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Comparison of Shear Strength Characteristics of Stone Matrix Asphalt Mixture with Waste Plastics and Polypropylene

Bindu C S and Beena K S
School of Engineering, Cochin University of Science & Technology, Kochi-22, India

Abstract—The triaxial test measures the mix stability in shear strength and gave better information for field performance prediction. The stresses acting on the specimen simulate pavement stresses. The Stone Matrix Asphalt mixtures (SMA) are investigated using triaxial shear strength testing (50.8 mm/min ram rate loading at 60°C) to investigate the effect of additives, waste plastics and polypropylene on strength properties. The test was conducted at 0, 50, 75 and 100 kPa confinements. Analysis using Mohr-Coulomb failure theory shows that the stabilized SMA had highest cohesion and shear strength as compared to control mixture (SMA without additive), but almost similar angle of internal friction. SMA with waste plastics shows the highest cohesion and shear strength at 7% waste plastics. The strain at failure and tangent modulus increases with increasing confinement pressure, indicating their stress dependent behavior. The increase in tangent modulus indicates the increased elastic stiffness of stabilized SMA. The stress-strain curves show that the peak stress and the time of its occurrence is higher in waste plastics mixtures when compared to polypropylene mixtures. For stabilized mixtures, shape change of stress-strain curves is more gradual with increase in additive content and brittle type failure does not seem to occur as in control mixture. 

Index Terms—triaxial test, shear strength, waste plastics, polypropylene

Cite: Bindu C S and Beena K S, "Comparison of Shear Strength Characteristics of Stone Matrix Asphalt Mixture with Waste Plastics and Polypropylene," International Journal of Structural and Civil Engineering Research, Vol. 2, No. 4, pp. 13-21, November 2013.