Cement

This is the hydraulic (hardening in the air and water) binder, obtained by co-grinding of clinker and various mineral supplements. This hydraulic (hardening in the air and water) binder, obtained by co-grinding of clinker and various mineral supplements. to cement, used for making mortar and concrete mixes, include Portland cement, pozzolanic Portland cement, slag cement, non-shrink and expanding cement, alumina cement, etc. The most common are Portland cement and alumina cement. Portland - a powder of greenish-gray color. starting material for its production are limestone (chalk) and clay that is fired in rotary kilns at a temperature of 1400-1500 ° C. The resulting cement clinker grind on special mills, adding a variety of active and inert additives (slag, silica sand, gypsum, etc.). mixing cement with water for some time converted into a monolithic solid high strength. An indicator of this quality is the brand of cement, which determines the compressive strength in kg/cm2 solution consisting of 1 part cement and 3 parts sand (by weight), reached a 28-day seizure. Portland release marks 400, 500, 600 and 700. aluminous cement is produced from alumina ( Bauxite) and lime, fused in electric furnaces at 1400 °. alloyed mass is crushed into pieces, then grind to a powder in tube mills. aluminous cement manufacture marks 400, 500 and 600. brand strength he gains after 3 days. aluminous cement, approximately mortar and concrete, makes them water resistant. Compared with binders such as lime and clay, cement rapid. Start of setting them coming no earlier than 40 ... 45 minutes, and the end - no later than 12 hours when using warm water hardening process is accelerated. Mark cement depends on the fineness. If the brand of cement used is not known, it is estimated it can be determined by the density of cement. Please note that during prolonged storage of cement, even in the dry strength is reduced: for 6 months - 25% for year - by 35 - 40% in two years - about 50%. Cement is considered good, if you squeeze it in his fist, he freely pours through his fingers. If, however, will remain in his fist into pieces the size of a pea, it indicates that that the cement has a lower strength. Store cement in dry places, the best in plastic bags.