Effect of anti-washout admixture on the compressive strength of alkali-activated underwater non-dispersible concrete

The issue of low compressive strength in concrete is primarily caused by the anti-washout admixture (AWA) added to cement-based cementitious materials (CBCMs). In this paper, the AWA was added to alkali-activated cementitious materials (AACM) to prepare underwater non-dispersible concrete (UNDC). The effect of different AWA contents on the compressive strength of AACM was studied by measuring the compressive strength, hydration process, pore structure, microscopic appearance, and chemical composition. The results show that the compressive strength of AACM-UNDC moulded underwater can reach higher than 80% of the compressive strength of AACM-UNDC moulded on land. The polymerization and decomposition reaction of AACM can lead to the formation of strong covalent bonds, which can not only interweave with the long chain structure of AWA to form a dense network structure, but also can avoid the AWA wrapping on the surface of the activated material through the charge effect, and hinder the hydration reaction process of AASM.