Impact of Surkhi on GSB Layer as Replacement to the stone dust

Nishant Kumar*, Vikas Kumar**, Akash Priyadarshee***, Anil Kumar Chhotu****

*National Institute of Technology Kurukshetra, India** National Institute of Technology Jalandhar, India*** National Institute of Technology Jalandhar, India**** National Institute of Technology Jalandhar, India

Abstract

Surkhi is a form of brick dust and has been collected from local brick kilns at nominal cost, far less than that of stone dust. The purpose of the study is to know whether locally available Surkhi can be used in road construction in granular sub base ( GSB) layer. The study has been conducted on six types of GSB mixes formed by partially and completely replacing the stone dust content with that of Surkhi. The proportion of Surkhi varies from 0 to 25% by weight of total mix in these GSB mixes. The study evaluates gradations and plasticity of fine aggregates used and OMC, MDD and CBR of various GSB mixes. OMC is found to increase with increase in proportion of surkhi from 0 to 25%. The MDD is found to increase with increase in proportion of surkhi from 0 to 10% after which it decreases. The maximum MDD is found to be for GSB Mix 3 with 10% surkhi and 15% stone dust. The test results on all six GSB mixes are found to fulfill the MORTH requirements of gradation, CBR and plasticity indicating that these combinations can be used in GSB construction of road works. The use of locally available surkhi in road construction in GSB will not only result in achieving economy in the road projects, but also save on environmental degradation by minimizing mining pollution and energy used in the quarrying of sand/stone dust.Key words: optimum moisture content, maximum dry density.

1.1 Introduction Road network provides the arterial network to facilitate trade, transport and social integration. Road infrastructure is an essential requirement of economic growth. It facilitates movement of man and material, helps trade and commerce, links industries and agriculture to markets and opens up backward regions. This will facilitate saving of conventional fine aggregates (sand /stone dust) and save on environmental degradation in terms of reduced mining and less pollution. Gravels and sands are the major road construction materials. However, depending upon the location, local aggregates of somewhat similar quality may also have to be used for highway construction and maintenance works because of financial and environmental reasons. It is of utmost importance to be economical in construction with proper selection of construction material, technology and design methodology. This study help us to aims at conducting experiments to determine the suitability of use of Surkhi in GSB construction; testing various combinations of Surkhi and GSB material by replacing sand with Surkhi and determine their suitability for road construction as per MORTH Specifications.1.2 OBJECTIVES OF THE STUDYThe research work "Laboratory Investigations on GSB Material Mixed with Surkhi" aims at conducting experiments to determine the suitability of use of Surkhi in GSB construction; testing various combinations of Surkhi and GSB material by replacing sand with Surkhi and determine their suitability for road construction as per MORTH Specifications, [1.a].The purpose of the study is to know whether locally available Surkhi can be used in road construction in GSB layer. The main objectives of the study are: 1. To carry out dry and wet sieve analysis of selected fine aggregates which can be used in GSB for road construction. 2. To study various properties of the selected fine aggregates like gradation, specify gravity and plasticity properties with a view to determine their suitability in GSB construction. 3. To design granular mixes for GSB with different proportions of Surkhi by replacing stone dust and study the MDD and CBR properties of these mixes with a view to determine their suitability for GSB construction.4. To discuss the results of the study.

1.3 MATERIAL USED

The material to be used for the work shall be natural sand, moorum, gravel, crushed stone, or combination of them depending upon the grading required. Materials like crushed slag, crushed concrete, brick metal and kankar may be used. The material shall be free from organic or other deleterious constituents. The grading of fine aggregate are given in table 2.

1.3.1 COARSE AGGREGATE

Coarse aggregate are available from various quarry zones. In addition, the coarse aggregate are also available in the form of gravels from various riverbeds. Fig. 2.1 and 2.2 shows various types of aggregates used in the study. The tests which are generally carried out as per MORTH and ARE specifications are used for judging the suitability of stone aggregates are listed in the Table 1.

