Resilient Behavior of Modified Asphalt Concrete Mixture

Abstract

Asphalt concrete pavement is designed to exhibit elastic behavior under loading at cold weather condition and a combination of elastic, plastic and viscous behavior at hot weather condition. Distress of the pavement usually starts with initiation of micro cracking due to load repetition, while such cracks can heal by themselves in slow process under repeated loading, external or internal heating, and provision of rest period at ambient temperature. The aim of this work was to assess the resilient behavior of modified asphalt concrete using three types of polymer additives such as starien- butadien- stairen (SBS), low density poluetheline (LDPE), and scrap tire rubber. Beam specimens of 381.0 mm length, 76.2 mm width, and 76.2mm thickness have been prepared with optimum asphalt content requirement and with extra 0.5% asphalt above and below the optimum. Beam specimens were tested under repeated flexure stress. The applied stress level was 138 kPa at 25°C. The loading cycle consist of 0.1 second loading application followed by 0.9 seconds of rest period. The test was conducted for 660 load repetitions using the Pneumatic repeated load system (RPLS) to allow for the initiation of micro cracks. After the specified loading cycles, the test was stopped and the Specimens have been withdrawn from the testing chamber of PRLS and stored in the oven for two hours at 60°C environment to allow for possible micro crack healing. The specimens were then subjected to another loading cycle. Permanent, total and resilient deformations were captured through LVDT. The resilient modulus was calculated and compared among various conditions. Test results showed that the implemented polymer additives and the process of micro crack healing have positive influence on resilient modulus and deformation variables of asphalt concrete.