International Journal of Research and Scientific Innovation (IJRSI) Volume III, Issue XII, December 2016 ISSN

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1 An Experimental Study of Rutting on Dense Bituminous Macadam of Grading-I (Middle) using Crumb Rubber Modified Bitumen and Waste Plastic Coated Aggregates Mohanlal Chandrawal 1, Goutam Verma 2, Kapil Kushwah 3, Vishwajeet Kumar Sharma 4 1 Shri Govindram Seksaria Institute of Technology and Science, Indore, Madhya Pradesh 2, 3 & 4 Assistant Professor (Department of Civil Engineering), Swami Vivekanand college of Engineering Indore Abstract:- Rutting is the permanent deformation in pavement usually occurring longitudinally along the wheel path. Permanent deformation or rutting in bituminous mixes depends on numerous factors such as aggregate gradation, shape and size of aggregate, quantity and quality of binder, volumetric properties of mix such as air voids and Voids in Mineral Aggregates (VMA), film thickness, temperature, construction practices and environmental conditions. Rutting resistance potential of any bituminous mix depends on the properties of its constituents. In this study crumb rubber and waste plastic is used to modify constituent s properties. Crumb rubber is used to modify bitumen generally termed as crumb rubber modified bitumen (CRMB). Waste plastic is used to form a coating around aggregates. Bituminous mix with CRMB and plastic coated aggregates having proper proportions of crumb rubber and waste plastic gives better results as compared to mixes having any one of the two waste materials. Thus in the areas prone to high rut depth on DBM, for use mainly, but not exclusively, in base/binder and profile corrective courses, modified bituminous mix (having crumb rubber modified bitumen along with plastic coated aggregates) is more suitable than conventional mix due to its high rut resistance. Plastic coated aggregate crumb rubber modified mix shown negligible increase in rutting even when significant temperature change occurs. Hence such modified mixes could be used in areas having large temperature variations. Thus modified mix with crumb rubber modified bitumen as binder and LDPE coated aggregate, could be successfully used to replace conventional mix for DBM, with advantage of project cost reduction, improvement in performance and environmental betterment R I. INTRODUCTION utting, loosely defined as longitudinal depressions in the wheel paths of asphalt concrete pavements, has historically been a primary criterion of structural performance in many pavement design methods. Rutting is also a serious safety issue for road user. Rutting has been a major concern for flexible asphalt pavement. It is also one of the most common pavement permanent deformations due to repetitive traffic loads which accumulate small deformations of pavement materials appearing as longitudinal depressions in the wheel paths of the roadways. 1.1 Possible Causes of rutting: Specific causes of rutting can be: 1. Insufficient compaction of HMA layers during construction 2. Subgrade rutting (e.g., as a result of inadequate pavement structure) 3. Improper mix design or manufacture 4. Improper gradation of aggregate 5. Lacking in the stability of mix to support the traffic etc. 1.2 Solutions Prevention:- To prevent rutting in bituminous pavement following are some of the solutions- 1. The use of quality design, quality aggregate and quality liquid asphalt. 2. Proper gradation of aggregate. 3. Using appropriate quantity of binder content Adequate drainage. 5. By using modified binder in place of normal bitumen such as CRMB and PMB. Rutting resistance potential of any bituminous mix depends on the properties of its constituents. In this study crumb rubber and waste plastic is used to modify constituent s properties. Crumb rubber is the common name used for granulated rubber produced from scrap types. Plastic waste used in this study refers to polybags generally used as carry bags for different grocery items. Both of these are available in abundance and use of these waste materials would be much more beneficial because it will reduce solid waste disposal problem, Crumb rubber is used to modify bitumen generally termed as crumb rubber modified bitumen (CRMB). Advantages of using CRMB are lower susceptibility to variations in temperature (daily and seasonal), lesser deformation at high pavement temperature, greater value of fatigue resistance, increased Page 99

