Every year, when it comes to the rainy season, it can be frustrating to encounter rainy days as soon as you hit concrete. Helplessness aside, construction quality and safety is definitely not to be underestimated! You know, heavy rains can have a huge impact on concrete slump and composition percentages!
Rainy season construction should be done
- The sand and gravel bin should be well drained.
- Means of transport shall be protected against rain and slippery conditions.
- The surface of the pouring bin should have rainproof measures and impervious cover material.
- Increase the frequency of determining the moisture content of aggregates and adjust the amount of water used in mixing in a timely manner.
When pouring in light rain, the following measures should be taken.
- Reduce the amount of water used for concrete mixing and the slump of concrete at the outlet, and reduce the water-cement ratio of concrete if necessary.
- Strengthen the drainage inside the warehouse and prevent the surrounding rainwater from flowing into the warehouse.
- Protect the newly poured concrete surface, especially the joints.
How to deal with sudden heavy rainfall?
- If the construction of rainwater flowing down the concrete, concrete irrigation down, like a handful of flour into the water, will be diluted, no strength of the concrete in the future to rework a large area.
- Pouring process, in case of heavy rain, heavy rain, should immediately stop feeding, leaving a good construction seam, has been in the warehouse concrete should be vibrated compacted and covered.
- After the rain must first exclude the water in the warehouse, the site should be immediately treated by rain erosion, such as concrete can also be remodeled, should be added after the laying of concrete joints to continue pouring, generally in this case concrete has been initially set, if the surface is very poor, then we should be chiseled, using high concrete treatment.
Precautions for concrete construction in rainy season
Scheduling of work and rest periods
According to the principle of “Sunny outside, rainy inside”, the outdoor operation time should be shortened as much as possible on rainy days, and the deployment of labour should be strengthened.
Organize reasonable working procedures interspersed, use all kinds of favorable conditions to reduce the capital consumption of rainproof measures, to ensure the quality of the project, to speed up the construction progress, in case of larger stormy weather should stop all operations, personnel to withdraw to a safe place.
On-site rain drainage measures
- Prepare sufficient materials and equipment at the site, such as straw bags, logs, steel wire rope, high power water pumping machinery, etc.
- Ensure a certain amount of self-generated power to prevent drainage in case of sudden power failure in the rainy season, and make sure that lightning protection devices and anti-leakage measures are in place.
- Set up drainage ditches in the excavated pits, and regularly check the drainage situation and the reliability of pumping equipment to improve rapid response capability.
- Drainage ditches excavated beside farmland should be inspected regularly, and once the soil is blocked, excavate and unblock in time.
- Site all mechanical and electrical equipment should be set up in advance of a good rain grille (cover., during the rainy season, set up a person often check. Check the grounding of mechanical and electrical equipment, grounding protection devices, each rain must be checked to ensure the normal operation of mechanical and electrical equipment. Click>>project information free download
- Special considerations.
In case of thunderstorm, stop open-air operation at height to prevent injuries from lightning.
All machinery must be operated in strict accordance with the corresponding safety and technical operating procedures, and should not be used during the rainy season.
During the work period, education and supervision and inspection should be strengthened.
The temporary power lines at the site should be well insulated and set up overhead, and the power switch box should have rainproof facilities.
Power distribution boxes, cable joints, boxes, welding machines, etc. Must have rainproof measures to prevent leakage or equipment failure caused by flooding and moisture.
Each operator should pay attention to anti-slip and anti-electrical shock, strengthen self-protection and ensure safe production.
The key points of concrete construction in rainy season
- You can contact the meteorological department to make a short term weather forecast. If it rains during the pouring of concrete, measures should be taken immediately to cover it with plastic sheeting to prevent the newly poured concrete from being washed away by the rain. If the project must be poured because of rush work, it must be covered by scaffolding.
- In the concrete construction process, as the concrete used is commercial concrete, the commercial concrete mixing plant is usually required to adjust the construction ratio according to the moisture content of sand and stone before the opening of the project, to strictly control the slump of the commercial concrete to meet the construction requirements during the rainy period. Normally, pouring of concrete is strictly prohibited during heavy rain.
- When the concrete delivered by concrete mixing pump has not yet reached the initial setting, if it rains, it should be covered with plastic sheet to prevent rain.
