Effect of Carbonation on the Water Resistance of Steel Slag—Magnesium Oxysulfate (MOS) Cement Blends

Abstract

Magnesium oxysulfate (MOS) cement has the advantages of lightweightedness, high strength, and low thermal conductivity, but the utilization of MOS cement is limited due to low water resistance. This paper studied the influence of steel slag and CO2 treatment on the compressive strength and water resistance of MOS cement. The hydration products and microstructures were characterized by X-ray diffraction (XRD), thermogravimetric analysis–differential scanning calorimetry (TG–DSC), scanning electron spectroscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results showed that the strength of MOS cement reached 89.7 MPa with steel slag and CO2 treatment; the water-resistance coefficients of the control and samples containing 10%, 20%, and 30% reached 0.91, 0.81, 1.01, and 1.08 MPa, respectively. The improvement in the strength and water resistance coefficients was because of carbonation that accelerated the hydration of C2S in the steel slag and formed a Ca–Mg–C amorphous substance. The carbonation products contributed to better water stability and denser matrix denser while inhibiting the hydration of MgO, which led to improving the water resistance of the sample.

Influence of Carbonation on the Properties of Steel Slag–Magnesium Silicate Hydrate (MSH) Cement

“…However, the high concentrations of CaO and MgO in SS compromise its stability [19]. Recent studies indicate that the stability of SS can be enhanced through carbonation [20]. Due to the high content of belite (C 2 S) and lime (CaO), SS demonstrates excellent carbonation reactivity, as illustrated in Equations ( 1) and (2) [21].…”

“…Kuenzel et al [27] studied hydromagnesite and found that it can react with MgO or Mg(OH) 2 to form a hydraulic basic magnesium carbonate and even a novel type of magnesium carbonate cement. Hu et al [20] investigated the impact of SS hydration and carbonation on the properties of MOS cement. By incorporating varying proportions of SS, the study explored the effects of different carbon dioxide pressures on the modified MOS cement, ultimately identifying the most effective carbonation parameters and the cement products with the highest compressive strength.…”

EFFECT OF MgO/MgSO₄ MOLAR RATIO ON THE HYDRATION AND MECHANICAL PROPERTIES OF BMS CONTAINING STEEL SLAG

“…Steel slag (SS) is a by-product of the steel industry, the mineral composition of which is mainly calcium silicate. In China, steel slag has become one of the most important sources of industrial waste, with less than 20 % of SS currently being utilised [18]. The waste steel slag occupies a large area of land and leads to many serious environmental problems, so the reuse of SS has also garnered increasing attention.…”

Desenvolvimento e avaliação de um cimento de oxissulfato de magnésio para aplicações de construção e engenharia civil

“…A utilização de escória de aço em substituição ao MgO no cimento MOS, também foi estudada por Hu et al (HU et al, 2020). Os autores estudaram a influência da utilização da escória de aço e a cura por carbonatação nas resistências à compressão e à água do cimento MOS.…”

“…O coeficiente de perda de resistência é utilizado para determinar a resistência à água das amostras, conforme (GOMES et al, 2021a;HAO;ZHAO, 2019;HU et al, 2020;ZHANG et al, 2020). Após a cura em ambiente controlado por 28 dias, 6 corpos de prova foram colocados em água a 20 ± 3°C, a resistência à compressão das amostras após 28 dias de imersão em água foi medida e utilizada para calcular o coeficiente de perda de resistência à compressão na água (Kcn) da amostra.…”