CONCRETE MIX AND METHOD OF ITS PREPARATION Russian patent published in 1999 - IPC

FIELD: manufacture of building materials, in particular, preparation of concrete mixes for manufacture of facing slabs from concrete, for instance, facade, pedestal or pavement ones. SUBSTANCE: concrete mix contains, wt.%: portland cement, 19.5-20.1; crushed stone, 48.2-48.5; sand, 30.0-31.5; superplasticizer based on sodium salt of condensation product of naphthalenesulfonic acid and formaldehyde, 0.21-0.50; powdery bentonite, 0.4-1.2. For preparation of concrete mix, introduced preliminarily into powder pentonite is 5-10% of portland cement of its total weight, and mixed. Concentrated solution of superplasticizer is prepared on the base of sodium salt of condensation product of naphthalenesulfonic acid and formaldehyde by dissolving in water of dry superplasticizer up to density of 1.03-1.2 g/cu. cm. Prepared concentrated solution of superplasticizer is poured into produced mixture of powdery bentonite and portland cement and mixed, for instance, in fixed-drum concrete mixer to obtain uniform material. Then added to concrete mixer is remaining portland cement and water for obtaining the required mobility of concrete mix, and mixing is performed again to obtain needed uniformity of material. Further on, introduced into concrete mixer are crushed stone and sand, produced mixture without mixing is held for 5-15 min and final mixing is performed to obtain homogeneous concrete mix. EFFECT: higher mechanical strength of articles, reduced distortion in wetting and drying of flat articles, prolonged their service life and provision of clear articles surfaces. 2 cl, 1 tbl