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.
A special person shall be assigned to monitor the temperature in the concrete and the greenhouse.
Each temperature measuring point must be numbered.
Temperature measurement of concrete 1.
The monitoring points shall not be less than 4 and the spacing shall not be greater than 500mm.
On each test axis, surface, bottom and central temperature measuring points shall be arranged along the thickness direction of the concrete pouring body.
4.
Therefore, in order to ensure the project quality, winter construction measures should be taken.
Beijing requirements: winter construction is mandatory on November 15.
The number of thermal insulation covering layers shall be determined according to the outdoor air temperature and concrete temperature measurement.
If it is accidentally damaged, it shall be repaired in time.
The temperature measuring points shall be arranged representatively.
If the cover is uncovered due to work needs during concrete insulation, the consent of relevant management personnel shall be obtained.
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.
At the same time, educate workers to pay attention to the protection of concrete cover during concrete insulation.
Points shall be set at a height of 500mm from the ground, and the temperature measurement shall not be less than 4 times every day and night.
The lap of quilt shall not be less than 200mm, and it shall be paved against the wind direction.
After the plastering of roof concrete is completed, it shall be covered in time in sections and sections.
First, a layer of plastic film shall be covered, and then covered with thermal insulation quilt.
The greenhouse method is applicable to underground works, foundation works and masonry structures with urgent construction period.
Before concrete construction, temperature measurement point diagram shall be drawn, and special personnel shall be assigned to measure temperature and make records.
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.
The temperature of each measuring point in the greenhouse shall not be lower than 5 ℃.
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.
Before concrete pouring, the column and wall formwork shall be wrapped with colored strip cloth for wind proof treatment.
Construction media ID: jianzhong001 source: Douding construction Author: Mr.
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.
Carry out the coverage inspection of concrete, especially in windy weather and at night, increase the duty inspection of management personnel and workers, and timely cover in case of strong wind or manual opening.
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.
During temperature measurement, the temperature measuring point shall be covered and isolated from the external temperature.
The temperature measuring points on the surface and bottom shall be 50mm away from the pouring body surface..
1、 Concrete curing 1.
The temperature measurement during mass concrete curing shall meet the requirements of code for construction of mass concrete: 1.
3.
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.
During the paving process, attention shall be paid to the finished product protection of the concrete, and the concrete shall not be damaged at will.
The minimum temperature in the greenhouse shall not be lower than 5 ℃.
When the heating method is adopted, it shall be measured every 1h in the heating and cooling stage and every 2h in the constant temperature stage.
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.
3.
Principle of winter construction: the division principle of winter construction period in the code for winter construction of Building 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.
For temperature measuring hole φ The 20pvc pipe shall be inserted into the concrete for retention just after the concrete is poured and not solidified, and the triangular flag shall be inserted into the temperature measuring hole; 2.
After the concrete reaches the critical strength of freezing, the temperature measurement can be stopped.
When the negative temperature curing method is adopted, it shall be measured every 2h before reaching the freezing critical strength; c.
The heating method shall not violate the local management requirements (for example, open fire is not allowed in Beijing).
4.
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.
For the parts of walls and columns that cannot be tiled due to vertical dowel bars, focus on control, fold the quilt into the middle of the wall after appropriate size, remove the thermal insulation when binding reinforcement, and accept, close the formwork and pour concrete for the corresponding parts as soon as possible to avoid freezing of concrete.
when the heat storage method or comprehensive heat storage method is adopted, it shall be measured every 4h-6h before reaching the critical strength of freezing; b.
(6.6.2) II.
The test of surface temperature difference, cooling rate and ambient temperature in mass concrete pouring body shall not be less than 4 times per day and night (equal time interval) after concrete pouring; The molding temperature shall be measured at least twice per shift.
2.
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.
Chen, this paper summarizes 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 very good guiding significance for on-site construction management of construction engineering.
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.
After the formwork is removed, it shall be wrapped and covered with plastic cloth and thermal insulation quilt in time.
2.
