Road performance and thermal-insulation effect in construction of asphalt mixture containing phase-change thermal-insulation agent

Abstract

Highway construction strategies impact the early damage of asphalt pavement and its sustainability. The pavement quality is directly influenced by the temperature of the asphalt mixture during paving and rolling, but delaying the cooling of the mixture at this stage has rarely been investigated. An asphalt mixture modified with a phase-change thermal-insulation agent (PCTIA) was prepared potentially improve the temperature of the asphalt mixture during construction. The high-temperature, low-temperature, and water-stability performance of asphalt mixtures with different PCTIA contents were analysed. The temperature regulation test was carried out, and the temperature field model of the asphalt pavement paving process was established. Based on the laboratory test and FEM models, the influence of different construction environmental conditions on the thermal-insulation performance of PCTIA and its thermal-insulation mechanism were analysed by using the distribution of temperature, average temperature, and equivalent temperature. The thermal-insulation effect of PCTIA was quantified by latent heat accumulated temperature value (LHATV). Results show that PCTIA improves the high and low-temperature performance of asphalt mixture, and has little effect on water stability. The best overall road performance is achieved at 2.5% PCTIA content. PCTIA can significantly reduce the cooling rate of asphalt mixture, and the distribution of temperature difference and time difference is obviously different in different positions of loose asphalt mixture layer and different external environments. Latent heat accumulated temperature value (LHATV) can characterize the phase-change insulation effect of PCTIA well. The wind speed increases and air temperature-bottom temperature decreases reduced LHATV indicating that too rapid cooling of asphalt mixture would weaken the thermal-insulation performance of PCTIA. Both average temperature and equivalent temperature can reflect the thermal-insulation effect of PCTIA, where the average temperature can be used to analyse the specific phase-change process of PCTIA in asphalt mixture and then analyse the insulation mechanism of PCTIA. Combining average temperature and equivalent temperature, PCTIA had the most application value in low temperature and low wind speed environments. This study aims to explore the effective method of delaying the cooling of high-temperature asphalt mixture from the perspective of phase-change energy storage and explain its mechanism.