EFFECT OF SOME SUPERPLASTICIZERS ON THE MECHANICAL AND PHYSICOCHEMICAL PROPERTIES OF BLENDED CEMENT PASTES

Blended cement pastes made of Portland cement and fine sand (known in Egypt as El-Karnak cement) were made using a water-cement ratio of 0.2 5 by weight. Three pastes containing admixture (water-soluble condensa tes) were also prepared using a water-cement ratio of 0.25 and condens ate (superplasticizer) content of 0.25% by the weight of cement; the s uperplasticizers used are Na-phenol sulfonate formaldehyde, Na-polysty rene sulfonate, and Na-beta-naphthol sulfonate formaldehyde condensate s. All pastes were cured for various time intervals within the range o f 0.02-90 days. Compressive strength tests, hydration kinetics, X-ray diffraction analysis, thermal analysis, and surface properties were st udied and related as much as possible to the pore structure of the har dened pastes. (C) 1995 John Wiley and Sons, Inc.