Assessment of mechanical, durability and microstructural performance of sulphate-resisting cement concrete over portland cement in the presence of salinity

Abstract

The current understanding of the sulphate attack mechanism on ordinary Portland cement (OPC) concrete within the construction sector is not yet well understood. The primary objective of this study is to focus on and discuss how to minimize the sulphate attack on concrete. The main purpose of this research is to better understand and improve the mechanical, durability, and microstructural characteristics of concrete under saline and non-saline/normal environments. This investigation involved the use of artificial seawater in the concrete mixing process and ensuring saline conditions for the concrete specimens in the laboratory. In addition, an approach for assessing the influence of using sulphate-resisting cement (SRC) in concrete to differentiate the performance from OPC concrete is also investigated. Silica fume (SF) is used as a partial cementitious material in SRC concrete by 10% and 20%. The concrete performances were examined by several rheological, mechanical, durability, and microstructural tests and compared the corresponding performances with the SRC-artificial seawater (SRCASW) and OPC-freshwater (OPCFW) concrete. Test results show that the strength of concrete decreased linearly from the OPCFW to SRCASW. Among SRC-artificial seawater concrete mixes, the mix with 10% SF shows the best strength outcomes i.e., 28.84, 36.22, and 37.54 MPa at 7, 28, and 56 days respectively, which is an average of 12.5% higher than the mix with 20% SF. A concrete mix of SRC with 10% SF displays the highest durable behavior, achieving chloride penetration and electrical resistivity at a very low range (936 columbus and 290.7 Ω-m, respectively). In addition, microstructural images of the SRC concrete mixes indicate no visible crack due to sulphate inclusion. An analytical approach has provided a conservative estimate with the experimental results and standard code of practice for predicting mechanical properties. Finally, this study revealed that SRC incorporation in concrete increased the long-term serviceability of the structures against salinity.