Abstract:
In this paper, the effect of calcined diatomite (CDT) content on the mechanical, microstructural, and mineralogical properties of high strength mortars (HSMs) exposed to 25, 400, 600, 800, and 1,000°C temperatures is investigated. The percentages of CDT that replace Portland cement (PC) in this work are 0, 5, 10, 15, and 20%, by weight. The researched properties of the HSMs are the unit weight (Uw), ultrasonic pulse velocity (Upv), flexural strength (fs), compressive strength (fc) and the analyses of X-ray powder diffraction, polarized light microscopy, and scanning electron microscopy/energy dispersive spectroscopy. The experimental results show that the CDT has a potential to be successfully employed as a partial replacement of PC in the HSMs exposed to elevated temperatures. The optimal replacement level of PC by CDT is determined as 15% from strength tests. Besides, the Uw, Upv, fs, and fc values progressively reduce as the temperatures subjected to the HSMs increase. The CDT has a positive effect on the fs and fc values the HSMs after exposure to elevated temperatures.