What measures does winter construction supervision take?

Supervision measures for winter construction The starting and ending date of winter construction is: when winter comes, if the daily average temperature for five consecutive days is stable below 5℃, the first day of these five days is the first day of winter construction, and when the temperature turns warmer, the last five days? If the daily average temperature is stable above 5℃, the last day of this 5d is the whole day of winter construction. According to the requirements, the winter construction date of our city this year starts from 65438+February 65438+May, and when the temperature is lower than 0℃, it will also be carried out according to the winter construction. According to the characteristics of this project, the following measures are formulated:

First, the winter regulations:

Masonry engineering: it is predicted that the daily average temperature of 10 will be lower than 5℃, that is, it will enter the winter construction stage. Concrete construction: When the daily average outdoor temperature is lower than 5℃ or the lowest outdoor temperature is lower than 0℃ or below for five consecutive days, concrete construction will enter winter construction.

Plastering works: When the minimum ambient temperature is lower than +5℃, it shall be carried out according to the relevant regulations of winter construction.

Second, the temperature characteristics:

According to the characteristics of temperature in our city, the starting and ending time of the average temperature below 5℃ is 65438+early February to March of the following year. However, according to the law of temperature change over the years, winter construction can be divided into general low temperature stage and extremely low temperature stage. The extreme low temperature period is from late June of 65438+February to mid-February of the following year, and the daily minimum temperature is about-10℃? During this period, the water and sand used in the mixture must be heated. And mixed with concrete antifreeze for construction, and covered with plastic film and straw bag for insulation after concrete pouring.

Third, the preparation of pesticide application in winter

1, organizational measures

(1) For winter construction projects, before winter, the construction unit shall organize personnel to prepare the winter construction plan. The principles of compilation are: to ensure the quality of the project; Economical and reasonable, try to reduce the increase of cost; The required heat source and materials are reliable, and the energy consumption is minimal; It can really shorten the construction period. The winter construction plan should include the following contents: construction procedures; Construction method; Website layout; Supply plan of equipment, materials, energy and tools; Safety fire prevention measures; Temperature measuring system and quality inspection system. After the scheme is determined, it is necessary to organize relevant personnel to study and make disclosure to the team.

(2) receive the weather forecast in time. Prevent the sudden attack of cold current.

(3) Assign special personnel to measure the outdoor temperature during construction. The temperature of mortar and concrete shall be recorded.

2, safety and fire prevention

(1) During winter construction, anti-skid measures should be taken. Living road and construction road? Shelves and ramps are often cleaned of accumulated water, ice and snow, and inclined runways should have reliable anti-skid strips.

(2) After the heavy snow, the snow on the shelf must be cleaned and leveled. If there is looseness or sinking, it must be handled in time.

(3) During construction, if it is in contact with steam source and hot water, it will prevent burns; Use calcium chloride. When bleaching powder, you should prevent skin corrosion.

(4) Hot work is strictly prohibited in the construction site and living quarters, and inflammable and explosive articles such as oxygen and acetylene should be kept away from fire sources. ⑤ There should be protective shed and other isolation measures around the entrance and exit stairs, elevator entrances and derricks for up-and-down interchange operation. Appearance reserved holes must be covered with cover plates, and reeds and straw bags are not allowed to cover them to avoid slipping. In winter construction, scaffolding demolition should have enclosure warning measures, and it is forbidden to throw from top to bottom.

⑥ Power switch, control box and other facilities should be uniformly arranged and locked for protection. In order to prevent the wires from being pulled randomly, a designated person should be responsible for the management to prevent leakage and electric shock.

All landowners winter construction, all aerial work should wear seat belts and rubber shoes. Prevent slipping and falling from high altitude. Today, the water sources and fire hydrants on the construction site should be marked.

Pet-name ruby straw bag, straw curtain and other thermal insulation materials shall not be piled up in the open air, so as to avoid losing the thermal insulation effect due to moisture.

Four, steel engineering

1, cold drawing and cold bending of steel bars

(1) The cold-drawn temperature of steel bars shall not be lower than-20 C,? The stretching temperature of prestressed steel bars should not be lower than-15 c ② The method of controlling stress or cold drawing rate can be used for negative temperature cold drawing of steel bars. Stress control method should be adopted for prestressed tendons of prestressed concrete structures. The method of controlling cold drawing rate is not suitable for cold drawing of hot rolled steel bars that cannot be divided into batches.

(3) When the cold-drawn steel bar is controlled by stress at negative temperature, the elongation decreases with the decrease of temperature. If the control stress is constant and the elongation is insufficient, the strength of steel bars can not meet the design requirements. Therefore, the control stress of cold-drawn steel bars at negative temperature should be higher than that at normal temperature. The determination of cold drawing rate should be the same as that of normal temperature construction.

(4) Oil for steel cold-drawn equipment, instruments and hydraulic working system should be selected according to the ambient temperature, and calibration should be used under the condition of temperature matching.

⑤ When the temperature is below -20℃, it is forbidden to carry out cold bending operation on low-alloy secondary and tertiary steel bars, so as to avoid strengthening the bending point of steel bars and causing brittle fracture of steel bars.

