After the scheme is determined, relevant personnel shall be organized to study and make disclosure to the team.
The minimum cement consumption shall not be less than 300kg / m3, and the water cement ratio shall not be greater than 0.6.
4.
Reinforcement engineering 1.
In the concrete mixed with antifreeze containing potassium and sodium ions, active aggregate or materials mixed with these substances in the aggregate shall not be used.
The component stacking site must be flat and solid without puddles and ice on the ground.
The removal time of formwork and thermal insulation is determined by calculating the maturity value of concrete and the test block of pressure test concrete under the same conditions.
The quality inspection and acceptance of reinforcement joints shall be carried out in batches.
4.
How to ensure the quality objective of the project under the condition of winter construction and rush to catch up with the construction period is the difficulty of construction technology and construction organization.
Repair in the light and re construction in the heavy will not only bring losses to the project, but also affect the service life of the project.
2.
For negative temperature welding of reinforcement, flash butt welding, electric arc welding, pneumatic welding and other welding methods shall be adopted.
Special measures for winter construction steel structure installation 1.
There must be a winter construction safety production plan and implement it according to the plan.
If nonconforming products are found, they shall be reworked immediately.
Winter construction features 1 winter construction is a season of frequent engineering quality accidents due to unfavorable construction conditions and environment, especially concrete engineering and steel structure engineering.
5.
4 arrange special personnel to measure the outdoor temperature, mortar and concrete temperature during construction and make records.
The components installed on the same day shall form a space stability system to ensure the installation quality of steel structure and the safety of structure.
3.
Anti skid measures must be taken when transporting and storing steel structures in winter.
The preparation principle is: ensure the project quality; Economic and reasonable, so that the increased cost is the least; The required heat sources and materials have reliable sources and minimize energy consumption; It can really shorten the construction period.
Winter Preparation 1 during winter construction, the construction of the project shall be carried out continuously.
When the reinforcement connector is used for connection, it can only be used after negative temperature test.
During the installation of high-strength bolt joints, the friction surface of components must be clean, free from snow, ice, rain, contact with soil, oil and other dirt.
5.
The uncooled joints after welding shall avoid touching ice and snow.
Special machines and tools for installing steel structures under negative temperature shall be inspected according to the requirements of negative temperature.
2 before winter, special personnel shall be organized to prepare winter construction scheme.
That is, the project is dry in winter, and most of them begin to be exposed in spring, which brings great difficulty to the accident treatment.
3.
2.
During welding, defects such as overheating, burns, biting and cracks shall be strictly prevented.
Concealment and lag of quality accidents.
3.
When the components of the same model are stacked, the levelness of the components must be ensured, and the cushion blocks must be on the same vertical line to prevent the components from sliding.
The admixture added into the concrete should be chlorine free salt type, which can effectively improve the process performance of the concrete, improve the durability of the concrete, ensure the early strength in the low temperature period and the hardening under the negative temperature, and prevent early freezing.
4.
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.
Reinforcement used under negative temperature conditions shall be inspected and inspected during construction; The reinforcement shall be protected from impact and scoring during transportation and processing.
Prepare the winter reinforcement welding operation instruction in advance, and organize the welding personnel to study to avoid blind construction.
3.
Before the installation of steel structure, in addition to the routine inspection, the component quality must be rechecked in detail according to the negative temperature conditions.
6.
If the component deformation caused by missing inspection in manufacturing and transportation and stacking is greater than the regulations and affects the installation quality, it must be repaired and corrected on the ground, and can be lifted and installed only after meeting the design requirements and specifications.
3 keep in touch with the local meteorological station, receive the weather forecast in time to prevent the sudden attack of cold current.
4.
When the steel cable for binding and lifting steel members is in direct contact with the hook, anti-skid spacer shall be added.
7.
2.
The appearance of welded joints shall be inspected by welders first, and then accepted by quality inspectors.
During the winter construction of formwork works, whether to add thermal insulation layer on the outside of formwork and the thickness of thermal insulation layer shall be determined by thermal calculation.
Wind proof and shelter measures shall be taken for site binding, and the ice and snow on the reinforcement shall be removed in time.
When the outdoor air temperature is too low, necessary sealing and thermal insulation measures shall be taken for the reinforcement processing shed to ensure that the reinforcement will not be bent and formed with straight thread at too low temperature.
5.
In order to ensure the mixing temperature of concrete, the heating temperature of water must be strictly controlled..
The aggregate used for mixing concrete shall be clean and free from ice, snow, frozen blocks and other substances prone to frost cracking.
When there is snow, ice and condensation on the components, they shall be removed before installation, but the coating shall not be damaged.
All gusset plates lifted at the same time with components, hanging ladders used by installers, fixtures and ropes for correction must be bound firmly.
Hire consultants and experts to evaluate, screen winter construction methods and conduct special tests.
When welding must be carried out, effective shielding and protection measures shall be taken.
Before stud welding, the welding current, welding time and other parameters shall be measured according to the negative temperature value to ensure the welding quality of stud under negative temperature.
8.
The planning and preparation time of winter construction are strong.
After the steel structure is installed at negative temperature, it shall be corrected immediately and permanently fixed immediately after correction.
Portland cement and ordinary silica cement with high hydration heat shall be preferred, and the cement grade shall not be lower than C42 Number five.
7.
This is because the preparation time is short and the technical requirements are complex.
Welding shall not be carried out on site in rainy and snowy weather.
Concrete works 1.
There are often some quality accidents, which are caused by the lack of follow-up and hasty construction.
6.
When directly using lifting rings and lifting lugs to lift components, check whether the connecting welds of lifting rings and lifting lugs are damaged.
