Скачать или смотреть Mitigating Curling of Concrete Pavement by Phase Change Materials: Incorporation, Measurement

Presented by Hongyan Ma, Missouri University of Science and Technology; and Wenyu Liao, Missouri University of Science and Technology

Temperature variations in the service environment can lead to curling of concrete pavement. Phase change materials (PCMs) are substances with high heat of fusion (also known as latent heat). A PCM melts and solidifies at a certain temperature and is capable of storing and releasing large amounts of energy during the phase transition processes. It is proposed to use PCMs in concrete pavement to mitigate curling and the resultant damages, since PCMs have a potential to regulate the temperature fluctuation in the concrete material. The present study addresses two key issues regarding the application of PCMs in concrete: (1) how to incorporate PCMs into concrete without sacrificing mechanical performance; (2) how to evaluate the detailed effect of PCMs through innovative measurements. To address the first issue, a protocol was developed to impregnate lightweight sand (LWS) by PCMs and to remove the PCMs adhered on the surface of LWS particles. The LWS-stabilized PCMs were used to replace fine aggregate in mortar or concrete. To address the second issue, fiber-optic sensors were used to monitor the temperature distribution in a mortar slab and the associated deformations. An innovative tilting sensor was placed on the top surface of the slab to measure the deformation due to curling. Results have shown that the PCM-incorporating LWS and cement matrix can be closely bonded, without showing weak interfacial zones. The compressive strength of the PCM-incorporated mortar is moderately higher than a reference mortar prepared using normal river sand. The incorporation of PCM can reduced the magnitude of temperature fluctuation, lower the heating/cooling rate, thus mitigate the build-up of thermal strain/stress and curling deformation.