Application of Concrete Pump in Slipform Construction of Silos

Shuangliu coal loading warehouse is located in Shuangliu Mine in Liulin County, northwest of Liuliu Mine in Liulin County. A total of two circular steel warehouses with a diameter of 16M are arranged in east and west directions. The height of warehouse eaves is 35M and the wall thickness is 0.25M. The warehouses are framed and brick- Belt room, the warehouse is equipped with reinforced concrete funnel, four per warehouse, the distance between the two positions 0.5M, a total of 2800 cubic meters of concrete pouring, based on the raft foundation design strength of C25. During the construction of the floor and beam pouring one-time molding. Group mode after the sliding body warehouse. C25 warehouse design strength, the amount of concrete 945 cubic meters, as required by conventional construction at least 16-17 days, 100 construction workers. In order to speed up the construction progress and grab the task of lifting the warehouse body before the arrival of the rainy season, it was decided to cancel the original construction plan: (1) within the upgrade mode, and (2) tower crane mode. Due to its construction method, the speed of ascension is limited, and the staff consumes a lot. After many discussions decided to adopt concrete pump for vertical transport of concrete. The original tower crane only as a steel, iron and auxiliary equipment vertical transport. The research has decided to use HBT60A type concrete pump, the main technical parameters of the pump are as follows: concrete output pressure 6.3Mpa, concrete output 18.4-67.3 cubic meters. Maximum output distance (diameter 0.1M) 100M. Concrete pump construction, is used to enhance the height of a 30M 300M, the thickness of 0.5M above the mass concrete, with saving manpower, material and time, short time, high efficiency, quick and easy features, but the concrete pumping on the mobility of concrete Higher requirements, the slump needs to be controlled between 12-16 cm, silo sliding mode requires the initial setting of the concrete, the final setting time controlled at 2 hours and 20 minutes, 3 hours and 30 minutes to prevent sticky mold, which will help slip Rise. Pumping concrete although widely used in most parts of our province, but for the silo sliding mold process in my company for the first time, how to pump concrete technology used in silo sliding mode construction and how to solve the concrete after demolding Conservation problems, increase the strength of concrete, to adapt to the speed of concrete slip, for which we take the following measures: 1, scientific and rational choice of additives to improve the mechanical properties of concrete to improve durability, a wide range of additives for the market, more Choose a factory in Taiyuan XX-B, XX-BH, Shanxi, an additive plant production of XX-4, Ministry of Chemical Industry Habitat building materials admixture plant production HS-NF, HS-AF additive A variety. In the use of Datong P. 042.5R cement, Liulin crushed stone (2-4), Lishi production washing sand (containing less than 5% mud) when compared with the trial found that HS-AF admixture and cement adaptability better, and with its configuration of concrete The concrete strength of 3 days, day and 28 days were 25.5Mpa, 32.8Mpa and 37.9Mpa respectively, and the slump was 13 + 2. The initial and final coagulation times were about 2: 20,3: 30 respectively, and the basic Meet the construction requirements. It is determined that the concrete mix proportion is designed as cement: sand: crushed stone: water: admixture: 1: 2.16: 3.34: 0,7, this admixture not only meets the technical requirements of concrete pump, Slip settling time and strength requirements, at the same time in accordance with the different amount of early strength superplasticizer, saving 15-20% of cement, only one of this more than 60 tons of cement savings. 2, the concrete pump requirements gravel maximum particle size flow is not greater than the diameter of 1/3, the slump of the pipeline entrance between 12-16 cm, while the slump of concrete into the mold should be between 10 to 12 cm, due to Silo slide height changes, the slump loss of the pipeline is also increasing, and gravel, sand moisture content of each batch, clay content, particle size is not the same size, the scene 24 hours temperature and humidity are Large changes, taken to set a special person in the central station to adjust the water-cement ratio, control the construction site mix, to ensure slump, set in the feed inlet iron grate to enter the large sand, mud for manual selection, To ensure the workability of concrete, fluidity, setting time requirements, to avoid the phenomenon of concrete 淅 淅. Due to the gravel particles are small, should result in the sand mud is not wrapped, and the phenomenon of blocking the pipe, gravel strictly control the grading, strict access to raw materials. 