Development and validation of methods for the determination of water-soluble and acid-soluble sulphate in concrete

Sulphate attack is one of the deterioration mechanisms of concrete. This is characterised by the formation of chemical species that cause expansion, subsequent cracking, and the eventual loss of concrete strength. Production of acid rain and high elevation of temperature, as manifestations of climate change, can initiate and/or accelerate the process of sulphate attack, reducing the service life of concrete structures which could lead to social, environmental, and economic damage. The laboratory developed and validated ion chromatographic-based and spectrophotometric-based methods for the analyses of water-soluble sulphate and acid-soluble sulphate in concrete, respectively. This is to assess the laboratory's capability in generating reliable and accurate measurement results for sulphate determination. This will support regulations on sulphate content of concrete, ensuring that construction products conform to the standard specifications. Method performance characteristics evaluated were linearity and working range, repeatability, intermediate precision, and trueness. The methods were found to be fit for the intended purpose of sulphate determination in routine analysis of concrete samples.