Composites: Part B 54 (2013) 255–264

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Composites: Part B

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Rutting evaluation of stone mastic asphalt for basalt andbasalt–limestone aggregate combinations

1359-8368/$ - see front matter � 2013 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.compositesb.2013.05.019

⇑ Tel.: +90 462 7717250; fax: +90 462 7717251.E-mail addresses: eroliskender@gmail.com, eiskender@ktu.edu.tr

Erol _Iskender ⇑Karadeniz Technical University, Faculty of Technology, Civil Engineering Department, 61830 Trabzon, Turkey

a r t i c l e i n f o a b s t r a c t

Article history:Received 16 October 2012Received in revised form 4 December 2012Accepted 20 May 2013Available online 1 June 2013

Keywords:B. High-temperature propertiesB. Plastic deformationC. Damage mechanicsD. Mechanical testingStone Mastic Asphalt (SMA)

The purpose of this study is to investigate the rutting of basalt and basalt–limestone aggregate combina-tions for coarser and finer SMA mixtures with a Laboratoire Central des Ponts et Chaussées (LCPC) wheeltracking test. The sensitivity of the LCPC wheel tracking test was also evaluated with different maximumaggregate sizes and changes in gradation. The coarse aggregate in the mixture was basalt. Four differentrock combinations were designed with basalt and limestone aggregates for filler and fine fractions. Inaddition to the gradation evaluation, the maximum aggregate size effects were studied with four grada-tions. Decreasing the maximum aggregate size is at the utmost importance on rutting resistance, accord-ing to the gradation and mineralogical factors of aggregate. It is believed that limestone aggregate can beused as filler and fine fractions in SMA with basalt. This matter has great importance for shortage of basaltaggregate quarries and management difficulties for these quarries. This provides added value for Turkey’shighway investments. Rutting resistance of SMA mixture relatively decreased in the incorporation oflimestone aggregate in the SMA mixture gradation as fine or filler aggregate (an average of 0.24% forSMA11 and SMA12, and 0.41% for SMA21 and SMA22). This low-level rutting difference can easily beobserved with LCPC wheel tracking tests. Reliability of LCPC test was clearly demonstrated.

� 2013 Elsevier Ltd. All rights reserved.

1. Introduction The major conclusions from the study were: (1) 85% of the sur-

Stone Matrix Asphalt (SMA) is a hot mixture asphalt consisting ofa coarse aggregate skeleton and a high binder content mortar. SMAwas developed in Germany during the mid-1960s and has been usedin Europe for more than 20 years to provide better rutting resistanceand to resist studied tire wear. Because of its success in Europe, someAmerican States, through the cooperation of the Federal HighwayAdministration, constructed SMA pavements in the United Statesin 1991. Since then, the usage of SMA in the US has increased signif-icantly. Japan also started to use SMA paving mixtures with greatsuccess. Recently the Ministry of Communications in Saudi Arabiahas introduced SMA as its road specifications. In addition, one testroad was constructed in the Eastern Province of Saudi Arabia.According to the SMA Technical Working Group, SMA is a gap-graded aggregate–asphalt hot mixture that maximizes the asphaltcement content and coarse aggregate fraction. This provides a stablestone-on-stone skeleton that is held together by a rich mixture of as-phalt cement, filler, and stabilizing additive [1].

A study was carried out to evaluate the performance of SMA inthe United States by evaluating 86 SMA projects. Data was col-lected in material and mixture properties, and performance wasevaluated on the basis of rutting, cracking, raveling, and fat spots.

veyed projects had an aggregate Los Angeles abrasion value greaterthan 30%; (2) SMA mixtures were produced in 90% of the time with25–35% of the material passing through the 4.75-mm sieve and80% of the time with 7–11% of the material passing through the0.075-mm sieve; (3) 30% of the surveyed projects had average airvoids during construction of less than 3%; (4) 60% of the projectsexceeded 6.0% asphalt content; (5) over 90% of the SMA projectshad rutting measurements of less than 4 mm; (6) SMA mixturesappeared to be more resistant to cracking than dense mixtures;(7) there was no evidence of raveling on the SMA projects; (8) fatspots appeared to be the biggest performance problem in SMAmixtures [2].

SMA is a gap-graded mix containing a high concentration ofcoarse aggregate (>70%), which maximizes stone to stone contactand provides an efficient network for load distribution. It is gap-graded, as this mix has very little material that is retained on thesand sized sieves (between 2.36 and 0.075 mm). The coarse aggre-gate particles are held together by a rich matrix (mastic) of mineralfiller, fiber, and polymer in a thick asphalt film. The differences be-tween SMA and dense graded mixes are the stone skeleton inwhich the load is carried and the higher asphalt content which is(6–7.5%) weight of the total mix [3,4].

According to the European study tour report, SMA in the UnitedStates was adopted after 1990 European asphalt study tour of sixEuropean nations. This study tour played a major role in the USA’s

Table 1SMA gradations for Turkey and Germany.

