Laboratory evaluation of moisture damage and rutting potential of WMA foam mixes

This study was conducted to evaluate the rutting and moisture damage distresses which are the two major concerns in warm mix asphalt (WMA) performance. Two different methods were used to produce WMA mixes using foam bitumen technology. In the first method, the samples were prepared by transforming total bitumen of the mix into foam bitumen, whereas in the second method, two bitumens (soft and hard), the latter in foaming state, were added to the mix resulting in the same bitumen penetration in the final cured samples. The results of testing indicated that lowering the mixing and compaction temperatures resulted in increased moisture susceptibility and rutting potential of both WMA foam mixes. The Marshall quotient values and wheel tracking test results showed that the rutting potential of the WMA foam mixes were significantly greater than the control hot mix asphalt. The addition of hydrated lime powder was found to be effective in decreasing rutting and moisture susceptibility of the WMA foam mixes.