The system ground clinker-polyphenol sulphonate-alkali metal salts (the Gypsum-Free portland cement)

Abstract

The sulphonated product of condensation of phenols with formaldehyde (polyphenol sulphonate) reacts synergistically with the alkali metal carbonate (bicarbonate, silicate) as a strong liquefying system in suspension of ground clinker of Portland cement. The liquefying effect of the polyphenol sulphonate-carbonate system enables the preparation of suspensions that possess practically Newtonian behavior without yield value under low water-to-cement ratio (as high as 0.20). The synergistic influence of the polyphenol sulphonate-carbonate (bicarbonate) system substitutes for the regulation reaction of gypsum in pastes or concretes. The ground clinker (without gypsum) with a specific surface of 250–700 m 2/kg--polyphenol sulphonate--alkali metal carbonate (bicarbonate) represents a new type of binding agent that differs from the conventional Portland cement by good rheological qualities of pastes under low water--cement ratios, by short and long term strength (compressive strength 20–40 MPa after 4–5 hours, 60–100 MPa at 24 hours), by the ability of setting and hardening under low and below zero temperatures, by a quick strength rise at short time with elevated external temperature (steam curing), and high resistance to aggressive media and high temperatures. The microstructure of hardened pastes made of gypsum-free Portland cements differs from the classic Portland cements by a high compactness and by the absence of characteristic portlandite crystals.