High-temperature damage characterization of polymer-modified hybrid fiber-reinforced cement-based composites and underlying mechanisms
摘要
Polymer-modified hybrid fiber-reinforced cement-based composites (PHFRCCs) have been widely applied in construction, with increasing attention on their applications in thermal engineering. In this study, the thermal strain of PHFRCCs was characterized through high-temperature experiments and digital image correlation techniques. The residual strength and microstructural characteristics of PHFRCCs after high-temperature exposure were investigated. A power-law damage model with an exponent of 0.5 was established. The results show that from 200 to 400 °C, a significant increase in thermal strain and horizontal flexural strain is observed in PHFRCCs. From 400 to 600 °C, an opposite trend occurs, which is attributed to the complete decomposition of most polymers, leading to pore formation and the release of thermal strain. These findings indicate that PHFRCCs exhibit superior thermal resistance. Compared to pure cement, PHFRCCs show higher residual strength and horizontal flexural strain, indicating enhanced flexural resistance due to the reinforcing effect of steel fibers. At 600 °C, PHFRCCs show a relatively low damage rate compared to pure cement. In contrast, between 200 and 400 °C, polymer degradation dominates, resulting in a higher damage rate. These findings provide valuable theoretical insights for the fire safety assessment and design of PHFRCCs.