It is about to rainy season, it has been raining, what to do if the concrete can't be poured in the construction period....How to do if the pouring rain stops or keeps in the middle of pouring concrete?
If you are forced to carry out construction under heavy rain, you have to know: the impact of the construction period is only a matter of money, but it affects the strength of the concrete and is a matter of life and property safety! Heavy rain has a huge impact on concrete slump and composition percentage!
01. Loss during construction in rainy season
According to the "General Rules of Civil Law" and the "Contract Law", objective conditions that cannot be foreseen, unavoidable, and insurmountable are force majeure.
The loss caused by force majeure is the extension of the construction period, and the costs shall be borne by each party. That is to say, if the construction equipment such as mechanical equipment is damaged, the construction party pays the bill, if the construction is damaged, such as the basement floor, the construction party pays the bill.
However, if the construction party does not take reasonable measures to avoid losses and cause losses to expand, the construction party should bear the responsibility.
In order to avoid unnecessary losses, we need to understand the problems encountered in the rainy season construction and solutions.
02. Work that should be done in rainy season
1. The gravel silo should be drained smoothly;
2. Transportation means should have rainproof and anti-skid measures;
3. There should be rainproof measures and impermeable covering materials on the pouring warehouse surface;
4. Increase the number of measurements of aggregate moisture content, and adjust the water consumption for mixing in time;
When pouring in light rain, the following measures should be taken:
(1), appropriately reduce the water consumption of concrete mixing and the slump of the concrete at the outlet, and if necessary, the water-to-binder ratio of the concrete should be appropriately reduced;
(2) Strengthen the drainage in the warehouse and prevent the surrounding rainwater from flowing into the warehouse;
(3) Do a good job of protecting the newly poured concrete surface, especially the joints.
03. How to deal with sudden rainstorm
1. If the rain continues to flow down the concrete, the concrete will be poured, just like a handful of flour thrown into the water, it will be diluted, and the concrete with no strength will be reworked in a large area in the future.
2. During the pouring process, in case of heavy rain or heavy rain, the feeding should be stopped immediately, the construction joint should be set aside, and the concrete that has entered the warehouse should be vibrated and densely covered.
3. The water in the silo must be removed after the rain, and the parts washed by the rain should be treated immediately. If the concrete can be reshaped, the joint concrete should be paved and continued to be poured. In general, the concrete has already been set. If the surface is very poor, gouge it and use No. 1 high concrete treatment.
04. Aspects of concrete construction in rainy season
Arrangement of working time
According to the principle of "clear outside, rain inside", the outdoor working time should be shortened as much as possible in rainy days, and the deployment of labor force should be strengthened.
Organize reasonable process interleaving, use various favorable conditions to reduce the capital consumption of rain-proof measures, ensure the quality of the project, and speed up the construction progress. In case of heavy stormy weather, all operations should be stopped and personnel should be evacuated to a safe place.
Rainproof and drainage measures on site
1. Prepare sufficient materials and equipment on the construction site, such as straw bags, square beams, wire ropes, high-power pumping machinery, etc.
2. Ensure a certain self-generated power capacity to ensure the water-proof and drainage needs in the case of sudden power outage in the rainy season, and make lightning protection devices and anti-leakage measures.
3. Set drainage ditch in the open-cut foundation pit, and regularly check the drainage situation and the reliability of the pumping equipment to improve the rapid response capacity.
4. The drainage ditch excavated beside the farmland should be inspected frequently. Once the earth blockage is found, excavation should be carried out in time.
5. All the electromechanical equipment on site should be set up with a rain grate (cover) in advance, and a special person should be regularly inspected during the rainy season. Check the zero-connection grounding protection device of the electromechanical equipment. It must be checked after each rain to ensure the normal operation of the electromechanical equipment.
6. Special precautions:
① Thunderstorm weather should stop high-altitude open-air operations to prevent lightning strikes from hurting people.
② The operation and operation of all machinery must strictly abide by the corresponding safety technical operation regulations. During the rainy season construction, education and supervision and inspection should be strengthened.
③ On-site temporary power lines should ensure good insulation, overhead installation, and rainproof facilities for power switch boxes.
④Distribution boxes, cable joints, boxes, electric welding machines, etc. must have rain-proof measures to prevent leakage or equipment failure caused by water immersion and moisture.
⑤Each operator should pay attention to anti-skid and anti-electric shock, strengthen self-protection and ensure safe production.
Main points of concrete construction in rainy season
1. You can first get in touch with the meteorological department to work out a short-term weather forecast. Before pouring concrete, you should know the weather forecast in time and try to organize the construction with sunny days. If you encounter rain during the pouring of concrete, you should immediately take measures to cover it with plastic cloth to prevent the fresh concrete from being washed by rain. If the project must be filled with concrete because of rush work, it must be covered with a tent.
