A novel method to improve sulfate resistance of concrete by surface treatment with super-absorbent resin synthesised in situ

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 $SO42−$ 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 $SO42−$ in cement mortar. After being subjected to sodium sulfate attack, the cement mortar specimens treated by SAR were not severely deteriorated.