There has been an ongoing effort to develop effective methods for using scrap tires in highway construction. Crumb rubber additive to hot mix asphalt has been developed as a potential method. In the present work, we evaluate the performance of crumb rubber modified hot mix asphalt. The triaxial testing procedure is used to evaluate the mechanical properties of different mix proportions. The triaxial testing procedure, although considered complex, gives more closely the actual conditions in a confined pavement layer. Therefore, the method provides a more logical approach to the measurement of stress-deformation and shear strength properties or stability of granular materials, such as hot mix asphalt. Based on the results of the triaxial compression tests, three criteria, viz. shear strength (stability), vertical strains at failure, and void ratios, are used to determine: (i) the optimum asphalt to aggregate ratios in plain hot mix asphalt, and (ii) the optimal proportion of rubber to asphalt in crumb rubber modified hot mix asphalt. The present work focusses upon the stone mastic hot mix asphalt.
