The Use of Water Immersion Tests in the Evaluation of the Effects of Water on Cold-Recycled Asphalt Mixtures

Abstract

The effectiveness of various immersion-mechanical tests in measuring the water susceptibility of cold-recycled asphalt mixtures was investigated. The immersion-mechanical tests involved subjecting compacted recycled asphalt mixtures to a 24-h water immersion process followed by mechanical tests. The various mechanical tests used in this study included the resilient modulus, Marshall stability, Hveem stabilometer S value, Hveem stabilometer R value, and Hveem cohesiometer tests. The test values obtained from the wet specimens were compared to the values obtained from the dry specimens, and the effectiveness of the test methods was evaluated. The results of the study indicated that the resilient modulus, Marshall stability, Hveem S value, and Hveem cohesiometer tests were effective in measuring the changes in stiffness, stability, and cohesion of cold-recycled mixtures caused by water damage. The Hveem R-value test was not very sensitive in measuring the effect of water when a recycled mixture was relatively stable. However, the R-value test became very sensitive when a mixture was unstable, and thus it was very effective in determining the recycled mixtures that were highly water-susceptible. The water resistance of cold-recycled mixtures generally increased with curing time and compactive effort. The effects of the type of added virgin binder and the type of added virgin aggregate to the water resistance of cold-recycled asphalt mixtures were significant. The proper consideration of curing time, compactive effort, added virgin binder, and added virgin aggregate will help to attenuate the effect of water on cold recycled asphalt mixtures.