Influence of magnesium slag as a mineral admixture on the performance of concrete

Magnesium slag is a byproduct of the magnesium industry. It has not been commonly used in the construction industry due to the poor hydration reactivity and soundness risk induced by a high content of MgO. However, magnesium slag has hydraulic potential for similar mineral compositions to Portland cement. This study aims to investigate the potential use of magnesium slag as a mineral admixture in cement concrete. The influence of magnesium slag content and fineness on the workability, mechanical properties and durability of concrete was discussed. Results showed that the concrete fluidity increased with increasing magnesium slag content. The fineness of magnesium slag in this study showed a slight influence on the fluidity. Magnesium slag was not beneficial to the early strength development of the concrete due to the retarding effect on hydration, but it had a positive effect on the later strength. It could also optimize the long-term properties of concrete with reduced drying shrinkage and an improvement of sulfate-and frost-resistant properties. Finally, as a mineral admixture in concrete, magnesium slag with an optimum content of 30% and a specific surface area of 485 m(2)/kg was suggested. (C) 2021 Elsevier Ltd. All rights reserved.