Research On Water Stability Of Warm Mix Asphalt Based On The Theory Of Surface Energy

Warm mix asphalt(WMA) has been researched and applied in the domestic and foreign most countries as a kind of energy saving and environmental protection type green pavement technology. But more road researchers focused on water stability of WMA and some researchers pointed out water stability may be the technical bottleneck of WMA for further application. Therefore, this paper applied surface theory that had been applied widely in the research on water stability of asphalt mix and widely recognized by road researchers. Surface energy theory think that it is important factor that adhesion work of asphalt mixture system for water stability.First of all, raw materials were selected and its basic nature were detected. Three-phase system adhesion model of asphalt, aggregate and water was validated and interpretation from the Gibbs free energy concept. The adhesion model of asphalt, warm-mixed agent, water and aggregate four phase system were established. Then select the suitable method which can test and calculation surface parameters of asphalt, warm-mixed agent and aggregate. How warm mix additives impacted on asphalt surface were analysis, and we also identified asphalt mortar in different filler-asphalt ratio, analyzed the change of asphalt mortar surface energy with filler-asphalt ratio changes. Finally, adhesion work of WMA were calculated by adhesion model and energy parameters of raw materials. WMA water stability were discussed by use surface energy theory. Through the above research and analysis, and we obtained the following results:From the Gibbs free energy concept to derive asphalt, water and aggregate adhesion model. It was reasonable from the Gibbs free energy concept establishment of asphalt, water and mineral aggregate adhesion model for the adhesion model expression and the existing are given by literature was the same way. On this foundation, four phase system of asphalt, water, warm-mixed agent and aggregate were established.Non-polar part namely van Edward force occupied the main role in Asphalt surface energy, and the polar component of Lewis acid-base force relatively occupied smaller role. Modified asphalt has greater cohesive force than matrix asphalt. Non-polar component is the main part in warm-mixed agent of surface energy parameters, and the polar account for only part of its gross22%. The surface of asphalt can increase or reduce for Warm mix additive. The surface energy of asphalt mortar by prepared different asphalt can not show regular changes as filler-asphalt ratio changes. Aggregate surface energy may be different largely as the different sources,,testing environment, test operation error.When WMA using matrix asphalt the adhesion work greater than using modified asphalt in Anhydrous conditions. The adhesion work of WMA greater than the hot mix asphalt mixture. WMA adhesion work decline sharply in the presence of water, and the decline greater than the hot mix asphalt mixture decline.WMA adhesion work results was different for different cementing material. When the aggregate was basalt, compared to hot mix asphalt mixture, WMA water stability will not reduced. But for granite and limestone, the work of adhesion appeared irregular change for cementing material selection. So in the application of WMA, we should select raw material according to the actual test results of asphalt mixture.