A comparative study on concrete slurry waste: performance optimization from the wet-milling process

Concrete slurry waste (CSW) is a mixture of fine aggregates, cement hydration products and residual cement particles obtained from the sedimentation pits during the production of concrete. In the present study, CSW with different grinding durations were evaluated; the properties of the CSW and the CSW-cement composition were compared under the influence of wet-milling. The results indicated that the particle size of the CSW decreased and the dispersion stability of the slurry was improved after wet-milling treatment. The increasing ettringite peak suggested that the mineral admixture hydrated during wet-milling. However, carbonization also occurred during the process. The nucleus effect of wet-milled CSW not only increased the hydration heat and compressive strength of cement, but also significantly enhanced the pore structure and chloride penetration resistance of the mixtures. Although the gel pore volume fraction for the mixture containing original CSW is higher than that of the reference mixtures, the compressive strength and chloride penetration resistance are weak due to the loose structure caused by the dilution effect.