EFFECT OF NATURAL RUBBER ON THE PROPERTIES OF BITUMEN AND BITUMINIOUS MIXES

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1 INTERNATIONAL JOURNAL OF CIVIL ENGINEERING AND TECHNOLOGY (IJCIET) International Journal of Civil Engineering and Technology (IJCIET), ISSN (Print), ISSN (Print) ISSN (Online) Volume 5, Issue 10, October (2014), pp IAEME: Journal Impact Factor (2014): (Calculated by GISI) IJCIET IAEME EFFECT OF NATURAL RUBBER ON THE PROPERTIES OF BITUMEN AND BITUMINIOUS MIXES D. VASAVI SWETHA Student (B.E. + M.E), civil engineering dept, Andhra University College of Engineering, Visakhapatnam, INDIA Dr. K. DURGA RANI Professor, civil engineering dept, Andhra University College of Engineering, Visakhapatnam, INDIA ABSTRACT In India the remnants of products of natural rubber latex are stockpiled every year often uncontrollable causing sever environmental and other socio economic negative impacts. The environmental solid waste like rubber, swim caps, gloves etc can be recycled in a better way so that it is helpful for the future. Many studies have been done to find other alternative material to use as modifiers in bitumen mixes on the improvement of its properties and highway quality. Studies still today mainly focused on mechanical and physical characteristics of rubberized mixtures in which balloon rubber is used either as alternative to natural aggregates or as additive. In this research Natural Rubber latex (in the form of balloons) has been used as bitumen modifier. Bitumen when compared to the rubberized bitumen is bit sensitive when exposed to traffic load and temperature. The Rubberized bitumen formed reduces permanent deformations due to overload on the road and thus unaffected by the changes in atmospheric temperature and improves skid resistance. Rubber increases resistance to flow of bitumen at higher temperature and improves the resistance to brittle fracture at low temperature. The upper surface layer of the pavement has been made of rubberized bituminous mixtures. Rheological characteristics of rubberized bitumen as well as basic properties of the implemented, rubberized bituminous mixture are presented. The behaviors of the two modifiers were investigated by comprehensive laboratory testing and evaluation. It was observed that the addition of natural rubber gave better overall performance in the bituminous mixes. Thus, this shows natural rubber may contribute toward better flexible roads in the future. The above properties increase the service life of rubberized roads in many cases to more than hundred percent when compared to that of bituminous roads. Thus modified rubber bitumen of roads will combine savings with safety. 9

2 Keywords: Balloon Rubber, Remnants of Environment, Natural Rubber Latex, Pavement, Traffic, Rubberized Bituminous Mixture. 1. INTRODUCTION Natural rubber modified bitumen is used for the prolongation of life of state roads. The need to adopt rubber for the use of construction of the roads is mainly that it reduces the cost of construction and also recycled rubber is used as it minimizes the environment pollution. The utilization of recycled rubber in pavement construction sector can be a very promising and environmentally friendly what to eliminate the nations stock of scrap. A steady stream of huge volume of waste remnant or natural rubber is generated due to the continual increase in the production of waste generated by the population. The availability of the Natural Rubber (Latex) is enormous, as the rubber is a product obtained from Latex (e.g., mattresses, gloves, swim caps, balloons) has become part of daily life. If it is not recycled, its present disposal is either by land filling or by incineration. Both the processes have certain impact on the environment. Various studies are being carried out to improve the quality of bitumen used in bituminous road construction. One of the results of such studies is to use polymer-modified bitumen. Polymer modified bitumen is emerging as one of the important construction materials for flexible pavements. Use of polymers in the construction of flexible pavement is gaining importance because of the several reasons. The polymer modified bitumen show better properties for road construction and plastics waste, otherwise considered to be a pollution menace, can find its use in this process and this can help solving the problem of pollution. Bitumen is a useful binder for road construction. Different grades of bitumen like 30/40, 60/70 and /100 are available on the basis of their penetration values. The steady increase in high traffic intensity in terms of commercial vehicles and the significant variation in daily and seasonal temperature demand improved road characteristics. The studies on the thermal behavior and binding property of the Natural Rubber promoted a study on the preparation of Natural Rubber-bitumen blend and its properties to find the suitability of the blend for road construction. The initial cost is higher by around 20 per cent, but life-cycle cost is considerably lesser than roads surfaced using modified bitumen. 1.1 Natural Rubber (Latex) Natural rubber is an elastomer that was originally derived from milky latex found in the sap of some plants. The purified form of natural rubber is the chemical polyisoprene, which can also be produced synthetically. Natural rubber is used extensively in many applications and products, as is synthetic rubber. Natural rubber is an ideal polymer for dynamic or static engineering applications. Natural rubber features: Excellent dynamic properties with a low hysteresis loss Good low temperature properties Strong bonding to metal parts High resistance to tear and abrasion and ease of processing 1.2 Properties of Natural Rubber Natural rubber has been successfully used as an engineering material for many years. The following range of properties shows just how versatile of a material natural rubber has proven to be to engineers: Natural rubber combines high tensile and tear strength with an outstanding resistance to fatigue. 10

