Examination of moisture sensitivity of aggregate–bitumen bonding strength using loose asphalt mixture and physico-chemical surface energy property tests

Abstract

In this study, the moisture sensitivity of different kinds of aggregates and bituminous binders is examined by comparing the performance between five empirical test methods for loose mixtures -static immersion test, rolling bottle test (RBT), boiling water test (BWT), total water immersion test and the ultrasonic method -with more fundamental surface energybased test data. The RBT and BWT results showed that limestone aggregates perform better than granite aggregates and that, for unmodified binders, stiffer binders provide better moisture resistance compared with softer binder. Both tests were sensitive to aggregate type, binder type and anti-stripping agent type. Ranking of the mixtures by RBT and BWT was in general agreement with the surface energy-based tests, especially for mixtures that performed worst or best in RBT and BWT. The magnitude of the work of debonding in the presence of water was found to be aggregate type dependent which suggests the physico-chemical properties of aggregates may play a fundamental and more significant role in the generation of moisture damage, than bitumen properties.

Influence of aggregate mineralogical composition on water resistance of aggregate–bitumen adhesion

“…Existence of moisture in the pavement can result in the loss of cohesion within the bituminous binder itself or the loss of interfacial adhesion between binder and the aggregates [5,6]. The resistance of asphalt mixtures to moisture attack has been related to aggregate mineralogy, surface texture of aggregate, bitumen chemistry and the compatibility between bitumen and aggregate [7,8].…”

Chemically modified bitumens with enhanced rheology and adhesion properties to siliceous aggregates

“…The surface energy components of the siliceous aggregate used in this work were previously determined by Liu et al [29] Figure 2 shows the viscous flow curves for the neat bitumen and modified binders measured at 60 ºC. A nearly Newtonian behaviour over the whole range of tested shear rates is shown for the neat bitumen and "Th-binder".…”

“…The surface energy components of each binder were determined from the contact angles that selected probe liquids, with known surface free energy components (Table 3), produced with the binder. The contact angles were obtained from the change in mass undergone by a bitumen-coated slide immersed in the probe liquid [29,30], as follows:…”

Effect of Varying Field Conditions on Stripping of Bituminous Roads

“…Stiffer binder (40/60 pen) provides better moisture resistance for unmodified mixtures when compared with softer binder (160/220), based on loose bitumen coated moisture sensitivity tests [4].Based on results from loose bitumen coated moisture sensitivity tests bituminous mixtures containing limestone aggregate have better moisture resistance than granite aggregate.…”