What are the concrete curing methods for winter construction?
1, as far as possible to speed up the concrete pouring, reduce heat loss, and ensure that the concrete mixture into the mold temperature is ≥5℃. When pouring thick integral structural concrete in layers, the temperature of the poured concrete layer should not be lower than 2℃ before being covered by the upper concrete.
2. After leveling and plastering of concrete, it should be covered with plastic film and thermal insulation materials (such as blankets and grass felt) immediately, and the thermal insulation coverage of bare concrete surface should be strengthened. The thermal insulation thickness of corner parts should be increased to 2-3 times that of surface parts. Rub 1-2 times between initial setting and final setting. When the average temperature of the day is lower than 5℃, water conservation is not allowed.
3. When the heat storage method is used for curing, pouring, vibrating and covering should be carried out at the same time to reduce heat loss; Thermal insulation and moisturizing materials must be closely covered on the surface of formwork or concrete, and windproof facilities should be set on the windward side to form a closed enclosure; For the angular parts of thin structures, heat preservation should be strengthened; The holes in the structure should be temporarily blocked.
Concrete has the characteristics of abundant raw materials, low price and simple production technology, so its consumption is increasing. At the same time, concrete also has the characteristics of high compressive strength, good durability and wide range of strength grades. These characteristics make it widely used, not only in various civil engineering, but also in shipbuilding, machinery industry, marine development, geothermal engineering and so on. Concrete is also an important material.
The most important mechanical properties of concrete after hardening refer to the ability of concrete to resist pressure (such as compression, tension, bending and shearing). Water-cement ratio, variety and dosage of cement, variety and dosage of aggregate, and mixing, molding and curing all directly affect the strength of concrete.
According to the standard compressive strength of concrete (cube with side length of 150mm as the standard specimen, cured for 28 days under standard curing conditions, the strength grade measured by standard test method with 95% guarantee rate is called label. It is divided into C 10, C 15, C20, C25, C30, C35, C40, C45, C50, C55, C60, C65, C75, C80, C85, C90, C95 and C105.
The properties of concrete include workability of concrete mixture, strength, deformation and durability of concrete.
The workability, also known as workability, refers to the convenience of concrete mixture for the operation of various construction procedures under certain construction conditions to ensure the uniform and dense performance of concrete. Workability is a comprehensive technical index, including fluidity (consistency), cohesiveness and water retention.
Strength is the main mechanical property of concrete after hardening, which reflects the quantitative ability of concrete to resist load. Concrete strength includes compressive strength, tensile strength, shear strength, flexural strength, flexural strength and bond strength. Among them, the compressive strength is the largest and the tensile strength is the smallest.
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