Table 1 Requirement of Coarse Aggregates for Various Tests Properties ofaggregatesRequirement of coarse aggregatesas per MORT&H for road workRequirement of coarseaggregates as per IS-383for concrete work

Aggregate crushingValue--< 30% for wearingcourse< 45% for other works

Los-Angelesabrasion value 40% max. for WBM, WMM, BM, BUSG, PC, MSS. 35% max. for DBM & SDBC< 30% for wearingcourse< 50% for other works

Aggregatesimpact value 30 % max. for WBM, ,WMM, BM, BUSG, PC & MSS. 27% max. for DBM & SDBC . 24% max. for BC.< 30% for wearingcourse< 45% for other works

Combinedflakiness and elongationindices. 30 % max. for WBM, WMM, BM, BUSG, DBM, SDBC, BC, PC,MSSFI < 35%

Soundness 12% max. (Sodium sulphate) 18% max. (magnesium sulphate) for BM, BUSG, DBM, SDBC, BC, PC, MSS (Only for five cycles for both)

12% max. (Sodiumsulphate)18% max. (magnesium sulphate)(Only for five cycles for both)

WaterAbsorption

2% max. for WBM, WMM, BM, BUSG, OBM, SOBC, BC 1 % max. for PC, MSS, CCP--

1.3.2 Fine aggregate

Generally, the sands used for road construction include the stone dust obtained from various crusher zones, natural sand obtained from river beds and local sands like tibba sands etc. Crusher sand and stone dust has been used in the study. Besides the crusher sand, the locally available surkhi has also been used in the study.

1) STONE DUST/CRUSHER SAND This type of sand is available in the quarry zones of Haryana where the stone crusher units are installed, which produce various types/sizes of aggregates in various parts of Haryana. Stone Dust is shown in Fig.2.3. It has fewer fines and has better engineering properties. Its colour is grayish. It finds its application in the construction of GSB, WMM and other pavement layers.2) SURKHI Marginal/Low cost materials are found in different varieties in our country as discussed earlier in Fig.2.3. However, Surkhi is available in local areas in good quantities. It presents good scope for economical use in various components of road construction such as subgrade, GSB and WMM constructions, etc. Accordingly, Surkhi along with Stone Dust has been selected for this study to judge its suitability in GSB layer of road construction (fig.2.4).

Fig 2.2 20 mm aggregateFig 2.1 53 mm aggregate

Fig 2.4 Stone dustFig 2.3 Stone dust

Sand is used in various types of road constructions. It can be used in sub grade, GSB, WBM, WMM layers, various bituminous constructions and cement concrete road construction. Keeping in view the objectives of this study, the use of surkhi in GSB has been given major consideration in this chapter. The standard specifications relating to the use of fine aggregate in these constructions are covered in relevant Indian standards, IRC codes and MORTH guidelines. In this chapter the relevant standard specifications covered mainly in IS: 383-1970 [2] and MORTH guidelines [1.a] are presented.

1.3.3 CHARACTERISTICS OF SAND

Sand to be used in sub grade (top 500mm portion) should have maximum dry density (heavy compaction) not less than 1.75 gm/cc; and not less than 1.52 gm/cc or 1.60 gm/cc for embankments depending upon height of embankment less than equal to 3 m or more than 3 m respectively [1.a]. For use in masonry/cement concrete works, sand as per IS: 383-1970 [2], should fit into one of the grading zones as given in Table 2.

Table 2 Grading Zone of Fine Aggregate

IS SieveDesignationPercentage Passing

Grading Zone IGrading Zone IIGrading Zone IIIGrading Zone IV

10 mm100100100100

4.75 mm90-10090-10090-10095-100

2.36 mm60-9575-10085-9095-100

1.18 mm30-7055-9075-10090-100

600 micron15-3435-5960-7980-100

300 micron5-208-3012-4015-50

150 micron0-100-100-100-15

1.3.4 GRANULAR SUB-BASE (GSB) The work consists of laying and compacting well-graded material on prepared sub-grade in accordance with the requirements of MORTH specifications. The material is laid in one or more layers as necessary according to lines, grades and cross-section shown on the drawings.1.3.4.1 Physical requirementsThe material shall have a 10 percent fines value of 50kN or more (for sample in soaked condition) when tested in compliance with IS:2386 (Part IV) 1963. The water absorption value of the coarse aggregate shall be determined as per IS:2386 (Part 3). If this value is greater than 2 percent, the soundness test shall be carried out on the material delivered to site as per IS:383. For Gradings II and IV materials, the CBR shall be determined at the density and moisture content likely to be developed in the field.

