Effect of Curing Temperature in the Alkali-Activated Blast-Furnace Slag Paste and Their Structural Influence of Porosity

Abstract

Due to the environmental problem posed by the use of Portland cement as construction material, it becomes necessary the search for supplementary cementitious materials that mitigate the ecological damage caused by it. Because the chemical similarity and the high cementitious powers of the blast furnace slag, it is used in the generation of geopolymers in a cement total replacement. This research focused on the study of the influence of the curing conditions on the final properties of blast furnace slag establishing three variables: no cured process (N-C), cured of controlled temperature of 45°C (CT45-C) and room temperature cure (RT-C); evaluating the mechanical behavior until 28 days of age and the water porosity index. The results show that geopolymers based on blast furnace slag has a behavior similar to hydration maturity of Portland cement and curing process decreases the porosity; On the other hand, applying a controlled temperature generates densest resistant pastes such as the variable CT45-C which reach the highest value of resistance in all curing ages.

Influence of curing on pore properties and strength of alkali activated mortars

“…In the case of AACMs, earlier research has shown a need for high temperature curing at 50 -80 0 C, such as steam or dry heat, for optimum geopolymerization reaction [2,11]. More recent work uses ambient temperature (20 ± 2 0 C), which is practical on construction site, for curing AACMs [12,13]. The optimum levels of relative humidity required for AACM curing are not established.…”

Carbonation and Chloride Ions’ Penetration of Alkali-Activated Materials: A Review

“…Besides the properties of precursors and the composition of activators, curing conditions (e.g., curing temperatures, curing time, and curing humidity) have been also demonstrated to affect chloride resistance in AAMs due to the changes in the kinetics of the reaction. Furthermore, experimental evidence has suggested that the changes in the kinetics of the reaction have impacts on improving the development of microstructures [23,129,140]. Table 5 lists the curing conditions affecting the chloride resistance of AAMs.…”

“…More specifically, the high-temperature curing in AAMs contributes to decreasing chloride penetration as a result of the reduced average pore sizes and reduced porosity [108,140,142,143]. Additionally, it is also reported that curing under a higher temperature can accelerate the dissolution of precursors and influence the overall generation of reaction products [14,90,144].…”

Kaolinite Claystone-Based Geopolymer Materials: Effect of Chemical Composition and Curing Conditions

“…Nevertheless, the history of alkali-activated cement is dated to the 1940s by Glukhovsky and then Krivenko [2,3]. Geopolymers (GP in the following text) are formed by alkaline activation of thermally treated aluminosilicate material like fly ash [4][5][6][7], furnace slag [8][9][10], kaolinite clay [11][12][13] etc. A reaction called geopolymerization creates polymeric Si-O-Al bonds in a three-dimensional network [14].…”

“…The negative charge of alumina tetrahedrons is balanced by the presence of alkali-metal ions, commonly Na + , K + or Ca + [14]. Several investigations considering the precursors' composition and curing conditions have been done [8,15,16].…”