Summary of the knowledge points about "temperature" in the practice of construction of a building: (according to the 24 new edition of the textbook).
2. Masonry engineering:
The water temperature of mortar mixing should not exceed 80, the heating temperature of sand should not exceed 40, and the cement should not be directly discharged with hot water above 80; The consistency of the mortar should be appropriately increased compared with room temperature, and the workability of the mortar should not be adjusted by adding water twice.
During masonry construction, the mortar temperature should not be lower than 5. When there is no requirement in the design, and the minimum temperature is equal to or lower than -15, the strength grade of masonry mortar should be increased by one level compared with normal temperature construction.
The temperature difference between bricks and mortar should be controlled within 20 and should not exceed 30.
The mortar mixed on site should be mixed with the mixing, and when the maximum temperature exceeds 30 during the construction period, it should be used within 2 hours.
The use of grouting method masonry masonry, during the construction of the temperature exceeds 30, the length of paving slurry shall not exceed 500mm.
3. Reinforcement engineering:
The straightening and cold-drawing temperature of the steel bar should not be lower than -20. The tensile temperature of the prestressed steel bar should not be lower than -15. When the ambient temperature is lower than -20, welding is not suitable. When the ambient temperature is lower than -20, the HRB400 and above grade steel bars shall not be cold-bent.
When the wind speed at the snow or welding site exceeds the first wind welding, shielding measures should be taken, and the uncooled joints after welding should avoid touching ice and snow.
4. Concrete engineering:
1）.Before the concrete mixing of winter construction, the preheating of raw materials should meet the following requirements:
It is advisable to heat the mixed water. When only heating the mixed water can not meet the requirements of thermal calculation, the aggregate can be heated. The water temperature can be increased to 100 °C, but the cement cannot be in direct contact with water above 80 °C.
Cement, admixtures and mineral admixtures shall not be heated directly, and shall be stored in the greenhouse for preheating in advance.
2）.The machine temperature of the concrete mixture should not be lower than 10, and the mold temperature should not be lower than 5; For ready-mixed concrete or concrete that needs to be transported over a long distance, the temperature of the concrete mixture can be determined according to the thermal calculation of the transportation and conveying distance, but it should not be lower than 15. The mold temperature of large-volume concrete can be appropriately reduced according to the actual situation.
3）.The temperature measurement during concrete curing shall comply with the following provisions:
When the heat storage method or the integrated heat storage method is used, it should be measured every 4 6 hours before the critical intensity of freezing is reached.
When negative temperature culture is used**, it should be measured every 2 hours before reaching the critical intensity of freezing;
When the heating method is used, the heating and cooling stages should be measured every 1 hour, and the constant temperature stage should be measured every 2 hours.
After the concrete reaches the critical strength of freezing, the temperature measurement can be stopped.
4）.When the temperature difference between the concrete surface and the environment is greater than 20 when the mold is removed, the concrete surface should be covered in time and cooled slowly.
5）.The critical strength of the concrete poured in winter shall comply with the following provisions:
When the outdoor minimum temperature is not lower than -15, the critical freezing strength of concrete constructed by comprehensive heat storage method and negative temperature maintenance should not be less than 40mpa;When the minimum outdoor temperature is not lower than -30, the critical freezing strength of concrete with negative temperature maintenance construction should not be less than 50mpa。
6）.When pouring concrete, if the ambient temperature of the site is higher than 35, it is advisable to sprinkle water to cool down the metal formwork, and no water shall be left after sprinkling.
7）.The temperature of raw materials entering the machine should not exceed:
8）.The test of surface temperature difference, cooling rate and ambient temperature of large-volume concrete pouring body should not be less than 4 times per day and night after concrete pouring; The temperature measurement of the mold should not be less than 2 times per shift.
5. Construction requirements for steel sleeve grouting :
The use of temperature measurement and normal temperature grouting and low temperature grouting should comply with the following provisions:
When the average temperature of the day is higher than 25, the construction environment temperature and grouting mixing temperature should be measured; When the maximum temperature of the day is lower than 10, the temperature of the construction environment, the temperature of the grouting part and the temperature of the grouting mixture should be measured.
