Rheological Properties of Very High-Strength Portland Cement Pastes : Influence of Very Effective Superplasticizers

Abstract EN

The influence of the addition of very effective superplasticizers, that are commercially available, employed for maximising the solid loading of very high-strength Portland cement pastes, has been investigated.

Cement pastes were prepared from deionized water and a commercially manufactured Portland cement (Ultracem 52.5 R).

Cement and water were mixed with a vane stirrer according to ASTM Standard C305.

The 0.38 to 0.44 water/cement ratio range was investigated.

Three commercial superplasticizing agents produced by Ruredil S.p.a.

were used.

They are based on a melamine resin (Fluiment 33 M), on a modified lignosulphonate (Concretan 200 L), and on a modified polyacrylate (Ergomix 1000).

Rheological tests were performed at 25°C by using the rate controlled coaxial cylinder viscometer Rotovisko-Haake 20, system M5-osc., measuring device MV2P with serrated surfaces.

The tests were carried out under continuous flow conditions.

The results of this study were compared with those obtained in a previous article for an ordinary Portland cement paste.