Abstract
Understanding the structural performance of concrete under fire, particularly during the cooling phase, is critical to ensuring post-fire safety. Concrete columns, as primary load-bearing elements, are especially vulnerable under such conditions. While Ordinary Portland Cement (OPC) concrete has been widely studied in fire, limited research has addressed the behaviour of sustainable alternatives such as Ground Granulated Blast Furnace Slag (GGBS) concrete, particularly under realistic thermal decay scenarios. GGBS, a by-product of steel production, offers a low-carbon alternative to OPC, reducing embodied CO₂ while enhancing long-term durability. This study investigates the fire response of 100 mm × 200 mm cylindrical specimens made with OPC (CS1) and 50% GGBS replacement (CS2). All specimens were preloaded to 30% of their 90-day compressive strength, heated to 600 °C at a rate of 10 °C/min, and cooled to ambient, 200 °C, or 400 °C under sustained loading. Digital Image Correlation (DIC) was used to monitor axial strain, and post-fire residual strength was measured. Results show that staged cooling improved strength retention in both mixes. CS1 retained 65–78% of its original strength, while CS2 retained 57–70%. CS2 exhibited slightly lower residual strength but showed stable behaviour and consistent failure patterns, likely due to its denser microstructure and lower thermal conductivity. DIC analysis revealed typical expansion followed by contraction, with reduced strain recovery in CS2, suggesting altered post-fire stiffness characteristics. These findings confirm the potential of GGBS concrete as a reliable, lower-carbon alternative in fire-exposed structural applications without compromising safety performance.
Keywords
low-cement concrete, preloaded, thermal strain, residual strength, fire exposure.
Date of Version
2025
DOI
10.5703/1288284318165
Recommended Citation
Rokade, Mahadev Sitaram; Lui, James; Sheng, Yu; Stratford, Tim; Rush, David; and Suryanto, Benny, "Thermo-Mechanical Behaviour of Preloaded Low Cement Concrete under Heating and Cooling Phase of Fire Exposure" (2025). International Conference on Durability of Concrete Structures. 2.
https://docs.lib.purdue.edu/icdcs/2025/act/2
Thermo-Mechanical Behaviour of Preloaded Low Cement Concrete under Heating and Cooling Phase of Fire Exposure
Understanding the structural performance of concrete under fire, particularly during the cooling phase, is critical to ensuring post-fire safety. Concrete columns, as primary load-bearing elements, are especially vulnerable under such conditions. While Ordinary Portland Cement (OPC) concrete has been widely studied in fire, limited research has addressed the behaviour of sustainable alternatives such as Ground Granulated Blast Furnace Slag (GGBS) concrete, particularly under realistic thermal decay scenarios. GGBS, a by-product of steel production, offers a low-carbon alternative to OPC, reducing embodied CO₂ while enhancing long-term durability. This study investigates the fire response of 100 mm × 200 mm cylindrical specimens made with OPC (CS1) and 50% GGBS replacement (CS2). All specimens were preloaded to 30% of their 90-day compressive strength, heated to 600 °C at a rate of 10 °C/min, and cooled to ambient, 200 °C, or 400 °C under sustained loading. Digital Image Correlation (DIC) was used to monitor axial strain, and post-fire residual strength was measured. Results show that staged cooling improved strength retention in both mixes. CS1 retained 65–78% of its original strength, while CS2 retained 57–70%. CS2 exhibited slightly lower residual strength but showed stable behaviour and consistent failure patterns, likely due to its denser microstructure and lower thermal conductivity. DIC analysis revealed typical expansion followed by contraction, with reduced strain recovery in CS2, suggesting altered post-fire stiffness characteristics. These findings confirm the potential of GGBS concrete as a reliable, lower-carbon alternative in fire-exposed structural applications without compromising safety performance.
