Water Sensitivity of Asphalt-Aggregate Mixes: Test Selection: Fid-Bau Portal

Water Sensitivity of Asphalt-Aggregate Mixes: Test Selection

R. L. Terrel / S. Al-Swailmi

The research presented in this report was conducted to identify the important factors influencing the water sensitivity of asphalt paving mixtures, and to develop a test method to evaluate water sensitivity of asphalt concrete mixtures for mix design. The test method was to be performance related. Based on a hypothesis that air voids in the mixture may be the major source and cause of water damage (i.e., if a water-sensitive mixture has very few air voids, minimal water damage can occur because moisture cannot penetrate the mixture, and if the mixture has many voids, water drains out, also minimizing damage), a test system was developed to evaluate the major factors that influence water sensitivity. The Environmental Conditioning System (ECS) was used to develop a test procedure that includes specimen preparation; measurement of permeability using air, water, or both; vacuum wetting (partial saturation); cycling at various temperatures; and continuous repeated loading while monitoring resilient modulus after each conditioning cycle. Results using four core mixtures (two aggregates and two asphalts) indicated that the ECS can distinguish different materials and their relative water susceptibility. A tentative test procedure is recommended. Companion reports by Scholz, Terrel, Aljoaib, and Bea (1994) and by Allen and Terrel (1994) illustrate the use of the test on a wider range of materials and demonstrate the validity of the test method through studies on actual field projects.