3 Excellent green strength and tack has the ability to stick to itself and other materials, making bonded natural rubber products easier to fabricate. Exhibits excellent dynamic properties with a low hysteresis which leads to low heat generation. Adjustable hardness from very soft to very hard (ebonite). Appearance and color ranges from translucent (soft) to black (hard). Compounded to meet nearly any mechanical requirement. The ability to be electrically insulating or fully conductive. Protect, insulate and sealing properties. Absorb vibration and silence noise. Available in any surface roughness and shape. To achieve the specific properties required for a given product, raw natural rubber has to be compounded using ingredients such as carbon black, anti-degradants, softeners and a vulcanization system. 1.3 Poly Isoprene One of the most well known natural polymers is polyisoprene, or natural rubber. Polyisoprene is diene polymer, which is a polymer made from a monomer containing two carboncarbon double bonds. Like most diene polymers, it has a carbon-carbon double bond in its backbone chain. Polyisoprene can also be made by Ziegler-Natta polymerization. This is a rare example of a natural polymer that we can make almost as well as nature does. 1.4 Environmental Concerns Due to it being non-biodegradable rubber is very lethal to the environment. It is one of the main contributions to land pollution. Besides plastic, glass, bottles, cans and other forms of litter. Rubber release a lot of toxins that have even lead to severe skin diseases, pollution of drinking water and fish being harmful to consume. If Rubber is burned it gives off chemicals into the surrounding air and exhibit toxicity in the environment which has several effects in life. 1.5 Types of Bitumen Modifiers and Their Indicative Dose Over the years, different types of materials have been investigated as additives for bitumen modifications. Some of them, which are reported to have desired potential and their indicative dose are given in table 1. 11

4 TABLE 1: TYPE OF ADDITIVES FOR BITUMEN MODIFICATION AND THEIR INDICATIVE DOSES Sl. No. Types of Modifiers Examples Indicative Dose Level, per cent by wt. of bitumen 1. Plastics Thermoplastics Thermosets 2. Elastomers Natural Rubber Synthetic Elastomers Low Density Polyethylene(LDPE) Ethylene Vinyl Acetate (EVA) Ethylene Butyl Acrylate (EBA) Epoxy Resins Latex or Dry Rubber Powder Styrene Butadiene Styrene Block Copolymer (SBS), Styrene Butadiene Rubber (SBR) Reclaimed Rubbers Type Crumb Rubber Powder from discarded truck, tyres further improved by additives Scope of the Study This study aims the utilization of polyisoprene in bitumen blend for road construction. Several tests are conducted on plain bitumen and bitumen blended with polyisoprene and the change in the properties is observed. For the present study polymer used is Polyisoprene (Natural rubber) as the availability of these materials is high and the preparation of blend is simple. Mix design for the blend is also done for marshal stability value to determine the optimum binder content level. The results obtained from plain bitumen are compared with those obtained from addition of Polyisoprene polymer. The benefits obtained with addition are analyzed. The experiments are done with 1%, 2%, 3%, 4%, 5%, 6% and 7% of bitumen modifier which on further increase from 0.5% of bitumen modifier we can get better results. 2. TESTS ON BITUMEN 2.1 BITUMEN Bitumen is a common binder used in road construction. It is principally obtained as a residual product in petroleum refineries after higher fractions like gas, petrol, kerosene and diesel etc. are removed. Indian Standard Institution (ISI) defines Bitumen as a black or dark brown non-crystalline soil or viscous material having adhesive properties derived from petroleum crude either by or by refinery process. 12

