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 self-polymerization, 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.