Preparation and properties of carbonated steel slag used in cement cementitious materials

Attributable to the advantages of low cost, easy availability and high density, et al., steel slag has become the research focus of the cement concrete industry. In this paper, the indirect carbonation process of steel slag is studied, the cementitious materials are prepared by replacing part of cement with carbonated steel slag, the mechanical properties and volume stability of the cementitious materials were studied. The reasons for the influence of carbonated steel slag on the properties of cementitious materials are explored from the hydration properties. The results show that carbonation reaction can reduce the content of free calcium oxide in steel slag. The carbonation products are mainly calcite and are in the form of non-uniform particles and carbonation layer morphology. The volume stability of cementitious materials containing carbonated steel slag is improved effectively due to the consumption of the expansion phase. Although the silicate phase in steel slag will be carbonated, the calcium carbonate produced by carbonation fills the microcracks or pores of the cementitious materials, or becomes the core of the hydration product, which significantly improves the 28-day strength of the cementitious materials. (C) 2021 Elsevier Ltd. All rights reserved.