Effects of alkali on one-part alkali-activated cement synthesized by calcining bentonite with dolomite and Na2CO3

Recent progress in low-carbon binders

“…Various different precursors, and combinations of precursors, have been validated for use in onepart AAM binders. In addition to the more commonly used GGBS [157,158], fly ash [159,160] and calcined clays [161], there has also been meaningful work dedicated to the development of one-part AAMs from industrial waste silicas and NaAlO2 [162] [163], and red mud [164,165]. In many of these binder systems, a careful balance needs to be drawn between adding sufficient alkalis to enable rapid strength development, and avoiding the excessive alkali levels that may lead to efflorescence.…”

Role of Natural Stone Wastes and Minerals in the Alkali Activation Process: A Review

“…As stated in the introduction, most of the works considered the use of carbonate powders only as filler added to the raw powders traditionally used in the alkali activation process [50,[55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72]; only two works investigated the use of carbonates alone [40,45]. In particular, carbonate fines have been used in combination with MK [50,55,57,67], FA [58,59,62,65,66,68], GBFS [56,59,61,65,[68][69][70]72], and clays (bentonite [60], smectite [64], halloysite [71], undefined [65]).…”

“…The main difference among all the studied carbonate stone powders is the calcite and/or dolomite content, resulting in a different chemical composition that can be mainly expressed in terms of CaO and MgO content (Table 3). Indeed, articles can be summarized in three different groups according to the chemical nature of the starting minerals: mainly composed of calcite [45,[55][56][57][58]60,[63][64][65][66][67][68][69][70][71][72], with prevailing dolomite content [50,55,[59][60][61][62] and a mixture of calcite and dolomite [72].…”

“…Some studies relate to the already mentioned one-part alkali-activated materials, in which the dry alkaline component is mixed with the raw powder so that only water is used to activate the mixture [56,60,61]. Abdel-Gawwad and Abo-El-Enein [56] mixed calcium carbonate and a sodium hydroxide solution (at different NaOH concentrations: 2%, 4%, and 6%, respectively) for the preparation of a dry activator to be used in combination with GBFS.…”

Development of reactive magnesia cement-based formulations with improved performance & sustainability

“…Dolomite can also be used as a starting material in the production of magnesium oxychloride cement, which also leads to the production of high-purity CaCO3 and CO2 . Other studies on the use of dolomite have reported the properties of an alkali-activated cement system involving a mix of dolomite and bentonite subjected to calcination under high temperatures (~1100-1200 °C) (Peng, Wang et al 2017). Another study (Szybilski and Nocuń-Wczelik 2015) The inclusion of a small amount of short polymeric fibers has been proven to be very effective in eliminating the brittleness and enhancing the tensile ductility of PC-based composites (Brandt 2008).…”