Preparation and effectiveness of composite phase change material for performance improvement of Open Graded Friction Course

Open Graded Friction Course (OGFC) brings sustainability benefits in safety, low noise, urban heat island, and storm water management. This study investigated the preparation and effectiveness of composite phase change material (PCM) for performance improvement of OGFC. The composite PCM with SiO2 as shell and PEG in the core was prepared with cement capsulation. The water-cement ratio of 0.4 and cement-PCM ratio of 2.0 was recommended to prepare the composite PCM. The effects of PCM on temperature reduction, raveling resistance, compressive strength, volume stability, and anti-icing performance of OGFC were evaluated using comprehensive laboratory tests. It was found that the addition of PCM could retard temperature change of OGFC as ambient temperature changed. The appropriate mass content of PCM was determined to be 0.8%-1.1% based on the test results of Cantabro loss ratio and compressive strength after freezing-thawing cycles along with the benefits of temperature adjustment. The volumetric change measured in the freezing-thaw process proved that the composite PCM improved volume stability of OGFC at dry and saturated conditions. The effect of freezing-thaw cycles on the performance of PCM was minor. The PCM could help reduce the adhesion strength of ice to OGFC and thus retard ice formation. The study findings suggest that the cement-encapsulated PEG/SiO2 can be used to adjust internal temperatures of OGFC and improve the performance of OGFC subject to freezing-thaw cycles. (C) 2019 Elsevier Ltd. All rights reserved.