A numerical and experimental analysis of compression-induced cracking in epoxy composite grout under thermo-mechanical loading

Grouts are designed to withstand high loads while resisting water, high temperatures, chemicals, and other factors. They are commonly employed in various practical structural applications due to their desirable attributes, such as excellent bonding, rapid strength development, ease of preparation, and free-flow ability. Much study has recently been conducted into replacing traditional cementitious grout with polymer composites. Most grout structures are subjected to compressive loads and significant temperature variations during their operational lifetime. As a result, it is critical to consider how the variation in thermo-mechanical loading impacts the performance of polymer grouting materials. The study presents an experimental and numerical analysis of the fracture behavior of epoxy polymer grout under compressive loads and at different temperatures. The primary fracture mechanism considered in this study will be a compressive fracture on an inclined through-crack. XFEM simulates cracking in the epoxy grout at 25 ?C and 65 ?C, while the cementitious samples are only modeled at 25 ?C. Experiments have been performed to benchmark the compression problem, and its results validate the XFEM simulation. The cementitious grout possesses meager compressive strength. The epoxy grout material can endure a very high load at 25 ?C. However, the compressive strength of the epoxy grout significantly decreases with an increase in temperature. The decrease in compressive strength is due to the weakening of the epoxy polymeric chain, interface debonding, and the formation of voids at high temperatures. The presence of multiple flaws of different sizes and shapes significantly impacts the fracture behavior of epoxy grout, as confirmed by the XFEM simulations. Smaller-sized defects exhibit a higher possibility of cracking due to the highstress concentrations.