The Effect of SCMs in Blended Cements on Sorption Characteristics of Superabsorbent Polymers

Abstract

Supplementary cementitious materials (SCMs), such as fly ash (FA) and ground granulated blast-furnace slag (GGBS), are often used as a partial replacement of cements to improve the sustainability of Portland cement-based materials and reduce their environmental impact. Superabsorbent polymers (SAPs) can be successfully used as internal curing agents in ultra-high performance cementitious materials by facilitating the hydration process and controlling the water supply in both fresh and hardened states. This paper intends to characterise the physical and chemical properties of SAPs and their sorption properties in different blended cement environments. The swelling capacity and kinetics of absorption of three superabsorbent polymers with different chemical compositions and grading were tested in different cement environments. Experimental results of their sorption performance in distinct solutions, including deionised water (DI), Portland cement (PC), and blended cements (PC-FA and PC-GGBS) and changes in pH of different solutions over time were investigated. The results showed that PC-FA solution had the lowest pH followed by PC-GGBS solution. Moreover, SAPs samples displayed the highest absorption capacities in PC-FA solutions, and the lowest swelling capacities were found in PC-GGBS solutions. Furthermore, SAP with smaller particle sizes had the greatest absorption capacity values in all solutions.

The Effect of Superabsorbent Polymers on Mechanical Characteristics and Cracking Susceptibility of Alkali-Activated Mortars Containing Ground Granulated Blast-Furnace Slag and Copper Slag

“…On the contrary, reference mixes showed a dilution effect, i.e., the same amount of alkaline ions diluted in a larger portion of free-water available in the solution. Moreover, the reference solutions are more sensitive to reduction in pH due to the carbonation effect [44,45]. Overall, SAP E solutions had a slightly higher pH reading, which can contribute to the alkali activation principle.…”

Delayed Absorption Superabsorbent Polymer for Strength Development in Concrete

“…SAP not only supplies water from the inside for the hydration reaction of cement in a low water-cement ratio, but also it provides water when there is not enough for the hydration reaction of cement due to its evaporation during concrete curing in an environment with low relative humidity [4]. The addition of SAP is reported to effectively improve the autogenous shrinkage, enhance freezing and thawing resistances, reduce drying shrinkage, increase self-healing, reduce the formation of micro-cracking, and enhance the durability of cementitious materials [5][6][7][8][9][10][11][12][13][14][15][16]. In addition to these positive effects, the inclusion of SAP can significantly change the rheology.…”