2 adhesion between aggregates and binder. It also solves disposal problem of solid waste generated. Waste plastic is used to form a coating around aggregates. For grading of aggregate the specification which is given in MORT&H is taken. There are two gradations given for Dense Bituminous macadam layers, grade-i and grade- II. For the present study grading-i (mid-point gradation) is selected to carried out different test. Mid-point gradation for Dense Bituminous Macadam (DBM) gradation-i in which nominal aggregate size of 37.5 mm and layer thickness of 75-1 as per MORT&H guidelines (213). The aggregate grading is given in Table-3.1 Table3.1 Composition of Dense Graded Bituminous Macadam (Section 5 as per MORT&H guidelines) Fig1.1 Rutting phenomenon occurrence in bituminous pavement In this study laboratory evaluation of rutting is done with the help of wheel tracker equipment in which rut depth on specimen is measured simulating field conditions of traffic and environment. Wheel Tracker or Wheel Rut Tester generates rut on a specimen of bituminous mix prepared with the help of Wheel Rut Shaper. Studies shows that wheel tracker devices proved to be mostreliable equipment for rutting measurement in laboratory. II. OBJECTIVE OF THE STUDY The objectives of this study are: To find out the Modified Marshall stability and other Marshall parameters for different modified and conventional bituminous mixes using Modified Marshall method for grading-1 of Dense Bituminous Macadam (DBM). Using Modified Marshall Mix design technique deciding the most effective proportions of crumb rubber and waste plastic in the bituminous mix which will produce least amount of rutting. To study the effect of temperature variation on rut depth for different modified and conventional bituminous mixes with optimum proportion of crumb rubber and waste plastic. Additionally percentage increase in rut depth with increase in temperature is to be investigated and comparison among different bituminous mix is to be studied. To study rut depth variation with increasing number of passes of wheel in wheel rut tracker at a specific temperature for different modified and conventional bituminous mixes with optimum proportion of crumb rubber and waste plastic. III. EXPERIMENTAL DETAILS 3.1 Selection of type of Surface Course for Experimental Study Grading 1 2 Nominal aggregate size 37.5mm 26.5mm Layer Thickness 75-1mm 5-75mm Cumulative %by weight of total IS Sieve (mm) aggregate passing Bitumen % by mass of total mix Min 4. Min Material Used Aggregates Aggregate constitutes the granular part in bituminous concrete mixtures which contributes up to 9-95 % of the mixture weight and contributes to most of the load bearing & strength characteristics of the mixture. Table 3.2 Physical Properties of Aggregate Physical Property Tested Aggregate Impact Value Flakiness and Elongation Index (Combined) Los Angeles Abrasion Value Test Methods Part 4 Part 1 Results Specification s MoRT&H (21) (%) 16.4% Max 27% 16.37% Max 3% Part % Max 35% Page 1

3 Water absorption Specific Gravity of Aggregate Combined Flakiness & Elongation Index,% Bitumen Part 3 Part 3 IS:2386 Part 1.8% Max 2% Max 35% Table 3.3 Physical Property of Bitumen of grade VG3 Aggregate Impact Value, % Crumb Rubber The specific gravity of crumb rubber is approximately 1.15, and the product must be free of fabric, wire, or other contaminants. In the present study Crumb rubber passing sieve IS 425 μ (.425 mm) is used as modifier for DBM mix. Property Tested Specific Gravity Penetration (1/1th of mm) Softening Point, C Test Method Results Specification as per IS Code IS IS (min) IS (min) Ductility, cm IS (min) Filler Filler is very fine less than.75mm and inert material that is mixed with graded coarse and fine aggregate. Its purpose of addition is to increase the density and strength of mixture. Various type of material is now being used as filler like Lime, Cement, Fly ash etc. Here Portland cement of Grade33 is taken as filler having Specific Gravity Waste Plastic as a modifier Low density polyethylene (LDPE) was used as a modifier for preparation of the samples.specific Gravity of polythene =.95. The size of shredded waste plastic is taken for the present study passing through 4.75 mm IS sieve and retained on 3 μ IS sieve & thickness between 1 μ to 3 μ Properties Fig3.2 scrap tyres Results CR-5 CR-1 CR-15 Penetration, at 25 C (.1mm) Softening point (R&B), C Ductility (cm) Specific gravity Equipments Used Modified Marshall Stability Testing Apparatus Modified Marshall Stability testing machine is used for find out the stability and flow value of bituminous mix for grading-i of DBM, where the maximum size of aggregate is more than 26.5mm. The method using 15mm diameter specimen described in MS-2 and ASTM D 5581 shall be used. Fig3.4 Shredded Polyethelyne Table3. 4 Properties of WP coated Aggregates Properties Results WP-5 WP-1 WP-15 Aggregate Impact Value, % Fig3.3 Breaking Head Page 11