1.3.5 Gradation of Granular Sub-Base (GSB) GSB when tested shall conform to the grading requirements set forth in Table 3 and 4. The grading in table 3 are in respect of close-graded granular sub base materials, one each for maximum particle size of 75mm, 53mm and 26.5mm, the corresponding grading for the coarse graded materials for each of the three maximum particle sizes are given in Table 4.

2.1 PROCUREMENT OF MATERIAL The material selected for the study have been procured from various quarry zones as shown in Table 2.1 Table 2.1 Various Types of Sands and their availability in local areas.Sr. NoMaterialCrusher Zone/River Bed/ fieldLocation

1Stone dustYamuna NagarYamuna Nagar

2SurkhiKirmich brick kilnKurukshetra

3Coarse Aggregates Gravels for GSBYamuna NagarYamuna Nagar

The materials used for testing in the study have been shown in Fig. 2.1 to 2.4. The fine aggregates are tested as per the guidelines of various IS Codes and the MORTH specifications.3. TESTING OF MATERIAL 3.1 Tests on Fine Aggregates Keeping in view the use of fine aggregates in Granular Sub Base (GSB) as per objectives of the study, various tests to be performed on the fine aggregates are as given in Table 3.1. The relevant IS codes giving the procedure of testing for these tests are also given in the table. Table 3.1 Tests on Fine and Coarse Aggregate [3 to 8]Sr. No.TestsIS Codes

1.Fine Aggregates

Grain Sizes AnalysisIS: 2720 (P-IV)-1985

Atterberg LimitsIS: 2720 (Part-V)-1985

Specific GravityIS: 2386 (Part-III)-1963

2.Coarse Crushed Aggregates

Sieve AnalysisIS: 2720 (Part-IV) 1985

3.Granular Sub Base

GradationIS: 2386 (Part-I)-1963

California Bearing Ration (CBR)IS: 2720 (P-XVI) -1987

Max Dry Density and OMCIS: 2720 (P-VIII)-1983

3.2. Tests on Crushed Coarse Aggregates Tests on coarse aggregates are conducted to judge their suitability in GSB. As per the knowledge available with the civil engineering department of the institute, the coarse aggregate obtained from Yamuna Nagar quarry zone fulfill the requirements of water absorption, impact values, and flakiness and elongation indices. These tests have therefore been not performed. Only the sieve analysis of the coarse aggregate has been carried out to use it in mix design of various GSB mixes. 3.3. Tests on Granular Sub Base Mixes The Granular Sub Base mix design is done by analytical method. For this purpose coarse aggregates of size 53 mm, 20 mm are mixed with stone dust and surkhi in the required proportion to meet the desired MORTH specified gradation. The Granular Sub Base mixes so prepared are tested for various tests as given in Table 3.2 as per requirements of MORTH specifications.

4 .1 ANALYSIS AND DISCUSSION OF RESULTSA series of tests are conducted in the laboratory for evaluation of various properties of fine aggregate materials selected for the study. All tests have been conducted as per the guidelines of relevant IS Codes, reference to MORTH specifications are given in table from 4.1 to 4.3.

