Cement brands: how to navigate them
When considering such a notion as markscement, you need to focus on official regulatory documents, among which you can note GOST30515-97, which divides all cements into special and general. Cement mixtures can have different bases (ferritic, aluminous or Portland cement clinker) and contain various mineral additives.
It is also worth noting that different brands of cementhave different levels of compressive strength, different curing speed (fast-hardening and normal-hardening), different setting times - there are mixtures that begin to harden in less than 45 minutes, and there are slow-setting (more than 2 hours).
Each brand of cement must match a numberparameters, including: specific composition, time of thickening, compressive strength, self-stress, density of cement test, linear expansion, content of required chemicals (chlorine ion, sulfur oxide, magnesium oxide), level of water separation, heat release and other characteristics.
You can find out about the composition of the cement mixture by itstitle. Detailed interpretation of the characteristics of cement is given in the above GOST, as well as in GOST 10178-85. If the name starts at the PC - then this brand of cement is based on Portland cement clinker, and if at the SHPC - then we have slag Portland cement with a high slag content (more than 20%).
After the full or abbreviated name goesfigures in the hundreds, which mean compressive strength. Portland cements are characterized by 600, 550, 500, 400, for portland slag - figures from 500 to 300. Also in the title the maximum number of additives from D0 (no additives) to D20 (additives - 20%) is indicated. It may contain an indication of rapid solidification (B), plasticization and hydrophobization of the cement mixture (PL, GF), the production of cement from clinker with a standard composition (H) and a reference to the corresponding GOST.
For example, cement grade PTS550-D5-B-PL is Portland cement with a compressive strength of 550, with 5% of additives, fast-hardening and plasticized.
When building a building it is very important that the workzero cycle were performed qualitatively. Particular attention should be paid to the foundation, which is often made of concrete. Concrete is a mixture of cement, sand and gravel. The cement grade for the foundation must have a sufficiently high compressive strength (400-500), and the higher this number, the less amount of remaining materials can be. For example, for cement grade 400 other materials are taken in the proportion of 133, and for cement grade 500 - 144, respectively.
Cement is a material that is very goodabsorbs water, which, of course, affects its properties - it eventually loses its declared strength. Therefore, when choosing cement grades for construction works, one should look at the date of manufacture and specify the storage conditions, because the 400 grade cement for a month of storage loses 10% of its strength, and in half a year it may lose 30% of this characteristic and become a 280 cement. For such cement, more additives will be needed, however, it can not be guaranteed that the foundation will get the required strength in this case.