5 2.2 General Uses of Bitumen For Civil Engineering works Construction of roads, runways, platforms Water proofing to prevent water seepage Mastic floorings for factories and warehouse Canal lining to prevent erosion Dump-proof courses for masonry Tank foundation Joint filling material for mason 2.3 Properties of Bitumen The bitumen should possess the following desirable properties In presence of water the bitumen should not strip off from the aggregate. There has to be adequate affinity and adhesion between the bitumen and aggregate used in the mix. The viscosity of the bitumen at the time of mixing and compaction should be adequate. This is achieved by heating the bitumen and aggregate prior to mixing or by use cut backs or emulsions of suitable grade. The bituminous should not be highly temperature susceptible. During the hottest weather of the region the bitumen mix should not become too hard and brittle, causing of surface. The material should be durable. Bitumen main property that of very strong and durable adhesive that binds together a very wide variety of other materials without affecting their properties. Bitumen is insoluble in numerous organic solvents. As it is highly water proof, it can act as an effective sealant, it also resists action by most acids, alkalis and salts. It does not contaminate water so it can be used to line water courses. Bitumen given good controlled flexibility to mixtures of mineral aggregates. 2.4 Requirements of Bitumen The desirable properties of bitumen depend on the mix type and construction. The general problems while using bitumen in paving mixes are 1. Mixing 2. Attainment of desired stability under adverse weather conditions. 3. To maintain the stability under adverse weather conditions. 4. To maintain sufficient flexibility and thus avoid cracking of bituminous surface. 5. To have sufficient adhesion with the aggregates in the mix in the presence of water. 2.5 Tests on Bitumen The various tests that have to be conducted of bitumen are Penetration test Softening point test Viscosity test Ductility test Flash & fire point Penetration Test The penetration test determines the hardness or softness of bitumen by measuring the depth in tenths of a millimeter to which a standard loaded needle will penetrate vertically in five seconds. The sample is maintained at a temperature of 25 C. The bitumen is softened to a pouring 13

