Building construction is sometimes a long-term process, and it is inevitable to experience winter. If you don't pay special attention at this time, it will cause a major accident to the project quality. Therefore, it is very important to carry out the construction at 5 degrees Celsius above zero as much as possible. Therefore, it is very important to control the temperature during construction in winter. 1 Getting ready is the guarantee for the success of seasonal housing construction. First of all, we should pay attention to collecting the data of winter temperature change on the construction site in advance. As the Code for Winter Construction of Building Engineering (JJ104-97) stipulates that winter construction will begin when the daily average outdoor temperature is stable below 5℃ for five consecutive days, it is necessary to make preparations and prevent in advance before the project is about to enter winter construction, eliminate unfavorable factors in the bud, collect local meteorological data in advance, and understand the local temperature change, duration, minimum temperature and maximum wind force. Secondly, prepare materials for winter construction. 2 Influence of project progress on project progress Before the project enters winter construction, it is the main measure of winter construction to prepare technical documents for winter construction in advance as technical guidance documents for winter construction. Technical documents for winter construction must include construction scheme and construction organization design or technical measures. The construction scheme and construction organization design or technical measures include the following main contents: the production task arrangement and deployment of winter construction; Construction materials approach plan; Labour force plan; Planning and deployment of heat sources and equipment; Key points of project quality control in winter construction personnel training plan: key points of safe production in winter; Construction process and schedule arrangement; Construction methods and technical measures of various subdivisional works. The key of the project lies in the training and management of construction personnel. 3. 1 Do a good job in the training of construction personnel. Because winter construction is operated under negative temperature, it is not familiar with the rules of winter construction, which is easy to cause engineering quality accidents. In order to ensure the engineering quality, personnel training must be carried out before winter construction. The training content is: 1). Learn the national and local norms, standards and regulations on winter construction, such as the Code for Winter Construction of Building Engineering (JJ104-97). 2) Learn the basic theoretical knowledge and construction methods of winter construction. 3.2 Technical disclosure before winter construction The purpose of technical disclosure is to prevent construction operators from violating winter construction laws, resulting in improper operation and man-made quality accidents. The key points of technical disclosure before construction are: 1) the use of raw materials. 2) heating or protecting raw materials. 3) Temperature measurement of raw materials or finished products. 4) Protection or maintenance of finished products. 3.3 to do a good job of raw materials and material mixture ratio inspection and second interview. In winter construction, all kinds of raw materials need to be rechecked to prevent unqualified materials from being used in the project. In winter concrete construction, some additives are often used. With the constant change of temperature, there are many fake and shoddy products. If it is directly used in the project without re-inspection, it may bring serious consequences to the project. In order to eliminate the factors that cause the hidden danger of engineering quality, it is necessary to re-examine the raw materials used in the project. 4. Strengthen quality management in an all-round way. 4. 1 Frost-resistant mortar method is mainly used in masonry construction in winter. 1) The content of antifreeze should be based on the air temperature at 13 and the experimental mixture ratio. 2) When the outdoor temperature is below-10℃ and the construction personnel need to heat raw materials, water heating should be given priority. When the temperature calculated by thermal engineering cannot be met, the sand should be heated again, but it should be noted that the water temperature should not exceed 80℃, the sand temperature should not exceed 40℃, and the cement should not be heated, but it should be placed not lower than. Enter the room at 30℃. 3) When the temperature is in the range of-10~20℃, the service temperature of masonry mortar is+10℃. Pay attention to the temperature loss of mixed mortar during transportation, storage and use, and it is best to use it with mixing. 4) The operator shall build mortar joint according to the trinity masonry method, and the mortar joint shall be controlled within10 mm. After the brick masonry is completed on the same day, the surface shall be covered with thermal insulation materials. 5) The ice, frost and snow on the brick should be removed, and watering is generally not allowed. Clinker-free cement, lime mortar or clay mortar shall not be used in winter construction masonry projects, and ice cubes shall be removed from the sand. 6) After daily masonry, the masonry surface shall be protected and covered in time, and mortar shall not be left on the masonry surface. 4.2 Control points in the process of reinforcement engineering construction. 