Characteristics of patch-repaired RC under influenced of chloride ions

Abstract

One of the key performances of repaired reinforced concrete is its ability to withstand corrosion due to harmful ions and should be compatible with substrate and repaired concrete structures. This research investigates the prediction of corrosion risk on repaired RC by comparing performance between PMM and conventional OPC as chosen materials for repairing RC structures under influenced of chloride ions. The effect of chloride ions on repaired RC will be analyzed according to microstructural analysis, half-cell potential and chloride content by weight of cement. For analysis, substrate concrete containing 9 kg/m3 chloride ions with W/C ratio 60% acts as the reference specimen. Meanwhile, for comparison purpose; two conditions of repaired RC namely OPC with W/C ratio 40% (R-0.4OPC) and PMM (R-PMM) that contain chloride free ions using similar casting and curing techniques were prepared respectively. Based on the results obtained, porosity and microstructural images using BSE were alternated under influenced of chloride ions since it correlated with surface charge of CSH due to Ca/Si amount in each specimen. The correlation between free and total chloride ions in concrete reveals the phenomena of co-matrix in R-PMM specimen since least chloride ions found in repaired section compared to R-0.4OPC specimen. The most striking result is R-PMM specimen able to resist chloride ions ingress in its repaired section but for HCP results obtained the R-PMM specimen beyond its threshold of passivity even though its porosity value is the lowest. To sum up, penetration of chloride ions throughout the specimens according to the wet chemical analysis giving effects to the porosity and microstructure. The R-PMM specimen was good in resistance of chloride ions to the repaired part but it was not the final predictions on its ability to withstand corrosion resistance.