Effect of CO2 concentration on strength development and carbonation of a MgO-based binder for treating fine sediment

Abstract

We previously described a MgO-based binder for treating fine sediment and simultaneously store CO. Here, we describe a study of the physical/mechanical characteristics and carbonation reactions of the MgO-based binder used to solidify/stabilize fine sediment in atmospheres containing different CO concentrations. Carbonation of the sediment treated with the MgO-based binder at the atmospheric CO concentration markedly improved the compressive strength of the product. The compressive strength was 4.78 MPa after 365 days of curing, 1.3 times higher than the compressive strength of sediment treated with portland cement. This improvement was caused by the formation of carbonation products, such as hydromagnesite, nesquehonite, and lansfordite, and the constant high pH (~ 12) of the specimen, which favored the growth of hydration products such as calcium silicate hydrates and portlandite. Very low compressive strengths were found when 50 and 100% CO atmospheres were used because of excessive formation of carbonation products, which occupied 78% of the specimen depth. Abundant carbonation products increased the specimen volume and decreased the pH to 10.2, slowing the growth of hydration products. The absence of brucite in specimens produced in a 100% CO atmosphere indicated that MgO carbonation is favored over hydration at high CO concentrations.

Experimental study on characterization of lime-based mineral carbonation reaction and CO2 sequestration

“…Mohammed et al (2021) have summarized the methods for ground improvement for CO 2 reduction routes in detail. Since the 1960s, lime, cement, and alkali-activated binders have been widely used, depending on the soil type to improve the engineering properties of soils not suitable as construction materials for earthworks (Salehi et al 2023;Vitale et al 2021;Hwang et al 2018;Priyanga et al 2018;Sherwood 1993). Among them, lime-based mineral carbonation is a soil improvement technique widely used for geotechnical engineering applications (Deneele et al 2021;Russo 2019).…”

“…Emissions from the lime industry were estimated to be 25.4 million metric tons of CO 2 equivalents in the US in 2004. 14.3 Mt is process-related emissions, and 11.1 Mt is on-site stationary combustion emissions (EPA 2009).However, Hwang et al report that 1 kg of MgO-based binder could sequester up to 0.507 kg of CO 2(Hwang et al 2018). Undoubtedly, energy consumption and the total cost of lime production are also important.…”

Effect of Carbonation on the Collapse Potential of Magnesium Oxide Treated Gypseous Soil

“…Hwang et al [11] studied the improvement of the silty sand sediment in South Korea by using unconfined compressive strength of soil treated with 30% of carbonated magnesium oxide. The results illustrated that the strength after 1 year was 4.78 MPa which is higher than Portland cement about 1.3 times.…”