Contents of this article
How much antifreeze is needed to repair a house in winter?
For winter construction, based on 2 bags of cement, how much antifreeze should be added?
Winter construction measures and quality control points?
How much antifreeze and early strength agent should be added to a dry hard mortar?
What will be included in the winter construction site during the construction period?
How much antifreeze should be used to repair a house in winter?
The proportion of antifreeze used in winter construction depends on the type of cement, and is generally 0.3% to 0.5% of the cement.
The correct proportion of C30 concrete and antifreeze is: 5% when the temperature is below 10 degrees Celsius, and 3% of the antifreeze when the temperature is below 5 degrees Celsius. The parameter of the antifreeze is 3% - 5% of the cement dosage.
Antifreeze concrete is a substance that hardens at negative temperatures, achieves expected performance under specified curing conditions, and prevents moisture in the material from freezing at low temperatures. Ensure the normal construction of concrete under negative temperature and reduce the freezing point in the concrete mixture. It can be combined with water-reducing agent, air-entraining agent, etc. to achieve better antifreeze effect. Used for various concrete projects and during construction in cold seasons.
Makes concrete hydrate normally in a negative temperature environment of 0℃ to -15℃; lowers the freezing point and improves the early strength of concrete.
For winter construction, based on 2 bags of cement, how much antifreeze should be added?
This has nothing to do with C20 to C60. Just put it this way, you will understand. Antifreeze is added according to the temperature and the percentage of cement dosage. For example, C30, at minus 5 degrees, you add according to the cement dosage. Just add antifreeze at 5 to 8%. If you mix it yourself, it’s best to add it according to the antifreeze instructions! ! !
Winter construction measures and quality control points?
1.
Do a good job of monitoring the temperature of winter construction, and measure the temperature of concrete coming out of the tank, pouring and entering the mold, no less than 4 times in each working shift; measure every 6 hours Primary curing temperature; for concrete mixed with antifreeze, before the strength reaches 4MPa, the curing temperature should be measured every 2 hours, and thereafter every 6 hours; outdoor air temperature and ambient temperature measurement records should be kept, no less than 4 times every day and night , In addition, it is necessary to measure the highest and lowest temperatures and fill in the concrete winter construction daily report.
2.
Cement must not be heated directly. Bagged cement must be transported into a greenhouse for storage before use. The strength grade of the cement shall not be less than 42.5mpa, and the minimum cement dosage shall not be less than 300kg. , the water-cement ratio shall not be greater than 0.6.
3.
Measures must be taken to insulate the concrete during transportation to ensure that the temperature of the concrete entering the mold is controlled above 10°C, and the curing temperature in the cave must not be lower than 5°C.
4.
When necessary, add antifreeze as appropriate according to the temperature conditions and actual conditions. The specific amount shall be implemented according to the mix ratio requirements. When antifreeze is added, the coagulation .
How much antifreeze and early strength agent should be added to a dry hard mortar?
One cubic meter of mortar
The amount of early strength agent required for one cubic meter of concrete is generally 3%-6% of the cement content in the concrete. The dosage of early-strength agent is calculated based on the dosage of concrete cementitious material multiplied by the dosage recommended by the manufacturer of the early-strength agent or the trial dosage. Early strength agent is one of the concrete admixtures. Concrete early strength additives refer to admixtures that can increase the early strength of concrete and have no significant impact on later strength.
Including winter construction sites during project construction?
Key points of winter construction
Definition of winter construction
According to the "JGJ/T104-2011 Winter Construction Regulations for Construction Projects": the average daily outdoor temperature is stable for five consecutive days When the daily average outdoor temperature is higher than 5℃ for five consecutive days, winter construction will be terminated.
According to the overall project construction progress plan, during the winter construction period this year, the sub-projects that will be carried out on site are roughly: steel bars, formwork, concrete projects, masonry projects, earthwork backfilling, etc.
Preparations before winter construction
1. Arrange the construction plan during the winter construction period, clarify the winter construction projects, implement them in each building, and supervise them to make various preparations as required.
2. Do a good job of insulating the water pipe outlets and exposed water pipes on site.
3. The winter construction leading group will conduct a comprehensive inspection and implementation of various preparations at the construction site to ensure normal winter construction.
4. Arrange dedicated personnel to conduct unified temperature measurement work such as atmospheric temperature and engineering temperature measurement, and keep records.
5. Add brackets to the lower part of the distribution box of mechanical equipment, and set up a protective shed on the upper part to prevent snow and moisture, and a grounding protection device should be installed.
6. The grounding devices of each large machinery must be fully installed in accordance with the regulations, and a comprehensive inspection must be carried out before winter installation.
7. Before winter, carefully inspect the on-site distribution boxes, gate boxes, temporary cable supports, welding machines and other electrical equipment and tools, and promptly reinforce those that need reinforcement, and repair missing covers, covers, and doors in a timely manner. It is completely protected from snow and moisture to ensure the safety of electricity.
8. The insulation materials used during winter construction should be brought into the site according to the planned usage, specifications, models and quality requirements, and should be properly kept to prevent damage and waste.
9. Organize materials, equipment supply and site acceptance during the winter construction period. .
10. Protect raw materials and semi-finished products.
11. Moisture-proof measures should be taken for materials that are sensitive to moisture, such as templates and wooden panels. If necessary, they should be covered with colored strips of cloth. The stacking area of the templates should be elevated and well ventilated.
