Impact Strength of Fiber Reinforced Geopolymer Concrete Exposed to Elevated Temperatures

Geopolymer (GP) materials have emerged as a necessary product for sustainable construction practices. In comparison to conventional concrete, geopolymer concrete (GC) is more brittle, and when it is subjected to elevated temperatures, the GC becomes more brittle. The inclusion of various fibers can considerably enhance the GC's performance at elevated temperatures. Thus, the main aim of this study is to examine the compressive strength and impact strength of various fiber-reinforced GC exposed to high temperatures using the ISO 834 standard fire curve. To develop M40-grade GC, ground granular blast furnace slag, and low-calcium fly ash are used as binders. A total of six mix propositions are adopted, such as plain GC (without fibers), polypropylene fiber-based GC, basalt fiber-based GC, crimped steel fiber-based GC, hybrid combination of polypropylene fiber and crimped steel fiber-based GC, hybrid combination of polypropylene fiber and basalt fiber-based GC. It was observed that, with the addition of fibers, the residual compressive strength and impact strength of GC has been improved. For 30 min (821 °C) and 60 min (925 °C) of heating, the BF-based GC showed more residual compressive strength and impact strength. At 90 min (986 °C) and 120 min (1029 °C) of heating, the BF and hybrid (BF and SF)-based GC showed more residual compressive strength and impact strength. Whereas PF-based GC exhibited a less residual compressive strength and impact strength.