Effects of hydrophobic modified fly ash on resistance of chloride corrosion and water penetration of cement mortar in the early hydration stage

The use of fly ash (FA) cement-based materials can solve the problem of environmental pollution, minimize land resources, and improve the utilization rate of fly ash. However, FA cement-based materials have the disadvantage of poor resistance to external water and aggressive chloride ions in the early stage of cement hydration. In this study, the resistance of cement mortars with different superhydrophobic fly ash (S-FA) contents to external water and aggressive chloride ions at the early hydration stage was investigated. The results of water absorption experiments revealed that the water absorption rate of superhydrophobic fly ash cement (S-FAC) mortar was reduced by 65.4% compared with ordinary cement mortar. The S-FA mitigated the problem of high water absorption in the early stage of hydration of mortar with FA. At the same time, the electrochemical analysis showed that the efficiency of S-FA cement mortar resistance to chlorine corrosion increased by 94.09% compared with ordinary mortar. Using S-FA is expected to be an effective way to mitigate the problem of poor resistance to external water and chloride ions at the early stage of hydration in FA cement mortar.