FIELD: building materials, particularly ecologically safe Portland cement.
SUBSTANCE: Portland cement with limited content of water-soluble chrome Cr6+ is product of clinker component, gypsum component and de-chromatic agent intergrinding. De-chromatic agent includes chromate reducing agent. Clinker component additionally has accelerator for linking water-soluble chrome compounds into insoluble hydration phase in the form of pre-hydrates - AFm/AFt phases. Above de-chromatic agent additionally has chrome promoter for compound linkage into insoluble hydrated phase including substances selected from the following group: calcium ulfoaluminate, aluminum hydroxide, aluminum sulfate or hydroxosulfate of anhydrous type or of crystalline hydrate type, double magnesium-magnesium sulfate of anhydrous type or of crystalline hydrate type, wherein pre-hydrates are taken in amount of 0.3 - 1.5 parts by weight per 100 part by weight of clinker component, reducing agent and accelerator are taken with ratio of 0.3-4:1 in parts by weight. Portland cement components are taken with the following mass ratio: clinker component:gypsum component recalculated to SO3:de-chromatic agent - 100:(1-3.5):(0.3-8.5). Portland cement includes at least one substance taken from group including ferrous iron sulfate or hydroxosulfate of anhydrous type or of crystalline hydrate type, double sulfate of sodium or potassium and ferrous iron of crystalline hydrate type, calcium sulfide of oldgamite or synthetic semi- amorphous product type, salts of products of oligomerization of sulfonic acids with formaldehyde, lignosulphonates modified with synthetic resins or mixtures of above substances with neutral salts or inert substances, namely mineral additives, wherein above substances are contained in amount of not less than 20% by mixture weight, are used as chromate reducing agent. De-chromatic agent is chemical compound including above reducing agent and accelerator of double sulfate of aluminum and ferrous iron or sulfoaluminate or sulfoalumoferrite or sulfoferrite clinkers including ferric monoxide or product of stoichiometric mixture reaction recalculated to active substances of ferrous iron hydroxosulfate and sulfuric acid of red gypsum and kaolin or kaolin clay taken in amount of 0.5-2 % by weight. Clinker agent includes tetragonal calcium aluminate R2O·8CaO·3Al2O3, where R is K, Na is taken in amount of 0.2 - 1 % by weight when specific surface area of Portland cement is 250-350 m2/kg or in amount of 0.3-2 % by weight when specific surface area of Portland cement is 350-700 m2/kg.
EFFECT: increased ecological safety, possibility to transport thereof without strength reduction.
4 cl, 1 ex, 1 tbl
