Mechanical and thermal performance of concrete with embedded organic and inorganic PCMs for building applications

• A novel comparative study of concrete with embedded organic vs. inorganic PCMs under realistic transient thermal loading. • Comprehensive testing reveals optimal PCM-concrete mix designs for enhanced mechanical strength and thermal resilience. • A custom transient heat flux testing method using a muffle furnace was developed to assess through-thickness thermal performance. • PCM-enhanced concretes significantly delayed heat transfer and improved fire resistance, preserving structural integrity during high-temperature exposure. High temperatures can severely degrade the structural integrity of concrete in residential buildings, underscoring the need for efficient thermal protection. Traditional insulation methods, while effective, are often labour-intensive and cost-prohibitive. This study explores the integration of Phase Change Materials (PCM) in concrete as a transformative approach to thermal insulation. It offers a scalable, and economically viable alternative to conventional insulation systems. Despite growing interest in PCM concrete, experimental research on inorganic PCM remains limited. Their behaviour under elevated temperatures is yet to be comprehensively evaluated. Addressing the said gap, this paper aims to evaluate the potential of PCM as an embedded insulation system. Two types of PCM, organic and inorganic, were introduced into concrete using the direct incorporation method. First, the mechanical performance was evaluated through standard tests for workability, compressive strength, split tensile strength, and dry density. Then, the thermal performance of PCM concrete was evaluated by subjecting the specimens to transient elevated temperatures (500 °C), focusing on heat transfer. The results demonstrate that incorporating inorganic PCM into concrete enhances workability and maintains compressive and tensile strength, largely due to its uniform dispersion and inherent lubricating properties. In contrast, organic PCM led to reduced workability and compressive strength, attributed to poor integration within the concrete matrix. Thermal analysis revealed that inorganic PCM concrete delayed heat transfer by ∼ 9 % and lowered peak temperatures by 5 % compared to its organic counterpart. These findings underscore the superior performance and strong potential of inorganic PCM as an effective embedded thermal insulation strategy for concrete structures.