Document Type : Original Article
Department of Civil Engineering, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran
Concrete has good strength and durability; however, it suffers from spalling and significant reduction of strength when exposed to fire. This study was aimed to enhance the fire resistance of concrete by applying two different techniques: 1) reinforcing with fiber, and 2) applying a fire-proof coating. For this purpose, mixes were made with steel fiber (SF), glass fiber (GF), and polypropylene fiber (PPF) applied at 0.5-2% of cement weight; in addition to a mix prepared with a 15 mm layer of fireproof coating material and a control mix. All mixes were subjected to elevated temperatures of 200-800 °C, and physical and mechanical properties were evaluated. According to the test results, both techniques were effective in enhancing the fire resistance of concrete mixes. The maximum residual compressive and flexural strengths were obtained for mix containing 0.5% GF, which were 117% and 145% higher than that of the control mix at 800 °C, respectively. Also, concrete with fireproof coating showed up to 76% and 113% higher compressive and flexural strengths compared to that of the control mix, respectively. It was found that addition of fibers in the manufacturing process of the concrete is a more desirable and economically-efficient approach to enhance the fire resistance. However, for an existing concrete structure, applying fireproof coating is the only option and can enhance the fire resistance comparably.