Exploring enhanced high-temperature resistance: Analyzing the combined impact of fibers and nanoparticles in mortars

Abstract

This study aims to explore the potential synergistic effect of polypropylene (PP) fiber and different types of nanoparticles to improve the high-temperature resistance of cementitious materials. For that, mortar samples with different PP fiber percentages, 0.6 wt% and 1.2 wt%, were produced. Different percentages of both colloidal nano-silica (CNS), 0.3 %, 0.6 %, and 0.9 %, and nano calcium carbonate (NCC), 0.5 %, 1 %, and 2 %, were used in the study. To test the resistance to elevated temperatures, mortar samples were exposed to different peak temperatures of 300°C, 600°C, and 900°C for 2 h, using unexposed samples as reference. Flexural and compressive strength, water absorption, surface electrical resistivity, and thermogravimetric analysis (TGA) of the heated and unheated samples were conducted. Results showed that, at 300°C heating regime, all samples with 0.6 % PP fiber exhibited an increase in flexural and compressive strength compared to their corresponding reference samples. For instance, specimens containing 0.6 % PP fiber and 2 % NCC content exhibited a 19 % increase in flexural strength compared to the unheated sample, whereas samples with 0.6 % PP fiber and 0.5 % NCC increased 32 % their compressive strength. In contrast, at 600°C, there was a major decline in mechanical properties in all samples, with samples containing NCC exhibiting the lowest amount (average of 61 % reduction in flexural strength and 32 % decrease in compressive strength). In general, a higher dosage of nanoparticles and lower PP fiber content will be better to resist temperatures up to 600 °C.