Influence of water and temperature on mechanical properties of selected asphalt pavements

One of the main causes of distress in asphalt pavements is water damage. The purpose of this paper is to compare different test methods to evaluate moisture susceptibility. This is of special importance because of the insufficient effectiveness of the procedures currently used. In this research experiments were conducted to investigate the effects of water and temperature on mechanical properties of mixtures with different air voids content. The evaluation of such properties concentrates on the following three approaches: innovative (Coaxial Shear Test), traditional (Indirect Tensile Test) and empirical (Cantabro Test). Specimens were prepared by means of Superpave Gyratory Compactor (SGC) and divided in two different subset for controlled dry and wet conditioned testing. Test results indicated that Indirect Tensile Test (IDT) is not able to discriminate between wet and dry condition as the Coaxial Shear Test (CAST) does. The CAST method reproduces closest the real field conditions and indicates clearly the risk of water damage for open graded mixtures (high air voids content). Dense graded mixtures (low air voids content) showed less influence probably due to the reduced amount of penetrating water. Cantabro Tests (CAT) provided also significant results in good correlation with air voids content and material properties of asphalt mixes.