Effect of Aging on Adhesion Properties of Asphalt Mixtures with the Use of Bitumen Bond Strength and Surface Energy Measurement Tests

Abstract

The interaction between asphalt binder and aggregate is fundamental to ensure adequate performance of asphalt mixtures, mainly in the presence of water. The work of adhesion generated between both materials directly affects the resistance of asphalt mixture to moisture damage, because it measures the ease with which water can displace asphalt binder from the aggregate surface. The objective of this study was to characterize the bond strength between asphalt and several aggregate sources. A PG 64-22 neat binder was modified with several additives to determine the effect on adhesion: polymers, nanomaterials, and adhesion promoters. To measure the strength of adhesion, the bitumen bond strength (BBS) test and contact angle measurements between asphalt binder and the aggregate surface by means of goniometry were used. The surface energy of the asphalt and the aggregate, with and without the presence of water, was estimated also. Testing was performed on all binders and on each binder–aggregate combination after ( a) rolling thin-film oven (RTFO) aging and ( b) RTFO and pressure aging vessel aging. The BBS results identified differences in bond strength as a result of moisture conditioning and aging. The differences depended on the aggregate source and binder type. Different failure modes were also observed (i.e., cohesive, adhesive). The results also indicated an increase in strength of adhesion associated with the aging process: the main resistance gain was observed after RTFO aging. Finally, changes in bond strength were compared with functional composition changes associated with the aging process and related to changes in performance.

Fundamental Approaches to Predict Moisture Damage in Asphalt Mixtures: State-of-the-Art Review

“…Polymer modification [46,52,53] • γincreases slightly; [20] • No clear effect on γtotal; [18] • γtotal increases, γLW increases, γ+ decreases, γvaries, γAB decreases; [49] • Increase after RTFOR, reduction after PAV in γtotal, similar trend for LW and basic component, the acidic component increases after each aging step.…”

“…Method to determine surface energies of bituminous binders [18,20,21,23,24,26,[28][29][30][34][35][36][37][38][39][40][41][42][43][44][45][46][47] Wilhelmy plate tests in probe liquids (VCG), ambient [20,39,[48][49][50][51] Sessile drops of probe liquids on bitumen surface (VCG) ambient [18,20,35] Inverse gas chromatography (CVS) [46,52] Pending drop (100-140 • C) combined with sessile drop on PTFE (OW) [53] Sessile drops on a microtome-cut bitumen surface 20 • C (OW) [39,54] Sessile drops of probe liquids on bitumen surface (OW) ambient [55] Dynamic sessile drop measurements of probe liquids on a bitumen surface (VCG) [56] Pending drops of bitumen (100-130 • C) (γ total) [53] Pending drops at equiviscous temperatures (γ total) [57] Pending drops of bitumen at a fixed G* 209 Pa (γ total) [39] Wilhelmy plate tests in probe liquids (OW) ambient [20] Atomic force microscopy (dispersive component)…”

“…Method to determine surface energies of aggregates used in asphalt applications [18,19,21,23,24,26,[28][29][30]35,36,38,40,41,45,46,[58][59][60] Universal sorption device (VCG) [49][50][51]55] Sessile drops of probe liquids on flat aggregate (VCG) [53,57,61] Sessile drops of probe liquids on flat aggregate (OW) [20,28] Micro calorimeter (VCG) [20] Inverse gas chromatography (VCG)…”

“…In some studies [49,52,53,56,57,[67][68][69][70], the bitumen-aggregate affinity is derived from contact angle measurements, between bitumen drops in direct contact with a (flat) aggregate surface. In such tests, surface energy components are not determined, however, later tests allow a direct measurement of bitumen-aggregate interaction, which can be measured both in air, as well as in water.…”

Kinetics-based aging evaluation of in-service recycled asphalt pavement

“…It is found that aging affects the adhesion of an asphalt-aggregate system based on the measurements of adhesive bond energy at different aging levels. Depending on the source of binder and aggregates, the adhesion may increase or decrease (Cheng, 2002;Aguiar-Moya et al, 2015;Kassem et al, 2016). Furthermore, aging may change the chemistry of the asphaltaggregate interface of RAP materials, which results in a different adsorption mechanism between asphalt and aggregates.…”