Influence of SAP on the chloride penetration and corrosion behavior of steel bar in concrete

Abstract

The steel corrosion induced by chloride penetration is a great threaten to concrete structures, in particular exposed to marine environments. Super absorbent polymer (SAP), as a water reservoir, is probably conducive to reinforced concrete suffered from steel corrosion in marine environments. Therefore, the influence of SAP on the chloride penetration and corrosion behavior of steel in concrete were investigated using concrete mixed with 0∼2 kg/m3 SAP. The results indicate that the permeability and chloride diffusion coefficient consistently rise up with increasing with SAP dosage. Furthermore, the higher SAP dosage results in an ascending free chloride content when subjected to tidal zone. However, when exposed to atmosphere zone, the effect of SAP can be neglected. Moreover, the corrosion current of the sample with SAP are larger than that without SAP, while more corrosion products can be observed in the sample with SAP. Since the stress and strain applied on concrete and internal steel bar of specimens with SAP are apparently smaller, the propagation of crack caused by steel corrosion is probably postponed. Thus, it can be roughly concluded that for concrete subjected to marine environment, adding SAP to concrete can delay the failure process of reinforced concrete to some extent and an optimized dosage of SAP is suggested to be 1 kg/m3.