The utilization of waste cheese whey for retardation in alkali activated slag-based materials: Retarding performance and molecular hydration mechanism

Document Type

Article

Publication Date

4-1-2026

Abstract

The strong early-stage reaction and short initial setting time characteristic of alkali activated slag hinders its potential for widespread field application, thus necessitating the use of retarders to prolong the setting time. However, conventional chemical retarders are generally characterized by high energy consumption and substantial carbon emissions. This study utilized waste cheese whey, biomass waste that causes resource depletion and environmental pollution, to prepare sodium galactonate (SGA) as a bio-retarder through a process involving biological fermentation and electrodialysis. The impact of SGA on the setting time, flowability, mechanical strength, and drying shrinkage of alkali activated slag (AAS) mixtures was assessed and compared with the commonly used sodium gluconate (SG) retarder. Results demonstrated that SGA effectively prolonged the setting time and enhanced the flowability, with effects becoming more pronounced as the dosage rose. SGA enhanced the setting time and maximum flowability by up to 120% and 32%, respectively. SEM-EDS, XRD, hydration heat test were conducted to investigate the effects of SGA on hydration products and microstructure. Meanwhile, SAXS test was used to investigate the impact of SGA incorporation on C-A-S-H gel agglomerations and the pore structure. Furthermore, in order to elucidate SGA's effect on the formation of silicate gels, XPS analysis of O 1 s, Al 2p, and Si 2p was performed. This study achieved a valorization of waste biomass resources with promoting the implementation of alkali activated materials in engineering applications.

Publication Title

Powder Technology

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