| Abstract [eng] |
This investigation delves into the intricate relationship between curing temperatures and the physical properties of calcium aluminate cement (CAC)-based refractory castables, including conventional castables (CC), medium cement castables (MCC), and low cement castables (LCC). Crucially employed in industries with extreme temperature demands—such as biofuel boilers, oil, steel, and chemical sectors—these castables must endure thermal shocks while upholding robust physical and mechanical characteristics and minimizing temperature deformations. The study focuses on castables with varying cement content—CC (25% of CAC), MCC (12%), and LCC (7%)—scrutinizing their mechanical strength after high-temperature treatment, resistance to thermal cycling, and shrinkage, with evaluations conducted with samples cured at different temperatures, specifically 10 °C, 20 °C, and 35 °C. The test results indicate that higher CAC content (i.e., CC materials) makes castables less sensitive to variations in curing temperature, resulting in minimal changes in cold crushing strength (CCS), maintaining it at approximately 95 MPa. In contrast, MCC castables exhibit high sensitivity to the curing temperature, with the CCS increasing from 96 to 103 MPa as the curing temperature rises. To mitigate sensitivity and stabilize mechanical performance, accelerator and retarder additives were employed to control the curing of castables at both low and high temperatures. The study showed that additives used for this purpose, such as lithium carbonate for acceleration at temperatures above 10 °C and citric acid for retarding at temperatures above 30 °C, positively impact the thermal properties of castables after heat treatment. These additives effectively mitigate undesirable variations in characteristics. |
