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A concrete surface was treated by in situ synthesised super-absorbent resin (SAR) of poly(acrylic acid-co-acrylamide). Experiments aimed at determining the resistance to carbonation and the chloride permeability of SAR-treated concrete compared with control concrete specimens were conducted. The corrosion risk and corrosion rate for the rebar embedded in SAR-treated and control concrete specimens at various periods of carbonation were evaluated through the accelerated corrosion test, wherein the rebar was subjected to 3·5% sodium chloride solution. The results show that the resistance to carbonation and chloride permeability of SAR-treated concrete is higher than that of control concrete, and that the corrosion risk and corrosion rate of steel embedded in SAR-treated concrete is smaller than that of steel in control concrete. Lighter carbonation can effectively decrease the chloride permeability of concrete, but serious carbonation is harmful to the long-term maintenance of the passive film of steel in concrete.

Sulfate attack is a key factor that results in the deterioration of concrete. In the current paper, a novel method to improve the sulfate resistance of concrete by surface treatment with super-absorbent resin (SAR) synthesised in situ is presented. The precursor solution of poly(acrylic acid-co-acrylamide) is soaked into the capillary pores of hardened concrete, initiated by infrared radiation and synthesised SAR, then the swollen SAR absorbs water and fills capillary pores to cut off the penetration pipes of external sulfates. The performances of SAR synthesised in situ were characterised by the swelling ratio for deionised water and 5% sodium sulfate solution. The osmosis of [Formula: see text] in cement mortar was compared before and after being treated by SAR. The sulfate corrosion characteristics of cement mortar were confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The laboratory testing results indicate that the SAR has a high swelling ratio, and the swollen SAR, which adhered to the capillary pores of cement mortar, can evidently reduce the osmosis of [Formula: see text] in cement mortar. After being subjected to sodium sulfate attack, the cement mortar specimens treated by SAR were not severely deteriorated.