Residual mechanical properties of concrete incorporated with nano supplementary cementitious materials exposed to elevated temperature

Abstract

The construction industry commonly employs concrete as a construction material, which sometimes may be subjected to fire exposure. It is important to adopt fire safety measures while planning and constructing such structures to ensure the safety of the occupants and the structural integrity of the concrete. So, determining its performance at elevated temperatures is of utmost importance. The main objective of this study was to investigate the impact of mineral incorporations, namely, nano bentonite clay (NBC) and nano fly ash (NFA), on the retained properties of concrete at normal (27°C) and at elevated temperatures. The feasibility of partly substituting ordinary Portland cement utilizing a mixture of NBC (0–5%) and NFA (0–50%) in concrete was assessed under the exposure to an elevated temperature ranging from 200 to 600°C. Several parameters were examined, including compressive strength, flexural strength, split tensile capacity, water penetration, loss of mass, ultrasound pulse velocity, and microstructure properties. After the experimental analysis, it was observed that the fire endurance was shown to be improved with the inclusion of nanoparticles (BC and FA). A reduction in the loss of mass by samples subjected to elevated heat was observed with the addition of nano bentonite and NFA. The mechanical strength results were obtained as maximum for the concrete specimens with 2% NBC and 20% NFA and further, the specimens performed better when exposed to elevated temperature as compared with normal concrete specimens. The microstructure of the concrete also upgraded with better impermeability owing to the use of NBC and NFA.