Exploring the Combined Influence of Load and Flowing Corrosion Solution on the Sulfate Resistance of Fly Ash-Based Geopolymer Concrete

This study investigates the combined influence of loading and flowing corrosive solutions on the sulfate resistance of fly ash-based geopolymer concrete (FABGC) under real service environments. The results demonstrate that both loading and flowing water erosion accelerate the degradation of the FABGC, as evidenced by a reduction in the relative dynamic elastic modulus and an increase in the thickness of the damaged layer. Results show that SO₄²⁻ concentration within FABGC increases progressively with exposure time across all corrosion conditions, with loading significantly facilitating SO₄²⁻ transport, particularly at higher load levels. The combination of loading and flowing water erosion not only accelerates SO₄²⁻ penetration but also enhances the formation of corrosion products through microscopic analyses, specifically ettringite (AFt) and gypsum. While the bending load optimizes the internal structure of the compression zone, it will introduce microstructural damage in the tension zone, thereby potentially accelerating the transport of SO₄²⁻ and modulating the effects of flowing water erosion. Load-induced microcrack expansion significantly enhances SO₄²⁻ transport, accelerating the formation of corrosion products such as AFt and gypsum. This process leads to the increase of porosity, particularly in the proportion of large pores. These results demonstrate that the combined influence of loading and flowing water erosion creates a synergistic effect on the durability of FABGC. This underscores the critical importance of considering these combined effects in the design and long-term maintenance of FABGC structures exposed to severe environmental.