The unqualified products found shall be reworked immediately.
2.
2.
How to ensure the quality objectives of the project under the conditions of winter construction and catching up with the construction period is the difficulty of construction technology and construction organization.
The temperature of water shall be controlled at 70-80 β (not higher than 80 β)..
The components installed on the day shall form a space stability system to ensure the installation quality of steel structures and the safety of structures.
Anti slip measures must be taken when transporting and storing steel structures in winter.
The lighter is to repair, the heavier is to re construct, which not only brings loss to the project, but also affects the service life of the project.
The construction in winter is planned and prepared in a timely manner.
Before winter, special personnel shall be organized to prepare winter construction plan.
That is to say, the project is dry in winter, and most of them are exposed in spring, which brings great difficulty to accident handling.
The negative temperature welding of reinforcement shall adopt flash butt welding, electric arc welding, gas pressure welding and other welding methods.
Characteristics of winter construction Due to unfavorable construction conditions and environment, winter construction is the season of frequent engineering quality accidents, especially for concrete engineering and steel structure engineering.
Reinforcing bars used under negative temperature conditions shall be inspected during construction; The reinforcement shall be protected from impact and scratch during transportation and processing.
Wind proof and shielding measures shall be taken for on-site binding, and the ice and snow on the reinforcement shall be removed in time.
The welder shall inspect the appearance of the welded joints first, and then the quality inspector shall accept them.
4.
This is due to the short time of preparation, complex technical requirements, and often the occurrence of some quality accidents, which are all caused by the rush of construction due to this link.
1.
5.
The admixture mixed in the concrete should be chlorine free, which can effectively improve the technological performance of the concrete, improve the durability of the concrete, ensure the early strength in its low temperature period and the hardening under negative temperature, and prevent early frost.
Portland cement and ordinary silicon cement with high hydration heat shall be preferred, and the cement grade shall not be lower than C42.5.
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8.
The winter construction scheme shall include the following contents: construction procedures, construction methods, site layout, supply plan of equipment, materials, energy and tools, safety and fire prevention measures, temperature measurement system and quality inspection system.
Welding shall not be carried out on site in rainy and snowy weather.
7.
Winter preparation During the winter construction, the construction of the project shall be carried out continuously, and the safety production plan for winter construction must be prepared and implemented according to the plan.
If the component deformation caused by missing inspection during fabrication and transportation and stacking is greater than the specified value and affects the installation quality, it must be repaired and corrected on the ground, and it can be lifted and installed only after meeting the design requirements and specifications.
3.
The principle of preparation is to ensure the project quality; Economically reasonable to minimize the increased costs; The required heat source and materials have reliable sources.
4.
The minimum cement consumption shall not be less than 300kg/m3, and the water cement ratio shall not be greater than 0.6.
Before stud welding, welding current, welding time and other parameters shall be measured according to the value of negative temperature to ensure the welding quality of stud under negative temperature.
When the air temperature outside the room is too low, necessary sealing and thermal insulation measures shall be taken for the reinforcement processing shed to ensure that the reinforcement is not bent and straight threaded at too low temperature.
Keep in touch with the local meteorological station, receive the weather forecast in time, prevent the sudden attack of cold current, arrange special personnel to measure the outdoor temperature, mortar and concrete temperature during the construction period and make records.
The quality inspection and acceptance of reinforcement joints shall be carried out in batches.
When the steel cables for binding and lifting steel members are in direct contact with the hooks, anti-skid spacers shall be added.
In addition to the routine inspection before the installation of the steel structure, the component quality must be re inspected in detail according to the negative temperature conditions.
After the scheme is determined, relevant personnel shall be organized to learn and make disclosure to the team.
Reinforcement works 1.
The stacking site of components must be flat and solid, without puddles and ice on the ground.
Invite consultants and experts to evaluate, screen winter construction methods and conduct special tests.
2.
In order to ensure the mixing temperature of concrete, the heating temperature of water must be strictly controlled.
Special measures for winter construction Steel structure installation 1.
Concealment and hysteresis of quality accidents.
Prepare the winter steel bar welding operation instruction in advance, organize the welding personnel to learn, and avoid blind construction.
7.
During welding, defects such as overheating, burns, undercuts and cracks shall be strictly prevented.
During winter construction of formwork works, whether additional insulation layer is added outside the formwork and the thickness of insulation layer are determined by thermal calculation.
When welding is necessary, effective shielding and protection measures shall be taken.
All gusset plates lifted at the same time with components, hanging ladders used by installers, fixtures and ropes used for calibration must be bound firmly.
6.
Special machines and tools for installing steel structures under negative temperature shall be inspected according to negative temperature requirements.
The removal time of formwork and thermal insulation is determined by calculating the maturity value of concrete and the test block under the same conditions of pressure test concrete.
When the members of the same model are stacked, the levelness of the members must be ensured, and the cushion blocks must be on the same vertical line to prevent the members from slipping.
During the installation of high-strength bolt joints, the friction surface of the component must be clean, free of snow, ice, rain, soil, oil and other dirt.
3.
5.
And minimize energy consumption; It can really shorten the construction period.
The steel structure shall be corrected immediately after installation under negative temperature, and shall be permanently fixed immediately after correction.
When the reinforcement connector is used for connection, it can only be used after negative temperature test.
The aggregate used for mixing concrete shall be clean and free from ice, snow, frozen blocks and other substances liable to frost cracking.
3.
The uncooled joints after welding shall be protected from ice and snow.
6.
When lifting components directly with lifting rings and lugs, check whether the connecting welds of lifting rings and lugs are damaged.
In the concrete mixed with antifreeze containing potassium and sodium ions, the active aggregate or materials mixed with these substances in the aggregate shall not be used.
If there is snow, ice and dew on the component, it shall be cleaned before installation, but the coating shall not be damaged.
