Research on Corrosion Resistance and Relevant Mechanism of Geopolymer Concrete and Ordinary Concrete in the Same Sulfate Solution

Fly ash based geopolymer concrete(FGC)and ordinary Portland cement concrete(PCC)were designed and tested in 5%solutions of sodium sulphate solution with dry-wet cycles according to preset national standard GB/T 50082-2009 to study their resistance to sulphate attack.The experimental results were assessed by the variations of structural morphology,compressive strength,dynamic elastic modulus,weight and volume.The microstructure of the specimens attacked by sulphates was also investigated using scanning electron micro-scope(SEM),energy dispersive X-ray spectrometer(EDS)and inductively coupled plasma emission spectrometer(ICP-OES)techniques.The damage mechanism and interaction influence factors of FGC and PCC in the same erosion condition were analyzed and discussed.Results turned out that compressive strength and volume of FGC and PCC first decreased after rising trend.Weight changes were small:0.3% of FGC and 0.6% of PCC.The dynamic elastic modulus of both FGC and PCC were different and complicated.Meanwhile,microscopic observation show that the key factors affecting the structure form of FGC and PCC are fly ash particles and swelling products,respectively.Chemical analysis showed that the basis of mutual influence between FGC and PCC is the composition of dissolved and infiltration in sulfate solution.