4 3.3.2 Wheel Rut Shaper Fig3.4 Modified Marshall Mould With the help of wheel rut shaper the specimen can be compacted to required density and thickness. Roller (Runner wheel) which is connects with machine compact the specimen up to the required thickness. Before compaction of specimen, heat up the runner wheel to the temperature required for the experiment. Following are the main technical index of the machine- Radius of roller- 5 mm Width of roller- 3 mm Speed of velocity model- 6 times round trip/min Pressure of roller- within 2 kn Warm-up temperature- 2 to 2 degree Wheel rut shaper machine is shown in Fig3.5 Fig3.5 Wheel Rut Shaper Wheel Rut Tester Wheel rut tester is used as to find out rut depth in bituminous concrete mix for different number of passes and for different temperatures under the loading similar to what the pavement surface is applied. Wheel rut tester with the reciprocating motion of loaded wheel on bituminous specimens determines the potential of asphalt pavement rutting. Following are the main technical index of Equipment- Pressure wheel speed: 42±1 time/min (single way) Moulds size: 3x3x5mm(standard),here the moulds height can be in a range between 3-1mm Displacement measuring range: -3mm Displacement measuring precision: less than ±.5mm Testing time of rutting wheel: 6 minute Adjusted range of the controlled temperature: 4-6 C Wheel rut shaper machine is shown in Figure 3.6 Fig3.6 Wheel Rut Tester IV. METHODOLOGY AND BITUMINOUS MIXES the experimental program can be comprehensively separated in three noteworthy stages as examination of materials and their characteristics, mix design lastly assessment evaluation test which is rut test with wheel rut tracker. In first stage quality standards of materials utilized were analysed. In second stage mix was designed to obtain proportions of materials to prepare specimens in third stage. Modified Marshall Method of mix design was adopted for grading-1 of DBM and three types of bituminous mixes were prepared with DBM gradation-i, which are: 1. Mix with VG-3 bitumen as binder 2. Mix with VG-3 bitumen modified with crumb rubber (5%, 1% and 15%), 3. Mix with VG-3 bitumen modified with crumb rubber (% of crumb rubber is selected for which most stable mix is generated) and LDPE (3%, 6%, 9%) coated aggregates. Marshall test was carried on these three types of mixes. Modification of bitumen with crumb rubber was done by Page 12

5 mixing granulated crumb rubber of size minus 425 microns; with bitumen at 7 revolutions per minute for 3 minutes at 177 C. Gradation of aggregates was one according to two sets of grading given in MORTH 213 for DBM binder course. Out of different proportions of crumb rubber modified mixes, 1% was selected on the basis of stability criteria. Then Marshall specimens were prepared with 1 % crumb rubber modified bitumen and LDPE (3%, 6%, 9%) coated aggregates. LDPE was used in shredded form of size not greater than 2 mm. Coating of LDPE was achieved by mixing shredded plastic with preheated aggregates till uniform coating is achieved. Specimens with 6% LDPE were most stable. OBC was determined for conventional mix, modified mix with 1% crumb rubber, modified mix with 1% crumb rubber and 6% LDPE. In third phase wheel tracker rut tests were performed. Specimens were prepared in rut shaper machine using dynamic compaction technique. Conventional and modified mixes were prepared with designed OBC as determined in second phase. Density of specimens was kept same as measured in mix design. Test temperature is varied from 4 C to 6 C to simulate different field conditions of various places. Rut depth variation with temperature and number of passes of wheel was recorded and analysed. 4.1 Modification of Bitumen and Aggregates For modified mixes either modification of bitumen or that of aggregates was performed before mixing procedure. Modification of bitumen was done by replacing bitumen with crumb rubber (5%, 1% and 15% of bitumen weight). Granulated crumb rubber obtained from tyre remoulding industry was sieved through 425 microns sieve, material passing is collected for use. Measured quantities of bitumen and crumb rubber are mixed in a mechanical mixer at 7 revolutions per minute for 3 minutes at a temperature of 177 C. Modified bitumen obtained from above procedure is termed as CRMB. Bitumen was modified in batches just before preparation of specimen. This process of bitumen modification is also