October 2015 - Journal of Materials in Civil Engineering: This paper investigates the potential use of phase change materials (PCM) in concrete pavements to store heat, which can be used to reduce ice formation and snow accumulation on the surface of the concrete pavement. The thermal properties of the PCMs are evaluated using a low-temperature differential scanning calorimeter (LT-DSC) while a longitudinal guarded comparative calorimeter (LGCC) is used to evaluate the thermal response of cementitious mortar containing the PCM. Paraffin oil (petroleum based) and methyl laurate (vegetable based) were selected as PCMs since they have high enthalpies of fusion (~130-170 J=g) and have desirable freezing temperatures (~2-3°C) during the liquid to solid phase transformation. Two approaches were used to place the PCM in the mortar specimens: (1) placing the PCM in lightweight aggregate (LWA) in mortar and (2) placing the PCM in an embedded tube that is placed in mortar. The durability and stability of the PCMs in the cementitious system were studied by monitoring the change in enthalpy of fusion, mass loss, pulse velocity, and compressive strength. When the PCM was placed in the mortar specimen using LWA, the paraffin oil can release a considerable amount of heat during phase transformation, which can be used to melt ice and snow. However, it was observed that the methyl laurate reacts with the cementitious matrix, causing damage to the mortar. Both paraffin oil and methyl laurate showed promising performance to melt ice and snow when the PCM was placed in an embedded tube in the mortar specimen.
October 2015 - Journal of Materials in Civil Engineering DOI:10.1061/(ASCE)MT.1943-5533.0001439