Volume II, Issue IV, April 2015 IJRSI ISSN 2321 - 2705 www.rsisinternational.org/IJRSI.html Page 28 Effect of Polypropylene Fiber on CBR Value of Sand Dhiren R Hasrajani 1 , Anuj K Shah 1 , Aditya M Patel 1 ,Jay P Panchal 1 , Alka M Shah 2 1 Students, Department of Civil Engineering, Gandhinagar Institute of Technology, Dist. Gandhinagar. 2 Asst. Professor, Dept of Civil Engineering, Gandhinagar Institute of Technology, Dist. Gandhinagar. Abstract- The term soil stabilization means the improvement of the stability or bearing power of the soil by the use of controlled compaction, proportioning and the addition of suitable admixture or stabilizer, but the stabilization using waste plastic is an economic method as they are easily and cheaply available. This paper presents the CBR test conducted on fine sand reinforced with randomly distributed polypropylene fibers, under both soaked and unsoaked conditions with varying fiber content. Results of CBR tests demonstrate that inclusion of polypropylene fibers in sand with appropriate amounts improves strength and deformation behaviour of sub grade soils .The fiber addition rate varies from 0% to 2.5% at 0.5% interval. In this paper CBR value of reinforced sand increases by 113% compared to unreinforced sand. The optimum fiber content was found to be 2.5% (w/w). The addition of fiber becomes impractical after 2.5%.The proposed technique can be used in embankment, road construction, industrial yards etc. Keywords: CBR Value, Polypropylene Fiber, Pavement, Fiber Reinforced I. INTRODUCTION einforcement aids the strength and stability of soil. Reinforcement of soils with fibers is possibly one of the most effective techniques for increasing soil strength. Therefore, a number of laboratory experimental studies have been carried out, wherein soil is mixed with polypropylene fibers. The present work discusses the behavior of a CBR test on soil specimen of fine sand (SP) reinforced with randomly distributed discrete polypropylene fibers, under both soaked and unsoaked conditions, when compared to a non reinforced soil specimen under similar conditions. In this paper it is shown that the sand reinforced with the polypropylene fibers have more strength then the non-reinforced sand II. EXPERIMENTAL WORK 2-1. Laboratory Testing Program: CBR test were carried out on fine sand (SP) reinforced with randomly distributed discrete polypropylene fibers under both soaked and unsoaked conditions. For soaking, the samples were kept submerged in water for 4 days before testing. The tests were conducted on remolded soil samples prepared at standard Proctor's density and optimum moisture content (IS-2720-7-1980, Light compaction). 2-2. Materials: 2-2-1. Soil: (As Per IS:2720(IV):1985 Methods of test for soils, determination of grain size Analysis) Co-Efficient of Uniformity( Cu) Co- Efficient of Curvature( Cv) Type Maximu m Dry Sensity Optimu m Dry Sensity 2.33 0.964 SP (Poorl y Grade d) 1.715g/c c 13% 2-2-2. Plastic: Fiber Properties (Source:- ShreeHari Fiber Products Ltd. Ahmedabad) Type Diam eter Len gth Tens ile Stren gth Softe ning Point Dens ity Elonga tion at Break Polyprop ylene 0.1m m 20m m 450 MPa 170ᵒC 0.91 GM/ C.C 10- 45% Fig:1 Polypropylene Fibers 2-3. Methodology The CBR test is one of the most commonly used methods to evaluate the strength of a sub grade soil, sub base, and base course material for design of thickness for highways and airfield pavement. The California bearing ratio test is penetration test meant for the evaluation of subgrade strength of roads and pavements. The results obtained by these tests are used with the empirical curves to determine the thickness of pavement and its component layers. This is the most widely used method for the design of flexible pavement. As per ISI, the CBR test was performed on remolded soil by static compaction. Required amount of fibers as well as soil R