Concrete construction measures in rainy season
- The project manager was established with the project manager as the leader, the head of each department as a team of flood control leadership, good emergency preparedness (people, materials, machines., to deal with emergencies.
- During the rainy season construction should pay close attention to the changing weather conditions, try to avoid rainy construction.
- Transport rain-proof supplies such as canopies and rain cloths to the concrete pouring site, raincoats and rain shoes to the workers, and cover the machinery and equipment with rain-proof cover, and at the same time, send special personnel to inspect.
- Improve the temporary drainage facilities, and strengthen the rainy season finished products, semi-finished product protection work to prevent flooding. Strengthen the maintenance and repair of construction causeway, to ensure smooth construction traffic in the rainy season.
- Do a good job in the rainy season construction materials and necessary materials for the reserve work. Cement reservoir to ensure that no rain, the ground is not anti-tide, set around the drainage ditch, water is strictly prohibited.
- Safety inspection of all electrical equipment, the implementation of defensive measures, to make arrangements for on-site mechanical equipment parking, to ensure that the construction is not affected by rain.
- All materials should be stacked off the ground, and cover the protection, keep the ground a thousand dry, there should be drainage measures around, steel materials should be used for steel bedding high waterproof.
- Templates to ensure that the support system should be supported on a firm and solid foundation. Column and plate, wall template leave sweeping mouth, to facilitate the exclusion of water, accumulation of material.
- The formwork coated with water-soluble release agent should prevent the release agent from being washed away by the rain to ensure smooth and safe demoulding and concrete surface quality.
- Steel welding shall not be carried out in rainy days to prevent the weld or joint from brittle cracking.
- The concrete construction of the beam slab is carried out by setting up a rain shelter, and the construction will be stopped in case of heavy rain or storm. For the concrete to be poured continuously, prepare sufficient rain gear to operate and adjust the construction ratio.
- Rainy season construction in a timely manner to determine the moisture content of sand and gravel materials, adjust the ratio at any time to ensure the quality of concrete. Weighing scales regularly check the accuracy and sensitivity to ensure accurate measurement.
- Strengthen the collection of weather forecast data to keep abreast of the weather condition so as to take effective preventive measures, and cover the poured concrete as soon as possible to prevent the concrete from being showered by rain before final setting.
- When there is a little rain in the process of concrete pouring, but not directly affect the quality of concrete, the concrete pouring can be continuous and uninterrupted, the mixing plant to reduce the slump of the concrete mix, and extend the mixing time of the tank. When pouring concrete, the degree of pouring should not exceed 1.5m each time, and increase the number of vibrations. At the same time, cover the poured concrete immediately to avoid rainwater washing the concrete directly, and drain away the rainwater accumulated in the pouring area in time.
- When the concrete pouring sudden heavy rainfall but its duration is short (2 hours or so.Should be immediately covered with molded concrete and changed to intermittent concrete cover pouring processing, concrete pouring interval should be less than the initial setting time of concrete, in order to avoid the construction of cold joints at the place after the rain stops promptly to clear the water and resume normal concrete pouring construction.
- When the concrete pouring sudden heavy rainfall and its duration is long, the concrete should be molded immediately to be covered and changed to intermittent concrete pouring, until the pouring to comply with the specifications of the location of the construction joints to stop pouring. Beam, slab construction joints must be left within 1/3 of the span. If the rain stopped after pouring concrete again when the initial setting period has passed, the place should be treated as construction joints, the treatment methods are as follows.
- For the beam, slab: The location of the construction joints should meet the design and “Concrete structure engineering construction and acceptance of the provisions of the code”, when the thickness of the beam, slab < 600mn, the concrete surface will be made of vertical construction joints; when the thickness of the beam, slab ≥ 600mm, the concrete surface should be left as an inclined construction joints. Another approach to be reinforced by inserting shear steel bars perpendicular to the construction joints, the bar for ≥ q16@500×500, bar length ≥ 600mm, insert 300mm, exposed 300mm.
- For the horizontal construction joints formed by the wall and the slope part formed by pouring, make chiseled hair.
- The construction joints shall be left and processed with the consent of the design, supervision and owner, and engineering changes shall be issued, and all the concrete at the construction joints shall be subject to concealed acceptance procedures before the second pouring.
- In the concrete pouring is completed, timely cleaning up the construction equipment and residual concrete and other debris, so that the work is completed and the site is clear.
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