Increasing truck loads on Egyptian road network cause several pavement distresses. The most common distress types occurring in the Egyptian roads are rutting and cracking. Several research studies trials were conducted to control pavement distresses by mix enhancement. Several trials were done to eliminate pavement rutting by using some additives. However, although these additives increase rutting resistance, it increases the propagation of cracking. One of the cheapest methods for mix enhancement is to use waste materials such as crumb rubber. This study aims at investigating the effect of using crumb rubber on the properties of asphalt binder and evaluating asphalt concrete mixtures modified by crumb rubber for increasing pavement resistance to cracking. To achieve the study objectives, the properties of asphalt binder modified by certain ratios of crumb rubber were measured. Furthermore, Marshall test was conducted on standard mix without rubber as a reference and on two groups of asphalt concrete mixtures. In the first group crumb rubber was used instead of fine aggregate by certain percents. While in the second group, crumb rubber was used instead of certain asphalt percents. Finally, some special tests were performed to measure the different mix characteristics. These tests included loss of stability test, modulus of elasticity test, wheel tracking test and indirect tensile strength test. Analyzing the study results it can be concluded that the use of crumb rubber greatly enhance the pavement resistance to cracking. Finally the study recommended a proposed mix with 20%and 5%by weight instead of typical percents of sand and asphalt respectively |