6 consistency, stirred and poured into a container to depth of 15mm. then it is placed in a temperature controlled water bath for one hour.. The sample with container is taken out and the needle is arranged to make contact with the surface of the sample. The dial is set to zero or the initial reading is taken and the needle is released for 5 seconds testing at a distance of 10mm apart. The final reading is taken on dial gauge and mean value is reported as penetration value Softening Point Test All semi-solid state bitumen grades need sufficient fluidity before they are used for application with the aggregate mix and the procedure is done by heating.. A brass ring containing the test sample of bitumen is suspended in liquid like water of glycerin at a given temperature. A steel ball is placed upon the bitumen and liquid medium is then heated at a specified rate. The temperature at which the softened bitumen touches the metal plate placed at a specified distance below the ring is recorded as the softening point of particular bitumen. The apparatus and test procedure are standardized by ISI. It is obvious that harder grade bitumen possess higher softening point than softer grade bitumen Viscosity Test Viscosity is defined as inverse of fluidity. High or low fluidity at mixing and compaction has been used to result in lower stability values. One method by which viscosity is measured is by determining the time taken by 50 CC of the material to flow from a cup through specified at a given temperature. The sample material is heated at the temperature 20 C above the specified test temperature and the material is allowed to cool. During this the material is continuously tirred. When the material reaches slightly above test temperature, the same is poured in the tar cup, until the leveling peg on the valve rod is just immersed. In the graduated receiver 20ml of mineral oil or one percent by weight solution of soft soup is poured. The receiver is placed under the orifice. When the sample material reaches the specified testing temperature within ±0.1 C and is maintained for 5 minutes, the valve is opened. The stop watch is started when cylinder records 25 ml. The time is recorded for flow upto a mark of ml Ductility Test In the flexible pavement construction where bitumen films around the aggregates, this serves as a satisfactory binder in improving the physical interlocking of the aggregates and if it does not possess sufficient ductility would crack and thus provide pervious pavement surface. The bitumen sample is melted to a temperature of to 100 C above the approximate softening point and poured in the casting assembly and placed on a brass plate, after a solution of glycerin and dextrin is applied at all surfaces of the mould exposed to bitumen. 30 to 40 minutes after the sample is poured the plate assembly along with the sample is placed in water bath maintained at 27 C for 30 minutes. The sides of mould are removed and the clips are carefully hooked on the machine without causing any initial strain. 2 or more specimens may be prepared in the mould and clipped to the machines to as to conduct the tests simultaneously. The pointer is set to read zero. The machine is started and the two clips are thus pulled apart horizontally. While the test is in operation, it is checked whether the sample is immersed in water at depth of at least 10 mm. The distance at which the bitumen thread of each specimen breaks, is recorded (in cm) to report as ductility value Flash and Fire Point Test Bituminous materials leave out volatiles at high temperatures depending upon their grade. These volatile vapors catch fire causing a flash. The material is filled in the cup up to a filling mark. The lid is placed to close the cup in a closed system. All accessories including thermometer of the 14

7 specified range are suitably fixed. The bitumen sample is then heated. The test flame is lit and adjusted in such a way that the size of beed is of 4mm diameter. The heating is done at the rate of 5-6 C per minute. The stirring is done at a rate of approximately 60 revolutions per minute. The test flame is applied at intervals depending upon the expected flash and fire points. First application is made atleast 17 C below the actual flash point and then at every 1 to 3 C. The stirring is discontinued during the application of the test flame. 3. TESTS ON BITUMINOUS MIXES 3.1 Bituminous Mixes Bituminous concrete or asphaltic concrete is one of the highest and costliest types of flexible pavement layers used in the surfacing course. The desirable properties of a good bituminous mix are stability, durability, flexibility, skid resistance and workability. Stability is defined as resistance of the paving mix to deformation under load and thus it is a stress which causes a specified strain depending upon anticipated field conditions. Durability is defined as the resistance of the mix against weathering and abrasive actions. Tensile strain is introduced in the top layer consisting of bituminous mix when wheel loads ply over it. Excessive strain causes cracking or plastic failure. Flexibility is a property of the mix that measures the level bending strength. Skid resistance is defined as the resistance of the finished pavement against skidding and is a function of surface texture and bitumen content. Workability is the ease with which the mix can be laid and compacted 3.2 Properties of Bituminous Mixes Mix design methods should aim at determining the properties of aggregates and bituminous material which would give a mix having the following properties. Sufficient stability to satisfy the service requirements of the pavement and the traffic conditions, without undue displacements. Sufficient bitumen to ensure a durable pavement by coating the aggregate and bonding them together and also by water-proofing the mix. Sufficient voids in the compacted mix as to provide a reservoir space for a slight amount of additional compaction due to traffic and to avoid flushing, bleeding and loss of stability. Sufficient flexibility even in the coldest season to prevent cracking due to repeated application of traffic loads. Sufficient workability while placing and compacting the mix. The mix should be the most economical one that would produce a stable, durable and skid resistant pavement. 3.3 Marshalls Method of Mix Design In this method, the resistance to plastic deformation of cylindrical specimen of bituminous mixture is measured when the same is loaded at the periphery at a rate of 5cm per minute. The test is extensively used in routine test programmed for the paving jobs. There are two major features of the Marshall method of designing mixes namely, Density-voids analysis Stability-flow test Gradation of Aggregates for Bituminous Macadam Mix Sieve analysis is conducted on the supplied samples of 20mm, 10mm, 6mm and stone dust. The specifications given by morth for bituminous macadam are presented in table 2. 15

