Therefore, in addition to thermal insulation materials, some covering materials, such as dense mesh net and straw curtain, shall be prepared for winter construction on the construction site
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antifreeze is often mixed in winter construction concrete
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Common concrete admixtures include fly ash, slag powder and pozzolan
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According to the test data of our company, the 28d strength of concrete will decrease by 3.7MPa for every 10kg / m3 water added; Adjust the consistency of concrete by adding water
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According to the data, the concrete is frozen immediately after forming, and its strength loss rate is as high as 30 ~ 70%（ 2) Some covering materials shall be prepared at the construction site in winter
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Its main component is sodium nitrite, which can reduce the freezing point in the concrete mixture, prevent the frost expansion damage caused by the construction of concrete under negative temperature in winter, and ensure the normal construction of concrete under negative temperature
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Therefore, the construction site shall be strictly controlled and no water shall be added to the concrete truck
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It is strictly forbidden to increase the slump by adding water at the construction site（ 2) When the concrete of two strength grades is poured at the same time, the concrete truck shall be equipped with strength grade signboard
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The newly poured concrete is not covered and insulated, so that the floor concrete with large heat dissipation surface will quickly cool in the negative temperature environment, so that the liquid phase has reached the freezing point when the concrete does not reach the critical frost resistance strength
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It is forbidden to use salt instead of sodium nitrite, because the salt contains chloride ions, which will rust the reinforcement
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The pump worker and the construction personnel shall also be in close contact to prevent mispouring of concrete（ 3) Plastering the pouring surface before the final setting of concrete is conducive to restraining surface cracks and improving the quality of concrete surface
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“Double mixing” technology is often used in engineering practice, that is, adding fly ash and slag powder at the same time
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Autumn I
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Antifreeze is mainly composed of antifreeze, early strength, air entraining, water reducing and other components
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If there is infringement, contact us to delete it
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The secondary vibration process is adopted for mass concrete, that is, it is vibrated again at an appropriate time and position after concrete pouring and before solidification, so as to eliminate the water and voids generated in the lower part of coarse aggregate and horizontal reinforcement due to bleeding, increase the compactness of concrete, reduce internal microcracks, improve concrete strength and improve crack resistance（ 2) The pouring surface of mass concrete shall be plastered and pressed twice in time
3、 Construction measures for mass concrete (1) secondary vibration process shall be adopted for concrete pouring
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Snowfall is frequent and heavy in winter
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After the beam and slab structural reinforcement is bound and before pouring concrete, it shall be covered to avoid snow falling into the beam and slab formwork, which will affect the construction quality and progress
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After each concrete pouring, in addition to the conventional curing of ordinary concrete, thermal insulation and curing shall be carried out in time according to the requirements of temperature control technical measures
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Disclaimer: the content comes from the Internet
.
Due to various reasons, the slump of concrete at the beginning of pouring is very small
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The types of concrete admixtures mainly include water reducing agent, pumping agent, antifreeze, waterproof agent, early strength agent, retarder, expansion agent, air entraining agent, etc
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Random addition of water during concrete pouring is a common adverse phenomenon, which seriously affects the later strength of concrete
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When it is difficult to pump, the concrete fluidizing agent can be used for secondary fluidization to achieve the pumping effect
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The strength will decrease by 1MPa for every 1cm slump increase
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In particular, the floor concrete shall be rubbed with a wooden trowel for more than two times after pouring to eliminate early cracks before the final setting of the concrete
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After the beam and slab structural reinforcement is bound, it shall be covered before pouring concrete
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Especially grade I fly ash, slag powder and silica fume have good application effects
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The high strength grade shall be poured first, and then the low strength grade shall be poured
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II Quality control of concrete pouring process (1) it is strictly prohibited to add water during concrete transportation, transportation and pouring
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selection of raw materials for ready mixed concrete
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Before the initial setting of concrete or after the pre settlement of concrete, the secondary plastering treatment process is adopted on the surface and covered with plastic film in time, which can effectively avoid the rapid loss of water on the concrete surface and dry shrinkage cracks（ 3) Mass concrete shall be subject to thermal insulation and moisturizing curing
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Summary of technical experience of ready mixed concrete construction autumn2021 / 08 / 07, combined with the common problems encountered in our daily concrete construction, summarizes some construction technical experience to learn and exchange with you, hoping to learn from future projects and jointly improve the quality of concrete engineering
.
4、 Winter construction (1) antifreeze concrete shall be used during winter construction, and covering and thermal insulation shall also be carried out
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The ordinary, high-strength and high-performance concrete prepared by this technology can save cement, improve the workability, strength and durability of concrete, significantly reduce the hydration heat of mass concrete, and meet the construction technical requirements of different projects
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The construction site often mistakenly believes that adding antifreeze will be all right
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If the beam and slab reinforcement has been bound at the construction site and it suddenly snows at night, a lot of snow will fall into the beam and slab structure formwork and cannot be constructed normally
.
