A technical review of moisture damage of asphalt pavements and antistripping additives has been completed as part of a review and testing study for the Transportation Association of Canada that has the objective of developing a Canadian manual on the assessment of moisture susceptibility and selection of antistripping additives. The review is based on practical asphalt technology experience, questionnaires to agencies and asphalt cement suppliers, and the technical literature on moisture damage of asphalt pavements. Methods of mitigating moisture damage in asphalt pavement structures, in addition to the use of antistripping additives, such as drainage, compaction, aggregates selection, mix designs and quality control, were reviewed in terms of stripping mechanisms and causes. The Strategic Highway Research Program has involved considerable research on the moisture susceptibility of asphalt concrete and appropriate laboratory procedures to assess moisture damage. Qualitative and quantitative (strength) tests for assessing the moisture susceptibility of hot-mix asphalt mixes are reviewed. There is strong technical support for the Tunnicliff-Root (ASTM D 4867), Modified Lottman (AASHTO T 283) and Ontario MTO Immersion Marshall (LS-283) tests. The use of liquid (amines generally) and hydrated lime antistripping additives is considered. There is considerable technical information on the comparative efficacy of hydrated lime as an antistripping additive. An important area of research need is appropriate quality control/quality assurance to monitor the field effectiveness of antistripping additives. (A)
Abstract