Thermo-mechanical influence of protective coatings on concrete column components under high-temperature conditions

Abstract

To better understand the effects of protective coatings on concrete under fire conditions, various coatings were applied to different sections of concrete columns for high-temperature simulation tests. The performance of these coatings at elevated temperatures and the extent of concrete damage were assessed to identify more effective protective measures. This study conducted experiments to obtain real-time high-temperature stress-strain curves, temperature rise curves, and the compressive strength of coated concrete. Additionally, particle flow codes were used to develop models that captured the macroscopic and microstructural characteristics of both coatings and concrete. The software simulated two fire exposure modes: one-sided and four-sided heating. Coatings effectively preserved concrete, with tunnel fireproofing coatings (SD) demonstrating superior performance compared to gypsum-based plaster coatings (SG) and composite silicate protective coatings. At 800°C, the compressive strength of SD reached 12.01 MPa, exceeding that of SG, GSY, and uncoated concrete (NC) by 8.39 %, 3.45 %, and 44.35 %, respectively. Under four-sided heating, the NC group exhibited reduced stress differentials due to its inability to bear the applied load at high temperatures, preventing effective load transfer. In contrast, one-sided heating, though generating less heat, caused the NC group to tilt toward the heated surface, compromising overall structural stability. Coatings mitigated this effect, with SD effectively protecting the bottom part of column. Preventing the occurrence of one-sided flames is crucial to enhancing fire resistance. This study advances the understanding of how coatings protect concrete in fire conditions and proposes more effective measures to safeguard concrete columns and improve building safety.