(1) pumpability of concrete. Pumping concrete should meet the pumpability requirements, if necessary, by pumping test to determine the pumping concrete mix.
1) The ratio of the maximum size of coarse aggregate to the diameter of the conveying pipe should be as follows: when the pumping height is below 50m, the gravel should not be larger than 1: 3, not larger than 1: 2.5 for pebbles; when the pumping height is between 50m and 100m , Should be in the range of 1: 3 ~ 1: 4; pumping height above 100m, should be between 1: 4 ~ 1: 5. Flaky particles should not be greater than 10%.
② for different pumping height, into the concrete slump can press (as shown) selection.
Pumping height (m) 30 or less 30 to 60 60 to 100 100 or more
Slump (m) 100 ~ 140 140 ~ 160 160 ~ 180 180 ~ 200
③ pumping concrete water-cement ratio should be (0.4 ~ 0.6): 1.
④ pumping sand content of concrete should be 38% to 45%. Fine aggregate should be used in sand, sand through 0.315m sieve should not be less than 15%.
⑤ The minimum content of cement in the pump concrete is 300kg / m3.
(2) After starting the concrete pump should pump the right amount of water to wet concrete pump hoppers, concrete tanks and pipes and other parts in direct contact with the concrete. Pumping water and then use one of the following methods to lubricate the above parts: pumping water slurry; pump loose 1: 2 cement mortar; pumping coarse aggregate except for other components with the ratio of cement mortar.
Lubricating grout or cement mortar should be dispersed cloth, shall not be concentrated in the same place.
(3) When starting to pump, the concrete pump should be in a slow, uniform running state, and then gradually accelerate. At the same time should observe the pressure of concrete pumps and the work of the system until the normal operation of the system after the normal pumping speed.
(4) The concrete pumping work should be carried out continuously as much as possible. The piston of the concrete cylinder should be operated with the maximum stroke in order to exert the maximum efficiency of the concrete pump and to make the concrete cylinder wear evenly in the longitudinal direction.
(5) If the concrete pump pressure is too high and unstable, the oil temperature rise. Pipeline significant vibration and pumping difficulties, etc., shall not force pump, should immediately identify the reasons to be ruled out. Can be hit with a mallet duct first bend. Conical tube and other parts, and slow pumping or anti-pump to prevent blockage.
(6) In the event of a blockage, the following measures should be taken to exclude:
① repeat the anti-pump and positive pump operation, and gradually withdraw the concrete back to the hopper, after mixing and then re-pumping.
② with a gavel and other methods to identify the jamming parts, to be repeated after the anti-pump concrete and anti-pump and positive pump operation to eliminate blockage.
③ When the above two methods are invalid, the concrete should be opened after the pressure relief blockage, to be discharged after the blockage to re-pumping.
(7) Ready-mixed concrete should be used for pumping concrete, and concrete should be provided at the mixing plant on the site, but hand-mixed concrete should not be pumped. The supply of concrete should be strictly controlled, always pay attention to changes in slump, do not meet the pumping requirements of the concrete is not allowed to enter the pump to ensure the effective operation of concrete pumps.
(8) Concrete pump hopper should be set up on the screen, and set up special monitoring feed, to avoid excessive diameter due to the aggregate or foreign matter into the blockage.
(9) When pumping, the stock of concrete in the hopper can not be lower than the stirring shaft to prevent the air from entering the pump tube to cause the pipeline to vibrate.
(10) When the concrete pumping process needs terminal, the interruption time should not exceed 1h. And every 5 ~ 10min anti-pump and positive pump operation, to prevent the pipeline due to concrete bleeding or slump loss is too large and plugging.
(11) After pumping, the hopper and piping system must be carefully cleaned. If the residual concrete in the concrete cylinder is not clean, it will be solidified on the cylinder wall. When the piston runs again, the piston sealing surface will directly bear the impact of the solidified concrete on the cylinder wall and lead to the local delamination of the push piston. This damage is different from the normal wear and tear of the piston seal, the sealing surface can not self-compensation under the pressure, resulting in leakage or suction, causing pumping weakness, blockage and so on.
(12) When the concrete pumpability is poor or the concrete is bleeding, segregation and difficult to pump, should immediately on the mix, concrete pumps, piping and pumping technology to study and take appropriate measures to solve.
----- TRANSIT VE83/V348 ENGINE PARTS
Transit Parts, Metal Processing Machinery Parts,Hot Forging,Concrete Machinery
Transit Parts,Brand Parts Co., Ltd. , http://www.nbtransitparts.com
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