RESTRICTED ZONE OF SUPERPAVE MIX DESIGN AND ITS IMPACT ON RESILIENT MODULUS AND PERMANENT DEFORMATION

Abstract

Back in 1993, Strategic Highway Research Program introduced new mix design method known as SUPERPAVE that is an acronym of Superior Performing Asphalt Pavement. Superpave caters filed performance of bituminous mixes and Superpave gradation chart includes 0.45 power line, restricted zone and control points. In Superpave, the gradation that compliance with the restricted zone was considered less rut resistant as compared to gradation passing outside the restricted zone. This study targets three types of gradations that passed above, below and through the restricted zone. The results show that the gradation passing through the restricted zone not only satisfy Superpave volumetric requirements but also performs better against rutting as compared to gradation passing outside the restricted zone. Resilient modulus (MR) measured through indirect tensile strength setup that defines the elastic properties of bituminous mix under repeated load test. Laboratory study was conducted to find factors that affect the gradation. Two-way factorial design was carried out by using Minitab-15 statistical software and the results reflected that the individual factor i.e. loads duration and temperature as well as interaction of factors has significant effect on the performance of HMA.