8 TABLE 2: GRADATION OF AGGREGATES S.NO SIEVE SIZE (mm) RECOMMENDED GRADATION AS PER %FINER (MORTH SPECIFICATION) µ µ 0-8 Approximately 1200g of the mixed aggregates and the filler are taken and heated to a temperature of C. The bitumen is heated to a temperature of 121 to 145 C and the required quantity of the first trial percentage of bitumen is added to the heated aggregates and thoroughly mixed at desired temperature of C. The mix is placed in a pre-heated mould and compacted by a rammer with blows on either side at a temperature of C(suitable heating, mixing and compacting temperatures are chosen depending upon the grade of bitumen). Number of blows on each side of marshall specimen is taken as. Three specimens are prepared using each trial bitumen content and cooled to room temperature.. The specimens are kept immersed in water in a thermostatically controlled water bath at 60±1 C for minutes. The specimens are taken out one by one, placed in the Marshall Test head and tested to determine Marshall Stability value which is the maximum load in kg before failure and the flow value which is the deformation of the specimen in 0.25mm units up to the maximum load. The corrected Marshall Stability value of each specimen is determined by applying the appropriate correction factor. The optimum content for the mix design is found by taking the average value of the following bitumen contents found from the graphs of the test results. Bitumen content corresponding to maximum stability Bitumen content corresponding to maximum unit weight The Marshall Stability value, Flow value at the average value of bitumen content is checked with the Marshall mix design criteria/ specifications given in table 3. TABLE 3: SPECIFICATIONS FOR MARSHALL STABILITY TEST Test Property Specified value Marshall Stability, kg 340(minimum) Flow value, 0.25mm units 8 to 16 Mix with very high Marshall Stability values and low Flow values are not desirable as the pavements constructed with such mix are likely to develop cracks due to heavy moving loads, if the pavement components permit relatively high deflection values. 4. TEST RESULTS AND DISCUSSIONS The results of the above tests are presented in the following tables and figures. 4.1 Table 4 shows the penetration values of ordinary bitumen (O.B) and bitumen mixed with natural rubber (N.R) 16

9 TABLE 4: PENETRATION VALUES OF O.B AND POLYMER MODIFIED BITUMEN TEST PROPERTY O.B 1%N.R 2%N.R 3%N.R 4%N.R 5%N.R 5.5%N.R 6%N.R 7%N.R Penetration Value(1/10 th )mm Average Value(1/10 th )mm 67.6 After conducting the penetration value test it is observed that there is gradual increase in penetration value upto 5% and the value gradually decreased. This indicates that initially the bitumen got softened upto 5% and then it got hardened. Henceforth bitumen with 1-4% binder content is suitable in colder regions and from 4-7% it is suitable in warmer regions. 4.2 Softening Point and Viscosity Results Table 5 shows the softening point and viscosity point results of ordinary bitumen (O.B) and bitumen mixed with natural rubber (N.R). TABLE 5: SOFTENING POINT RESULTS OF ORDINARY & POLYMER MODIFIED BITUMEN TYPE OF SAMPLE SOFTENING POINT VALUE( C) VISCOSITY POINT VALUE( C) Ordinary Bitumen Ordinary Bitumen + 1% (N.R) Ordinary Bitumen + 2% (N.R) Ordinary Bitumen + 3% (N.R) Ordinary Bitumen + 4% (N.R) Ordinary Bitumen + 5% (N.R) Ordinary Bitumen + 5.5% (N.R) Ordinary Bitumen + 6% (N.R) 58 0 Ordinary Bitumen + 7% (N.R) 59 3 After conducting the softening point test it is observed that the base bitumen softening point value is 52 C and decreases at 1% of bitumen modifier to 48 C which is not beneficial. Perhaps 1% Binder content values can be ruled out. As there is steady increase from 2% we can limit our study to 2-7% of Binder content. 17

