Mitigating desiccation cracking in bentonite using novel microencapsulated phase change materials

Abstract

Bentonite, widely employed in geotechnical projects, faces a pressing challenge in addressing desiccation cracking. Leveraging its high latent heat, microencapsulated phase change material (microPCM) holds promise in ameliorating this issue. This study pioneers the application of microPCM as an additive to enhance bentonite's resistance to cracking. Employing an automated measurement platform, a series of desiccation cracking tests were conducted on bentonite blends with varying microPCM contents. Techniques including mercury intrusion porosimetry, scanning electron microscopy, digital image processing, infrared thermography, and particle image velocimetry, were employed to elucidate these mechanisms. Quantitative metrics were defined and meticulously analyzed across samples with different microPCM ratios. Additionally, qualitative and quantitative assessments of pore structure features were conducted. Key findings demonstrate that the incorporation of microPCM can delay evaporation by up to 33 % (at a microPCM mass fraction of 15 %) while intensifying volumetric contraction. This delay effectively postpones crack initiation and doubles crack propagation duration. However, microPCM agglomeration tendencies leading to formation of additional cavities may act as initial defects in the bentonite. This study not only illuminates the potential of microPCM as an effective additive in enhancing bentonite's resistance to desiccation cracking but also identifies associated challenges, thus paving the way for further innovative research.