Dear customer, first of all, thank my company the use of commodity concrete, in order to ensure the construction quality, our company according to the performance of the prepared concrete, refer to the ready mixed concrete GB/T14902-2012, concrete construction standard and construction process often encounter problems formulated the construction notice, please carefully read the and executed according to the operating rules.
Ready mixed concrete consists of cement, materials (sand, stone), water, and according to need the incorporation of mineral admixture doped material composition according to a certain proportion, in the mixing station by measuring, mixing after the sale and the transport vehicle, within a prescribed time shipped to locations of concrete mixture "does not include transported to the place of delivery the construction unit of the pouring, vibrating molding and curing.
Because the concrete mixture is mixed concrete, it has the following main characteristics: 1 time. Because of restrictions on the setting time, the performance of concrete mixture will change with time, so it has obvious time characteristics, self stirring to initial setting must be completed before pouring tamping, semi-finished products. Ready mixed concrete is actually half finished, the pouring and curing is completed by the construction unit. As a concrete mixture of ready mixed concrete to the final quality of the received time, the construction and maintenance of the impact of multiple factors,, there is a qualified commercial concrete, but the possibility of structure concrete unqualified; 3 concrete production, the strength of exactly how much, when no know, to standard curing 28 days (admixture concrete age longer) to know, according to the standard of ISO9001 system, which belongs to the special process, need through the related aspects of the guarantee, the production of concrete is qualified. So the quality management of concrete covers many processes, such as raw materials, equipment, production control, transportation, delivery, construction technology and maintenance. Also in order to meet the requirements of the work, ready mixed concrete have the following characteristics: one is the high fluidity, general concrete slump larger concrete slurry bone ratio is large; the second is the concrete by adding mineral admixture synthetic raw materials and additives. Serous bone in the concrete ratio increases mean increase autogenous shrinkage cracking possibility; and due to the mineral admixture of raw materials and additives used, make the concrete shrinkage cracking increases the risk. And from the mating than angle of ready mixed concrete ratio increases from the possibility of cracking of concrete mix, which requires to improve the concrete construction and maintenance technology to solve. The ultimate concrete quality must depend on the concrete enterprise and the construction unit of the mutual cooperation can be ensured.
Because of the ready mixed concrete are widely used in a variety of new materials and new technology, rapid construction speed, used in the construction with traditional field mixed concrete have very different needs to take corresponding measures in the construction, of concrete pouring, vibrating ramming and maintenance have higher requirements in order to better ensure the concrete quality.
Ready mixed concrete construction, in addition to in accordance with the current construction specification requirements for operation, there should be according to the ready mixed concrete and from concrete to mix the different characteristics of doing the work are as follows:
1, Before pouring concrete, will be grassroots and the template uniform, not have water.
2, concrete delivery arrived at the construction site to prohibit any water, to meet the construction requirements, minimize the construction slump, direct discharge should be for 80 + 20mm; pump suitable for 140 + 20mm; in the meet and the premise of sand ratio something as small as possible.
3, concrete from the mixing factory to the site to finish unloading should be completed within 3 hours, not more than 4 hours (except for the special requirements of concrete), to avoid concrete plastic (slump, fluidity) small to affect quality and construction of the quality of the concrete itself.
4, pouring concrete, coarse aggregate distribution in the slurry should be uniform. Construction operation personnel from the concrete under the material is prohibited from pulling the vibrating rod drive concrete mix to move to the distance. In time, the concrete shrinkage and shrinkage performance of concrete should be kept in a timely manner.
5, vibration should be dense. Floor, floor, floor pavement, large area concrete vibration rod, after at least one vibration plate, then leveling compaction. Operation to avoid the leakage of vibration, vibration is little, also cannot too vibration, vibration will make concrete moisture concentration on the surface, this surface water cement ratio, surface strength decreased significantly, leading to the concrete surface appear powder or peeling phenomenon.
6, large area, large volume concrete should avoid high temperature, wind speed, humidity, when construction. When the weather is hot, the working surface is not too big, while pouring the flat surface and the side of maintenance.
7, Large area concrete should strengthen repeatedly with plaster or pressure light, rough collection, scraper, wooden slippers can be smooth, and then fine collected, with wooden knife (facial hair) or iron spatula (smooth), effectively prevent or reduce plastic crack. At the same time, also to solve the low grade easy bleeding from the powder.
8, Maintenance should timely, concrete collection after the surface, until the surface slightly dry immediately curing with water, spray water to fine and dense, avoid direct scouring concrete, always keep the concrete surface wet state, effectively prevent the concrete from cracking, but also conducive to concrete strength growth (wet curing time shall not be less than 14 days).
9, Autumn and winter, large temperature difference between day and night, dry weather, low humidity, especially high wind speed, finishing pouring concrete should pay attention to take the heat, moisture retention measures, can be covered with film or sack pouring water conservation.
10, The surface, wall reinforcement parts should be fine and dense, refine the shrinkage stress, inhibit the cracking of concrete.
11, Pouring road concrete within 2 hours should be unloaded and vibration and precausions, embossed after curing were covered immediately. The concrete is cut in time after the end of the concrete, to prevent shrinkage and restraint and produce cracking.
12, For pouring pile, foundation, floor volume is large or the vertical distance larger site concrete, should adopt the hierarchical ring casting, each layer thickness should be controlled in the 300mm~500mm. In concrete initial setting cover the second layer and strengthen the transfer surface interspersed with vibration, early take covered with wet sacks or water moisture conservation measures, effectively reduce the temperature difference inside and outside of the concrete.
13, The slow construction site concrete (such as columns and walls), should take the high level slump mix ratio, or to a small number of distribution, to avoid concrete super construction time.
14, Pouring of underwater concrete and pile concrete, should strictly control the slump and workability and keep continuous casting; prohibited cutting too long catheter inserted to prevent the concrete in the water or ground water diffuse across the surface of the concrete.
Due to the rapid development of new technology of concrete, prepared by the above operation rules inevitably have defect, please construction units to put forward valuable opinions or suggestions.
Guangzhou Shi Chang Yun Ready Mixed Concrete Co., Ltd.
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