Experimental investigation on the performance of ground granulated blast furnace slag and nano-silica blended concrete exposed to elevated temperature

Abstract

Minimising the risk of fire and structural collapse are primary goals in the design of concrete buildings. This study aimed to determine how nano-silica (NS) and ground granulated blast furnace slag (GGBFS) additives, used to replace some proportion of cement, affected the behaviorof concrete when subjected to elevated temperatures ranging from 27 °C to 1000 °C. The mechanical and durability properties of concrete containing NS (0%-5%) and GGBFS (0%-25%) were investigated after being exposed toelevated temperatures. The concrete samples were heated according to ISO 834 standardized fire curve. After exposing the concrete to a higher temperature, it was cooled using the water cooling (WC) and air cooling (AC) process. It was found that when exposed to increased temperatures, concrete containing nano-silica and GGBFS performed better than concrete without any of these additives. The addition of 4% of nano-silica and 20% of GGBFS in concrete enhanced the instinctive and resilient characteristics of concrete up to the raised temperature of 400 °C after that drastic degradation of mechanical and durability properties was recorded for higher temperatures of the range 1000 °C. It showed that using nano-silica and GGBFS in concrete needs to be done delicately when the building could be exposed to a temperature of 400 °C and beyond. The microstructure analysis was performed and it showed that the utilization of nano-silica and GGBS in concrete can enhance the post-fire performance of concrete. Further, the relationship between residual properties of concrete exposed to raised temperature was assessed and empirical relations were proposed. It was observed that the predicted result of residual properties was in good agreement with the experimental results.