Development of structural–functional integrated concrete with macro-encapsulated PCM for thermal energy storage

Abstract

Abstract In this research, we prepared macro-encapsulated paraffin-lightweight aggregate (LWA) for the development of structural–functional integrated normal weight aggregate concrete (NWAC). The macro-encapsulated paraffin–LWA was prepared by incorporation of paraffin into porous LWAs through vacuum impregnation. The sealing performance of the epoxy was evaluated by thermal cycling test while the thermal conductivity of macro encapsulated Paraffin–LWAs was improved by incorporating different percentages of graphite powder into epoxy. The chemical compatibility, thermal properties, thermal stability and reliability of macro-encapsulated paraffin–LWA was also determined. Finally, the compressive strength and thermal performance of concrete containing macro-encapsulated paraffin–LWA was evaluated. Test results showed that the maximum percentage of paraffin absorbed by LWA was 70%. The thermal conductivity of the macro-encapsulated paraffin–LWA with 15% graphite powder was 162% higher than that of epoxy. Moreover, the developed macro-encapsulated paraffin–LWA was found to be chemically compatible, thermally stable and reliable (did not show any sign of degradation below 150 °C and sustained 1000 cycles of melting and freezing) and it has high latent heat storage capacity (102.5 J/g). The compressive strength of NWAC with macro-encapsulated PCM-LWA at 28 days ranged from 33.29 to 53.11 MPa, therefore presenting an opportunity for structural applications. The indoor thermal performance test revealed that NWAC with macro-encapsulated paraffin–LWA can function in reducing the energy consumption by decreasing the indoor temperature and shifting the loads away from the peak periods. Thus, we demonstrated and produced concrete with structural and thermostatic properties.