Table 4.1 Zone and Fineness ModulusSr. No. Type of Fine Aggregates Grading Zone Fineness Modulus (FM) MORTH Requirement

1 Stone DustII 2.22For masonry and concrete work the F.M. should be between 2 to 3.5 and grading Zone between I to III

2 Surkhi II 3.05

Table 4.2 Atterberg LimitsType of SandsLiquid limit (%)Plastic limit (%)Plasticity index (%)

Stone Dust17.89Non PlasticNon Plastic

Surkhi20.08Non PlasticNon Plastic

Table 4.3 Specific GravitySpecific Gravity of Stone Dust2.66

Specific Gravity of Surkhi2.52

5.1 JOB MIX DESIGN OF GSB (Grading-I) AND TESTINGJob mix design is done for combining the aggregates and proportioning of aggregates to obtain the required gradation. Following materials are used for preparing various mixes of GSB. The various GSB mixes formed for the study & proctor test result for the given mixes are given in table 5.1 & 5.2 respectively. 53mm Aggregates 20mm Aggregates Stone dust Surkhi

Table 5.1 Constituents of SamplesMATERIAL CONSTITUENTS (In %)

GSB Mix53 mm20 mmStone DustSurkhiTotal

14035250100

24035205100

340351510100

440351015100

54035520100

64035025100

Table 5.2 Proctor Test Results for various GSB MixesGSB MixProportion of Fine AggregateOptimum Moisture Content (%)

Maximum Dry Density (gm/cc)

SurkhiStone Dust

10255.102.250

25205.902.325

310156.102.346

415106.252.277

52057.052.196

62506.952.194

It is observed from table 5.2 that OMC increases with increase in proportion of surkhi from 0 to 25% in the GSB Mix. The MDD is found to increase with increase in proportion of surkhi from 0 to 10% after which it decreases. The maximum MDD is found to be for GSB Mix 3 with 10% surkhi and 15% stone dust.

Fig 3 OPTIMUM MOISTURE CONTENT AND MAXIMUM DRY DENSITY FOR GSB MIXES

5.2 CALIFORNIA BEARING RATIO

The CBR is a measure of resistance of a material to penetration of standard plunger under controlled density and moisture conditions. CBR value is highly dependent on the condition of material at the time of testing. The tests were performed on GSB mixes remoulded at OMC and MDD as per IS: 2720 (part-XVI)-1987 [8]. Fig 5.20 to 5.22 depict the CBR tests being conducted in the laboratory. The CBR tests have been conducted for both un-soaked and soaked conditions (4 days soaking).

Table 5.3 Standard Loads for CBR TestPenetration Depth (mm)Unit Standard Load (Kgf/ cm2)Total Standard Load (Kgf)

2.5701370

5.01052055

Table 5.4 Mould Dimensions for CBR TestMould Height (cm)Mould Diameter (cm)Spacer height (cm)Volume of Mould (cc)

17.5154.772248.44

Soaked GSB MIX 3

Penetration(mm)Dial gaugereading Load(Kg)CBR(%)

000

0.5130144.56

1220244.64

1.5330366.96

2425472.60

2.5525583.8042.61

3580644.96

4655728.36

5695772.8437.61

6795884.04

Unsoaked GSB MIX 3

Penetration(mm)Dial gauge readingLoad(Kg)CBR(%)

000.00

0.5215239.08

1360400.32

1.5475528.20

2570633.84

2.5645717.2452.35

3730811.76

4825917.40

59201023.04

610051117.5649.78

Table 5.5 CBR values for GSB Mix-3 Table 5.6 CBR values for GSB Mix-3

The results of CBR value of various GSB mixes are given in table 5.3 to 5.6 and graphically presented in Fig. 5.1and 5.2. Table 5.7 summarizes the CBR values for various GSB mixes for both Unsoaked and soaked conditions. It is observed that CBR value (soaked) of GSB with all proportions of surkhi satisfies the minimum requirement of 30% as prescribed by MORTH for GSB Grading - 1. CBR values of GSB with different proportions of surkhi are found to vary over a small range (34 to 43%) due to almost similar gradation of GSB granular mix with selected proportions of surkhi. The CBR value of Unsoaked GSB mixes is found to be 23 % to 34% more than soaked GSB mixes for various proportions of surkhi. The maximum value of CBR is found to be for GSB Mix 3 with 10% surkhi and 15% stone dust.

