Polydopamine: A novel high-efficiency accelerator for Portland cement

This study develops a novel accelerator with dopamine for rapid setting of shotcrete. Based on the oxidative selfpolymerization, the dopamine reacts with O2 to produce polydopamine (PDA) in the agitation process of cement paste. The as-prepared PDA facilitates the generation of ettringite. Additionally, it controls ettringite to nucleate and grow on the surfaces of various clinkers, which decreases the negative effect of surface-bound hydrate on the dissolution of C3A. As a result, with 0.10% dosage of dopamine, the initial setting time of cement paste is shortened from 118 min 45 s to 3 min 38 s, and the final setting time is shortened from 212 min 45 s to 11 min 8 s. This dosage is much lower than those achieved by any hitherto-reported materials. Besides, the compressive strength of cement mortar reaches 33.6 Mpa in 28 days, which can meet the requirements of building engineering.