Effects of CaCl 2 on hydration and properties of lime(CaO)-activated slag/fly ash binder

Gypsum-Dependent Effect of NaCl on Strength Enhancement of CaO-Activated Slag Binders

“…When NaCl and/or gypsum were incorporated in this study, hydrotalcite was mostly removed, and the use of NaCl ( , which is known as a strength enhancing material by filling pores [12,37]. These reaction products have often been observed in earlier studies of construction binders containing chloride [13,[38][39][40] or sulfate sources [12,41,42].…”

“…In the sample that did not have NaCl or gypsum (Ca-N0-G0), weak peaks of hydrotalcite (Mg 6 Al 2 CO 3 (OH) 16 •4H 2 O) were identified. Hydrotalcite has often been found in alkali-or CaO-activated GGBFS pastes and in blends of Portland cement with GGBFS [2,6,12,13,36]. Hydrotalcite belongs to layered double hydroxides (LDHs), which consist of a family of minerals with the general formula of…”

“…Recently, calcium-based activators (e.g., Ca(OH) 2 , CaO) have been reported for their use of activating GGBFS because these activators are less expensive and have less alkaline than sodium-based activators [6,[11][12][13]. In the manufacturing process of commercial GGBFS, sulfate sources (e.g., gypsum (CaSO 4 •2H 2 O), anhydrite (CaSO 4 )) are often incorporated to improve grinding efficiency and satisfy the required national standards of chemical composition for industrial uses [14].…”

Recycling of Reverse Osmosis (RO) Reject Water as a Mixing Water of Calcium Sulfoaluminate (CSA) Cement for Brick Production

“…Thus, although the formation of ettringite has often been reported as a main cause of substantial strength increase in various cementitious binders [39,40], in this study, the ettringite formation hardly explained why the use of RO reject water significantly increased strength. Rather, given that earlier studies [41][42][43] reported that the formation of Friedel's salt filled pores in hardened cementitious materials, the greater strengths of the samples with RO reject water (i.e., ROG) were also likely related to the formation of Friedel's salt in this study.…”

“…Given that, in Figure 4d, the sample ROG showed~12.7 wt% of weight loss up to~120 • C, and this weight loss corresponds to~27.7 wt% of ettringite formation, the 1.2 wt% of difference in ettringite formation was not significant. Thus, the strength differences among the samples were likely not significantly correlated with the influence of changing mixing water on ettringite formation, but rather more related to the formation of Friedel's salt in this study because earlier studies demonstrated that even a small increase in Friedel's salt notably decreased the porosities of the hardened pastes of cementitious binders [41][42][43].…”