The mixing of concrete seems simple, but in the actual production process, there are strict requirements on the order of raw materials and the mixing time. Far East Machinery has been committed to the complete set and supporting equipment solutions of the concrete batching plant industry for several years. Far East Machinery has been making progress, summarizing and innovating continuously in the long-term production practice process. It is your wise choice to choose Far East Machinery when purchasing mixing equipment. The feeding sequence of concrete during the mixing process is an important part of the entire concrete mixing process. Mastering the feeding sequence of the commercial concrete batching plant plays an important role in improving the quality of concrete.
Common feeding sequences of commercial concrete batching plants include one-time feeding method, two-feeding method and cement-wrapped sand method.
1. One-time feeding method: This is the common method at present. The one-time feeding method refers to adding stones into the hopper first, followed by cement and sand. For the self-falling mixer, part of the water needs to be added to the barrel first, and then the water is added successively; Water should not be added first, and water should be added slowly and evenly when the dry ingredients are put in. One-time feeding method: This is the common method at present. That is, the sand, stone, cement and water are mixed together and added to the mixing drum while stirring. In order to reduce the flying of the cement and the sticking of the cement during the feeding process, pour the sand (or stones) first, then the cement, and then the stones (or sand), that is to say, add the cement between the sand and stones, The dry material is sent into the mixing drum from the upper hopper, and water is added for stirring.
2. Secondary feeding method: The secondary feeding method is divided into ready-mixed cement mortar method, ready-mixed cement paste method and cement-wrapped sand method. Method 2: Cement + water are put into stirring and then sand and stone are added. Method 3: Add all the stones, sand and 70% water and stir for 10-20 seconds, then add all the cement and stir for 30 seconds, then add the remaining 30% water and stir for 60 seconds. This feeding method is further divided into ready-mixed cement mortar method and ready-mixed cement paste method. The ready-mixed cement mortar method is to add cement, sand and water into a concrete mixer for full mixing to form a uniform cement mortar, and then add stones to mix to form a uniform concrete. In China, the cement mortar is generally mixed with a forced mixer for about 1~1.5min, and then the stone is added for about 1~1.5min. The ready-mixed cement slurry method is to fully mix cement and water into a uniform cement slurry, and then add sand and stones to mix into concrete. Tests at home and abroad show that the strength of concrete mixed by the secondary feeding method can be increased by 15% compared with the primary feeding method, and the cement can be saved by 15% to 20% under the same strength.
3. Cement-wrapped sand method: also known as SEC method, the concrete mixed by this method is called SEC concrete or shell concrete. The mixing procedure of this method is to add a certain amount of water to adjust the water content of the sand surface to a specified value (usually 15%~25%), then add stones and mix with the wet sand, and then mix all the cement It is mixed with sand and gravel to form a layer of cement slurry shell with low water-cement ratio on the surface of sand and gravel, and then the remaining water and admixtures are added and mixed into concrete. Compared with the one-shot method, the concrete prepared by the SEC method can increase the strength by 20%~30%, the concrete is not easy to produce segregation and bleeding, and the workability is good.
