Gypsum (alabaster)

Gypsum (alabaster) get populated by natural gypsum at a temperature of 150-170 °. It is a whitish powder-gray color. Mixed with water, plaster of Paris hardens quickly. Catching up begins at 4 minutes and lasts from 6 to 30 minutes. Available in three grades: coarse, medium and fine grind. Used in the manufacture of plaster, and interior partition wall plates and panels, air ducts and other construction details, operating at a relative humidity above 65% • Products made of gypsum have low density, incombustibility and several other valuable properties, but their strength when wet decreases. Gypsum is added to the mortar, accelerate setting and increases durability. Such a solution is called lime-gypsum. For retardation in it add various inhibitors, such as animal glue (in the form of adhesive strength of the water to 2%), which closes and gypsum. The more water in the glue, the longer the setting time of gypsum, and setting and hardening of gypsum increases in volume by 1%, which is a very important practical significance for many construction jobs. Black binders - these are different bitumen and tar black or dark brown. Used mainly for devices waterproofing works for the manufacture of pokryvochnyh mastics and as additives in mortars. All of these binders waterproof, waterproof, elastic, resistant to atmospheric influences. When heated, they soften (thinning), and cooling, on the contrary, become more viscous and harder.