Sean P. Casey

Thermal, mechanical and microstructural analysis of concrete containing microencapsulated phase change materials

This paper studies the thermal, mechanical and microstructural aspects of concrete containing different amounts of microencapsulated phase change materials (PCMs). In addition, numerical simulation is carried out to study the potential application of PCM-modified concrete for reduction in summer surface temperature. It is shown that increasing PCM content in concrete led to lower thermal conductivity and an increase in the heat storage ability of concrete. However, the compressive and flexural strength of concrete significantly decreased. Microstructural analysis showed that PCMs appear to remain intact during mixing; however, PCM particles appear to fail by bursting under loading, creating hemispherical voids and crack initiation points as well as possible entrapped air behaviour. The result of numerical simulation revealed that reduction in summer concrete pavement surface temperature by several degrees was possible, with implications for reduction in concrete thermal stresses, shrinkage and urban heat island effect.

Nanocomposite materials for rapid-response interior air humidity buffering in closed environments

Three different mesoporous silica (MS) samples were selected as template materials for designing novel, high-performance desiccants to give rapid-response temperature and humidity buffering in closed environments. The aim was to investigate how the functional properties of the MS materials can be tuned to suit differing psychrometric conditions in closed environments, and to inform the design process by conducting sensitivity analysis using building performance simulation software. Their humidity buffering performance was compared with other materials using WUFI Pro v5.1 to conduct numerical hygrothermal simulations. The MS materials had more than two orders of magnitude greater humidity buffering than traditional interior building materials (e.g. painted gypsum plaster) due to their high vapour storage capacity and high dynamic vapour sorption (DVS) response rates. Analysis showed that the gradient of the w 50–w 80 portion of the absorption branch isotherm is the most sensitive parameter when using the hygrothermal numerical model as a design tool for materials tuning.