Effects of accelerated carbonation on the microstructure of Portland cement pastes containing reactive MgO

CO2 sequestration through aqueous accelerated carbonation of BOF slag: A factorial study of parameters effects

“…In a study on carbonation of pure minerals typically present in steelmaking slag (Bodor et al, 2013), bredigite (Ca 7 Mg(SiO 4 ) 4 ) was the most reactive phase during carbonation, followed e depending on the process conditions e by dicalcium silicate polimorphs (b-and g-Ca 2 SiO 4 ) and cuspidine (Ca 4 Si 2 O 7 F 2 ), or by srebrodolskite (Ca 2 Fe 2 O 5 ) and calcium monoferrite (CaFe 2 O 4 ); however, other investigators (Berryman et al, 2014) reported some low reactivity of srebrodolskite upon carbonation. In real industrial residues the ranking of affinity towards CO 2 observed for pure mineral phases may be altered by a number of factors (Santos et al, 2013b), including differences in sizes of the individual particles, presence of impurities and degree of ion substitutions in crystals (Fern andez Bertos et al, 2004;Mo and Panesar, 2012), as well as accessibility of reactive components within the solid (Bodor et al, 2013). Mineralogical studies on various carbonated steel slags reveal that the reactive minerals include dicalcium silicate, periclase (MgO), akermanite (Ca 2 MgSi 2 O 7 ), merwinite (Ca 3 Mg(SiO 4 ) 2 ), cuspidine as well as a number of CaeAl oxides and CaeMgeAl-silicates (Baciocchi et al, 2015;Chang et al, 2013a;Johnson et al, 2003;Salman et al, 2014;Uibu et al, 2011).…”

Mixture design and treatment methods for recycling contaminated sediment

“…Accelerated carbonation in a chamber filled with compressed carbon dioxide gas (i.e., CO 2 curing) could facilitate setting/hardening rate and reinforce the matrix strength via carbon dioxide dissolution, penetration, and subsequent formation of calcium and magnesium carbonates, such as calcite, aragonite, magnesium calcite, and magnesium carbonates [26,27]. The cement hydration products (CH and C-S-H) could be converted into calcium carbonate, calcite, modified C-S-H gel, or polymerized silica gel in a short period of curing time, thus contributing to microstructural development, reduction in pore size and total pore volume, and increase in apparent density and mechanical strength [28][29][30].…”

Geo-parametric study of dredged marine clay with solidification for potential reuse as good engineering soil

“…For instance, the common range of cement content for clay treatment recommended by Lee and Ali (2004) is 3-16 % by dry weight of soil, though this is a conservative estimation, taking into account the high variability of soil properties which dominates the solidification outcomes. Besides, there has been continuous innovation in the cement treatment of soft soils, such as induced carbonation of reactive magnesia for accelerated solidification (Mo and Panesar 2012;Cai et al 2015), early-age preloading for strength enhancement (Nishimura and Abe 2015) as well as fibre addition for improved load resistance (Xiao et al 2015).…”