Atomistic C-S-H Sample Clauses

Atomistic C-S-H model with a C/S ratio of 1.75 illustrating the cleavage plane (002) to create a slit-like nanopore model. b) A 1 nm C-S-H slit pore model with confined H2O/CO2 mixture. Color legend: O, red; H, white; Ca, green, Si, yellow, C, grey. Modifying the chemistry of C-S-H leads to the modification of the pore surfaces (Figure 2). Specifically, as the C/S ratio is increased, the pore size widens due to deletion of SiO2 units and the number of surface calcium atoms increases. This alteration is expected to affect the fluid-C-S-H surface interactions. Due to the porous nature of C-S-H, CO2 and ions, if present, may intercalate into the well cement casings during carbon storage processes. In our simulations, the created C-S-H pores were filled with CO2/H2O fluid mixtures following the approach of similar modeling studies for swelling clays (Xxxxx et al., 2010; Xxx and Xxxx, 2016). The equilibrium concentrations of CO2 and H2O in the nanopores were calculated from GCMC simulations. Table 1 shows the resulting mole fractions of CO2 (xCO2) intercalated within the C-S-H pores, as well as in quartz pores, which are discussed below. Our results indicate that xCO2 decreases with increasing C/S ratio. We relate these differences to the increasing amount of Ca2+ ions on the C-S-H surface. Others have also shown that ions play a role in the intercalation of CO2 in smectite clays (Xxxxxxx et al., 2015; Xxxxxx et al., 2017; Xxxxxxxxxx et al., 2018).