Effects of Heating and Reheating of Hot Mix Asphalts Mixtures on Marshall Properties and Indirect Tensile Strength.

Marshall Test is the only hot mix asphalt design method depended in Iraq. Asphalt concrete mixtures subjected to continuous heating starting from asphalt plant to compaction location that may be continuous for many hours. Furthermore, these mixtures may subjected to cooling under its compaction temperature for any reason, when reheating them will be requesting matter. Heating and reheating process have an effect on mixtures properties and durability due to its effect on asphalt viscosity. In addition to that, it’s become a major concern for both the state and the contractor to measure these properties. Minor changes in Marshall Properties may be the difference in whether contractor receives full pay or reduced pay for produced mixtures. It is believed that differences in how mixtures are handled and tested have played a role in discrepancies between government agency and contractor test results. The objective of this study was an attempt to evaluate the effects of asphalt mixtures heating and reheating on the Marshall Properties and indirect tensile strength. Mixture from three asphaltic layer (base, binder, surface) courses confirm with Iraqi specification subjected to continuous heating for (3, 6) hr., and another samples leaving to cool in room temperature for (1, 3) day then reheating to compaction temperature. Results showed that the heating of mixtures had a bigger defect on mixture properties than that caused by reheating as compared with initial properties recorded. Furthermore, reheating mixtures after 3 day had no effect as compared with that after 1 day.