Application of sulphoaluminate cement to repair deteriorated concrete members in chloride ion rich environment-A basic experimental investigation of durability properties

This paper presents a basic experimental investigation of the durability properties of Sulphoaluminate cement concrete (SACC) and Portland Cement Concrete (PCC). It is to discuss the potential application of Sulphoaluminate cement towards the repair of deteriorated concrete members in chloride ion-rich environment such as coastal engineering, using a SACC repair layer with higher strength than original damaged concrete. The chloride-related durability properties of SACCs were comprehensively studied through some experiments including concrete internal chloride ion content test, chloride ion migration test, X-ray diffraction analysis, scanning electron microscopy and pore structure analysis, when compared with the results of PCCs that have same mix proportion and curing conditions. The analyses and comparisons presented in this paper verified the SACC repair layer has high early strength and chloride-related durability which will effectively improve the capacity of damaged concrete to resist chloride ion penetration. When without any admixtures, compared with PCCs' results, SACCs can provide more compactness hardened internal structures, more micro fillers between internal cracks and more favorable hydration products to bond/resist chloride ions, as well as can also provide lower porosity and more winding pore passageway to resist and postpone the transportation of chloride ion in the concretes. Based on the investigation, the chemical and physical mechanisms of SACC were discussed.