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In this work, five different viscosity modifying admixtures (VMAs) including natural polymer, semi-synthetic polymers, and synthetic polymers were selected and compared. The adsorption, fluidity, bleeding and rheological properties of the cement pastes mixed with different polymers were tested, respectively. The structure-property relationships and action mechanism of the polymers in cement pastes were fully discussed. The results indicate that the anionic monomers of the polymers can adsorb on cement surface and lead to particle-particle bridging, and both the anionic and nonionic monomers effect on the properties of cement paste cooperatively. [ABSTRACT FROM AUTHOR]

In this paper, four single-chain air entraining agents with different ionic groups are selected: anionic air entraining agent (K12), cationic air entraining agent' DTAB'. zwitterionic air entraining agent (OA) and nonionic air entraining agent AEO'. The structure-activity relationship of these air entraining agents was studied, and their performance differences in aqueous solution, fresh mortar and hardened mortar were compared. The results showed that the higher the surface activity of the air entraining agent, the better the foaming ability and foaming stability in the solution and the foaming and foam stabilizing properties in the fresh and hardened mortar are also more excellent. The best foaming ability and the foaming stability in solution was K12>OA>AEO-9>DTAB: the order of bubble size in the mortar was K12OA>AEO-9>DTAB. [ABSTRACT FROM AUTHOR]