2, steel welding

(1) Welding steel bars under negative temperature conditions in winter should be arranged indoors as far as possible. If outdoor welding is required, the ambient temperature shall not be lower than -20℃ and the wind force shall not exceed 3? Level 1 should have windproof measures. Joints that are not cooled after welding are strictly prohibited from contacting with ice and snow.

② Negative temperature flash butt welding. ? Negative temperature flash butt welding should adopt preheating flash welding or flash-preheating-flash welding process. When the reinforced end face is relatively flat, preheating flash welding should be adopted; When the end face is uneven, flash-preheating-flash welding should be adopted.

③ Negative temperature automatic electroslag pressure welding. Welding of negative temperature automatic electroslag pressure welding

The procedure is the same as normal temperature, but the welding current should be increased appropriately to increase the power-on time. ? The time for dismantling the joint medicine box should be extended for about 2 minutes, and the slag shell of the joint should be extended for 5 minutes before slag can be discharged.

Before rebar welding in winter, a trial welding must be conducted according to the construction conditions. After the inspection is qualified, the welding can be formally carried out.

Five, concrete engineering

1. General

(1) When using commercial concrete, it is necessary to know the performance of commercial concrete mixed with antifreeze before pouring, and take corresponding measures to prevent freezing and keep warm.

(2) Ensure that the concrete pouring temperature is 65438 00℃, at least not lower than 5℃. When the temperature of concrete entering the mold is less than 5℃ by thermal calculation, the mixing water and aggregate should be heated.

(3) Before pouring concrete, the ice, snow and dirt on the formwork and steel bars should be removed, and the containers used for transporting the mixture should have heat preservation measures. When freezing occurs during pouring, it must be heated and stirred before pouring to ensure that the temperature of concrete entering the mold is not lower than 65438 05℃.

2. Maintenance of concrete

(1) The compressive strength of concrete poured in winter should not be less than 40% of the design strength, and the concrete below C 10 should not be less than 5Mpa before negative temperature curing.

(2) thermal insulation materials (straw bags, sacks) should be kept dry.

(3) When the formwork is externally insulated, other structures can only be poured after the insulation material is solidified, except that the foundation can be insulated with pouring. Before concrete pouring, thermal insulation materials such as straw curtains and sacks can be hung on the surface of steel formwork and fixed.

(4) thermal insulation materials should not be directly covered on the newly poured concrete layer. Plastic film can be covered first, and then thermal insulation materials such as straw bags and sacks can be covered. The laying thickness of thermal insulation material is: generally, one layer is laid above 0℃; Spread two or three layers below 0℃; Mass concrete should be covered with insulation layer immediately after pouring and secondary compaction, and the thickness and material of insulation layer should be determined according to calculation.

⑤ The concrete after formwork removal should also be covered with thermal insulation materials in time to prevent cracks caused by the sudden drop of concrete surface temperature.

3. Design of concrete test block

According to the specification, at least two groups of specimens with the same curing conditions should be retained at room temperature. One group is used to measure the strength of concrete before freezing, that is, the critical strength, and the other group is used to measure the 28d strength. The concrete specimen shall be made of the pouring structure mixture at the pouring site. Before the pressure test, the specimen should be parked indoors at normal temperature, and then the pressure test should be carried out after thawing. The parking time is 4- 12h.

4. After the concrete is cooled to 5℃, the formwork and insulation layer can be removed. When the temperature difference between the concrete and the outside is greater than 20℃, the concrete surface after formwork removal should be temporarily covered to allow it to cool slowly. The formwork of load-bearing members shall be removed when the members meet the design and specification requirements.

5, found that frostbite should be handled in time.

Six, masonry engineering

(1) Before laying the block, the surface dirt, ice and snow shall be removed. Bricks and blocks frozen after immersion shall not be used. (2) Medium sand should be used for sand, and the silt content should meet the specification requirements. Sand should not contain ice and frozen blocks with a diameter greater than 1cm.

(3) The consistency of masonry mortar should be properly adjusted than that of normal temperature construction, and additives (NC-W mortar antifreeze) should be selected to improve the consistency of mortar. At negative temperature, the consistency of mortar can be 1 ~ 3cm higher than that at normal temperature, but not more than 12cm, so as to ensure the bonding force between mortar and brick.

(4) It is forbidden to use frozen mortar for masonry.

⑤ When the outdoor temperature is lower than +5℃, bricks, blocks and other materials should not be watered, and the mixing time of mortar should also be increased, which is generally 1.8 times of the mixing time at room temperature, about 2.5~3 minutes.

6. Before calling it a day, the vertical mortar joint on the top surface should be filled, and at the same time, the masonry surface should be covered with thermal insulation materials (such as straw bags and plastic films).

⑦ Increase the design of on-site test blocks and maintain them under the same conditions at the site to test the actual strength of on-site masonry mortar.

Seven, plastering engineering

(1) Indoor plastering curing temperature should not be lower than 5 C. ..

(2) Thermal insulation and anti-freezing measures should be taken for mortar used in plastering project in winter.

(3) Before plastering indoors, doors and windows should be sealed, and the construction hole, air supply outlet and stairwell should be closed for thermal insulation; The minimum problem at 50 cm from the ground of the North House should not be lower than 5℃

(4) After the indoor plastering project is completed, the indoor temperature shall be kept at not less than 5℃ within 7d. Plaster layer can be heated to accelerate drying, and attention should be paid to ventilation and moisture removal when heated with hot air.