Alkaline sulfoaluminosilicate hydraulic cement and process for its manufacture

摘要

An alkaline sulfoaluminosilicate hydraulic cement contains water, calcium magnesium aluminosilicate glass, portland cement clinker, sinter made from sodium zeolite and an SO₄^2--containing component, metakaolin and alkali metal compounds. Used as zeolites may be either synthetic zeolite and zeolite-containing rock in which the main rock-forming minerals are clinoptilolite, mordenite, gmelinite and analcime at their total content in the rock not less than 40 % by weight. Used as a SO₄^2--containing component is a technical product, Na₂SO₄ or natural raw materials, by-products or aluminopotassium alums. The sinter is obtained by thermal activation in the temperature range 500° to 800°C of sodium zeolite and SO₄^2--containing component taken in a ratio ranging between 1:1 to 4:1. The metakaolin is obtained by sintering a kaolinite clay in the temperature range 700-800° C until its full dehydration. The alkali metal compound are compounds that create an alkaline reaction in an aqueous medium. A bonding matrix obtained from the alkaline sulfoaluminosilicate hydraulic cement upon mixing with water is characteristic of the presence of alkaline sulfoaluminate and sulfoaluminosilicate phases. The cement is produced by mixing in a certain sequence all the constituents and sets in both normal conditions and under heat curing. The cement can be used as a neat cement or with fillers, such as sand, crushed stone and gravel, to make mortars and concrete, that are characteristic of high sulfate resistance, stable strength characteristics under alternate wetting-drying as well as low shrinkage along with high compressive strength and rapid strength gain.