UCLA

This thesis aims to investigate design strategies for concrete construction materials containing microencapsulated phase change materials (PCMs) for energy- efficient buildings and sustainable infrastructure. First, numerical studies based on rigorous finite element simulations were carried out to predict the effective elastic moduli and thermal deformation coefficient of composites consisting of spherical core-shell microcapsules in a continuous matrix, and to identify effective medium approximations (EMAs) capable of accurately estimating these effective properties. Next, experiments studying the thermal behavior of small- scale test cells were conducted to evaluate the performance of microencapsulated PCM-composite building envelope materials. Scaling analysis was used to show how these small-scale test cells, conveniently placed in an environmental chamber, could represent the thermal behavior of time- and space-intensive full-scale outdoor test structures. Furthermore, a thermal model of a room with a PCM- composite envelope was used to examine the energy and cost savings potential of PCM-composite walls in the presence of an active indoor temperature control scheme. A model predictive control (MPC) algorithm that could preemptively account for melting and freezing of the PCM was developed. However, it did not significantly increase the energy and cost savings compared with a traditional proportional control scheme. Finally, temperature evolutions within microencapsulated PCM-composite concrete pavement sections were studied numerically. The inclusion of microencapsulated PCM within the pavement section was found to reduce early-age temperature rise and corresponding spatial temperature gradients induced by cement hydration, thereby reducing the risk of early-age thermal cracking. Overall, the results of this thesis will be useful in the design of composite concrete containing microencapsulated phase change materials for sustainable infrastructure projects, including energy-efficient building envelopes and road pavements with enhanced lifetime.