Gypsum, alabaster

Gypsum - the oldest building material, dazzling white or light gray in powder form. Plaster - a fine powder made from the gypsum rock - by roasting and grinding or milling and обжигаПреимуществамистроительного gypsum is fast and hard, tough fight. Start of setting plaster should occur no earlier than 4 min, the end - no earlier than 6 minutes, but no later than half an hour after the preparation of gypsum test. To chtobyprigotovit gypsum paste to take the 2 parts (by weight) of gypsum, 1 part cold water, and first and foremost by pouring water on a stirring it vigorously, pour plaster of Paris. Prepared gypsum paste to spend immediately. For the retardation of gypsum paste was added 0,5 ... 2% water-soluble animal glue (in the form of adhesive strength of water from 0.5 to 2%), mortar and put in bowl plastic bag. When setting and hardening of gypsum plaster is capable of increasing in volume by 1%, which is of great practical importance in many construction works. The disadvantage of plaster is that plaster has low strength and water resistance, and yet it simply scratch the surface. Issued 12 stamps plaster. For the construction applied gypsum on the brand T-5 to grade G-25, a feature which is that the compression onivyderzhivayut from 5 to 25 kg / cm 2, but can be applied to higher marks. Highest markastroitelnogo gypsum - 250 kg/cm2. Gypsum is sold vmeshkah or loose (in bulk). Keep plaster Must in dry places with floors raised above the ground at least 50cm. From long-term storage gipsotsyrevaet and stops grasping, thus can not continue to be used. Another indisputable advantage of gypsum that gypsum - an environmentally friendly, non-combustible building material. When the plaster hardens, it can absorb excess moisture from the air in the room if the room humidity, and release it when the air becomes too dry. Gypsum as it breathes, keeping moisture at some level. Plaster can be used for construction and finishing, as well as create unique architectural masterpieces. Many believe that building plaster and stucco are identical concepts. But you should know that the studio (from the Greek. Alebastros) - is the name of two different minerals: Gypsum: calcium sulphate and karbonatakaltsiya. How to get cast? Today, gypsum alabaster prepared as follows: first, two-water extract of natural gypsum, plaster of Paris then this is treated with a thermal method at a temperature of 150-180 0 C. For the process of obtaining gypsum use special devices, in which the mass is converted into semi-aquatic gypsum 2CaSO4 * H2O. After firing izmelchaetsyav gypsum fine powder and is called plaster. You can certainly continue to process the gypsum, and thus receive the molding plaster or medical plaster. If the burn gypsum at low temperatures (95-100 ° C) in a hermetically sealed container, then we obtain high-strength gypsum. Why the need for gypsum? Builders gypsum or alabaster found widespread for plastering walls and ceilings in buildings with a relative humidity of 60% in the production of plaster walls, molded products, sheets of drywall, plasterboard, ventilation ducts, Arbolita, gypsum and gipsostruzhechnyh and for many other products.