LC3 mortar with fly ash cenosphere-based phase change materials: Performance and mechanism

초록

This study aims to develop a thermal energy storage LC3 high-performance mixture by incorporating fly ash cenosphere-based phase change materials (FAC-PCMs) and to systematically evaluate its thermal, mechanical, and durability performance. Fly ash cenospheres (FACs) were first etched to increase surface porosity and improve paraffin loading efficiency, after which FACPCMs were prepared via vacuum adsorption. The morphology, structure, and thermal properties of FAC-PCMs were characterized, and their effects on the LC3 mixture were experimentally investigated. The results show that FAC-PCMs exhibit excellent thermal stability and energy storage capacity, with a loading efficiency (LE) of 40.56% and a loading ratio (LR) of 38.62%. The incorporation of FAC-PCMs significantly improved the thermal regulation performance of the LC3 mixture, reducing the temperature variation by 8.45% during heating and 15.5% during cooling. However, the addition of FAC-PCMs leads to notable decreases in mechanical properties and durability. The microstructural analysis revealed that this deterioration is primarily attributed to the formation of a loose and porous interfacial transition zone (ITZ) and the reduced generation of hydration products. These results indicate that while FAC-PCMs are effective at increasing the thermal energy storage capacity of LC3 mixtures, their incorporation introduces significant challenges to structural integrity and durability. The novelty of this study lies in the integration of FAC-supported phase change materials into LC3 systems and the systematic elucidation of the coupled effects between thermal enhancement and performance degradation, particularly the role of ITZ deterioration and suppressed pozzolanic reactions. Therefore, achieving an optimal balance between thermal functionality and mechanical performance is critical for practical applications. This study provides a useful reference for the development of multifunctional cementitious materials that simultaneously target energy efficiency and sustainability in building applications.

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