Optimal Integration of Phase‐change Microcapsules and Nano‐Silica for Improve the Strength of Phase‐change Concrete

Abstract Phase‐change microcapsules, consisting of urea‐melamine‐formaldehyde as the shell material and n ‐tetradecane as the core material, offer effective temperature regulation within concrete under low‐temperature conditions, mitigating the impact of freeze–thaw cycles. However, their incorporation can exert a notable influence on concrete strength. In this study, microcapsules were utilized as an admixture, and nano‐silicon dioxide replaced an equivalent amount of cement to prepare modified phase‐change concrete, focusing on investigating mechanical properties. Results indicate that under consistent parameters—emulsifier concentration of 10% and an oil–water ratio of 1:6—the produced microcapsules exhibit uniform dispersion, with particle sizes ranging from 10 to 20 μm and latent heat of phase change reaching 117 J g −1 . Incorporating microcapsules reduced concrete strength, with a decrease in compressive strength within the range of 15% when microcapsule dosage was set at 10%. On the other hand, nano‐silica demonstrated the capability to significantly enhance the strength of phase‐change concrete by 15%–30% at dosages ranging from 5% to 10%. Optimal enhancement in concrete strength was achieved when phase‐change microcapsules were dosed at 10% and nano‐silica replaced 10% of the cement mass, resulting in compressive strength reaching 90% of normal concrete. © 2024 Society of Industrial Chemistry.