2. During the concrete construction process, since the concrete used is commercial concrete, the commercial concrete mixing plant is usually required to adjust the construction mix ratio according to the sand and stone moisture content before the opening, strictly control the slump of the commercial concrete to meet the construction during the rainy period Claim. Under normal circumstances, pouring concrete is strictly prohibited during heavy rain.
3. When the concrete delivered by the concrete mixing pump has not reached the initial setting, if it encounters rain, it should be covered with plastic cloth in time to prevent rain.
05. Concrete rainy season construction measures
(1) Construction principles
1. The project manager department establishes a flood control leading group with the project manager as the team leader and the heads of various departments as the team members, to make emergency preparedness (people, materials, and machinery) to respond to emergencies.
2. During the rainy season construction, pay close attention to weather changes and try to avoid construction during the rainy season.
(2) Preventive preparation
1. Transport rain-proof articles such as awnings and rain cloths to the concrete pouring site. Raincoats and rain boots are sent to workers. The machinery and equipment are covered with rain, and special personnel are sent to check.
2. Do a good job of temporary drainage facilities, strengthen the protection of finished products and semi-finished products in the rainy season, and prevent floods. Strengthen the maintenance and repair of construction access roads to ensure smooth construction traffic during the rainy season.
3. Do a good job in the storage of construction materials and necessary materials for the rainy season. The cement storehouse is guaranteed not to leak rain, the ground is not damp, and there are drainage ditches around it. Water accumulation is strictly prohibited.
4. Carry out safety inspections on all electrical equipment, implement defensive measures, make arrangements for the parking of on-site mechanical equipment, and ensure that construction is not affected by rain.
1. All materials should be piled off the ground and covered to protect and keep the ground dry. There should be drainage measures around it. Reinforced materials should be waterproof with wooden pads.
2. The template ensures that the support system should be supported on a firm and solid foundation. Columns, slabs, and wall formwork should be cleaned to facilitate the removal of water and deposits.
3. The template coated with water-soluble mold release agent should prevent the mold release agent from being washed away by rain to ensure smooth and safe mold release and the quality of the concrete surface.
4. Welding of steel bars shall not be carried out on rainy days to prevent welding seams or joints from brittle.
5. Beam and slab concrete constructions are all constructed with rain shelters, and construction will be stopped in case of heavy rain or heavy rain. Concrete that needs to be poured continuously should be prepared for rain gear operation, and the construction mix ratio should be adjusted.
6. In the rainy season, the moisture content of the gravel material is measured in time, and the mix ratio is adjusted at any time to ensure the quality of the concrete. The measuring scale regularly checks the accuracy and sensitivity to ensure accurate measurement.
(4) Operation guidance
1. Strengthen the collection of weather forecast data and timely grasp the weather conditions in order to take effective preventive measures. Cover the poured concrete as soon as possible to prevent the concrete from being washed by rain before final setting.
2. When there is light rain in the process of concrete pouring but it does not directly affect the quality of the concrete, the concrete pouring can be carried out continuously and continuously, the mixing station reduces the slump of the concrete mixture, and extends the mixing time of each tank. When pouring concrete, each pouring competition should not exceed 1.5m, while increasing the number of vibrations. At the same time, the poured concrete should be covered immediately to prevent rainwater from directly flushing the concrete, and the rainwater accumulated in the pouring area should be drained away in time.
3. When the concrete is poured, the heavy rain falls suddenly but its duration is short (about 2 hours), then the concrete that has been put into the mold should be covered immediately, and it should be replaced with intermittent coverage with concrete. The time should be less than the initial setting time of the concrete, to avoid the cold water in the construction site after the rain stop and clear the water in time and resume the normal pouring construction of the concrete.
4. When the concrete is poured, there is a sudden heavy rain and its duration is long, then the concrete that has been put into the mold should be covered immediately, and the concrete is poured intermittently until the pouring is stopped at the construction joint location that meets the specifications. . The construction joints of beams and slabs must be set within 1/3 span. If the initial setting period has passed when the concrete was re-cast after the rain stopped, the place should be treated according to the construction joints, and the treatment method is as follows.
a. For beams and slabs: the location of the construction joints should meet the requirements of the design and "Code for Construction and Acceptance of Concrete Structure Engineering". When the thickness of the beams and slabs is less than 600mn, the concrete surface at this location is made into vertical construction joints; when the beams and slabs When the thickness is ≥600mm, the concrete surface should be left as a slope construction joint. In addition, a method of inserting a shear bar perpendicular to the construction joint is used to reinforce the place, the insertion bar is ≥q16@500×500, the insertion bar length is ≥600mm, the insertion is 300mm, and the exposed 300mm.
b. Chisel the horizontal construction joints formed by the wall and the slope part formed by pouring.
c. The design and supervision of the construction joints and the disposal of the owners must be approved, and engineering changes must be issued, and all the concrete at the construction joints must go through concealed acceptance and other procedures before the second re-concrete construction.
d. After the concrete is poured, clean up the related construction machinery and residual concrete and other debris in time, so that the site can be cleaned after completion.
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