Sustainable strategies to improve indoor comfort and reduce energy consumption in winter: Integration of fly ash and rice husk ash in PCM concrete

The thermal performance of a building envelope is closely related to its energy consumption. Merging industrial by-products like fly ash (FA) and rice husk ash (RHA) with phase change material (PCM) concrete unlocks a pathway to significantly enhanced thermal insulation properties for envelopes. This study investigated the effects of two different proportions of industrial by-products (5%−15% RHA and 10%−30% FA) on PCM concrete. The test results show that, at the same dosage, RHA is superior to FA in reducing thermal conductivity, especially at an incorporation rate of 15% RHA. Adding 15% RHA and 30% FA resulted in a 2.3 °C increase in the minimum temperature of the PCM concrete. Moderate RHA and FA resulted in a more uniform pore distribution and finer pore size. With increasing RHA content, the capillary pore volume increased and the fractal dimension decreased. In comparison, a higher FA content led to a significant increase in the total pore volume, particularly in the macropore volume, accompanied by a reduction in fractal dimension. The results of the correlation analysis indicated that capillary pores have a significant impact on the thermal properties. It is shown that PCM concrete can be used to obtain available insulated concrete, which has the potential to reduce winter energy consumption.