The Influence of Alkali Content on the Hydration of the Slag-Based Geopolymer: Relationships between Resistivity, Setting, and Strength Development

Abstract

This study investigated the influence of alkali content on the early-age hydration process of slag-based geopolymer and the feasibility of non-destructive resistivity. Results showed that there existed a threshold of alkali content in adjusting the early-age hydration. Initially, increasing the alkali content tended to accelerate the dissolution period (detected by resistivity and heat release rate) and resulted in a denser microstructure (detected by TEM). When the alkali content surpassed 6 wt%, the increasing alkali content mitigated the structural development of a slag-based geopolymer, as it lowered the liquid water content and caused local precipitation, which trapped the early-age ions transmission and, therefore, the later-age mechanical development was inhibited. It was proven that the resistivity acted as a linkage among the reaction degree, workability, and strength development.

Pozzolanic potential of sustainable precursors for engineered geopolymer composites (EGC)

“…Additionally, SAI results are affected by the water requirement of various mixtures (table 2), showing a maximum requirement for BOF, followed by IOT and FA to attain a standard consistency mix. Moreover, the control OPC specimens (SAI) involved a water usage of ∼230 ml, inconsistent with the hydration stoichiometry, which suggests a water-to-cement ratio (w/c) requirement of 0.23 (∼103.5 ml) for OPC hydration [78]. This deviation in water content possibly impacts the hydration process and in turn the rate of pozzolanic reaction [77].…”

“…(iv) Hydration stoichiometry: this particular parameter in geopolymer based composites is considered complex involving the reaction of alumino-silicate sources with the alkaline activators to form a stable geopolymer gel structure, denoting the properties of the composite [79]. Any discrepancies in this hydration stoichiometry can possibly affect the pozzolanicity and thereby resulting in reduced strength characteristics [78].…”