Preparation and thermal performance of binary fatty acid with diatomite as form-stable composite phase change material for cooling asphalt pavements

The diatomite (DI) was selected as the load matrix, and the stearic acid (SA) and palmitic acid (PA) were chosen as the eutectic binary fatty acids to synthesize the form-stable composite phase change material (CPCM). The microtopography and characteristics of CPCM were described by scanning electronic microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The thermal performance and stability were confirmed by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The maximum eutectics absorption of IN could reach 65.2%. The phase change temperature and enthalpy of CPCM are 52.93 degrees C and 106.70 J/g, respectively. The crystallization fraction of (SA + PA)/DI could reach 83.10%. Moreover, the DSC results after 100 times heating-cooling process show that CPCM has excellent thermal and chemical stability. For the preparation of temperature-adjusting asphalt mixture, some fine aggregate of 0.075 mm and filler were replaced with (SA + PA)/DI CPCM for the corresponding particle size. The highest temperature reduction of the upper and bottom surface of temperature-adjusting asphalt mixture could reach 8.11 degrees C and 6.36 degrees C in laboratory, showing a great promising application for cooling asphalt pavements. Furthermore, pavement performance test of temperature-adjusting asphalt mixture was also conducted. The CPCM with binary fatty acids and DI has the potential to alleviate the rutting diseases of asphalt pavements and the effect of urban heat island. (C) 2019 Elsevier Ltd. All rights reserved.