Improvement the Shear strength of Asphalt Mixture by using crumb tire Rubber

Abstract

Rutting is one of the big problems in hot-mix asphalt (HMA) pavements. The primary mechanism of HMA rutting is shear deformation, often caused by high stress in HMA layers during traffic loading, especially at high temperatures. Current HMA rutting tests are not necessarily designed to capture HMA shear properties such as shear strength, shear strain, and shear module. The present work explores the behavior of the shear strength properties of HMA modified with Crumb Tire Rubber (CTR) and two types of filler (brick and lime dust in comparison with passing sieving No.200 as control filler) by developing a Simple Punching Shear Test (SPST) under control of temperature and loading rate. A series of laboratory sample tests to formulate and set up the SPST protocol and the related test parameters, derive the SPST results analysis sample to capture the HMA shear parameters from the results and comparatively evaluate the shear properties of HMA mixes. Results have shown that the SPST is relatively receptive to the form of modifier and filler. Using limestone dust as with (5%) CTR content increased higher shear strength, the rate of increase was about (44.44%) and (51.38%). Also 5% to 7% CTR content with lime dust filler lowering shear strain more than for brick dust filler.