Sicheng Jia

Porous asphalt pavement shows lower internal temperature than does dense-graded asphalt pavement under high temperature conditions in summer. To study the cooling effect of porous asphalt pavement, the thermophysical properties of a dense-graded asphalt concrete (AC) mixture and a porous asphalt concrete (PAC) mixture were determined using a parallel model. Then, a laboratory-simulated sunshine experiment was carried out, and the convective heat transfer coefficients of specimens were inferred by virtual experiment. Lastly, the temperature field distribution simulation of PAC pavement was analyzed. The results show that the thermophysical properties of the PAC-13 mixture are lower than those of the AC-13 mixture; the larger the proportion of air voids, the greater the difference appears. Under windy conditions, the convective heat transfer coefficients of the PAC specimen surfaces are higher than those of AC specimens, and the convective heat transfer coefficient of the specimen surface shows an upward trend with increasing air voids. The cooling effect of the porous pavement increases with increasing proportion of air voids, and the cooling effect of the porous asphalt pavement is better than that of the dense-graded asphalt pavement. There is a good positive linear correlation between cooling effect and air voids, and mathematical models between them which can provide an important reference for PAC pavement design were fitted.

Permeable pavement is often known as “cool road”. However, the cooling performance will be weakened due to clogging. In this paper, the temperature field distribution model of asphalt pavement was obtained by Green’s function. Gradations of porous asphalt mixture were designed to obtain different porosities, and the thermal properties of specimens with different porosities were tested and calculated. The simulation test was carried out to obtain the heating curves, which were used to verify the accuracy of the temperature model by comparing the results of the theoretical calculation to results of the test. The daily solar radiation intensity and air temperature changing functions were plugged into the model to calculate the temperature at the bottom of the middle surface. In this way, the simplified model of void fraction and cooling performance of the porous asphalt pavement was obtained. The results showed that the temperature at the bottom of the middle surface for permeable pavement was lower than that for traditional asphalt pavements. The gap was between 0.29 to 2.75 °C and it increased as the porosity of permeable pavement increased.