3, the concrete pump in order to play an effective delivery capacity of 60 cubic meters of Sichuan, when the delivery height of 60M, you need continuous operation, the construction of centralized mixing station mixing, feeding by the loader with raw materials by the centralized mixing station accurate measurement after the mix Hop together with the loading by the loader, the raw materials by the centralized mixing station accurate measurement of mixing, re-entry pump tank trough secondary mixing so that concrete can be fully mixed, and good workability. The fixed part of the pump pipe sliding with the position of the warehouse, between the two positions every 3m to weld the embedded parts to fix the steel pipe, warehouse on the face with a rubber tube with 90 degree elbow steering east and west two positions on the sliding platform With a small man-car pick-up materials to 300mm per layer of continuous concrete pouring. When concrete pouring plan to change direction, that is, as a counter-clockwise direction, the next layer for the clockwise direction to reduce the time of sliding warehouse body twist, steel banding should be in place in time to avoid continuous concrete can not occur The plugging phenomenon. In the transfer of two classes, should be depending on the temperature level, every 15-20 minutes to pump once to prevent tube. 4, the high-altitude maintenance of the book storehouse hanger bags are used in the past water conservation law, both labor-saving and laborious, and when watering easy to form water marks on the warehouse body surface, affecting the appearance, so choose HS-4 concrete curing spray method . The agent is based on organic compounds, formulated with other inorganic silicate, non-flammable, non-corrosive. When the protective solution is sprayed on the concrete surface, calcium silicate and the silicate in the maintenance solution produce calcium silicate and hydroxide. Silicate is insoluble and can close the gap on the concrete surface and generate a solid Membrane, to prevent the free water in concrete premature evaporation and can effectively prevent temperature-dependent cracks. Concrete surface to be treated when the construction of the molding surface, razor, the surface without water stains (after the initial setting of concrete), arranged to use high-pressure sprayer curing agent sprayed on the concrete surface, the nozzle from the concrete surface about 30cm, spraying staff standing on the upper hand, Spraying sequentially by row to move forward. The first use can be taken into account the unskilled workers to avoid leakage spray, spray two times (interval of about 1 to 2 hours, once or twice), skilled spray can be changed once. Through the above measures, we use the pump to lift the concrete in Shuangliu silo, use the tower crane as auxiliary material, enhance the steel bar, and apply new techniques and methods such as early strengthening agent and curing agent, which not only save a lot of cement and reduce the engineering cost, Speed ​​up the progress, but also set a new image of the enterprise. Performance: 1, safety, due to the use of pump, reducing the warehouse operators. In the past, winches were used to enhance the positions of 10 persons / shift, while 2 persons are now in positions to avoid the danger of personnel in the positions due to cross-operation and warehousing. No accidents occurred during the construction. 2, In engineering quality, concrete slump and mix control, sand, stone than the appropriate, normal water-cement, tamping density, steel banding spacing to meet the requirements of raw materials, strict control, especially the concrete pump twice Mixing, increasing the workability of concrete, which are difficult to do in the past construction. And each pouring depth 300mm, the time interval is basically the same, the concrete does not appear stratification, vibrating dense, the use of conservation liquid to solve the concrete curing incomplete quality problems, the supervision by the Party site spot checks project quality fully meet the requirements, The project has been well received by the departments concerned at the higher level for acceptance. 3, on the economic benefits, the construction of shared staff of 80 people, duration 10.5 days, if the artificial cost of 30 yuan / man-made, direct costs; conventional legal manpower costs: 16 days * 100 * 30 yuan / person = 48,000 yuan Pumping labor costs: 10.5 days * 80 people * 30 yuan / person = 25200 yuan Cement (Datong) 60 tons * 440 yuan / ton = 26400 yuan Direct savings costs: 49200 yuan in the silo sliding Mold, we also found some shortcomings, such as: 1, lashing lashing affect steel pouring, and steel joints greater waste, such as the use of pressure welding process will be better. 2, concrete pump should be used in the warehouse selection lever, shorten the time of concrete pouring.

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