Thermal Effects on Compression Behavior and Microstructure of Wheat and Rice Fiber-Reinforced Polymer Hybrid Composite Bricks for Civil Infrastructure

The environmental impact of conventional construction materials has driven the need for sustainable alternative in civil infrastructure. In current times, natural fibers-based composites have increasingly used as non-metallic reinforcement for new construction and for strengthening of structures, making assessment of their mechanical and thermal properties, and performance essential. In this study, the compressive behavior of hybrid wheat and rice fiber-reinforced polymer (WRFRP) composites is assessed at low to moderate temperatures as encountered during typical environmental and service scenarios in structural systems. An alkali treatment is applied on wheat fibers before composite preparation. These composites are exposed to 40°C, 50°C, and 60°C prior to compressive behavior analysis and their performance is compared with that at room temperature (RT). Further, scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) analyses are performed to investigate damage patterns, surface morphology, and thermal behavior at elevated temperatures. Natural fibers in these composites are treated in an alkaline solution to remove impurities and enhance the bond between fibers and binders. The peak average compressive strengths of WRFRP composites are reported as 21.5 MPa at RT, which reduces by 50% at 60°C. Moreover, empirical equations are proposed to estimate relations for linear stress–strain and peak compressive strength-temperature increment, respectively. The study helps understand the behavior of agricultural residue-based composites at low to moderate temperatures.