Study On Preparion And Performance Evaluation Of Temperature Control Asphalt Pavement With Phase Change Materials

Asphalt, as a black material has strong heat-absorb ability and will result high temperature of asphalt pavement. High temperature of pavement severely affectes durability of pavement, traffic safety and ecological environment. For example, it accelerates the aging of asphalt, aggravates rutting of pavement, causes traffic accident, and aggravates the urban heat island (UHI) effect. With the global warming and wide use of asphalt pavement, the problem of high temperature of pavement becomes more and more serious. This paper explored and studied the feasibility of phase change material (PCM) used in asphalt pavement to reduce temperature based on phase change theory and provided a new ideal for improving the adaptive ability of asphalt pavement to environment.Firstly, PCM was added into asphalt to prepare asphalt mastic. Penetration tests, Brookfield viscosity tests and dynamic shear rheometer (DSR) tests were conducted to investigate the influence of different kind (PCM-45、PCM-50) and content PCM to temperature susceptibility and rheological properties of asphalt. The results showed that the addition of PCM decreased the penetration and viscosity of asphalt and more content of PCM would make the value of penetration and viscosity smaller. The effect of PCM on the rheological properties of asphalt was related to temperature. When the test temperature was below the phase change temperature, the complex modulus increased with the increase of PCM. While when the test temperature was above the phase change temperature, the increase of PCM would decrease the complex modulus. When compared PCM-45with PCM-50, PCM-45showed slighter influence on asphalt.Secondly, three different methods were introduced to amalgamate PCM with asphalt mixture. Traditional hot mix method showed some temperature control result, but the dynamic stability of rutting test was not qualified to the standard of Chinese specification (800time/mm). Then cold mix method was used and the result showed that addition of PCM had some temperature control effect, but the strength in higher temperature was still needed to improve. Finally, a new structure with a mix of cement mortar and asphalt was used. The cement mortar which incorporated with PCM and had high liquidity was poured into asphalt with high porosity to form a complex structure. The complex structure showed good temperature decrease effect than others.Lastly, high temperature stability, low temperature crack resistance, water sensitivity and thermal properties were investigated. The results showed that the dynamic stability of the complex structure without PCM was31500time/mm, the phase change complex structure was as high as21000time/mm, which was much bigger than common hot mix asphalt mixture (HMA). Low temperature bending test showed that the complex structure was not only had the strength of cement mortar but also had the flexibility of asphalt mixture. Marshall stability and freeze-thaw indirect tensile test indicated that the water stability of the structure was good. Thermal properties tests proved that the heat-absorb ability of the complex structure was smaller than common HMA.The research of this paper on different mix methods of PCM and asphalt mixture provides future directions of research on PCM used to control temperature of asphalt pavement.