Development and validation of an enhanced test setup for assessing HMA stripping potential under hydrody namic pressure

摘要

A custom enhanced and modified Rice test setup was utilised in this laboratory study to assess and quantify the moisture sensitivity of hot-mix asphalt (HMA) under hydrodynamic pressure testing. The hydrodynamic pressure was simulated by repeatedly alternating the pumping and vacuum suction forces, which separately represented the positive and negative pore pressure on the HMA under a hypothetical combined action of moving vehicles and moisture effects. The overall research approach involved the following sequence of work activities: freeze-thaw and Hamburg wheel track testing for hydrodynamic pressure simulative effects, X-ray fluorescence analysis for stripped and suspended material identification followed by the development of the anti-stripping test (i.e. the enhanced/modified Rice test setup) and sensitivity analyses. In the study, laboratory validity of the new anti-stripping test was preliminary and successfully demonstrated through moisture sensitivity evaluation and analyses of various HMA with different types of aggregates (limestone, diabase, and basalt), asphalt binders (AH-70, SK-70, and styrene-butadiene-styrene (SBS)), and fillers (limestone mineral powder, hydrated lime, and brake pad waste (BPW) powder). For the aggregates, the rank order of superiority in terms on moisture resistance was found to be basalt (best) followed diabase and lastly limestone (poorest). As theoretically expected, the SBS-modified asphalt binder out-performed the AH-70 and SK-70 asphalt binders in terms of resistance to moisture damage, while the BPW powder demonstrated superiority over the other fillers, with the limestone mineral powder being the poorest.