Reaction of hydrated cement paste with supercritical carbon dioxide

Application of Fourier Transform infrared spectroscopy (FTIR) coupled with multivariate regression for calcium carbonate (CaCO3) quantification in cement

“…These chemical processes produce calcium carbonate (CaCO 3 ) and amorphous silica, among other minority compounds, which induce several changes in the chemical composition, mechanical strength, and pore size distribution of the cement matrix [30]. The main consequence of CO 2 attack on the cement matrix is a potential loss of material's integrity [27], which can be accelerated by exposure to supercritical CO 2 [31]. In this context, some factors can influence the carbonation rate of cement, including: (i) curing conditions of the material, (ii) type of cement (chemical composition), (iii) presence of additives and (iv) water-tocement ratio [65].…”

“…Among the characterization methods, the analysis of CaCO 3 in cementitious materials can be performed in the following way: (i) qualitative, by means of phenolphthalein, TEM and SEM methods, (ii) semi-quantitative, using the IR, MicroCT, XRD and XRF instruments and (iii) quantitative, through TGA analysis [11,[35][36][39][40]. In addition, XRD, SEM, IR and TGA can be applied, with their respective limitations, to identify the presence of different CaCO 3 polymorphs (amorphous carbonate, vaterite, aragonite and calcite) [31,[41][42]. Otherwise, NMR is applied only to analyze the siliceous ( 29 Si NMR) and aluminate ( 27 Al NMR) cement phases; however, it is not usually applied to analyze CaCO 3 from 13 C NMR [11,39,43].…”

Supercritical CO2-Induced Evolution of Alkali-Activated Slag Cements

“…The carbonation of PC when subjected to high concentrations of CO 2 , especially at supercritical concentrations is very rapid [ 33 , 34 ]. The powdered samples subjected to supercritical carbon dioxide were observed to reach their full carbonation within 24 h [ 35 ]. The mechanism was reported to be different from accelerated testing.…”

“…However, in another study, the CaCO 3 coating is observed to be present in a non-passivating form and hence carbonation is not arrested [ 37 ]. The carbonation of Ca(OH) 2 is observed to form predominantly calcite [ 36 ], the formation of different phases is also observed in PC subjected to supercritical CO 2 [ 35 , 38 ].…”

Fundamental Studies on CO2 Sequestration of Concrete Slurry Water Using Supercritical CO2

“…Since typical conversion of CO 2 to carbonate is very slow and inefficient under the conditions of ambient temperature and pressure, there has recently been an increasing trend in research on maximizing the mineral carbonation reaction using supercritical CO 2 . Existing studies on mineral carbonation using supercritical CO 2 have revealed an absence of any significant effect of temperature in the supercritical state and have also shown that the carbonation efficiency increases with increasing pressure [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. The temperature–pressure conditions explored in recent studies on mineral carbonation using supercritical CO 2 are summarized in Figure 1 .…”