Fig. 5.2 CBR values for GSB Mix - 3Fig. 5.1 CBR values for GSB Mix - 3

Table 5.7 CBR values for Unsoaked and Soaked GSB MixesGSB MixProportion ofSurkhi : Stone Dust (%)UNSOAKED CBRSOAKED CBRUNSOAKED CBR / SOAKED CBR

2.5 mm5.0 mm2.5 mm5.0 mm

10 : 2548.7044.9136.5335.441.33

25 : 2050.3247.6239.3736.531.28

310 : 1552.3549.7842.6137.611.23

415 : 1049.5146.0037.7435.711.31

520 : 546.2743.2934.5033.011.34

625 : 045.4542.7534.9033.551.30

The results of CBR value of various GSB mixes are given in table 5.5 and 5.6 and graphically presented in Fig. 5.1 and 5.2. Table 5.7 summarizes the CBR values for various GSB mixes for both Unsoaked and soaked conditions. It is observed that CBR value (soaked) of GSB with all proportions of surkhi satisfies the minimum requirement of 30% as prescribed by MORTH for GSB Grading - 1. CBR values of GSB with different proportions of surkhi are found to vary over a small range (34 to 43%) due to almost similar gradation of GSB granular mix with selected proportions of surkhi.The CBR value of Unsoaked GSB mixes is found to be 23 % to 34% more than soaked GSB mixes for various proportions of surkhi. The maximum value of CBR is found to be for GSB Mix 3 with 10% surkhi and 15% stone dust.6. CONCLUSIONS

The study "Laboratory investigations on GSB material mixed with Surkhi has been carried out with a view to judge the suitability of locally available surkhi in road construction works as per MORTH Specifications. For this purpose, six types of GSB mixes were formed by partially and completely replacing sand with that of surkhi. The main conclusions drawn from the study are:1. Gradation of the fine aggregates indicates that both stone dust and surkhi fall in grading Zone-II. The fineness modulus for stone dust and surkhi are found to be 2.22 and 3.05 respectively. The gradation and fineness modulus indicate that both can be used for structural works. 2. Both stone dust and surkhi have liquid limit less than 21 % and are non-plastic in nature. They fulfill the requirement of plasticity for road construction.3. Maximum dry density (heavy compaction) for various GSB mixes is found to be varying between 2.194 gm/cc to 2.346 gm/cc. It is found to be maximum for GSB Mix 3 with surkhi and stone dust in the ratio 10:15.4. OMC is found to increase with increase in proportion of surkhi from 0% to 25% 5. The test results on all six GSB mixes are found to fulfill the MORTH requirements of gradation, CBR and plasticity indicating that these combinations can be used in GSB construction of road works.6. The CBR value of GSB Mix 3 (Surkhi: Stone :: 10:15) shows maximum values for both Unsoaked and soaked test conditions. A saving in the cost of sand in GSB can be achieved by replacing sand with that of surkhi.7. The use of locally available surkhi in road construction in GSB will not only result in achieving economy in the road projects, but also save on environmental degradation by minimizing mining pollution and energy used in the quarrying of sand/stone dust.

7. REFERENCES1. Annual Report 2012 2013, MORTH. 1. a. MORTH (Ministry of Road Transport and Highways), IV Revision, 2001, 1.b. Specifications for Road and Bridge Works, Indian Roads Congress, New Delhi 2. IS: 383-1970, Specification for Coarse Sand and Fine Aggregate from Natural Source for Concrete. 3. IS: 2720 (Part-IV)-1985, Method of Test of Soil, Grain Size Analysis. 4. IS: 2720 (Part-V)-1985, Method of Test for Soils, Part-V, Determination of Liquid and Plastic Limit. 5. IS: 2720 (Part-VIII)-1987, Method of Test For Soils, Part-VIII Determination of Water Content-Dry Density Relation Using Heavy Compaction. 6. IS: 2386 (Part-III)-1963, Method of Test for Aggregate for Concrete, Part-III, Specific Gravity, Density, Voids, Absorption and Bulking. 7. IS: 2386 (Part-I)-I963, Method of Test for Aggregate for Concrete, Part-I, Particle Size and Shape. 8. IS: 2720 (Part -XVI)-I987, Method of Test for Soils, Part XVI, Laboratory Determination of CBR.