New treatment technology: The use of wet-milling concrete slurry waste to substitute cement

Concrete slurry waste is a dewatered solid residue generated from the production of concrete. The high discharging cost of concrete slurry waste strikes the concrete industry so that it is imperative to find an effective method to dispose concrete slurry waste. This study is conducted to utilise wet-milling to refine concrete slurry waste to partially replace the use of cement. In this method, concrete slurry waste was considered as filler and nucleus site to densify the microstructure of paste by filling the space and accelerating hydration. The results showed that both the initial and final setting time gradually decreased as the wet-milling concrete slurry waste dosage increased. The W15 mixture presented a cumulative heat evolution lower than that of the W10 mixture, however, all the mixtures with wet-milling concrete slurry waste showed cumulative heat evolution higher than the reference mixture. Similar to heat evolution results, compressive strength showed a positive effect when the wet-milling concrete slurry waste dosage was lower than 15%. Mercury intrusion porosimetry analysis results suggested that wet-milling concrete slurry waste can refine pore structure of hardening cement paste. The wet-milling concrete slurry waste energy intensity, carbon emission and cost showed a downward trend according to the quantitative calculation compared to Portland cement.