Influence Of Recycling Process On Physical Properties Of Asphalt Concrete

Recycling of aged and distressed asphalt concrete pavement is considered as one of the sustainable measures to restore the pavement quality. Various types of additives are usually implemented as rejuvenators for such process. In this investigation, an attempt has been made to recycle the laboratory aged binder by digestion with various percentages of polyethylene and crumb rubber. Specimens of 102 mm diameter and 63.5 mm height have been prepared using Marshal Method at 150 °C at optimum binder content. Additional asphalt concrete specimens have been prepared using asphalt cement of 0.5% above and below the optimum asphalt content. Specimens were subjected to the indirect tensile strength test at (25 and 40) ºC, and double punching shear strength determination at 25 ºC. The temperature susceptibility and the resistance to moisture damage were determined. It was concluded that indirect tensile strength ITS at 25 ºC for polyethylene and crumb rubber recycled mixtures decreased by (35.4 and 19) % at optimum asphalt content while it decreases by (27.7 and 4.2) % and (9.8 and 23) %  for mixtures with 0.5 % asphalt lower and upper than OAC respectively as compared to control mixture. Higher percentages of crumb rubber of (1 and 1.5) % were able to reduce the Temperature Susceptibility of asphalt concrete by (54.4 and 61) % as compared to control mixture. (0.5 and 1.0) % of polyethylene exhibit no significant variation in tensile strength ratio TSR as compared to the control mixture. On the other hand, 1.0 % of crumb rubber exhibit 2.6 % increment in TSR as compared to control mixture. The addition of more asphalt content or rejuvenators exhibit negative influence on shear strength of asphalt concrete.