Production Process Of Circular Prestressed Concrete Pole

2017-04-13 23:58:11 admin 107

Production Process Of Circular Prestressed Concrete Pole



1, Overview of Concrete Pole


1), Production process flow

Clean steel mold → painting demolding oil→place the prestressed steel cage →pour concrete → close the mold and tighten the mold→ tensioning steel bar → centrifugal forming → steam curing→ release the tension of the steel bar → finished concrete pole stacking.

2), structural features:

This pole is a pre-tensioned prestressed concrete structure.

3), Application

Our plant produce prestressed concrete electric pole with length of 8 meters to 15 meters, for low-voltage transmission line of the poles, that is, 6KV below the transmission line.

2, with the ratio requirements

Prestressed pole concrete strength grade C50, with the ratio: P.O42.5 cement: sand: pebbles = 1: 1.31: 2.04, water-cement ratio: 0.36, cement: P.O42.5 ordinary Portland cement , Sand in the sand, stone: 5-20mm pebbles, slump: 30-50mm.

3, technical requirements

1), centrifugal poles drawings using Suzhou Institute of concrete products structural design Atlas.

2), prestressed tendons for the spiral carbon wire φs4.8, using the overall tension, control the tensile stress σcon = 0.75fpyk, super-tension control stress 1.05con.

3), the relative error of the length of the prestressed tendon should not be greater than the length of steel bars 0.15 ‰.

4), prestressed tendons should not be broken ribs.

5), the same rod with the head after the fixed length of the prestressed steel, the effective length of the relative deviation of not more than 0.2 ‰.

6), concrete raw materials and admixtures must meet the specifications, the concrete should be the ratio of 30-50mm slump required for mixing, qualified after pouring, prestressed release, the concrete strength must be designed to 75% the above.

7), the factory, the concrete strength must be designed to 80% or more. The poles should be flat inside and do not allow clogging. Do not allow honeycomb, holes, the surface of the skin should also be in a certain area (5%), do not allow the Mishapao skin phenomenon.

4, process operation method

1), the steel mold clean: If the steel mold wall ash, with a curved shovel and wire brush cleaning mold and the mouth, is strictly prohibited with a hammer or other hard things hit steel mold wall and mouth. The inner wall of the steel mold and the mouth must be cleaned and evenly coated with a layer of release agent. Steel mold mouth should be straight, close seam, bolts and accessories complete.

2), the production of steel:

(1), steel before cutting, should remove the floating rust and oil. Steel bars with iron oxide skin, honeycomb rust, heavy skin and cracks should not be used. In order to ensure that the length of the prestressed steel bars of each pole is the same, the steel bars shall be cut and bundled with each bar.

(2), put on the spiral tendons, put on the anchor plate, you can head up. Reinforcement pier should be a molding, not heavy pier, should not have cracks, and eccentricity is not greater than 1mm, after the head of the effective length of its steel bars should not be greater than 0.2 ‰.

(3), steel into the mold, should check the location of the two ends of the anchor plate is correct, whether the steel bar parallel with the steel, there should not be a cross-twisting situation, and then tighten the steel die of the two screw, Has a certain initial stress banding spiral tendons.

3), watering concrete: put the steel skeleton on the lower half of the steel mold hanging in the concrete cast steel bracket, you can pour concrete. With a cage-type watering vehicles for watering, the amount of a poles once finished watering, in order to make small head dense, the bulk of the appropriate to put some less. At the same time pay attention to not make the concrete scattered on the ground and steel mold mouth. Does not meet the requirements of concrete can not be used.

4), clamping and tightening the screw: before clamping, steel mold mouth must be clean, and coated with release agent and leak-proof mortar seal. Mold, the upper and lower steel mold surface should be aligned without dislocation. After clamping, steel mold should be symmetrical tightening, no omission, no loose.

5), tensioning steel: tensioning the center of the head of the steel mold axis after the start of tension. The tensioning procedure is as follows: 0 → 105% σcon, high strength steel wire reinforcement plan of the prestressed tension oil pressure gauge see table below: (unit MPa)

(KN) super tension (KN) super tension oil pressure gauge (MPa)
Y150 × 8000 × C1 8ΦS4.8 184.63 193.86 11.93
Y150 × 9000 × C1 9ΦS4.8 207.71 218.10 13.42
Y150 × 10000 × C1 9ΦS4.8 207.71 218.10 13.42
Y190 × 10000 × G 12ΦS4.8 276.95 290.80 17.90
Y150 × 11000 × C1 13ΦS4.8 300.03 315.03 19.39
Y190 × 12000 × G 14ΦS4.8 323.11 339.27 20.88
Y190 × 15000 × G 16ΦS4.8 369.26 387.72 23.88
Note: When the cylinder for the YC-60 type of its area of 162.5cm

Tension machine shall not leak oil, regular maintenance, pressure gauge to be regularly checked.

