Room-temperature alkaline activation of feldspathic solid solutions: Development of high strength geopolymers

Reactivity and mechanical performance of geopolymer binders from metakaolin/meta-halloysite blends

“…The absorption band occurring at 771 cm -1 is assigned to bending modes of Al-O bonds. The last absorption band located at 688 cm -1 is assigned to a vibration mode of Si-O bonds attributable to quartz mineral as reported by Nana et al [27] and Tchakoute et al [32]. That is also the reason why this absorption remains unchanged during the reaction.…”

Influence of Thermal Activation and Silica Modulus on the Properties of Clayey-Lateritic Based Geopolymer Binders Cured at Room Temperature

“…With the exception of the kaolinite mineral, the rest of the mineral phases were present in calcined laterites. In addition, increasing the calcination temperature from 25°C to 750°C in the present study increases the formation of amorphous phase content requires for the geopolymer synthesis as reported by others on different clays used as solid precursors [20,27]. The presence of halo between 15° and 30°2 Theta range indicates the formation of amorphous phase after calcination which has been identi ed by other researchers [28, 30,31].…”

“…The characteristic bands of the Si-O-Si links located respectively at 1009 cm − 1 and 1032 cm − 1 in a Q 2 and Q 3 con guration seem to transform into a single wider band located around 1116 cm − 1 characteristic of Q 4 type silicon sites. This correlates with the formation of amorphous metakaolinite which results in the transition from the Q 3 tetrahedral environment of silicon to a Q 4 type environment corresponding to sites characteristic of silica [27,29]. The change in the Si-O band and the disappearance of the Si-O-Al band suggest a distortion of the tetrahedral-octahedral layers and therefore suggests some amorphization within the material.…”

“…Furthermore, the OH hydroxyl bands (between 3693 cm − 1 and 3620 cm − 1 ) are characteristic of kaolinite [2,16,26]. The same is true for quartz with the doublet whose positions are respectively located at 789 cm − 1 and 745 cm − 1 [27].…”

Recent progress in low-carbon binders

“…The selection of precursors available for use in alkali-activation has also broadened significantly in recent years, with particular emphasis being placed upon the use of materials for which there is not strong competition in demand from utilization in blends with Portland cement. For example, calcined non-kaolinitic clays [17][18][19][20], palm oil fuel ash [21,22] or other minerals [23][24][25][26], have been shown to yield alkali-activated binder systems with technical properties that are attractive in given applications. Various industrial by-products or wastes without current large-scale utilization as supplementary cementitious materials have been tested and validated for use in alkali-activated binders, including red mud [27][28][29] and various glassy wastes including slags, some of which can benefit from thermal re-processing or modification to improve their reactivity before use [10,[30][31][32][33][34][35].…”