quarry and at the trial lay area. At the time of arrival at Kajang, the batching plant was producing mix for other client.

11.00 am Preparation to start the batching of SMA.

11.20 am Started batching.

11.37 am The SMA mixture was loaded onto the first lorry. The mix looked fine and there was no sign of bitumen drainage. The temperature recorded on top of the first lorry using the infra-red digital thermometer was 181.5°C. The mix was covered with a double sheeted tarpaulin sheet.

11.51 am The SMA mixture was loaded onto the second lorry. The mix also looked fine and there was no sign of bitumen drainage. The temperature recorded on top of the second lorry using the infra-red digital thermometer was 171.5°C. The mix was covered with a triple tarpaulin sheet.

12.11 pm After weighing in at 25.83 tons, the second lorry left the batching plant.

1.50 pm The first lorry arrived at the trial lay area. The second lorry arrived ten minutes after the first lorry.

Earlier, the trial lay area of width 3.00 meters and length 180 meters was sprayed with Neomed tack coat. The trial lay area was located at the exit ramp of Bukit Beruntung Interchange SB towards Rawang (Ramp D) from Ch 15+950 to Ch 15+770. The temperatures taken on top of the first and second lorries using the normal premix thermometer were both at 170°C respectively. In addition to testing the SMA material from Kajang Rocks Innopave Premix for approval to be used for this project, this trial was also intended to investigate the temperatures of the material after the 3-hour period, as specified in the Specifications.

2.22 - 3.10 pm The mix from the first lorry was loaded onto the paving machine. The temperature of the mix in the hopper of the paving machine was at 185°C, which was quite high. Paving started when the temperature cooled down to below 155°C. The mix that came out from the screed looked consistent, with a constant un-compacted thicknesses varying from 47 to 50 mm. The temperature taken at the laid SMA or mat was at 150°C. The first Macadam roller of 12 tonnes started to compact with no vibration allowed. The proposed rolling pattern was 3 passes for both the rollers. After 3 passes of the first roller, the mat was observed to be smooth and dense. There was practically little movement of the mat when the roller traversed on the edge of the laid SMA mix. The first roller then began to move forward to follow as closely as possible behind the paving machine. A second tandem roller of 8 tonnes was used to carry out the finishing compaction of the mat. The mat seemed to be


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fine during the first few passes of the second tandem roller. There seemed to be some slight movement of the mat as the second tandem rollers were compacting to correct the irregularities and uneven surfaces. In addition, each time when the old irregularities were eliminated, new ones were formed along the edges of the wheels of the tandem roller.

In the meantime, the temperatures of the materials from the second lorry were checked at intervals of every half hour after the 3-hour period. At 3.10 pm, the temperature was at 165˚C and at 3.40 pm, the temperature was at 155˚C, after 3.5 and 4 hours after the time of batching respectively. The contractor decided to stop the temperature checking after the 4-hour period after batching and to start laying the SMA from the second lorry.

3.50 – 4.25 pm The mix from the second lorry was loaded onto the paving machine. The temperature of the mix in the hopper of the paving machine was at 150°C. Paving started. The mix that came out from the screed looked consistent, with constant un-compacted thicknesses varying from 47 to 50 mm. The temperature taken at the laid SMA or mat was at 145°C. All the temperatures recorded up to 4 hours after batching were found to be in compliance with the requirements of the Specifications.

In conclusion, the batching of the SMA mix appeared to be in order. The mix was batched at the allowable temperature range and the consistency of the mix appeared to be acceptable (pending the test results of the mix such as sieve analysis, binder content, Marshall Properties, Schellenberg Binder Drain-off Test and Cantabro Abrasion Test). The mix that arrived at the trial lay area was checked to be within the acceptable range of temperatures, and there was no sign of binder drainage of the SMA mixture.There was also no problem encountered with the laying of the SMA mixture. The mixture was easily laid and the mat looked consistent after laying. Initially, there was also no problem associated with the compaction on the mat for both rollers, but as the second tandem rollers began to compact more to remove the uneven surfaces, the laid mat started to move slightly and more uneven surfaces and irregularities began to form at both ends of the wheels of the tandem roller. The mat seemed to have become slightly tender. However there was no crushing of the aggregates observed on the surfaces of the compacted mat. The probable cause of the tenderness of the mat when being compacted by the second 8 tonnes tandem roller was that the second roller was too heavy.


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Our recommendations and suggestions are as follow:-

To provide a portable density tester such as Density Nuclear Gauge which can provide quick density results in order to prevent over compaction;

To install wetter on both the rollers to minimize the amount of water used for the compaction. Both the rollers were equipped with the sprayer system. The operators shall control and adjust the amount of water coming out form the sprayers. Too much water will cause the mat to cool down fast and too little water will cause the mix to stick to the wheels of the rollers;

To use a tandem roller of 6 tonnes instead of the present 8 tonnes for the finishing compaction. A lighter compactor is sufficient to provide the finishing compaction and may prevent the mat from being overly compacted in removal of any irregularities and unevenness of the surfaces;

To monitor the production at the batching plant to ensure that the mixing temperatures are between 150°C to 180°C. Under no circumstances that the mixing temperature is allowed to greatly exceed the maximum 180°C. The temperature of the mix inside the hopper for the first load was recorded at 185°C, after an elapsed time of more than 2 hours after batching, which implied that the mixing temperature had exceeded 190°C. The plant personnel should pay particular attention to the mixing temperatures, especially at the start of batching.

To ensure that both the rollers are not allowed standing or stopping on top of the newly laid and compacted materials. This will leave indentation marks or depression on the laid surfaces, which might not be easily spotted and corrected. In the event of minor breakdown, the rollers shall be taken outside the newly laid areas for carrying out repairs and adjustments; and

To designate someone to keep track of the number of passes of each roller so that over-compaction can be avoided. The same personnel shall check and inspect the mat during and after compaction so that any area that was not properly compacted could be immediately re-compacted with the smaller roller.


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Photo 1: Prepared Surface Sprayed with Neomed

Photo 2: Start of Discharge of Mix onto Paving Machine.


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Photo 3: Start of Laying.

Photo 4: Start of Compaction Using Macadam Roller of 12 Tonnes.


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Photo 5: Tandem Roller of 8 Tonnes Used for Finishing Compaction

Photo 6: The Material Coming Out from the Paver Machine looked Consistent.


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Photo 7: Both Rollers In Action.

Photo 8: View of the Compacted Mat.
