Optimizing the bond performance of stainless-steel bars in CAC-based refractory castables under elevated temperatures

Abstract

Forty years ago, calcium aluminate cement (CAC) based refractory castables were invented specifically for the metallurgical and petrochemical industries. These castables have exhibited exceptional mechanical resistance even when heated above 1000 °C. Due to the combination of temperature and mechanical loads, these materials can withstand compression stresses without structural reinforcement. This study is part of a research project aimed at developing composite materials that can withstand high temperatures and are suitable for protecting building structures from fire and explosions. However, for this application, structural reinforcement is necessary, and the problem of bond performance becomes crucial under high temperatures. Continuing the pull-out test campaign [https://doi.org/10.3390/jcs7120485], this study investigates the bonding performance of austenitic stainless steel ribbed bars in refractory castables after high-temperature treatments. This investigation includes three chamotte-based refractory materials, i.e., conventional castable (CC), medium cement castable (MCC), low cement castable (LCC), and one low cement bauxite-based castable (LCB). The first three material compositions were designed to achieve a cold compressive strength of 100 MPa, undergoing curing at 110 °C. In contrast, the LCB material was engineered to reach a cold compressive strength of 150 MPa following the same curing process. Results showed that the ribbed stainless-steel bars formed a reliable bond with the high-performance castable, making it a promising material for high-temperature applications. However, the bonding efficiency, expressed in the deformation energy terms, is not proportional to the compressive strength that describes the object for further optimization.