Evaluation of HMA Moisture Sensitivity Using the Nottingham Asphalt Test Equipment

Moisture damage is a significant problem for flexible pavements. The damaging effect of moisture on pavements, specifically hot mix asphalt (HMA), is a significant environmental distress that should be considered. As a pavement is subjected to a freeze/thaw cycle, the material expands and contracts. During expansion, water can seep into permeable air voids created with the increased volume and can freeze. When the material contracts during thawing, the water can propagate the cracks created during freezing and cause further damage in the next freeze cycle, ultimately weakening the structural strength of the pavement layer. Over time, the repetition of the freeze/thaw cycle deteriorates the pavement and can lead to mix instability and road damage, such as ruts, if the moisture-susceptible mix is below the surface mix. Surface mixes that are susceptible to moisture damage can experience raveling. Identifying pavements susceptible to moisture damage and the effects of moisture damage on the life of pavement can reduce maintenance costs accrued with the placement of a poorly performing HMA.