Konjac glucomannan: A promising environmental friendly anti-washout agent for ordinary Portland cement mortar

Adding polymer-based anti-washout admixture (AWA) is considered one of the most effective methods to improve the anti-washout performance of underwater-cement. However, the addition of polymer-based antiwashout admixture suffers from the unclear anti-washout mechanism and the potential micro-plastic pollution. This study reported an eco-friendly, high-performance AWA based on konjac glucomannan (KGM) extracted from biomass-based Konjac. The results from the interaction between the KGM and the pore solution indicate that KGM can effectively increase the viscosity of underwater cement mortar by chelation ions. The increase of viscosity made by introducing a small amount of KGM solution (0.2 wt%) can effectively enhance the antiwashout performance of underwater cement mortar. Simultaneously, introducing KGM will not adversely affect other working properties of cement mortar. This study not only proves the mechanism of KGM-based AWA to adjust the anti-washout performance of cement materials but also provides a new strategy for developing green, high-performance AWAs.