Experimental evaluation of energy storage and hydration of lauric acid/expanded vermiculite composite phase change cementitious materials

Incorporating phase change material (PCMs) into concrete to functionalize concrete for energy storage, due to their high latent heat, has been demonstrated as an effective strategy for improving building energy efficiency. This study aims to synthesize a shape-stabilized composite phase change material (PCMs) to explore its potential in mitigating early thermal cracking in concrete. To reduce the risk of leakage, vacuum impregnation was employed to load lauric acid (LA) between layers of expanded vermiculite (EV) treated at different firing temperatures. The structural composition and thermal storage performance of the LA/EV composite PCMs (LA/EV-PCMs) were systematically evaluated using various characterization techniques to assess stability and efficiency. The synthesized PCMs exhibits excellent thermal storage capacity (183.8 J/g), a low melting point (31.1 °C), and thermal conductivity 1.43 times higher than that of EV alone. For the first time, the influence of LA/EV-PCMs on the cement hydration process and heat of hydration was studied using non-contact resistivity and adiabatic heating experiments. The results indicated that the PCMs delayed the peak hydration temperature, with the maximum difference in hydration temperature reaching 11.6 °C. Additionally, the set-hardening phase of the cement was accelerated by 8.97 % and 7.96 % due to pore filling by the LA/EV-PCMs. These findings offer innovative insights into the design of energy-efficient concrete and the prevention of early cracking caused by temperature variations. • Encapsulation of lauric acid in expanded graphite by vacuum impregnation. • Contactless resistance method used for the first time to study the hydration process of phase change cementitious materials. • Composite phase change materials can regulate the hydration temperature to delay the time of peak appearance.