What If It Rains Suddenly When Pouring Concrete? Stop or Not?
Recently, I can always see workers complaining that it rains as soon as concrete is hit, and this job can't be done! It's been raining, and the concrete can't be hit. What about the construction period? What should I do if I stop or stop in the middle of pouring concrete? In order to avoid unnecessary losses, it is necessary for us to understand the problems encountered in rainy season construction and their solutions.
I. The rainy season construction should do the following work:
1. The sand silo should be well drained.
2. Means of transport should have rain-proof and anti-skid measures.
3. The pouring bin surface shall be provided with rain-proof measures and waterproof covering materials.
4. Increase the determination times of aggregate moisture content and adjust the mixing water consumption in time.
II. When pouring in light rain, the following measures should be taken:
1. Appropriately reduce the concrete mixing water consumption and the slump of concrete at the outlet, and appropriately reduce the water-binder ratio of concrete when necessary;
2. Strengthen the drainage in the warehouse and prevent the surrounding rainwater from flowing into the warehouse;
3. Do a good job in protecting the newly poured concrete surface, especially the joints.
III. How to deal with sudden rainstorm
1. If the rain continues to flow down the concrete, the concrete will be poured down, just like a handful of flour thrown into the water, which will be diluted, and the concrete without strength will be reworked in a large area in the future.
2. In the pouring process, in case of heavy rain and rainstorm, the feeding should be stopped immediately, and the construction joints should be retained. The concrete that has been put into the warehouse should be covered after vibrating and compacting.
3. After the rain, the accumulated water in the warehouse must be removed first, and the parts washed by the rain should be treated immediately. If the concrete can be remolded, the joint concrete should be paved and poured again. Generally, the concrete has been initially set, so if the surface is poor, it should be chiseled and treated with a higher concrete.
IV. Specifically, concrete construction in rainy season can be carried out from the following aspects:
1. The arrangement of the schedule
According to the principle of "sunny outside, rainy inside", the outdoor operation time should be shortened as much as possible in rainy days, and the allocation of labor force should be strengthened:
Organize reasonable procedures to alternate, use various favorable conditions to reduce the capital consumption of rainproof measures, ensure the project quality, and speed up the construction progress. In case of severe stormy weather, all operations should be stopped and personnel should be evacuated to a safe place.
2. The rain drainage measures
1) Prepare sufficient materials and equipment at the construction site, such as straw bags, square timber, wire ropes, high-power pumping machinery, etc.
2) Ensure a certain self-generating capacity to ensure the waterproof and drainage needs in case of sudden power failure in rainy season, and do a good job in lightning protection and leakage prevention measures.
3) Set a drainage ditch in the open-cut foundation pit, and regularly check the drainage situation and the reliability of pumping equipment to improve the rapid response ability.
4) The drainage ditch excavated beside the farmland should be inspected regularly. Once earthwork blockage is found, it should be excavated and dredged in time.
5) All mechanical and electrical equipment on site shall be equipped with rain barriers (covers) in advance, and regular inspection shall be conducted by designated personnel during the rainy season. Check the zero grounding protection device of mechanical and electrical equipment, and check it every time after rain to ensure the normal operation of mechanical and electrical equipment.
6) Special notes:
Thunderstorm weather, should stop high-altitude open-air operation, to prevent lightning injury.
All mechanical operation, must strictly abide by the corresponding safety technology operating rules, the rainy season.
Education, supervision and inspection should be strengthened during work.
The site temporary power lines to ensure good insulation, overhead setting, power switch box should have rain-proof facilities.
Distribution boxes, cable connectors, boxes, electric welding machines, etc. must have rainproof measures to prevent leakage or equipment failure caused by water immersion and moisture.
All operators should pay attention to anti-skid and electric shock prevention, strengthen self-protection and ensure safety in production.
3. Key points of concrete construction in rainy season
1) You can get in touch with the meteorological department first and work out a short-term weather forecast. Before pouring concrete, we should know the weather forecast in time, and try our best to organize the construction in sunny days. If it rains in the process of pouring concrete, we should immediately take measures to cover it with plastic sheets to prevent the newly poured concrete from being washed away by rain. If the project has to be concreted because of work rush, it must be covered by scaffolding.
2) In the process of concrete construction, because the concrete used is commercial concrete, the commercial concrete mixing station is usually required to adjust the construction mixture ratio according to the moisture content of sand and stone before opening, and strictly control the slump of commercial concrete to meet the construction requirements in the rain period. Under normal circumstances, it is forbidden to pour concrete in heavy rain.
3) When the concrete delivered by the concrete mixing pump fails to reach the initial setting, if it rains, it should be covered with plastic sheets in time to prevent the rain.