Sieve size (in.) Sieve size (mm) SMA 0/12.5 SMA 0/9.5 Tolerance limits (%)Percentage passing (%) Percentage passing (%)

Gradation for Turkey [9]3/4 19.0 100 –1/2 12.5 90–100 100 ±43/8 9.5 50–75 90–100 ±4No. 4 4.75 25–40 30–45 ±3No. 10 2.00 20–30 20–30 ±3No. 40 0.42 12–22 12–22 ±3No. 80 0.177 9–17 9–17 ±3No. 200 0.075 8–14 8–14 ±2

Gradation for Germany [11]Sieve size 0/11 S 0/8 S 0/8 0/516 mm 100 – – –11 mm 90–100 100 100 –8 mm 60 max 90–100 90–100 1005 mm 30–40 30–45 30–55 90–1002 mm 20–25 20–25 20–30 30–40Filler (<90 lm) 9–13 10–13 10–13 10–13

Stabilisers [11] 0.3% minBinder type B65/PmB45 B65/PMB45 B80 B80/B200Binder content (%) >6.5 >7.0 >7.0 >7.2Laid thickness (mm) 35–50 30–40 25–35 15–25Voids content (%) 3.0–4.0 3.0–4.0 2.0–4.0 2.0–4.0

Fig. 1. Basaltic rocks formation of Eastern Black Sea Region [10].

256 E. _Iskender / Composites: Part B 54 (2013) 255–264

adoption of SMA as an alternative asphalt mixture. SMA in the Uni-ted States is known as stone matrix asphalt, which is simply theAmericanized version of the SMA in Europe [5].

According to the performance evaluation by National Center forAsphalt Technology (NCAT), SMA is found to be highly resistant torutting, cracking and other distresses compared to conventionalHMA mixes [6]. According to the state department of highways,SMA provided 33–103% longer service life than conventionaldense-graded mixes [7].

Hot mix asphalt (HMA) pavements have always been affectedby the susceptibility for permanent deformation or rutting in theUnited States. Rutting is the accumulation of small amounts ofunrecoverable strain caused by applied wheel loads. The strain iscaused by consolidation or lateral movement, or both, of theHMA under traffic loading. The potential for rutting has recentlyincreased in the nation’s highways due to higher traffic volumesand increased the usege of radial tires that typically exhibits inhigher inflation pressures. Hence, a standardized laboratory equip-

Table 2A range of different European countries, which use SMA [12].

Different European countries using SMAAustria Greece PolandBelgium Hungary PortugalCroatia Iceland RomaniaCzech Republic Ireland SlovakiaDenmark Italy SloveniaEstonia Latvia SpainFinland Lithuania SwedenFrance Luxembourg SwitzerlandGermany Netherlands TurkeyGreat britain Norway

SMA is also proved in the following countries worldwide as a high stable asphaltconcept:

Argentina Guatemala MalaysiaAustralia Hong Kong MexicoBrazil India New ZealandBulgaria Iran PhilippinesCanada Israel TaiwanChile Japan VenezuelaChina Korea

E. _Iskender / Composites: Part B 54 (2013) 255–264 257

ment and test procedure that predicts rutting potential in the fieldwould be a great benefit to the HMA industry. The most commontypes of laboratory equipments of this nature that are currentlyused are loaded wheel testers. There are different kinds of loadedwheel testers that are used in the United States. These are theGeorgia Loaded Wheel Tester (GLWT), Asphalt Pavement Analyzer(APA), Hamburg Wheel Tracking Device (HWTD), LCPC (French)Wheel Tracker, Purdue University Laboratory Wheel Tracking De-vice (PUR Wheel), and one-third scale Model Mobile Load Simula-tor (MMLS3) [8].

Turkey has introduced its own SMA specifications (part 408).The bitumen standard must be suitable with TS 1081 EN 12591.40/60 penetrations bitumen binder or a 50/70 binder should beused. Fiber should be used as a bitumen drainage inhibitor. Fibershould be added to the mixture as 0.3–1.5% weight of total mix-ture. Aggregate gradations are given in Table 1 for Turkey [9]. Tur-key SMA project implementation manifested an important subjectwithin the Eastern Black Sea Region. The cities of the Eastern BlackSea Region, including Rize, Artvin, Trabzon, Gümüs�hane, Giresunand Ordu have a large landfill area with the basaltic rock forma-tions. The Eastern Black Sea Region is the land along the BlackSea coast, and except Gümüs�hane, all cities have sea ports. SMA

Table 3Used gradation and fraction proportions in the study and gradation for Turkey trial.

Sieve size (in.) Sieve size (mm) SMA11 SMA12

Used gradation3/4 19.0 100 Coarse aggregate,

70.9%100 Coarse ag

63.9%1/2 12.5 92.7 963/8 9.5 63.5 70No. 4 4.75 29.1 Fine aggregate, 18.7% 36.1 Fine aggrNo. 10 2.00 21.6 27.3No. 40 0.42 14.8 19.2No. 80 0.177 12.4 14.4No. 200 0.075 10.4 Filler, 10.4% 10.9 Filler, 10.