10 After conducting the viscosity point test it is observed that the base bitumen viscosity value is 293 seconds and decreases at 1% of bitumen modifier which is 222 seconds and then it increases. This trend is also similar to softening point trend but there is steep increase upto 7%. Since it is softer at 1% it is ruled out and from 2-4% it is optimum criterion for determining optimum binder content from Marshall Stability Test. 4.3 Ductility and Flash & Fire Test Results Table 6 shows the ductility value and flash & fire point results of ordinary bitumen (O.B) and bitumen mixed with natural rubber (N.R). TABLE 6: DUCTILITY RESULTS OF ORDINARY & POLYMER MODIFIED BITUMEN TYPE OF SAMPLE DUCTILITY VALUE (CM) FLASH POINT( C) FIRE POINT( C) Ordinary Bitumen Bitumen + 1% natural rubber latex Bitumen + 2% natural rubber latex Bitumen + 3% natural rubber latex Bitumen + 4% natural rubber latex Bitumen + 5% natural rubber latex Bitumen + 5.5% natural rubber latex Bitumen + 6% natural rubber latex Bitumen + 7% natural rubber latex After conducting ductility value test it is observed that the base bitumen ductility value is 120cm. There is sudden decrease in ductility value from 2 to 3%. Then it gradually decreases and goes less than 50 cm at 6% and continues upto 7%. According to ISI specifications ductility values below 50 cm are not suitable for road construction. Flash & fire point test is conducted on 60/70 bitumen grade mixed with Natural Rubber (Latex) and graph is drawn between % of bitumen modifier added on x-axis and temperature in degrees on y-axis. In Flash point from 1-3% we can see steady graph and after 3% it is increasing. Even though from 1-3% it is decreasing it is not much lower so it is suitable for working conditions without causing fire hazards from safety point of view. The minimum value of flash point specified by ISI is 1 C for all grades of bitumen. 4.4 Marshall Stability Test Results Table 7 shows the marshall stability test results are presented below. TABLE 7: MARSHALL STABILITY RESULTS FOR BITUMINOUS MACADAM MIX SAMPLE MARSHALL STABILITY FLOW VALUE (mm) VALUE (kg) Sample with 3.3% Ordinary bitumen Sample with 3% bitumen containing 3% natural rubber Sample with 3% bitumen containing 4% natural rubber Sample with 3.5% bitumen containing 3% natural rubber Sample with 3.5% bitumen containing 4% natural rubber

11 For ordinary bitumen of 60/70 grade, maximum strength is obtained at 3.3%. 3% and 4% natural rubber is added to two percentages of bitumen levels (3% & 3.5). 3.5% is selected because for normal 60/70 bitumen the optimum binder content is obtained at 3.3%. From Marshall Stability test maximum strength 616kgs is obtained for 4% natural rubber at 3% bitumen level. By adding 4% bitumen modifier, the bitumen content can be decreased considerably, thereby the cost of road construction is reduced. As 1% and 5% above binder contents are ruled out, 2%, 3% and 4% are taken as optimum binder content for the calculation of Stability and flow tests. 4.7 Figures of Various Tests are Presented Below 19

