Properties of concretes enhanced with phase change materials for building applications

Phase change materials (PCMs) have been widely used in building applications as a thermal storage medium for passive thermal regulation and for increasing the efficiency of HVAC systems. Both applications have shown great potential in reducing energy demand or peak loads for both heating and cooling in buildings. Literature shows different ways to incorporate PCMs in the building envelope. This review focuses on the use of PCMs as an additive or replacement material in typical concrete mixtures for building applications. Literature shows that organic paraffin and non-paraffins are the most suitable PCMs for incorporation into concrete mixtures, as they have suitable melting points that match human comfort temperature, high heat capacity, low volume changes during phase change transition, and good chemical and thermal stability. To avoid PCM leakage from the concrete, indirect methods of PCM incorporation in concrete are highlighted, such as encapsulation methods and vacuum impregnation techniques combined with macro-encapsulation methods. Updated information related to the influence of the type of PCM and different incorporation methods on the physical, mechanical and thermal properties of fresh and hardened concrete is presented. Literature shows that by adding PCM to the concrete mixture the heat storage capacity of concrete is generally increased. However, various studies showed that PCMs also have some negative impacts on the physical and mechanical properties of concrete. New relationships between the quantity of PCM and the change in both the thermal and mechanical properties of the concrete are provided. From the reviewed literature, it can be concluded that the potential of using PCM in concrete still requires further research, to study solutions that allow increasing the amount of PCM that is effectively incorporated into concrete and to develop standard testing procedures for measuring the thermal properties of inhomogeneous materials such as PCM-concrete composites. (C) 2019 Elsevier B.V. All rights reserved.