Mechanical Characterization of Combi-layer

摘要

Combi-layer consists of a porous asphalt concrete layer with very high voids content (25 percent), of which the voids are filled with cement slurry. In this paper research is reported into the mechanical characterization of combi-layer. This was necessary because many asphalt technologists see combi-layer as an intermediate between asphalt concrete and cement concrete with some concrete-like properties at high temperatures. No relevant material characterization was available from literature. The normal testing procedures for the mechanical characterization of asphalt concrete mixtures have been executed. From the test results master curves for the stiffness over a large temperature area, indirect tensile strength and fatigue lines at design temperatures are reported. Because of the suggested difference with the standard asphalt concrete mixes a fundamental characterization of the material was deemed necessary. Uni-axial tension and compression tests were performed at several temperatures and strain rates. In this paper monotonic tension and compression tests with a constant strain rate are reported. In the paper the uni-axial properties of the combi-layer material are compared with asphalt concrete and cement concrete. From the comparison it becomes clear that the combi-layer behaves similar to an asphalt mix. At high temperatures it cannot perform without confinement under loading like cement concrete. This is best shown with the temperature dependence of the material properties.