Corrosion Resistance Mechanism of Concrete Containing Modified Fly Ash and Modified Zeolite Powder in a Wet–Dry Cyclic Sulfate Environment
Pengcheng Zhu, Xiaohan Zhou, Xinrong Liu, Ninghui Liang, Lijun Wang, Linpeng Li
Abstract
This study aims to elucidate the mechanisms underlying the enhancement of concrete’s resistance to sulfate corrosion by subjecting modified fly ash (MFA) and zeolite powder (MZP) concrete to dry–wet cyclic sulfate corrosion tests. Through laboratory tests (surface morphology, mass change, compressive strength, and ion concentration), we have established the concrete corrosion resistance grade prediction model and the sulfate ion concentration distribution model. The results indicate that the judicious incorporation of MFA and MZP enhances the concrete’s resistance to sulfate corrosion. This augmentation manifests in mitigated deterioration of surface morphology, reduced loss in mass and strength postcorrosion, and lowered sulfate ion concentration. The established concrete corrosion resistance prediction model demonstrates commendable applicability, with its predicted values closely aligning with experimental results and an error margin within 15%. The established sulfate ion concentration distribution model exhibits high predictive accuracy. Based on the predictive results, the effective diffusion coefficients (De) for 20% dosages of MFA and MZP concretes represent only 72.7% and 48.1%, respectively, of those for baseline group concrete. Therefore, the utilization of MFA and MZP offers novel perspectives for enhancing the durability of concrete in sulfate environments, providing guidance for the construction of highways and tunnels in saline geological strata.