However, before winter construction, in case of sudden cold current invasion and sudden temperature drop below 0 ℃, in order to prevent negative temperature from freezing, emergency protective measures shall also be taken for the project according to the relevant requirements of winter construction.
4.
2.
After the formwork is removed, the wall shall be completely covered with a quilt immediately, and the thermal insulation quilt shall be tightened after the lead wire passes through the bolt hole of the wall.
First, it shall be covered with a layer of plastic film, and then covered with thermal insulation quilt.
The greenhouse method is applicable to underground works, foundation works and masonry structures with urgent construction period.
Beijing requirements: winter construction is mandatory on November 15.
The hole depth of the wall temperature measuring point is 10-15cm, and the plate temperature measuring hole is 1 / 2-1 / 3 of the plate thickness.
The number of thermal insulation covering layers shall be determined according to the outdoor air temperature and concrete temperature measurement.
Temperature measurement of concrete 1.
For temperature measuring hole φ The 20pvc pipe shall be inserted into the concrete before the concrete is poured and solidified, and the triangular flag shall be inserted into the temperature measuring hole; 2.
When the heating method is adopted, the measurement shall be conducted every 1h in the heating and cooling stage and every 2h in the constant temperature stage.
The minimum temperature in the greenhouse shall not be lower than 5 ℃.
Principle of winter construction: Article 1.0.4 ， of this specification proposes that special winter construction scheme shall be prepared for all engineering projects for winter construction.
The test of surface temperature difference, cooling rate and ambient temperature of mass concrete pouring body shall not be less than 4 times every day and night after concrete pouring (equal time interval); The molding temperature shall be measured at least twice per shift.
A special person shall be assigned to monitor the temperature in the concrete and greenhouse.
4.
The monitoring points shall not be less than 4 and the spacing shall not be greater than 500mm.
The temperature measuring points on the surface and bottom shall be 50mm away from the surface of the pouring body..
Principle of winter construction: the division principle of winter construction period in the code for winter construction of Construction Engineering (JGJ / t104-2011) is: when the outdoor daily average temperature is stable below 5 ℃ for 5 consecutive days, the winter construction will be started, and when the outdoor daily average temperature is higher than 5 ℃ for 5 consecutive days, the winter construction will be cancelled.
3.
Winter construction features: during winter construction, the water contained in soil, concrete and mortar freezes, and building materials are easy to crack, which brings many difficulties to building construction.
(article 6.6.2) II.
During temperature measurement, the temperature measuring point shall be covered and isolated from the external temperature.
Therefore, in order to ensure the project quality, winter construction measures should be taken.
Source: Douding construction Author: Mr.
④ After the vertical concrete pouring is completed, a layer of thermal insulation quilt shall be covered on the top of the column and wall.
For walls, columns and other parts that cannot be tiled due to vertical dowel bars, we should focus on the control, fold the quilt into a suitable size and insert it into the middle of the wall, remove the thermal insulation when binding the reinforcement, and accept, close the formwork and pour concrete for the corresponding parts as soon as possible to avoid freezing of the concrete.
The temperature measurement during the curing of mass concrete shall meet the requirements of code for construction of mass concrete: 1.
If the cover is uncovered due to work needs during concrete insulation, the consent of relevant management personnel shall be obtained.
Chen, this paper summarizes the concrete curing, temperature measurement and test block retention; Fabricated construction; Earthwork backfilling; Masonry works; Roofing works; The key points of winter construction such as ground engineering have a very good guiding significance for the on-site construction management of construction engineering.
The temperature measuring points shall be arranged in a representative way.
Points shall be set at a height of 500mm from the ground, and the temperature shall be measured at least 4 times every day and night.
Before concrete pouring, the column and wall formwork shall be wrapped with colored strip cloth for wind proof treatment.
After the concrete reaches the critical strength of freezing, the temperature measurement can be stopped.
Before concrete construction, temperature measurement point diagram shall be drawn, and special personnel shall be assigned to measure temperature and make records.
Each temperature measuring point must be numbered.
2.
During the paving process, pay attention to the finished product protection of concrete, and do not trample on the concrete at will.
3.
The atmospheric temperature during the whole winter construction period and the temperature of concrete from pouring into the formwork to the time when the concrete temperature is the same as the external temperature shall be measured and recorded, and the temperature measurement times shall comply with the following provisions: A.
On each test axis, surface, bottom and central temperature measuring points shall be arranged along the thickness direction of the concrete pouring body.
The temperature of each measuring point in the greenhouse shall not be lower than 5 ℃.
Warm shed method: the construction method of placing concrete components or structures in the erected shed and setting radiators, exhaust pipes, electric heaters or furnaces inside to heat the air in the shed so that the concrete components or structures can be cured in a positive temperature environment.
After the formwork is removed, it shall be wrapped and covered with plastic cloth and thermal insulation quilt in time.
If it is trampled on carelessly, it shall be repaired in time.
It is required that the lap of the quilt shall not be less than 200mm, and it shall be paved against the wind direction.
When the negative temperature curing method is adopted, it shall be measured every 2h before reaching the critical strength of freezing; c.
Carry out the coverage inspection of concrete, especially in windy weather and at night, increase the on duty inspection of management personnel and workers, and cover it in time in case of strong wind or artificial opening.
when using the heat storage method or comprehensive heat storage method, it shall be measured every 4h-6h before reaching the critical strength of freezing; b.
In case of windy weather, the quilt shall be pressed with steel pipe and other heavy objects to prevent the strong wind from blowing over the insulation layer.
After the plastering of the roof concrete is completed, it shall be covered in time in sections and sections.
At the same time, educate workers to pay attention to the protection of concrete cover during concrete insulation.
1、 Concrete curing 1.
The location and number of monitoring points in the temperature test area can be determined according to the distribution of the concrete pouring temperature field and the provisions of temperature control.
The heating method shall not violate the local management requirements (for example, open fire is not allowed in Beijing).
The measuring position shall be 20mm below the structural surface, and the time for the thermometer to stay in the temperature measuring hole shall be no less than 3 minutes.
