Mitigation of freeze-thaw damage to open-graded friction courses in seasonal climate areas via a binary phase change system

Abstract

For the road performance deterioration of the open-graded friction courses (OGFCs) due to the scenarios of rainfall, snowfall, rapid temperature change, large temperature difference, and freeze-thaw cycle in seasonal climate areas, it will be necessary to utilize new techniques for improving the temperature regulation capability and freeze-thaw damage resistance of OGFC mixtures. A combined technique of mixing simultaneously two microencapsulated phase change materials (MPCMs) with different phase change temperature ranges and proportions has a special attractiveness for asphalt pavement. Successful application of a binary phase change system concept to improving asphalt pavement temperature regulation still has many problems, such as environmental conditions, coating MPCMs with Portland cement, mixing contents and proportions of different MPCMs, and factors affecting the temperature regulation capability and improving the freeze-thaw damage resistance of OGFCs. Composite MPCMs (CMPCMs) were prepared by two MPCMs of P46 and P5 coated by cement, in which P46 and P5 use paraffin and n-tetradecane respectively as the core material and SiO2 as the shell. The heating, cooling, freeze-thaw, and uniaxial compression tests on CMPCM-OGFC specimens were performed, to evaluate the temperature regulation capability of OGFC mixtures with different contents and proportions and the dependences of compressive strength, strength loss rate, and strain of OGFC mixtures on freeze-thaw cycle. The results reveal that the OGFC mixtures with different CP46 contents have a cooling effect due to the phase change heat absorption in a higher temperature range during the rising temperature and with different CP5 contents have a warming effect due to the phase change heat release in a lower temperature range during the cooling temperature. After mixing simultaneously CP46 and CP5 in different proportions, the temperature regulation capability of mixtures with a 3% content has a great improvement due to triggering respectively two types of phase change effects in a higher temperature range for CP46 and in a lower temperature range for CP5. Adopting this binary phase change system as mixing CP46 and CP5 can reduce the rising/cooling temperature rates in the freeze-thaw process and mitigate the damage of OGFC mixtures due to the high-temperature thawing and low-temperature frost heave effects.