Effect of latex and superplasticiser on Portland cement mortar in the fresh state

This report deals with the individual and combined effect of latex and superplasticiser on Portland cement mortar in the fresh state. The compatibility of five commercial superplasticisers with four latexes of the vinyl polymer group and SBR latex in varying dosages was studied with respect to setting time, consistency of fresh cement pastes, subjective workability (surface texture, segregation), bleeding, air content, water reduction capacity and the flow-time relationship of fresh mortar. It has been observed that superplasticisers of melamine formaldehyde and a blend of melamine and naphthalene formaldehyde eliminated shortcomings like delayed setting, high air entrainment in the fresh latex-modified system whereas lignosulphonate and a blend of lignosulphonate and naphthalene formaldehyde aggravated it. In a consequent report, performances in the hardened state will be discussed.