Concrete deterioration due to sulphate- A case study

Abstract

Chemical ions present in the concrete ingredients are major cause of deterioration of the concrete structures, which are in contact of water. Ions like sulphate and chloride present in concrete ingredients or in water causes efflorescence, leaching, corrosion of reinforcement and spalling of concrete. In this paper a case study from Greater Noida region, where a concrete surface near a water tank shown deposition of very fine white crystalline material. Concrete specimens, water from the tank and white crystalline material collected from the different places. The complete water quality analysis was carried out on water samples. X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM) tests performed on the concrete and white crystalline samples. X-Ray Diffraction analysis shows that the white crystalline material is sodium sulphate crystallised as thenardite and mirablite crystals. The concrete specimens showed, apart from C-S-H, calcite, and portlandite, ettringite formation was there in the concrete samples by analyzing with the XRD and SEM, which was the major cause of spalling at the site