UCLA

Superabsorbent polymer (SAP) has been widely employed in cementitious composites to improve their properties and broaden the range of applications. Extensive experimental studies have been performed to investigate the mechanical properties of cementitious composites featuring SAP. Despite the experimental research carried out, multiscale models from the micro/nanoscopic features to the macroscopic properties were rarely developed to study the mechanical properties and self-healing mechanism of cementitious composites. This dissertation conducted a comprehensive multiscale investigation of the mechanical properties and self-healing mechanism of cementitious composites featuring SAP.A multiscale (nano to macro) micromechanical model was first developed to quantitatively evaluate and optimize the effective elastic properties of cementitious composites featuring SAP at different scales. This multiscale model bridges the nano/micro information to the macro properties of cementitious composites. The model reveals the effects of hydration degree, water-to-cement ratio, and SAP addition ratio on the elastic properties, providing a tool for designing and optimizing durable and multifunctional composites. Subsequently, a multiscale micromechanical progressive elastic-damage model was presented to predict the overall damage process and mechanical behavior of cementitious composites featuring SAP. This model characterizes the progressive damage by determining various stages of microcrack evolution (debonding, cracking, propagation). The feasibility of the model was confirmed by experimental validations, which allowed optimization of the tensile performance based on microstructural parameters. To characterize the self-healing mechanism, a novel hydration-induced continuum damage-healing framework was constructed to capture the complex interactions between damage, healing, and hydration to describe the self-healing behavior of cementitious composites featuring SAP under various conditions. This framework is applicable to model the hydration-induced self-healing process and the mechanical behavior of partial/complete healing of cement-based materials. Finally, a poro-elastoplastic-damage model was developed to characterize the dynamic interactions between external stress-induced damage and SAP-induced internal pore pressure to accurately predict the damage response and stress-strain constitutive relationship of cementitious composites featuring SAP. The results highlighted the importance of optimizing SAP parameters to improve the durability and functionality of cementitious composites in engineering applications. This model can contribute to the simulation, parameterization, and optimization of composites with porous matrix.