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Concrete construction process

Views:17     Author:Site Editor     Publish Time: 2018-09-27      Origin:Site

Ⅰ.Concrete wet spray process flow chart 

Concrete construction process

Ⅱ.Select equipment support

1. Work rig: A work rig that processes the length of the gantry (the length of a jet operation cycle) according to the length of the tunnel section.

2. Feeding platform: The height of the jet hopper is 1.5m. In order to reduce the labor intensity, the loading platform with a height of 0.7m is set.

The concrete jet machine adopts the wet spray concrete machine,

1. the structure and principle of the wet spray machine, and the general jet machine, which mainly consists of air pipeline system, feeding system, conveying system and quick-setting agent metering and adding system. The feeding system is a core component, which is mainly composed of a hopper, a vibrator, a cam, a rotor, a piston, a rotation, a lining plate, a bonding plate and the like. The feeding and feeding are completed by moving the rotor piston in the cavity up and down in the cavity. After the concrete material is forcedly fed into the gas mixing warehouse by the piston, it is mixed with compressed air to form a thin flow form, which is transported to the nozzle through the pipeline; the colleague metering pump pumps the liquid quick-setting agent, accelerates by atomization, and passes through the pipeline. After being sent to the nozzle and mixed with the concrete, it is sprayed onto the slope by the nozzle. The problem of adhesive clogging of the wet mixing material in the rotor cavity is better solved, and the small-grain feeding and the thin-flow conveying in the pipeline are realized. The mixing mixer is a forced concrete mixer equipped with weighing equipment scales, platform scales, etc

2. Air compressor: air supply capacity: 0.5Mpa or more, air supply volume greater than 9m / min.

3. Water supply equipment: ensure that the water pressure is 0.15-0.2Mpa.

4. Between slump: 10*10 anti-pressure standard abrasives, impervious abrasives, jet slab bottom molds and other auxiliary tools. Ⅲ. Material selection and concrete ratio

1. Materials used: cement is P.0425, ordinary Portland cement, sand, fineness modulus 2.59. coarse aggregate, 5-15mm continuous grade crushed stone. Water is drinking water. The admixture is a quick-setting agent, a water repellent, and a drainage blind tube.

2. According to the technical requirements of the wet spray machine, according to the technical requirements of the wet spray machine, the mix ratio of the plain concrete is used as the reference mix ratio, and the different admixtures are mixed and tested. The mixing ratio of the admixture should meet the C20 strength standard.

3. According to the geological survey on site, the mixing ratio is mixed with the quick-setting admixture to carry out the experiment. In order to ensure the quality, the rock surface with large local water seepage or dripping water is changed, and the mixing ratio is changed. Only the coarse aggregate is used without coarse aggregate, and 6% is added. The quick-setting agent is sprayed 2cm thick and then sprayed according to the normal mix ratio.

Ⅳ. Mechanical operation requirements: The operator should do the 

following before starting:

1. Check all materials and the materials meet the above requirements before use.

2. Check the hopper for foreign matter, the level of the quick-setting agent, adjust the metering pump, and use the quick-setting agent to increase the proportion to meet the concrete mix design requirements.

3. Check the operating pressure of the pressure controller and whether it is compatible with the relevant parameters such as the conveying distance. The general setting value is greater than the working wind pressure 0.1-0.2Mpa.

4. Take over to prevent the concrete pipe from sharp turning and squatting.

5. Check the circuit, the voltage is within the range specified by the machine.

6. Check if the direction of the rotor is consistent with the direction of the mark, and observe whether the liquid flow in the suction pipe is normal and whether the nozzle is blocked.

7. After the inspection is completed according to the above method, about half of the mortar is added to the inclined bucket. Start the main motor and transfer the mortar into the rotor cavity and the gas mixing chamber.

8. Fill the bucket with concrete and vibrate to get the concrete into the hopper.

9. After completing the above work flow, start up and observe the change of wind pressure value; general wind pressure, spray edge wall 0.2-0.5Mpa, spray arch 0.3-0.45Mpa, but adjust the main damper according to nozzle discharge condition degree.

Ⅴ.Before spraying concrete, it is necessary to keep the rock surface to be sprayed without loose rock and clean without oil and dirt, and it is necessary to take the steel mesh and anchor rod in the development section of surrounding rock joint to strengthen the sprayed concrete layer and surrounding rock. The overall support effect.

Ⅵ. After the completion of the spraying, by observing the concrete surface, there are mainly two kinds of leakage water on the surface of the sprayed concrete: one is wet stain, the concrete surface is wet without obvious water stain, and appears in large form; the second is It is dripping and has obvious water droplets on the surface. For the drip or seepage of the rock surface, the blind pipe can be specially set up for refilling or direct sealing. From the field experiment, it is difficult to achieve the effect of no leakage and leakage. This is mainly 

because the groundwater distribution of the initial injection is not concentrated, and it is difficult to find the water outlet point for the larger water inrush. Therefore, when there is more groundwater, the waterproof requirement is higher. A layered spray method is employed. Ⅶ. Clean aggregate has large adhesive force and small rebound. The cleanness of aggregate is very important for jetting. For wet-sprayed concrete, the water-cement ratio is too large, the quick-setting effect is worse, the rebound amount is increased, the concrete strength is low; the water-cement ratio is small, the construction is difficult to spray, the cement ratio is insufficient, the strength is low, and the rebound is increased. Big. The cement setting time increases with the increase of temperature. When the temperature reaches 30 °C, the concrete after the test admixture of the speeding agent is unfavorable in the final setting time and the late strength. The concrete temperature should preferably be 15-25 °C. The effect of the thickness of the spray layer is that the primary spray layer is too thick. Under the action of its own weight, the spray layer will collapse due to the cracking; when too thin, most of the coarse aggregate will rebound, and the spray layer will only leave the mortar, which will affect Spray effect and quality, after field experiment, the thickness of the arch part is 6cm, and the side wall is 8cm. The wind pressure is too high, so the jetting speed is too high and the rebound amount is increased. If the wind pressure is too small, the jet force will be weakened, making the concrete compact. Impact strength; too little water pressure will affect the quality of construction.


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