12. Steel bars�.
(5) Concrete Project
1. During winter construction, all structural parts will use pumped commercial concrete. In order to improve the early strength and shorten the curing time, the cement used for concrete is ordinary Portland cement. (PO.42.5R), the amount of cement per cubic meter of concrete should not be less than 300kg, the water-cement ratio should not be greater than 0.6, and early-strength antifreeze should be added. In order to control the slump and reduce water consumption to a minimum, add Highly efficient water reducing agent.
2. When the temperature drops below 0℃, the hydration of concrete basically stops, and when the temperature drops to -2--4℃, the concrete begins to freeze and generate ice crystal stress, which reduces the strength of the concrete. Therefore, before the temperature of concrete drops to 0°C, it reaches the critical frost resistance strength. It is very important to have a strength of no less than 30% of the designed concrete strength standard value. It is particularly critical to select concrete that meets the required frost resistance level. The standard for adding antifreeze to concrete is the local minimum temperature plus 3°C. Therefore, when the lowest temperature in the next five days is above -5°C, choose concrete with a frost resistance grade of -8°C; when it is -5-10°C, use a frost resistance grade. -13℃ concrete, when the temperature is below -10℃, in order to ensure the quality of the project structure and consider the performance of early-strength antifreeze, concrete pouring will be stopped on site for safety reasons.
3. Control the concrete supply and on-site pouring speed to reduce concrete heat loss before pouring. Concrete temperature control requirements: tank exit temperature ≥ 12℃, mold entry temperature ≥ 5℃.
4. Before pouring concrete, the ice, snow, frozen blocks and dirt on the steel bars and formwork should be removed in time to avoid pouring concrete in rainy and snowy days; for scaffolding, the frozen blocks on the working platform should be removed in time to prevent slipping. Falling upside down.
5. Concrete must be fully mixed before unloading. The mixing time of each tank should be no less than 180S. When it is found that the slump is too low and construction is difficult, it is strictly forbidden to add water without permission. The commercial mixing station should be notified to process the concrete.
6. Before pouring concrete for vertical structures, check whether the wall and column formwork is tightly insulated to prevent local freezing of the concrete. During vertical concrete construction, grass fibers are directly covered outside the formwork for insulation.
7. The beams and slabs are poured at the same time. The pouring method adopts the "rushing method" from one end to the other end. The concrete is vibrated and smoothed, then covered with a layer of plastic film and covered with two layers of grass fiber quilts to keep it warm for 72 hours.
8. Strictly control the loading time and load on the board.
9. Concrete insulation and maintenance: immediately after the wall columns are removed from the formwork, they should be covered with plastic sheeting, and the external grass fibers should be hung for insulation. 10. Strictly control the concrete removal insulation and formwork removal time. When the temperature is -5℃--8℃, the formwork removal time is no less than 48 hours; when the temperature is -8℃--12℃, the formwork removal time is a lot of time. Within 72 hours; the formwork removal strength should be no less than 5N/mm2, and the insulation coverage of formwork and concrete must be timely and effective.
(6) Underground garage membrane waterproofing
The underground garage of this project uses SBC membrane waterproofing. According to the requirements of the "Technical Specification for Waterproofing of Underground Engineering (GB50108-2011)", the average daily When the minimum temperature is below 5℃ and below 0℃, SBC membrane waterproofing construction shall not be carried out. The waterproofing construction of underground garage membrane shall be carried out after the winter construction is completed.
Safety assurance measures
1. Earnestly implement relevant regulations on safety operating procedures, safety protection standardization and site management, and organize relevant personnel to learn relevant safety documents and winter implementation plans. Before winter, conduct a comprehensive inspection and repair of power lines and electrical equipment in the site and living areas, and eliminate hidden dangers in a timely manner. The scaffolding erected must be solid, firm and reliable, and inspected regularly.
2. Special operations personnel are required to wear insulating shoes and non-slip shoes during construction.
3. When entering the construction site, you must wear a safety helmet and fasten your seat belt when working at heights. Each team leader must conduct a safety briefing before work. In strong winds above level 5, work at heights must be stopped. There must be sufficient safety equipment for night construction. illumination.
4. When constructing after wind and snow, the snow on roads, operating platforms, etc. should be cleared first and the power supply lines should be checked to prevent electric shock accidents caused by disconnection.
5. For special types of work, such as scaffolders, welders, etc., conduct fire prevention and safety training and education based on the characteristics of winter work. Ensure safe construction during winter construction and implement it gradually according to actual conditions.
6. On-site power switches and control box facilities should be locked, and designated personnel should be responsible for preventing electric shock and leakage accidents.
7. Designate a dedicated person to be responsible for cleaning the road surface, getting on and off the horse, etc., and take anti-slip measures. On-site drainage pipes, trenches and wells are dredged in advance and cleaned regularly. After snowfall, promptly clear the snow on the shelves and check the horse track platform. If there is any looseness and sinking, be sure to deal with it in time.
8. Strengthen the monitoring of slopes during winter construction, arrange for special personnel to monitor the slopes, and take timely measures when abnormal conditions are found to prevent slope instability caused by freezing and thawing.
9. Measures should be taken to heat the furnace in a closed room, and arrange for someone to watch the fire. Fire watchers are strictly prohibited from sleeping to prevent fire and gas poisoning.
10. On-site materials should be stacked 3 meters away from the edge of the foundation pit. Ultra-high stacking is strictly prohibited, and the displacement of the foundation pit slope should be observed regularly. </p
微信扫一扫打赏
