Effect of Fiber Dosage On Mechanical Properties Of Geopolymer Mortar Under The Coupling Of Sulfate Erosion And Dry-Wet Alternation

Abstract

Coastal buildings are susceptible to long-term sulfate erosion and alternating wet-dry cycles, leading to rapid degradation in mechanical properties and durability. Therefore, there is an urgent need to find a construction material that is superior to ordinary silicate concrete. Geopolymer concrete, an innovative environmentally-friendly material, offers advantages like early strength, fire resistance, and durability. Research reveals that even after sulfate erosion, geopolymer concrete outperforms regular silicate concrete in terms of mechanical properties and durability. However, geopolymer concrete suffers from high brittleness. A remedy is found in the incorporation of fibers, which substantially enhances its mechanical properties and durability. This study investigates the influence of carbon fibers and polypropylene fibers on the mechanical traits of metakaolin-geopolymer mortar, exposed to sulfate action and wet-dry cycles for 60 repetitions. Results indicate that the addition of 0.6% carbon fibers yields the highest compressive strength, while a 1:1 combination of carbon and polypropylene fibers produces peak flexural strength. Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) confirm uniform fiber distribution within the mortar, reinforcing material bonds and retarding crack propagation. Consequently, mechanical properties and durability are improved.