Investigate the Mechanical Characteristics and Microstructure of Fibrous-Geopolymer Concrete Exposure to High Temperatures

Abstract

The main objective of this study is to evaluate the mechanical properties of geopolymer concrete (GPC), made from alkaline-activated fly ash and Ground Granulated Blast Furnace Slag (GGBS), compared to conventional M30 grade concrete. Additional samples of GPC incorporating steel fibers were also tested. To investigate the behavior of these materials under elevated temperatures (0°C, 250°C, 500°C, 750°C), thirty-six specimens were cast and tested, including cubes, cylinders, and prisms. These specimens comprised slag-based GPC (containing GGBS and fly ash) and standard M30 concrete. The results of the compressive strength tests indicated that GPC demonstrated 22.3% greater strength than conventional concrete. Furthermore, adding steel fibers to GPC enhanced its compressive strength by 61%. The split tensile strength of GPC was 71.8% higher than standard concrete, and GPC with steel fibers exhibited a 118.5% increase. Similarly, the flexural strength (modulus of rupture) increased by 22% for GPC and 54% for GPC reinforced with steel fibers, compared to conventional concrete. Overall, the findings reveal that incorporating steel fibers significantly improves the mechanical properties of slag-based GPC, particularly in compressive, tensile, and flexural strength, making it superior to ordinary Portland cement (OPC)-based concrete.

Keywords

• geopolymer concrete
• fire exposure
• alkaline activation
• steel fiber