1) The most important thing in winter steel bar construction is the welding of steel bars. Welding quality is directly related to the safety of engineering structures. There are many factors affecting the welding of steel bars in winter. Before rebar welding, trial welding must be conducted according to local construction conditions and temperature conditions. During the trial welding, the welding parameters and welding process should be adjusted according to the temperature conditions. After the welding parameters and process are determined, a trial welding should be carried out. Trial weldments should be sent to the laboratory for experiments, and then batch welding should be carried out. 2) Coated covered electrode, flux flux or coated covered electrode are very susceptible to moisture during transportation and storage in winter. The use of wet flux or covered electrode will make the gas mixed in the welding pool stay in the welding meat, resulting in blowholes, which will affect the quality of welded joints. When covered electrode or flux is used, covered electrode or flux should be baked according to the requirements of the manual and dried before use. 4.3 Key points of concrete engineering construction quality control. Control the heating temperature of raw materials. The heating of concrete raw materials in winter construction is an important factor to ensure the early strength growth of concrete. In the process of construction, it is necessary to determine the heating temperature of raw materials, take heating measures, measure the temperature regularly, ensure that the heating temperature meets the requirements, and control the temperature of concrete entering the mold. In general, the pouring temperature of concrete should not be lower than 2 degrees. If the temperature is too low, it will easily lead to the rapid cooling of fresh concrete, which will reduce the concrete to freezing point temperature in a short time and affect the early strength growth of concrete. Do a good job of retaining test blocks. According to the specification, there are not less than 2 groups (6 blocks) of test blocks in winter construction, which are maintained under the same conditions as the structure, and are used to test the strength of concrete before freezing and strengthen the finished product maintenance after 28 days of normal temperature maintenance. The maintenance management of concrete in winter is an important measure to ensure the quality of concrete. For newly poured concrete, first, do a good job of covering and heat preservation, and check it frequently. The other is to do a good job of concrete temperature measurement, and keep abreast of the internal temperature of concrete to ensure that the initial setting period of concrete is not frozen. Key control points in structural engineering construction. High strength bolt connection in steel structure engineering construction. The quality of high-strength bolt connection is an important factor affecting the quality of steel structure. The torque coefficient in the product manual of high-strength bolt is the calibration value at room temperature. There are many factors that affect the torque coefficient, such as ambient temperature, final tightening time and tightening speed. , especially the ambient temperature. Generally speaking, the torque coefficient in the product manual is the calibrated value at room temperature, so it should be calibrated again at negative temperature. Otherwise, it will still be controlled according to the numerical value given in the manual, otherwise the tensile stress of the bolt may be caused. Negative temperature welding in winter. There is a great difference between negative temperature welding in winter and normal temperature. When welding, the welder should be trained to master the rules of negative temperature welding, and the covered electrode should be baked according to the requirements of the manual. After drying, the welding quality and structural safety can be guaranteed. 4.4 Technical measures. The heat preservation and heating method is called normal temperature curing technology, and its specific method is: 1) heating raw materials in advance to make the concrete still have a certain normal temperature after stirring and vibration, wrapping the poured components with heat preservation materials, and manually heating if necessary, so as to gradually harden the concrete under the normal temperature condition. 2) raw materials are preheated, so it is most convenient to heat water, the temperature is easy to control, and the heat capacity of water is large. Heating water can bring more heat to concrete, but heating stone is uneconomical. Therefore, when the daily average temperature during the construction period is higher than 5℃, only heating water can meet the requirements. 3) When the cement meets 80℃ hot water, false coagulation or caking will occur, so when the water temperature is higher than 60℃, the feeding order will be changed, so that the water is preheated with the aggregate first, and then the cement is put into formal mixing. 5. Formulate measures to deal with emergencies. There are many factors that cause safety accidents because of the low construction temperature in winter. Before construction, corresponding winter safety construction measures should be formulated, necessary safety protection articles should be equipped, safety education should be given to construction personnel, especially for aerial work and special types of work, and on-site construction management should be strengthened to ensure the safe construction of the project. Although winter construction does not happen often, once it happens, it will affect the quality and progress of the project, and improper measures will bring hidden dangers to the quality of the project. Therefore, it is necessary to take preventive measures before the project is about to enter the winter period and control them during the construction period.
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