known as wet process of bitumen modification. Mixing is done for 3 minutes because it is assumed that by that time crumb rubber particles would form physio-chemical bonds with bitumen. Although such mix should be used within 24 hours otherwise settling of crumb rubber starts which would lead to inferior mix. Hence modification was done in batches. Modification of aggregates was done by adding shredded LDPE to aggregate (preheated to temperature of 17 C) in a heating container and mixed further. Plastic softens and forms film around aggregates. Amount of LDPE (3%, 6%, 9%) was taken as percentage by weight of bitumen content although bitumen is not replaced by it. Aggregate modification was also done at the time of specimen preparation. 4.2 Modified Marshall Test For preparation of Modified Marshal specimen for grading-1, total weight of specimen was considered as 45 grams. Then required weight of aggregate of desired gradation were weighed and heated up to C. Bitumen (virgin VG 3) was separately heated up to C. The measured quantity of bitumen was mixed with aggregate till proper coating was achieved. The mix was poured into marshal mould (152.4mm diameter and 95.25mm thick) and compacted with 112 blows on each face. The mould was taken out and kept under normal laboratory temperature for 24 hours. Specimens were extracted from mould and it s height and weight were measured. It was immersed in a water bath kept at constant temperature of 6 C for 3 minutes and after that it was taken out for testing in the Marshall testing machine. Stability and flow values for each specimen were noted down. OBC was determined for grading-1 with the help of graphs drawn between bitumen content and stability, density, and percentage air voids in mix. OBC is average of bitumen content at which maximum stability, maximum density and 4% air voids in mix. Modified mixes specimens were also prepared similarly except that instead of virgin bitumen, modified bitumen was used as binder material. Three types of modified mixes were prepared by replacing bitumen, varying the crumb rubber content as 5%, 1% and 15% for grading-1. Thus total three combinations of CRMB mix specimens were prepared and Marshall Test was done to determine stability and other test parameters. CRMB mix with 1% crumb rubber has given most stable mix. Hence OBC of mixes with 1% crumb rubber was determined for grading-i Most stable mix obtained above with 1% crumb rubber is further modified by replacing normal aggregates with modified aggregates. Again three types of modified mixes were prepared by coating aggregates with different amount of LDPE as 3%, 6% and 9%. Thus total three combinations of CRMB mix specimens were prepared and Marshall Test was done to determine stability and other test parameters. Mix with 6% LDPE has given most stable mix. Hence OBC of mixes with 6% LDPE was determined for grading-1. Fig4.1 Modified Marshall Sample Page 13

6 V. OBSERVATION AND RESULTS 5.1 Modified Marshall Stability Test Table 5.1 Maximum Modified Marshall stability for conventional and modified bitumen mixes Maximum Types of Bitumen mixes stability For grading-ii VG % CRMB % CRMB % CRMB % CRMB + 3% LDPE % CRMB + 6% LDPE % CRMB + 9% LDPE Rut Test Fig4.2 Modified Marshall Test Wheel Rut Test is done with the help of Wheel Tracking Device and Rut Shaper. Prepared mix is poured in cubical moulds and then specimen is compacted to achieve desired density in Rut Shaper. Prepared specimen is then tested in Wheel Tracker. Three types of bituminous mixes were prepared for which binder content is taken as OBC as determined by Modified Marshall Method of mix design for grading-1 of DBM. 1. Conventional mix with VG-3 as binder and normal aggregates, 2. Modified mix with VG-3 modified with 1% crumb rubber and normal aggregate, 3. Modified mix with VG-3 modified with 1% crumb rubber and 6% LDPE modified aggregates. Specimens were prepared with the help of Rut Shaper. Prepared mix was poured in cubical mould and placed for compaction in Rut Shaper. After proper compaction mould was left until it acquired room temperature. Then mould was placed in Wheel tracker to perform rut test for one hour at different temperatures (4 C, 5 C, and 6 C). Test results were collected for different mixes and analysis was done. 5.2 Wheel rut Tester Table 5.2 Rut test on conventional mix (G1) with VG-3 as binder and normal aggregate Number of Passes at Temperature of 4 c 5 c 6 c Table 5.3 Rut test on conventional mix (G1) with 1 as binder and normal aggregate Number of Passes at Temperature of 4 c 5 c 6 c Table 5.4 Rut test on conventional mix (G1) with 1 as binder and LDPE-6 aggregate Fig4.3 Rut Mold after rutting test Number of Passes at Temperature of 4 c 5 c 6 c Page 14