V. Construction measures of concrete in rainy season
1. Construction principles
(1) The project intends to set up a leading group for flood control with the project manager as the team leader and the heads of various departments as the team members, and make emergency preparations (personnel, materials and machines) to deal with emergencies.
(2) During the rainy season construction should pay close attention to the weather changes, try to avoid the rain period construction.
2. Preventive preparation
(1) Transport rain-proof articles such as awnings and ponchos to the concrete pouring site, distribute raincoats and rain boots to workers, cover the machinery and equipment with rain, and assign special personnel to carry out inspection.
(2) Do a good job in temporary drainage facilities, strengthen the protection of finished products and semi-finished products in rainy season, to prevent floods. Strengthen the maintenance and repair of construction access roads to ensure smooth construction traffic in rainy season.
(3) Do a good job in the rainy season construction engineering materials and necessary materials reserve. Cement silo shall ensure no rain leakage, the ground shall not be damp, and drainage ditches shall be set around it, and no water shall be accumulated.
(4) Conduct safety inspection on all electrical equipment, implement defensive measures, and make arrangements for the parking of on-site mechanical equipment to ensure that the construction is not affected by rain.
3. Matters needing attention
(1) All materials should be piled up from the ground, and cover to protect and keep the ground dry, there should be drainage measures around, and the reinforced materials should be padded with wood to be waterproof.
(2) The template to ensure that the support system should be supported on a solid foundation. Column and plate, wall template cleaning mouth, to help eliminate water, product.
(3) Formwork coated with water-soluble release agent should prevent the release agent from being washed away by rain to ensure smooth and safe demoulding and concrete surface quality.
(4) Steel welding shall not be carried out in rainy days, to prevent the weld or joint embrittlement.
(5) Beam slab concrete construction, all build fortification canopy, in case of heavy rain or rainstorm, stop construction. For the concrete to be continuously poured, prepare enough rain gear for operation, and adjust the construction mixture ratio.
(6) The rainy season construction in a timely manner to determine the moisture content of aggregate, adjust the mixture ratio at any time, to ensure the quality of concrete. The measuring scale shall regularly check the accuracy and sensitivity to ensure accurate measurement.
Ⅵ. Operational guidance
1. Strengthen the collection of weather forecast data, grasp the weather situation in time, in order to take effective preventive measures, the cast concrete should be covered as soon as possible to prevent the concrete from being washed by rain before the final set.
2. When there is light rain in the process of concrete pouring, but it will not directly affect the quality of concrete, the concrete pouring can be continuous and uninterrupted, the mixing station can reduce the slump of concrete mixture, and extend the mixing time of the tank, and the general tank can be extended by 305. When pouring concrete, the pouring competition should not exceed 1.5m at a time, and the vibrating frequency should be increased. At the same time, the poured concrete should be covered immediately, so as to avoid the rain directly washing the concrete, and the rainwater accumulated in the pouring area should be drained away in time.
3. When there is a sudden heavy rain during concrete pouring, but its duration is short (about 2 hours), the concrete that has entered the mold should be covered immediately and be covered with concrete intermittently. The interval between concrete pouring should be less than the initial setting time of concrete, so as to avoid the occurrence of cold joints in the construction here. After the rain stops, clear the accumulated water in time and resume the normal concrete pouring construction.
4. When the concrete pouring sudden heavy rain and its duration is long, you should immediately cover the concrete that has entered the mold and change it to intermittent concrete pouring until it reaches the construction joint position that meets the specification. Construction joints of beams and slabs must be set within 1/3 span. If the initial setting period has passed when the concrete is poured again after the rain stops, it should be treated according to the construction joints, and the treatment methods are as follows.
A. For beams and slabs, the position of construction joints shall meet the requirements of design and Code for Construction and Acceptance of Concrete Structure Engineering (GB50204-2002). When the thickness of beams and slabs is less than 600mn, the concrete surface here shall be made into vertical construction joints; When the thickness of beam and plate is ≥600mm, the concrete surface here should be designed as inclined construction joints. In addition, the place is reinforced by inserting shear reinforcement perpendicular to the construction joint. The steel dowel is q16 @ 500× 500 or more, the length of the steel dowel is ≥600mm or more, and it is inserted 300mm and exposed 300 mm..
B. For the horizontal construction joint formed by the wall and the slope part formed by pouring, cut hair.
C. The design and treatment of construction joints must obtain the consent of the design, supervision and the owner, and issue engineering changes, and all the concrete at construction joints must go through the formalities of hidden acceptance before the second pouring construction.
D. Cleaning: after concrete pouring, timely clean up related construction machines and tools, residual concrete and other sundries, so as to clean up after work.