Characteristics of cement-based thermo-concretes containing capric acid impregnated hemp for thermal energy storage and sound isolation in buildings

Enhancing the lightweight structure, insulation, and thermal storage capacity of concrete is critical for energy efficiency and environmental impact reduction. The innovative application of using waste hemp shives as a phase change material (PCM) carrier in cementitious composites was performed in this study to enhance sustainable construction practices. Although previous studies have incorporated lightweight aggregates and PCMs, challenges such as PCM leakage and the reliance on synthetic materials have limited their effectiveness. This study utilized waste hemp shives as a natural porous support for capric acid (CA) PCM in diatomite-based lightweight concrete, offering an eco-friendly and leakage-resistant solution with improved thermal and acoustic performance. No leakage was observed in shape-stabilized hemp/CA composites with 45 wt% CA. The melting and solidification temperatures were determined as 30.6 °C and 28.7 °C, with corresponding enthalpy values of 80.9 and 80.8 J/g, respectively. Concrete composites containing hemp/PCM reduced indoor temperatures by up to 4 °C compared to control samples. Moreover, composites with 30 % hemp/PCM content achieved sound absorption coefficients up to 0.6 and transmission loss values exceeding 24 dB, demonstrating their dual functionality for thermal energy conservation and acoustic comfort in building applications.