Aggregate grading for 0/12.5 SMA trial [11]Sieve size (mm) Basalt % passing Basalt % passin

3/4–3/8 1/2 – No.419 (3/400) 100 –12.5 (1/200) 84.8 1009.5 (3/800) 10.1 83.54.75 (No.4) 0.6 3.52 (No.10) 0.5 1.00.42 (No.40) 0.5 0.90.177 (No.80) 0.4 0.80.075 (No.200) 0.4 0.8

enforcement in Turkey by the General Directorate for Highwaysadds value to the Eastern Black Sea Region because of its rich basal-tic rocks and quarries. In Fig. 1, the basaltic rock distribution of theBlack Sea Region is presented. Before SMA application, densegraded wearing courses were constructed, mostly limestone aggre-gates, but limited limestone aggregate can be used as a coarseaggregate in SMA pavement types because of coarse aggregatestone and stone contact or else strength of this material. Thereare many different limestone quarries in this region and these re-sources can be used as fine and filler materials in SMA design withbasaltic rocks. Thus, both basaltic new formations and old lime-stone deposits can be used together.

The purpose of this study is to investigate the rutting of basaltand basalt–limestone aggregate combinations for coarser and finerSMA mixtures. The sensitivity of the LCPC wheel tracking test werealso evaluated with different maximum aggregate size and grada-tion changing.

2. Materials and method

The SMA gradations are illustrated in Table 1 for Turkey andGermany, and a range of different European countries that useSMA are given in Table 2.

The gradations that were used are defined in Table 3. A grainsize distribution curve can be seen in Figs. 2 and 3.

Basalt and limestone aggregate properties are given in Table 4.Basalt aggregate was defined with wise mineralogical tests interms of rock petrography. A chemical analysis for the main oxidesand an X-ray analysis were conducted. Basalt mineralogical com-position was defined with these tests and confirmed by truly mate-rial selection. The chemical compositions of the rocks, both basaltand limestone, are presented in Table 5.

Figs. 4 and 5 show thin section images of the limestone and ba-salt aggregates respectively. The basaltic rocks chosen for theaggregate were made up for plagioclase phenoscrysts set in micro-litic groundmass and secondary chlorite and calcite were observedin the samples.

X-ray diffraction (XRD) was performed on the basalt and lime-stone samples. Results are given in Fig. 6 for the basalt sample andin Fig. 7 for the limestone sample.

Bitumen properties, cellulose fiber properties and Marshall de-sign results are given in Table 6–8. AC50-70 penetration bitumen

SMA21 SMA22

gregate, Coarse aggregate,65.9%

Coarse aggregate,59.6%

100 10092.3 93

egate, 25.2% 34.1 Fine aggregate, 22% 40.4 Fine aggregate, 25.3%21.3 26.614.4 18.112.1 15.1

9% 10 Filler, 10% 12.5 Filler, 12.5%

g Limestone % passing Limestone % passing

No.4 Filler– –– –100 –99.8 –73.2 10028.8 96.016.8 79.811.2 57.2

0

10

20

30

40

50

60

70

80

90

100

0.01 0.10 1.00 10.00 100.00

Perc

enta

ge P

assi

ng, %

Sieve Size, mm

Upper limit

SMA 11

SMA 12

Lover limit

Fig. 2. Gradation curve for SMA11 and SMA12.

0

10

20

30

40

50

60

70

80

90

100

0.01 0.10 1.00 10.00 100.00

Perc

enta

ge P

assi

ng, %

Sieve Size, mm

Upper limit

SMA 21

SMA 22

Lover limit

Fig. 3. Gradation curve for SMA21 and SMA22.

258 E. _Iskender / Composites: Part B 54 (2013) 255–264

was used. SMA11–SMA12 and SMA21–SMA22 mixtures were de-signed. Designs were found as suitable for Turkey boardspecifications.

Table 4Properties of used basalt and limestone aggregates.

Properties Test method

Specific gravity (coarse agg.) ASTM C 127BulkApparentSpecific gravity (fine agg.) ASTM C 128BulkApparentSpecific gravity (filler)Los Angeles abrasion (%) ASTM C-131Flakiness (%) BS 812 (Part 105)Stripping resistance (no additive) (%) ASTM D-1664Stripping resistance (Wetfix BE, 0.4% additive) (%) ASTM D-1664Water absorption (%) ASTM C-127Soundness in NaSO4 (%) ASTM C-88Plasticity index for sandy aggregate TS 1900

3. Rutting evaluation with LCPC wheel tracking tests

The Laboratorie Central des et Chausees (LCPC) wheel tracker[also known as the French Rutting Tester (FRT)] has been used inFrance for over 15 years successfully to prevent rutting in HMApavements. The FRT has recently been used in United States, espe-cially in Colorado and FHWA’s Turner Fairbank Highway ResearchCenter. The FRT is capable of simultaneously testing of two HMAslabs with dimensions of 180 mm wide, 50 mm long, and 20–100 mm thick (7.1 in. � 19.7 in. � 0.8 to 3.9 in.). The samples arecompacted with a LCPC laboratory-tired compactor. Loading ofsamples is accomplished by applying a 1124-lb. load onto a400 � 8 Treb Smooth pneumatic tire inflated to 87 psi. The pneu-matic tire passes over the center of the sample twice per second[8]. Samples were prepared at a 50 mm height. The test tempera-ture was 60 �C. Samples were kept at least 12 h at this temperaturelevel.

