Carbonating magnesia for soil stabilization

Abstract

This paper investigates the potential for carbonating reactive magnesia (MgO) to serve as a more sustainable soil stabilization method by providing rapid and significant strength development of the stabilized soil through absorbing substantial quantities of CO2. Gaseous CO2 was forced through laboratory-prepared reactive MgO-treated soil samples in a triaxial cell set-up, and their resulting mechanical and microstructural properties were investigated using unconfined compressive strength, X-ray diffraction, and scanning electron microscopy. The results showed that adequately carbonated MgO-treated soils could, in a few hours, reach a similar strength range to corresponding 28 day Portland cement (PC)-stabilized soils. Hydrated magnesium carbonates, namely nesquehonite and hydromagnesite–dypingite, were the main products of the carbonated MgO in the soil, and were responsible for the significant strength development.

Physical properties, electrical resistivity, and strength characteristics of carbonated silty soil admixed with reactive magnesia

“…(1)). It has been observed by the researchers Al-Tabbaa 2009, 2012;Yi et al 2013a) that brucite has a limited binding ability and hence has relatively low contribution to the strength development.…”

“…These studies have focused on the hydration, microstructures, mechanical properties of the carbonated reactive MgO cement-based pressed masonry units as well as reactive MgO cements (Vandeperre and Al-Tabbaa 2007;Al-Tabbaa 2013, 2014;Jin and Al-Tabbaa 2014). Yi et al (2013a) investigated the strength characteristics of carbonated reactive MgO-admixed sandy soil.…”

“…The treated or stabilized soil exhibits higher strength, lower permeability or compressibility as compared to its untreated counterparts, which is beneficial for reducing the settlement and increasing the stability of the ground (Terashi and Tanaka 1981;Shen et al 2008;Liu et al 2012). The strength development of the soils stabilized with cement-based additives is primarily attributed to the formation of cementitious materials including calcium silicate hydrates (Yi et al 2013a;Du et al 2013Du et al , 2014a. Generally, formation of the hydration products and consequent strength gain of the treated soils are relatively slow and time-dependent.…”

“…Generally, formation of the hydration products and consequent strength gain of the treated soils are relatively slow and time-dependent. Moreover, the Portland cement (PC), considered as one of the major sources of the increase in atmospheric concentration of carbon dioxide (CO 2 ) (∼ 0.95 t CO 2 /t PC), has negative impacts on the environment and necessitates huge energy consumption (Yi et al 2013a;Jin and Al-Tabbaa 2014;Unluer and Al-Tabbaa 2014). Therefore, it is necessary to utilize alternative stabilization materials which can completely or partially eliminate the use of the PC.…”

“…Therefore, it is necessary to utilize alternative stabilization materials which can completely or partially eliminate the use of the PC. These materials could be recycled construction and demolition (C&D) debris (Mohammadinia et al 2014), supplementary 4 industries, thereby reducing fuel consumption and strengthening environmental protection as well Yi et al 2013a). Previous studies reveal that the reactive MgO-admixed soil, when exposed to CO 2 for carbonation, is able to fulfill the rapid and significant enhancement of soil strength (Yi et al 2013a;Cai et al 2014a).…”