Comparison of influence of surfactants on thermokinetic characteristics of alkali-activated slag cement

Abstract

Increasing the durability of concrete and reinforced concrete structures according to the criterion of crack resistance is a relevant task of construction materials science. To solve this task, this paper proposes effective solutions for adjusting thermofinite characteristics of alkali-activated slag cement (ASC) by using surfactants of various chemical nature in order to control the thermally-stressed state of concrete based on it (ASC concrete). The method of calorimetry was applied to show that the problematic issue is to adjust the structure formation of ASC by anion-active surface-active substances based on complex polyesters. This is predetermined by the instability of the molecular structure of surfactants in the hydration environment of ASC due to the destruction of complex ester bonds as a result of alkaline hydrolysis. Thermokinetic analysis has demonstrated the effectiveness of using anion-active surfactants, which do not contain ester bonds, as regulators of crack resistance of ASC concrete. Simple polyesters and multi-atom alcohols provide the ability to adjust the duration of the induction period while ensuring the required completeness of ASC hydration within a time frame. The effectiveness of cation-active surface-active substances has been shown, which are characterized by the stability of the molecular structure in the hydration environment of ASC and an increased level of adsorbing capacity. The decrease in the effectiveness of surface-active substances has been shown, in terms of the effect on the heat release of ASC, in the following series: alkaline salt of carboxylic acid>salt of the quaternary ammonium compound>simple polyester> polyalcohol>complex polyester. The reported results are important in view of the possibility of effective adjustment of ASC heat release by influencing the structure formation of surfactant with a certain molecular arrangement in order to predictably reduce crack formation in a thermally-stressed state and a corresponding increase in the durability of structures

Mitigation of Corrosion Initiated by Cl− and SO42−-ions in Blast Furnace Cement Concrete Mixed with Sea Water

“…However, the increase in the GGBFS content and the presence of alkali metal compound leads to a diminution in the effectiveness of plasticizing admixtures [41]. The principles to be considered for the choice of suitable admixtures depending on the content of GGBFS and the alkali metal compound in cement have been proposed: plasticizing admixtures [42,43], shrinkage reducing admixtures [44][45][46] and expanding admixtures [47,48]. For example, the highest plasticizing effect in the case of concretes based on the mentioned cement can be provided thanks to sodium lignosulfonate, sodium gluconate, polyols and by other acyclic low and high molecular compounds [42].…”

Influence of Dosage and Modulus on Soluble Sodium Silicate for Early Strength Development of Alkali-Activated Slag Cements

“…This is due to a complex of special properties, though their potential has not yet been fully determined. A series of articles are devoted to opening questions on the peculiarities of alkali-activated materials, such as the regulation of drying shrinkage [10], freeze-thaw resistance [11], crack resistance [12], transport properties [13,14], etc. Controlling the above setting times while ensuring high strength is a priority.…”