Strength and fire resistance of a high-strength nano-polymer modified cementitious composite

This study evaluated the strength and fire resistance of a high-strength nano-polymer modified fireproof cementitious composite in which a part of the cement was replaced by chamotte, nanoclay and silica fume. To secure high strength and fire resistance, chamotte was substituted in the range of 10-30 wt%, nanoclay in the range of 1-3 wt%, and silica fume in the range of 5-10 wt%, with respect to the unit weight of cement. A basic mixing test was conducted in accordance with each substitution variable and the compressive strength was statistically analysed. Based on this analysis, the replacement ratio of nanoclay was adjusted to 0.5-1 wt% and that of silica fume to 5-7 wt%. Statistical response surface analysis was used to identify candidate and optimal mixes. The initial (28-day) and residual (after exposure to high temperature) compressive strengths were measured for these mixes. The compressive strengths were also predicted from the response surface model. The highest measured value occurred when chamotte was substituted at 10-12 wt%. The best balance of cost and physical properties was identified for the composition having substitution levels of 0.5 wt% nanoclay and 5.6 wt% silica fume.