The use of room temperature grout should comply with the following provisions:
In any case, the temperature of the grouting mixture should not be lower than 5 and should not be higher than 30; When the temperature before the grouting construction begins, the construction environment temperature is lower than 5, heating and sealing insulation measures should be taken, it is advisable to ensure that the construction environment temperature and the temperature of the grouting part are not less than 5 within 24 hours from the beginning of grouting construction, and then it is advisable to continue to close and keep warm for 2D; When the temperature of the grouting construction process is lower than 0, the normal temperature grouting material shall not be used for construction.
The use of low-temperature grout and low-temperature sealing grout should comply with the following provisions:
When the maximum value of the continuous 3D construction environment temperature and the temperature of the grouting part is lower than 10, the low-temperature grouting material and the low-temperature sealing material can be used; The temperature of the construction environment and the temperature of the grouting part should not be higher than 10 in the process of grouting construction; Closed insulation measures should be taken to ensure that the temperature of the construction environment during the grouting construction is not lower than 0, to ensure that the temperature of the grouting part is not lower than -5 within 24 hours from the beginning of the grouting construction, and heating measures should be taken if necessary; When the continuous 3D average temperature is greater than 5, it can be changed back to room temperature type grout and room temperature type sealing material.
6. When paving coils by hot adhesive method and melting hot-melt modified asphalt binders, it is advisable to use a special heat conduction oil furnace for heating, the heating temperature should not be higher than 200, and the use temperature should not be lower than 180.
7. The construction environment temperature of the isolation layer shall comply with the following provisions:
Dry-laid plastic film, geotextiles, and coils can be constructed at negative temperature;
Paving low-strength grade mortar should be 5 35.
8. Environmental temperature requirements for insulation layer construction:
Dry-paved insulation can be applied at negative temperatures;
The block insulation material pasted with cement mortar should not be less than 5;
Spraying rigid foam polyurethane should be 15 35, the relative humidity of the air should be less than 85%, and the wind speed should not be greater than **;
Cast-in-place foam concrete should be 5 35;
Construction will be suspended in rainy, snowy, and windy weather above level 5.
9. Waterproof engineering:
1）.The winter construction of waterproof concrete should take moisturizing and thermal insulation measures, the difference between the central temperature and the surface temperature of the large volume waterproof concrete should not be greater than 25, the difference between the surface temperature and the atmospheric temperature should not be greater than 20, the temperature gradient should not be greater than 3 d, and the curing time should not be less than 14 days.
2）.Cement mortar waterproofing layer:
The cement mortar waterproof layer can be used on the front or back surface of the main structure of underground engineering, and should not be used for underground engineering waterproofing that is subject to continuous vibration or temperature higher than 80.
The cement mortar waterproof layer shall not be constructed in rainy days, level 5 and above winds. During winter construction, the temperature should not be lower than 5. In summer, it is not suitable to work above 30 years or under the scorching sun.
After the final setting of the waterproof layer of cement mortar, it should be cured in time, and the curing temperature should not be lower than 5, and the surface of the mortar should be kept moist, and the curing time should not be less than 14d.
3）.Indoor waterproof layer construction: The construction environment temperature of residential indoor waterproof project should be 5 35.
4）.The waterproof project should not be constructed at a temperature higher than the maximum construction environment of the waterproof material, and should avoid construction under the scorching sun. The maximum temperature control of the construction environment of waterproof materials is shown in the table
5）.Winter construction environment temperature requirements for waterproofing projects:
10. Construction of wall finishing engineering:
In winter, the indoor temperature of the construction should not be lower than 5, the relative humidity should be below 85%, and the heating conditions should be carried out, and the room temperature should be kept balanced and should not change suddenly.
11. When the average outdoor daily temperature is stable for 5 consecutive days and lower than 5, it will enter the winter construction.