Effect of different warm asphalt admixtures on the mechanical properties of bituminous mixtures

One of the scientific advances put into practice in asphalt production is warm mix asphalt technology. Warm mix asphalt technology enables asphalt production and casting at lower temperatures. In the thesis study, Pawma-1 and Leadcap warm mix asphalt admixtures and SBS admixture were tested in mixture samples. In addition, the effects of the use of the hydrated lime as fillers in the warm mix asphalts that were observed to improve some properties of the hot mix asphalts in previous studies have been investigated. Modified binders were prepared and binder experiments were carried out. Mixture samples were prepared by determining the optimum bitumen contents according to the Marshall method. Half of the mixture samples, 2% hydrated lime was used instead of filler. Aggregate and binder material are mixed in warm mixes at lower temperatures and compacted. Marshall stability and flow, indirect tensile stiffness modulus, resistance to moisture damage, indirect tensile fatigue and dynamic creep tests were applied on the mixtures. Stability and ITSM values were increased in the warm mix asphalt, but the tensile strength and creep modulus values were found to decrease. The tensile strength and creep performances of the warm mix asphalt with hydrated lime increased, resulting similar to the control samples. While Pawma-1 contributor increased the fatigue strength slightly, Leadcap contributor reduced in a small amount. With the contribution of hydrated lime in Leadcap modified mixtures fatigue performance are improved. It would be beneficial to use together the hydrated lime additive because it appears to give positive results in all experiments on Leadcap modified mixtures. In Pawma-1 modified mixtures, hydrated lime has a negative impact on indirect tensile stiffness modulus and fatigue performance, but has a positive effect on other experiments. SBS modified mixtures with hydrated lime additive were found to give the best results.