12 5. CONCLUSIONS Huge amount of scrap rubber is generated from surroundings which can totally be used for this purpose by reusing it and solving the problem of disposal of rubber and its waste generation. Penetration test at 25 C is the most commonly adopted test on bitumen to grade the material in terms of hardness. So, in warmer regions lower penetration grades are preferred and in colder regions higher penetration values are used. Since the obtained value is in between 60mm (1/10 th mm) and mm (1/10 th mm), it can be used for both regions in pavement construction. Softening point test gives an idea of temperature at which the bituminous material attains a certain viscosity. So bitumen with higher softening point preferred in warmer place and it is also used to specify hard bitumen. Since the obtained value is between 50 C and 55 C, it can be preferred in warmer places. From the viscosity values, it can be concluded that resistance to flow increases with increase of % bitumen modifier. So, higher the duration more viscous is the material. As viscosity value is more, it can be used in pavement construction. The minimum value specified by Indian Standards Institution is 50cm, % of bitumen modifier more than 5.5 should not be used in pavement construction. As it is less than 50cm after 5.5% of bitumen modifier, due to its low ductility value, the pavement may crack especially in cold weather. Flash & fire point has no significance about strength of bitumen. They are used to know the working temperatures of the bitumen. If the working temperatures are more than flash & fire point values, then fire hazards may occur. Since Bitumen gets soften at 1% it is ruled out and percentages above 5.5% are ruled out in ductility. Hence from 2-4% we can get the optimum binder content value for determining Marshall stability test. 6 REFERENCES [1] International Journal of Engineering and Advanced Technology (IJEAT). ISSN: , Volume-2, Issue-3, February 2013 on Pavement Performance with Carbon Black and Natural Rubber (latex). [2] [3] Rheology of Polymer Modified Bitumen:A Comparative study of three binders and three binder/filler materials. [4] Journal on Bitumen Scrap Rubber Seals, Engineering Road Note No.7 (October 2003), Main Roads Government of Western Australia. [5] Indian Standard Methods for testing Tar and Bitumen, Determination of Penetration, IS: 1203 Indian Standards Institution. [6] Indian Standard Methods of Testing Tar and Bitumen: Determination of Softening Point, IS: 1205, Indian Standards Institution. [7] Indian Standard Methods for Testing Tar and Bitumen: Determination of Viscosity, IS: 1206, Indian standards institution. [8] Indian Standard Methods for Testing Tar and Bitumen; Determination of Ductility, IS: 1203, Indian standards Institution. [9] Indian Standard Methods of Testing Tar and Bitumen: Determination of Flash and Fire Point, IS: 1209 Indian Standards Institution. [10] SK khanna and CEG Justo, Highway Material Testing Laboratory Manual, Nem Chand Bros; Rourkee. [11] Highway Engineering Materials by Khanna and Justo. 20

13 [12] Recommended Practice for Bituminous Penetration Macadam (Full Grout), IRC. [13] Indian Standard Specifications for Paving Bitumen,IS:-1961; Indian standards Institution [14] Bituminous Road Construction, Barmah Shell. [15] Manual for Construction and Supervision of Bituminous Works, Published by IRC on behalf of the Government of India; Ministry of Road Transport and Highways, New Delhi; [16] [17] [18] (NRMB).html. [19] [20] N.Ganesan, Bharati Raj, A.P.Shashikala and Nandini S.Nair, Effect of Steel Fibres on the Strength and Behaviour of Self Compacting Rubberised Concrete, International Journal of Civil Engineering & Technology (IJCIET), Volume 3, Issue 2, 2012, pp , ISSN Print: , ISSN Online: [21] M.Satyakumar, R.Satheesh Chandran and M.S. Mahesh, Influence of Mineral Fillers on the Properties of Hot Mix Asphalt, International Journal of Civil Engineering & Technology (IJCIET), Volume 4, Issue 5, 2013, pp , ISSN Print: , ISSN Online: [22] Islam M. Abo El-Naga, Performance of Asphalt Mixes Containing Rubber, International Journal of Civil Engineering & Technology (IJCIET), Volume 5, Issue 7, 2014, pp. 7-16, ISSN Print: , ISSN Online: [23] M. Venu and P. N. Rao, Study of Rubber Aggregates in Concrete:An Experimental Investigation, International Journal of Civil Engineering & Technology (IJCIET), Volume 1, Issue 1, 2010, pp , ISSN Print: , ISSN Online: