Experimental evaluation of anti-stripping additives in bituminous mixtures through multiple scale laboratory test results

This paper presents performance changes and material characteristics associated with moisture damage due to anti-stripping additives in asphalt mixtures through various laboratory tests. Two additives (hydrated lime and fly ash) are investigated by adding them into two types of mixes where different asphalt binders and aggregates are used. Two widely-used asphalt concrete mixture performance tests (the AASHTO T-283 and the asphalt pavement analyzer under water) and two mixture constituent tests (the boiling water test and the pull-off tensile strength test) are conducted to characterize the effects of anti-stripping additives on the binder–aggregate bonding potential in mixtures. Results from laboratory tests indicate that the mixes, where high-quality aggregates and polymer-modified binder are used, are fairly self-resistant to moisture damage without treating any anti-stripping additive and do not show any visible sensitivity between additives, whereas the effects of additives and their sensitivity are significant in the mixes that use the unmodified binder and low-quality aggregates. With the limited amount of test data, both hydrated lime and fly ash contribute to reducing moisture damage, which implies potential significant cost savings by the use of fly ash as an alternative additive.