7 Rut Depth Rut Depth Rut Depth International Journal of Research and Scientific Innovation (IJRSI) Volume III, Issue XII, December 216 ISSN Rut Depth Vs Number of Passes Fig5.1 normal mix C Rut Depth Vs C.5 C Fig5.2 modified mix (G1) with 1 as binder and normal aggregate Rut Depth Vs C Fig5.3 modified mix (G1) with 1 as binder and LDPE-6 aggregate Fig 5.4 Rut depth variation with no. of passes for diff. type of mixes (G1) at 4C Fig 5.5 Rut depth variation with no. of passes for diff. type of mixes (G1) at 5C Fig 5.6 Rut depth variation with no. of passes for diff. type of mixes (G1) at 6C V. RESULTS AND DISCUSSIONS In this study following results were obtained: NORMA L 1 1+LDP E NORMA L 1 1+LDP E NORMA L 1 1+LDP E Marshall Test results for stability, flow, density, percentage air voids, VFB, VMA of conventional Page 15

8 DBM mix lie well within limits as given in MoRTH 213 for both grading. As a result of modification of binder alone stability increased by 26.67% when VG-3 bitumen is modified with 1% crumb rubber. When this modified mix (1) is further modified with 6% LDPE coated aggregates (1 + LDPE-6), stability increased by 37.69% with respect to normal mix (For grading 1). Optimum bitumen content in conventional mix is obtained as 4.91% which is reduced to 4.83% in case of 1 mix and 4.56 in case of 1 + LDPE-6 mix (For grading I). The percentage increase in rut depth on conventional mix, In the mix of grading I, when temperature changes from 4 C to 6 C, is 69.15% whereas that for 1 mix is 55.3% and for 1 + LDPE-6 mix this value is 47.18%. The decrease in rut depth at 25 cycles for the mix of Grading I at 4 C, is observed 14.1% when instead of conventional mix, 1 mix is adopted and 32.85% of decrease in rut depth is observed when instead of conventional mix 1 + LDPE-6 mix is adopted. The decrease in rut depth at 25 cycles for the mix of Grading I at 5 C, is observed 17.95% when instead of conventional mix, 1 mix is adopted and 35.7% of decrease in rut depth is observed when instead of conventional mix 1 + LDPE-6 mix is adopted. The decrease in rut depth at 25 cycles for the mix of Grading I at 6 C, is observed 21.1% when instead of conventional mix, 1 mix is adopted and 41.3% of decrease in rut depth is observed when instead of conventional mix 1 + LDPE-6 mix is adopted. VI. CONCLUSIONS Based on the study, following conclusions have been drawn: Analysis of results shows that an optimum proportion of crumb rubber addition improved mix properties significantly, although further modification by coating aggregates with optimum amount of LDPE resulted in manifold improvement with respect to conventional mix. In the areas prone to high rut depth on DBM base/binder course, modified bituminous mix (having crumb rubber modified bitumen along with plastic coated aggregates) is more suitable than conventional mix due to its high rut resistance. Study shows considerable decrease in bitumen content in bituminous mix by use of crumb rubber and plastic which are waste materials. Hence use of such modified mixes would reduce cost of project significantly along with reuse of waste material. Plastic coated aggregate crumb rubber modified mix shown negligible increase in rutting even when significant temperature change occurs. Hence such modified mixes are strongly recommended for areas having large temperature variations. Thus modified mix with crumb rubber modified bitumen as binder and LDPE coated aggregate, could be successfully used to replace conventional mix for DBM, with advantage of project cost reduction, improvement in performance and environmental betterment. VII. FUTURE SCOPE India as a developing country still needs to connect many villages to road skeleton of country. Hence DBM as a base/binder and profile corrective course has good scope ahead. Amount of plastic waste and scrap tyres is increasing day by day. Also such materials are found to be useful as a modifying agent in bituminous mix modification. Modified bituminous mixes with crumb rubber and plastic coated aggregates have proved to be more effective and more economical at the same time. Hence present and expected future scenario is demanding increased use of modified bitumen in place of conventional mixes. Many studies have shown improved behaviour of modified mixes for different type of base and surface courses. Still there is need of research work in this field at local level and for local roads REFERENCES [1]. Stacy G. 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