Wheel-tracking devices are popular to estimate or evaluate thepermanent deformation of asphalt pavement. The Hamburg WheelTracking Device (HWTD), the Georgia Loaded Wheel Tester(GLWT), the Asphalt Pavement Analyzer (APA), the LCPC (French)Wheel Tracker, the Purdue University Laboratory Wheel trackingDevice (PUR Wheel), and the one-third scale Model Mobile LoadSimulator (MMLS3) are the currently available devices in world-wide. Each wheel-tracking device has its own advantages and dis-advantages. Advantages include similar rutting and deformationvalues of field performance for HMA. Disadvantages are differentcompaction and tests devices lack of other pavement coarse typeeffects, steel wheel effects and single adopted axles [13].

LCPC test results are presented in Tables 9–12 for SMA11–12–21–22 mixtures for 1000, 3000, 5000, 10,000, 30,000, 50,000 cy-cles. Rutting values for basalt and basalt–limestone combinationsare illustrated in Figs. 8–11.

In the event of basalt aggregate as the coarse aggregate, all mix-tures resemble rut resistance as presented in Fig. 8–11. A coarseaggregate provides a mechanical orientation and creates interlock-ing, while other aggregates fill the mastic part of the selected gra-dation. In Turkey, SMA is an innovative mixture and lots oflimestone quarries are concerned. Within this scope, limestonedeposits have great importance for both dense and gap-gradedmixture gradation. Harmonious results can be obtained with LCPCwheel tracking tests for different SMA gradation. Rutting evalua-tion can be made truly with LCPC wheel tracking tests. Thesetrends are valid for SMA11–12 and SMA21–22 mixtures.

Aggregates constitute about 95% of hot mix asphalt (HMA) mix-tures. The most important features of aggregates in HMA mixturesare the aggregate shape, gradations, and types. The importance of

Value Specification limit in Turkey

Basalt Limestone

2.684 2.6502.744 2.716

2.656 2.6212.754 2.7372.821 2.81012 14 Max 2514 13 Max 2535-40 30-3580-85 80-85 Min 600.81 1.18 Max 20.92 4.56 Max 8Non-plastic Non-plastic Non-plastic

Table 5Chemical analysis results of used aggregates.

Components (%) Formula Basalt aggregate Limestone aggregate

Sample 1 Sample 2 Sample 1 Sample 2

Silicium dioxide SiO2 57.28 59.41 5.52 7.53Aluminum oxide Al2O3 13.58 13.44 0.45 0.53Ferrous oxide Fe2O3 6.75 6.72 0.88 0.61Calcium oxide CaO 5.25 4.49 46.47 39.45Magnesium oxide MgO 3.41 3.75 1.83 1.50Sulfur trioxide SO3 0.00 0.00 0.00 0.00Sodium oxide Na2O 1.95 1.68 0.56 0.00Potassium oxide K2O 1.78 2.63 0.83 0.34Chlorine Cl- 0.0216 0.0260 0.0127 0.0064Loss on heating 4.68 3.01 36.23 33.51Calcium carbonate + magnesium carbonate CaCO3 + MgCO3 5.30 2.80 86.90 83.30

Fig. 4. Thin section image of limestone aggregate.

Fig. 5. Thin section image of basalt aggregate.

0

20

40

60

80

100

120

5 10 15 20 25 30 35 40 45 50 55 60 65

Inte

nsity

(co

unts

)

Theta (deg)

Fig. 6. XRD traces of crack surface of basalt sample.

0

100

200

300

400

500

600

5 10 15 20 25 30 35 40 45 50 55 60 65

Inte

nsity

(co

unts

)

Theta (deg)

Fig. 7. XRD traces of crack surface of limestone sample.

Table 6The results of tests performed on asphalt cement (AC 50-70).

Properties Test method Unit Value

Specific gravity (25 �C) ASTM D-70 g/cm3 1.025Softening point (�C) ASTM D36-76 �C 52Flash point (Cleveland) ASTM D-92 �C 240Penetration (25 �C) ASTM D-5 0.1 mm 63Ductility (25 �C) ASTM D-113 cm 100+

E. _Iskender / Composites: Part B 54 (2013) 255–264 259

aggregate characteristics to the performance of HMA mixtures hasbeen emphasized in the super-pave mixture design procedure. Cer-tain gradation limits for different nominal maximum size aggre-gates as well as aggregate consensus tests, have been put intosuper-pave mixture design guidelines. In addition, it has been sug-gested that gap-graded Stone Mastic Asphalt (SMA) has a great po-tential to form strong, durable pavements. When the gap-gradedSMA mixes are used, the influence of coarse aggregate propertiesbecome even more prominent [14]. The use of basalt in asphalt

concrete mixes was evaluated and the optimal mix was found tobe basalt coarse aggregate, limestone fine aggregate and mineralfiller, 1% hydrated lime by total weight of aggregate was [15].The SMA mixture gradation can be constituted with differentaggregates in terms of coarse, fine, and filler aggregates. Limestone

Table 7Conventional properties of cellulose fiber.

Properties Value

Cellulose content (%) 66.7Bitumen content (%) 33.3Inflammability temperature (�C) �500Apparent density (g/l) 480–530Average particle thickness (mm) 4 ± 1Average particle size (mm) 2–8Physical shape Cylindrical dollop

260 E. _Iskender / Composites: Part B 54 (2013) 255–264

can be used for a limited aggregate type such as coarse becausemechanical strength for stone on stone contact is a problem forSMA. Fine and filler aggregates may be selected as limestone.Figs. 8–11 clearly show that basalt–basalt–basalt combinationsprovide the highest rutting resistance.

Table 8Marshall design test results.

Design parameters Mixtures

SMA11 SMA12

Bulk specific gravity, Gmb 2.433 2.432Marshall stability (kg) 1200 1130Air voids, Pa (%) 3.0 2.9Void filled with asphalt, Vf (%) 81.4 82.1Flow, F, 1/100 in. 3.1 3.4Asphalt cement, Wa 6.10 6.25Voids in mineral aggregate (%) 16.1 16.2Schellenberg binder drainage test (%) 0.19 0.17

Table 9LCPC test results of SMA11.

Aggregate combination Measurement Number of cycles/r

1000 3

Basalt basalt basalt Left wheel 2.81 3Right wheel 2.19 3Average 2.50 3

Basalt basalt limestone Left wheel 1.98 3Right wheel 2.42 3Average 2.20 3

Basalt limestone limestone Left wheel 3.36 4Right wheel 2.55 3Average 2.96 3

Basalt limestone basalt Left wheel 2.55 3Right wheel 2.53 3Average 2.54 3

Table 10LCPC test results of SMA12.

Aggregate combination Measurement Number of cycles/r

1000 3

Basalt basalt basalt Left wheel 2.38 3Right wheel 2.91 3Average 2.65 3

Basalt basalt limestone Left wheel 3.63 4Right wheel 2.10 2Average 2.87 3

Basalt limestone limestone Left wheel 3.78 4Right wheel 2.25 3Average 3.02 3

Basalt limestone basalt Left wheel 4.24 5Right wheel 3.06 3Average 3.65 4

SMA asphalt pavements were evaluated with limestone and ba-salt aggregates. Rut depth (mm) at 19,200 cycles for limestone andbasalt were obtained with a UTM Machine. At a 60 �C test temper-ature, rut depths were calculated as 4.6 mm for limestone aggre-gate and 1.3 mm for basalt aggregate. The basalt aggregate had a72% rutting reduction. Also, rut depth (mm) at 200,000 cycles forlimestone and basalt were saved. At a 60 �C test temperature, rutdepths were calculated as 21.7 mm for limestone aggregate and2.6 mm for basalt aggregate. The basalt aggregate had an 88% rut-ting reduction. Same number of loading cycles to rutting failurewas studied. Rutting failure was shown with 48,000 loadings forlimestone, but 167800 loadings for basalt rock. A 250% increasein rutting failure resistance was found [16]. Rutting ratios for dif-ferent rock combinations are illustrated in Figs. 12–15. As shownin Fig. 16, rutting resistance for a completely basalt aggregate com-bination for 19 mm maximum nominal size (SMA11–12) was 20%

Board in Turkey

SMA21 SMA22 Min. Max.

2.416 2.415 – –1050 1040 – –3.3 3.4 2 480.4 80.0 – –3.3 3.5 – –6.30 6.4516.8 17.0 16 –0.20 0.16 – 0.3

ut depth (%)

000 5000 10,000 30,000 50,000

.77 4.39 4.97 5.36 5.59

.18 3.75 4.43 4.87 5.19

.48 4.07 4.70 5.12 5.39

.05 3.90 4.56 4.83 5.07

.58 4.37 4.99 5.34 5.63

.32 4.14 4.78 5.09 5.35

.10 4.71 5.53 5.89 6.17

.34 3.89 4.47 4.86 5.12

.72 4.30 5.00 5.38 5.65

.73 4.48 5.30 5.87 6.04

.38 3.96 4.61 4.96 5.14

.56 4.22 4.96 5.42 5.59

ut depth (%)

000 5000 10,000 30,000 50,000

.26 3.97 4.98 5.73 6.28

.41 3.87 4.43 4.84 5.14

.34 3.92 4.71 5.29 5.71

.34 4.87 5.36 5.85 6.19

.98 3.65 4.57 5.26 5.41

.66 4.26 4.97 5.56 5.80

.41 4.91 5.49 5.94 6.33

.24 3.93 4.74 5.37 5.75

.83 4.42 5.12 5.66 6.04

.08 5.42 5.66 5.99 6.16

.79 4.48 5.06 5.57 5.82

.44 4.95 5.36 5.78 5.99

Table 11LCPC test results of SMA21.

Aggregate combination Measurement Number of cycles/rut depth (%)

1000 3000 5000 10,000 30,000 50,000

Basalt basalt basalt Left wheel 3.51 4.35 4.89 5.67 6.41 6.95Right wheel 3.07 4.31 5.16 5.80 6.18 6.28Average 3.29 4.33 5.03 5.74 6.30 6.62

Basalt basalt limestone Left wheel 3.45 4.33 4.88 5.53 5.94 6.21Right wheel 3.89 4.81 5.42 6.24 6.87 7.13Average 3.67 4.57 5.15 5.89 6.41 6.67

Basalt limestone limestone Left wheel 4.02 4.86 5.54 6.26 6.81 7.25Right wheel 3.26 4.17 4.86 5.73 6.48 6.77Average 3.64 4.52 5.20 6.00 6.65 7.01

Basalt limestone basalt Left wheel 4.14 5.17 5.66 6.12 6.54 6.76Right wheel 3.76 5.02 5.86 6.51 7.00 7.40Average 3.95 5.10 5.76 6.32 6.77 7.08

Table 12LCPC test results of SMA22.

Aggregate combination Measurement Number of cycles/rut depth (%)

1000 3000 5000 10,000 30,000 50,000

Basalt basalt basalt Left wheel 2.97 4.55 5.39 6.23 6.77 6.92Right wheel 3.73 4.72 5.24 5.98 6.45 6.77Average 3.35 4.64 5.32 6.11 6.61 6.85

Basalt basalt limestone Left wheel 4.19 5.04 5.62 6.17 6.75 7.21Right wheel 2.68 3.79 4.68 5.67 6.26 6.53Average 3.435 4.415 5.15 5.92 6.505 6.87

Basalt limestone limestone Left wheel 3.88 4.78 5.44 6.31 7.16 7.55Right wheel 2.16 3.42 4.41 5.56 6.64 7.01Average 3.02 4.10 4.93 5.94 6.90 7.28

Basalt limestone basalt Left wheel 4.54 5.67 6.27 6.82 7.32 7.68Right wheel 2.99 4.23 5.22 6.17 6.61 6.74Average 3.765 4.95 5.745 6.495 6.965 7.21

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

Basalt basalt basalt

Basalt basalt

limestone

Basalt limestone limestone

Basalt limestone

basalt

Rut

dep

th, %

SMA aggregate combination (coarse-fine-filler)

Fig. 8. Rutting ratio of SMA11 mixture.

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

Basalt basalt basalt

Basalt basalt

limestone

Basalt limestone limestone

Basalt limestone

basalt

Rut

dep

th, %

SMA aggregate combination (coarse-fine-filler)

Fig. 9. Rutting ratio of SMA12 mixture.

E. _Iskender / Composites: Part B 54 (2013) 255–264 261

higher than the 12.5 mm maximum aggregate size (SMA21–22)mixtures.

Stone Mastic Asphalt (SMA) improved for road constructionwhich has been utilized in Europe and America for 40 years is arather new process in Turkey. The use of basalt waste of stone pro-cessing plants as aggregates and mineral filler in SMA might helpto meet increasing aggregate demand. That solves environmentalproblems. In this study, primarily some important material proper-

ties of fine and coarse basalt waste taken from basalt processingplants in Diyarbakir in Turkey such as sieve analysis, chemicalanalysis, specific gravity, water absorption, Los Angeles abrasionloss value, soundness of aggregate by Na2SO4, flakiness index andstripping strength were determined. Then by using this wastematerial, a SMA was designed according to Turkish Highway Tech-nical Specifications. Marshall Stability and flow tests have beencarried out on designed SMA specimens. Test results indicate that

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

Basalt basalt basalt

Basalt basalt

limestone

Basalt limestone limestone

Basalt limestone

basalt

Rut

dep

th, %

SMA aggregate combination (coarse-fine-filler)

Fig. 10. Rutting ratio of SMA21 mixture.

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

Basalt basalt basalt

Basalt basalt

limestone

Basalt limestone limestone

Basalt limestone

basalt

Rut

dep

th, %

SMA aggregate combination (coarse-fine-filler)

Fig. 11. Rutting ratio of SMA22 mixture.

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

0 10000 20000 30000 40000 50000

Rut

dep

th, %

Number of cycles

SMA 11 (coarser)

SMA 12 (finer)

SMA 21 (coarser)

SMA 22 (finer)

Fig. 12. Rutting ratio of basalt–basalt–basalt (coarse–fine–filler) aggregatecombination.

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

0 10000 20000 30000 40000 50000

Rut

dep

th, %

Number of cycles

SMA 11 (coarser)

SMA 12 (finer)

SMA 21 (coarser)

SMA 22 (finer)

Fig. 13. Rutting ratio of basalt–basalt–limestone (coarse–fine–filler) aggregatecombination.

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

0 10000 20000 30000 40000 50000

Rut

dep

th, %

Number of cycles

SMA 11 (coarser)

SMA 12 (finer)

SMA 21 (coarser)

SMA 22 (finer)

Fig. 14. Rutting ratio of basalt–limestone–limestone (coarse–fine–filler) aggregatecombination.

262 E. _Iskender / Composites: Part B 54 (2013) 255–264

properties of the basalt waste and the SMA produced were withinthe specified limits and that these waste materials can be used asaggregates and mineral filler in SMA. Material properties of Diyar-bakir basalt wastes (water absorption, Los Angeles abrasion lossvalue, soundness of aggregate by Na2SO4, flakiness index, strippingstrength) were within the desired limits for the production of SMA.Because of having 1032 kg Marshall stability value, it can be saidthat designed SMA has considerably high strength. Properties ofthe designed SMA such as Marshall stability, Marshall flow, Vh,VMA, amount of fiber and drainage of bitumen were within thetechnical specification limits. Therefore, this SMA can be used inpractice. It is possible to use 667,875 tons basalt wastes if this de-signed SMA is accepted as application project to construct the San-liurfa–Habur Highway 325 km in length and 22 m width in 2011.

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

0 10000 20000 30000 40000 50000

Rut

dep

th, %

Number of cycles

SMA 11 (coarser)

SMA 12 (finer)

SMA 21 (coarser)

SMA 22 (finer)

Fig. 15. Rutting ratio of basalt–limestone–basalt (coarse–fine–filler) aggregatecombination.

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Basalt (coarse)basalt (fine)basalt (filler)

Basalt (coarse)basalt (fine)

limestone (filler)

Basalt (coarse)limestone (fine)limestone (filler)

Basalt (coarse)limestone (fine)

basalt (filler)

Rut

dep

th r

atio

s

Mixture composition

SMA11

SMA12

SMA21

SMA22

Fig. 16. SMA aggregate combination and 19–12.5 mm Dmax mixtures rut depthratios.

E. _Iskender / Composites: Part B 54 (2013) 255–264 263

Using basalt wastes in production of SMA not only solves environ-mental problems but also produces more sustainable and cheaperconstruction materials [17].

The FRT can be used to differentiate between good and poorfield rut performance in the US [18]. The FRT is reportedly not validfor HMA mixtures with a nominal maximum aggregate size(NMAS) greater than 0.8 in. (20 mm). The slab width is relativelysmall compared to the tire width and mixtures with aggregates

Table 13Rutting proportion of SMA mixtures according to aggregate combination.

SMA11 SMA1

Basalt–basalt–basalt 5.39/5.39 = 1 5.71/5Basalt–basalt–limestone 5.35/5.39 = 0.992 5.80/5Basalt–limestone–basalt 5.59/5.39 = 1.037 5.99/5Basalt–limestone–limestone 5.65/5.39 = 1.048 6.04/5

greater than 0.8 in. (20 mm) may be inhibited from shearing out-ward and upward. Aggregates larger than 0.8 in. (20 mm) may alsowear the tires severely and often cannot be compacted properlyusing the French Plate Compactor [19]. The LCPC compactor showsgood correlation with the real field roller. Field roller compactedsamples showed higher permanent deformation than the LCPCcompactor. It is believed that higher void contents can be con-cerned in highway pavements. The original LCPC compactor andfield roller compaction results resembled each other [20]. In thisstudy, LCPC tests revealed harmonious results of 19 mm and12.5 mm aggregate size SMA mixtures shown in Fig. 16 andTable 13.

All proposed methods for estimating rutting require furtherfield and test-track validation. A complete mechanistic validationshould include determining whether the correct plastic strain pro-file, both vertical and lateral, can be estimated. Procedures used bythe Laboratorie Central de Ponts et Chausses (LCPC) for practicalmixture design were described. It was emphasized that for designapplications, laboratory applications, and laboratory simulation ofrutting must duplicate stress conditions in actual pavement [21].

Unconditioned HMA specimens prepared using basalt aggregateresist creep better than those prepared using limestone. However,after conditioning, mixes prepared using basalt were less resistantto creep strain than those prepared using limestone aggregate. Per-cent absorbed asphalt was found to be directly related to strippingresistant. Also, mixes prepared using aggregate following ASTMupper limit of dense aggregate gradation presented the highestresistance to stripping. The results of the calculated adhesion workwere able to detect the effect of stripping on creep behavior formixes prepared [22]. Control specimen tensile strength ratio(TSR) (with no hydrated lime addition) prepared with basalt–lime-stone aggregate mixture is smaller than TSR for the control speci-men prepared with limestone aggregate. On the other hand, aswith the addition of 1% hydrated lime, a significant change in theTSR is observed for both types of aggregate. The trend related tothe TSR changes towards to greater values of TSR for basalt–lime-stone aggregate mixtures compared to limestone aggregate. Thisindicates that the addition of hydrated lime has a more pro-nounced effect on the moisture susceptibility characteristics of ba-salt type aggregate. Hydrated lime improved binder–aggregateadhesion by interacting with carboxylic acids in the asphalt andforming insoluble salts that are readily adsorbed at the aggregatesurface also stated that it is an important reaction since the hydro-xyl (OH) groups are found on the surfaces of siliceous aggregatessuch as basalt. These SiOH groups form hydrogen bonds with car-boxylic acid groups from asphalt and strongly affect the adhesionbetween the asphalt and aggregate [23–25]. Because of the basaltaggregate and hydrated lime anti-stripping agent competition itis thought that this is an important advantage for Turkey. As faras moisture affects and traffic combinations are concerned withmodified SMA is a logical choice for additive applications or elsehydrated lime.

