Influence of Mixing Conditions of Modified Bitumen on Moisture Sensitivity of Asphalt Compounds

Modification of bitumen allows an improving the properties of bitumen, which can be a useful technique to enhance asphalt’s characteristics. Therefore, this research intended to study the effect of mixing time of different percentages of epoxy resin, between 0 to 8%, doped into bitumens on the moisture sensitivity of asphalt compounds containing two types of aggregates, i.e. limestone and siliceous. For this aim, the Sessile Drop Method (SDM) was employed, and moisture resistant parameters associated to surface free energy concept such as surface free energy components, work of cohesion, work of adhesion, work of debonding, adhesion bitumen to aggregate, and wetting bitumen around aggregate surface were assessed. The results revealed that the effect of the mixing time of bitumen and epoxy resin on moisture resistance properties of asphalt compounds significantly depends on the percentage of epoxy resin used in bitumen mixture. For bitumens with 4 and 6% epoxy resin, adhesion and wetting parameters had a similar performance for both mixing times of 10 and 60 minutes. However, asphalt compounds containing 2 and 8% epoxy resin modified bitumens prepared for 10 min mixing time had a better adhesion and wetting performance than those prepared for the longer mixing time, 60 minutes. The effect of mixing time of bitumen modified with epoxy resin on the bitumen and asphalt compound’ performance depend on the percent of additive in the bitumen.