White sequence
The white sequence is used only for decorative decoration of special products (mosaic steps and window sills, facing plates, large wall blocks, etc. p.).
Expensive clay and expanding cements at factories of reinforced concrete parts are used only during refinement, small repair, sealing of individual parts, etc. p. (without steaming).
The choice of the type of cement for the plant of prefabricated reinforced concrete parts is of great importance. In this case, the properties of cement, its mineralogical composition, technological features of application, as well as the cost should be carefully taken into account.
For better support of the plants of prefabricated reinforced concrete parts, the cement is necessary that the consumer plant is associated with the same cement plant by the supplier. The use of cement of the stable composition and permanent production relations of factories can ensure the savings of cement and the release of high -quality prefabricated reinforced concrete parts.
Soviet and foreign scientists have found out the composition and nature of Portland cement hardening.
The content of three -calcium aluminum ranges from 3 to 15%.
As for the ratios of the brands of consumed cements and brands of concrete obtained from them in prefabricated reinforced concrete, then with the use of mobile concrete mixtures, according to U-107-54, for ordinary (heavy) concrete with a durability of up to 250 kg/cm2, the brand cement should not be used below «400», and with a strength of more than 250 kg/cm2- not lower than «500» (with conventional heat treatment). With a stand of production (see. Below) these instructions relate to concrete with a strength of 200 kg! cm2. With autoclave processing, cement should have a brand at least «300».