Recently BP has promoted the use of PMB technology in Turkey.In collaboration with Enfalt, BP supplied a PMB for use in an SMAroad trial near to Ankara, Turkey. The binder had to meet the rig-orous requirements of the newly introduced Turkish PMB Specifi-

2 SMA21 SMA22

.39 = 1.059 6.62/5.39 = 1.228 6.85/5.39 = 1.271

.39 = 1.076 6.67/5.39 = 1.237 6.87/5.39 = 1.274

.39 = 1.111 7.08/5.39 = 1.313 7.21/5.39 = 1.337

.39 = 1.120 7.01/5.39 = 1.300 7.28/5.39 = 1.351

264 E. _Iskender / Composites: Part B 54 (2013) 255–264

cations. The mix design was developed by the Turkish HighwayAuthorities (TCK). A limited laboratory test programme was carriedout to ascertain the suitability of the aggregates and filler for theSMA design. A feature of the design (based on a 0/12.5 grading)was that fibers could not be used because the resultant materialwould be prohibitively expensive for the Turkish market. The Olex-obit ‘TS3’ binder (150 tonnes) was supplied direct to the contrac-tor’s mixing plant prior to mixing. The road trial site is about80 km south of Ankara on the southbound lane of the Bala-Kulusection of the Ankara–Konya highway. Recently, Turkey introducedits own SMA mixture specifications, based on the German stan-dards; these are reproduced in Table 1. It should be noted that fi-bers (between 0.3% and 0.5%) are specified only for paving gradebitumens; for PMBs no fibers are specified. The principal reasonfor this is cost as the fibers need to be imported. If PMBs are tobe used, they need to comply with the new Turkish Specificationfor modified bitumen properties. For the SMA trial proposed, BPBitumen formulated a binder to meet the Type 3 Specification;The 0/12.5 SMA design was satisfactory but could have been im-proved through the use of a better quality filler. For a higherPMB binder content SMA mixture using these aggregates, fiberswould be required. There were problems initially with the layingbut these were easy to overcome, once the causes had been iden-tified. Many of the problems would have been solved prior to theactual road trial if a plant trial had been carried out first [11].

4. Conclusion

This research was based on a rutting evaluation of SMA mix-tures designed with basalt and limestone aggregates. The coarseaggregate in the mixture was selected as basalt. Four different rockcombinations were designed with basalt and limestone aggregatesfor filler and fine fractions. In addition to the evaluation of grada-tion, the maximum aggregate size effects were studied with fourgradations. Design processes were obtained from basalt aggregatesfor four gradations. Below considerations can be drawn from theresearch.

SMA11 and SMA12 have 19 mm and SMA21 and SMA22 have12.5 mm maximum aggregate size respectively. Decreasing themaximum aggregate size has the utmost importance on ruttingresistance according to the gradation and aggregate mineralogyfactors. These results were obviously observed with LCPC wheeltracking tests. It is possible to take logically accepted test resultswith LCPC tests for coarser and finer SMA mixtures.

It is believed that limestone aggregates as fine or filler parts to-gether with basalt aggregates can be used as filler and fine frac-tions in the SMA process. This issue is of great importanceconsidering the shortage of basalt aggregate quarries and the man-agement difficulties in these quarries. This matter reveals providedadded value for Turkey highway investments.

The rutting resistance of the SMA mixture relatively decreasedwith the incorporation of limestone aggregate into the SMA mix-ture gradation as fine or filler aggregate (on average 0.24% forSMA11 and SMA12 and 0.41% for SMA21 and SMA22). This low-le-vel rutting difference can be easily observed with LCPC wheeltracking tests. The reliability of LCPC test was clearly shown.

In the field conditions all wearing coarses suffer from the cli-matic conditions and vehicle tire pavement interaction with waterconditionings. According to the literature about anti-strip hydratedlime and basalt usage together with high degree of harmonizationare concerned. This is an important advantage of active adhesionconditions and damage mechanisms for Turkey SMA applicationsin the future.

Acknowledgements

This investigation is a part of the research supported by Karad-eniz Technical University (Project Number: 8628). The North Con-struction Laboratory is gratefully acknowledged for theirlaboratory capabilities. The authors are also indebted to Assoc.Prof. Orhan Karsli for mineralogical study support, and Assoc. Prof.Atakan Aksoy for evaluating the test results.

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