Microstructural analysis of bio-based PCM-enhanced lime mortars: Durability and energy efficiency for sustainable buildings

The development of energy-efficient and sustainable building materials is crucial in reducing energy consumption and environmental impact in the construction sector. This study presents a novel approach by integrating a bio-based microencapsulated phase change material (PCM) into air lime-based mortars, aiming to enhance thermal performance while ensuring durability and mechanical integrity. Unlike conventional PCM-enhanced mortars, this research emphasizes the use of renewable, biodegradable PCMs derived from agricultural sources, reducing reliance on fossil-based alternatives. The optimized formulations were designed to function as rendering mortars, balancing workability, adhesion, and durability for application in both modern and historic buildings. A thorough microstructural investigation through SEM and MIP revealed that controlled PCM dosages (5–10 %) preserved matrix cohesion, whereas higher PCM contents (20 %) led to increased porosity. Thermal performance assessments, including DSC and hotbox experiments, confirmed the effectiveness of the PCM-enhanced mortars in regulating temperature fluctuations and improving energy efficiency. Additionally, durability testing demonstrated the superior resistance of PCM-modified mortars to freeze-thaw cycles and salt crystallization, while cyclability analyses confirmed their long-term thermal stability over multiple phase transitions. These findings establish bio-based PCM-enhanced lime mortars as a resilient, eco-friendly solution for sustainable construction, contributing to climate-responsive design and energy-efficient buildings. • Bio-based PCM lime mortars enhance thermal performance and structural integrity. • PCM integration preserves cohesion at 5–10 % but increases porosity at 20 %. • PCM-bearing lime mortars improve freeze-thaw and salt attack resistance. • Hotbox tests confirm temperature regulation and improved energy efficiency. • Bio-based PCMs offer a viable, eco-friendly solution for improving energy efficiency.