Roles of hybrid activators in improving the early-age properties of one-part geopolymer pastes

Comparison of One-Part and Two-Part Alkali-Activated Metakaolin and Blast Furnace Slag

“…Subsequently, a second exothermic peak is observed [21,26]. This peak is generally associated with the nucleation, growth, and precipitation of the reaction products [21,27]. From the heat flow curves, it can be seen that there is no difference in the reaction kinetics between one-part and two-part systems, when using the same precursor in both.…”

“…The samples were introduced to 7 mm zirconia rotors and the spinning frequency employed was 7 kHz. The frequency of the 27 Al experiments was 78.24 MHz, and 2048 scans were collected with a repetition time of 2 s. The excitation pulse length and angle were 1.0 μs and 30°, respectively. Chemical shift referencing was performed using Al (NO 3 ) 3 as an external standard.…”

“…The results of the 27 Al MAS NMR analysis of the one-part and two-part metakaolin-based AAMs are shown in Fig. 10a.…”

Synergistic effects of CNTs/SiO2 composite fillers on mechanical properties of cement composites

“…The hydrophobicity, high aspect ratio, coupled with strong van der Waals forces, commonly contribute to the inherent agglomeration bias of CNTs, which may be a reasonable interpretation for that the nal reinforcing efficiency of CNTs is much lower than the theoretical value. Although the initial dispersion can be obtained by combining mechanical ultrasonication with chemical surfactants, [29][30][31][32][33][34] this equilibrium is easily broken with the extended time or varied external environment. Additionally, the surface functional modications represented by strong oxidation of concentrated acid tend to introduce damage on CNTs surfaces in addition to operation difficulty and environment pollution.…”

Alkali-Activated Hybrid Cements Based on Fly Ash and Construction and Demolition Wastes Using Sodium Sulfate and Sodium Carbonate

“…Wang et al [9] studied the reactivity of alkali-activated slag binders, using a mixture of calcium oxide and sodium carbonate as activators; the authors reported optimal proportions of 2.5% CaO and 5% Na 2 CO 3 in order to obtain a much denser microstructure and higher compressive strength. Wang et al [11], using a mixture of sodium silicate (49%), sodium aluminate (2%), and Na 2 CO 3 (49%), obtained a longer setting time and lower heat of reaction in a FA/GBFS geopolymer. Bernal et al [12] examined the mechanism of slag activation when using Na 2 CO 3 and proposed that the activation is carried out in three different stages, starting with the dissolution of the slag and the formation of gaylussite and zeolite A on the first day.…”