PC 500 D0
PC 500 D5
PC 300 D0
PC 300 D5
PC 300 D5
PC 300 D20
PC 400 D0
PC 400 D5
PC 400 D20
The main properties of Portland cement (GOST 10178-85) are fineness, water demand, setting time, soundness and strength (Mark): cement. If desired value and other properties: density, bulk density, heat resistance, in various environments, etc.
Fineness - one of the factors that determine the speed and strength of the hardened cement paste. Ordinary Portland cement is ground finely enough - sieve residue number 008 (4900otv/sm2) should not exceed 15%, which corresponds to a specific surface of cement 2500 ... 3000 cm2 / g
Portland Water demand is characterized by water (% by weight of cement), which is necessary to obtain a cement paste of normal density, ie, a predetermined standard plasticity determined by dipping the dough cylinder pestle device Vic. Water demand is dependent on the mineral composition and fineness of cement and ranges 22 ... 26%.
Setting time and soundness of cement is determined on the normal density test. Initial setting time of cement paste should occur no earlier than 45 minutes and the final set - tie within 10 hours Setting time is determined by the device Vic by dipping the needle of this instrument in the dough of normal density. For the normal setting time of grinding the clinker introduced additive dihydrate gypsum, and if necessary - special additives, retarders or accelerators.
The process of hardening cement is accompanied by volumetric expansion: swelling of hardening in water, shrinkage during solidification in the air. These inevitable changes in volume are taken into account in the production of construction work, providing device expansion joints. The uneven changes in the volume of cement hardening due to the presence of clinker free oxides of calcium and magnesium, which are expanded upon hydration, causing local deformation. By standard soundness is determined in samples, cakes made from normal density test that after 24 hours pre-curing was refluxed for 3 hours in water. Cakes should not deform, they are not allowed groove cracks.
Cement does not have a uniform volume change can not be used in construction.