6), centrifugal molding: centrifugal before the steel mold runner and centrifuge roller is stable. When lifting the steel mold on the centrifuge, be careful to avoid violent impact with the wheel. If the steel mold rotates on the centrifuge and the product is violated and the product quality and equipment safety are affected, the maintenance speed should be disabled. See the table below.

Steel mold (revolutions per minute) time (min)
Slow 100 ~ 120 1.5 ~ 2.5
Speed 120 ~ 400 1.5 ~ 2.5
Fast 400 ~ 600 10 ~ 12
Total centrifugation time 13 ~ 17
Low-speed centrifugation mainly makes the concrete mixture evenly flat along the mold wall, from low to high speed transition must be evenly and gradually increase the speed, not allowed to rush to speed up to speed.

In order to ensure that the pole is large, small head wall thickness uniform, in the high-speed stage from the small head appropriate to add some concrete so that the thickness of the quality standards so far.

7), conservation: electric pole into the kiln after the mold hanging in the maintenance. Concrete with low pressure saturated steam curing, to strictly control the curing temperature and time, and do a good job of temperature measurement. In the mold when the gas, the gas from the bulk into the bar, is strictly prohibited into the concrete pipe into the concrete.

8), release steel bars: rod maintenance is completed, the concrete strength to 75% of the design strength before the release of prestressed steel. Relax the prestressed tendons, the use of welding from the bulk symmetrical root cut off the steel, and then cut off the small head of steel, steel left less than 10mm. Cut the ribs can be loose after the mold.

9), finished product stacking: stripping, such as stripping difficult, can only beat the steel plate of the stiffener, not allowed to beat the cylinder. After the mold after passing the finished product is qualified. Stacked to sub-specifications, models, layers should not exceed 6 layers. Head in summer generally after the code in the winter should be indoors, not the head does not allow the factory.

5, quality standards

The quality of annular prestressed pole should conform to GB50204 "Code for acceptance of construction quality of concrete structure engineering".

1), the quality of cement should be consistent with GB175 "Portland cement, ordinary Portland cement."

2), the quality of natural sand should be consistent with GB / T14684 "building sand".

3), the quality of stones should be consistent with GB / T14685 "building pebbles, gravel."

4), water should be used for drinking water. The water should not contain harmful impurities that can affect the normal condensation and hardening of cement, or grease, sugar and so on; sewage PH value of less than 4 acidic water and sulfate content (according to SO42-meter) more than 1% water, Do not use.

5), admixture quality should be consistent with GB8076 "concrete admixture."

6), the quality of steel should be consistent with GB / T5223 "prestressed concrete wire."

7), concrete mix should be consistent with JGJ55 "ordinary concrete mix design technical specifications"

6, safe production measures

Workers must strictly adhere to safety rules.

1), the workers in the post must wear uniforms, work shoes and gloves.

2), centrifuge before the station is not allowed. Tensioner and pull the end of the operator, the station is not allowed. When the centrifuge is running, do not walk back and forth on both sides of the centrifuge.

3), the pole out of the kiln and hoisting steel and steel mold, the upper and lower left and right should pay attention to, have someone to command, to prevent people hurt.

4), poles stacked, each layer must have a separator, the side pole to stabilize, to prevent rolling down.

7, the construction of the necessary equipment and equipment

1), tensioning equipment: high-pressure pump, rod jack, oil pressure gauge.

2), lifting equipment: 5t bridge hanging 2 sets.

3), watering equipment: Cage-type feeding a watering truck.

4), centrifugal equipment: the use of stereotypes of centrifugal equipment and console 2.

5) concrete transport vehicles: dump truck.

6) steel processing: steel straightening cutting machine 1; spiral bar winding machine one.

7), other: tooling equipment to hopper, wire rope, spreader, sled stick, welding machine, hammer, wrench, mop and broom and so on.

 

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