A study on adhesion characteristics of gneiss with asphalt

Gneiss is a common type of rock on the surface of the Earth, the use of gneiss as aggregates might help meet the demands of asphalt pavement construction. However, the study of gneiss as aggregates in asphalt mixture is few, especially the influence of gneiss on adhesion and surface properties of aggregates. In this paper, the mineral composition and texture morphology of gneiss were respectively investigated by X-ray Diffractometer (XRD) and Scanning Electron Microscope (SEM). The contact angle of gneiss with asphalt was studied by Heating Microscope, and adherence test was also carried out by the boiling water test methods in accordance with ASTM D3625. The adhesion characteristic about gneiss as aggregates in asphalt concrete mixture, which combines microcosmic composition, structure and macrophysics analysis, was ascertained. Mainly composed of silicon dioxide mineral, gneiss represents the flaky shape, rough surface texture with few porosity, which result to adhesion between gneiss and asphalt of only grade 3. When these gneiss materials are used as aggregates in asphalt pavement, some measures must be taken to improve the adhesion between gneiss and asphalt. Experiment results also indicate that the contact angles of gneiss with asphalt were smaller than that of granite, and the adhesion characteristics of gneiss are better than granite.