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 0.25 by weight. Three pastes containing admixture (water-soluble condensates) were also prepared using a water-cement ratio of 0.25 and condensate (superplasticizer) content of 0.25% by the weight of cement; the superplasticizers used are Na-phenol sulfonate formaldehyde, Na-polystyrene sulfonate, and Na-beta-naphthol sulfonate formaldehyde condensates. All pastes were cured for various time intervals within the range of 0.02-90 days. Compressive strength tests, hydration kinetics, X-ray diffraction analysis, thermal analysis, and surface properties were studied and related as much as possible to the pore structure of the hardened pastes. (C) 1995 John Wiley and Sons, Inc.