(3) The floor temperature measuring holes shall be arranged at a spacing of no more than 5m in the vertical and horizontal directions.
3.
(3) High alumina cement shall not be used for concrete mixed with antifreeze.
(5) Cast in situ reinforced concrete column: a temperature measuring hole is set at the lower end of each column.
(7) When the negative temperature curing method is adopted, it shall be measured every 2h before reaching the freezing critical strength.
With the coming of winter, many photovoltaic projects will enter the severe winter mode.
(2) The temperature of concrete out of the tank and into the mold shall be tested at least 4 times per shift.
The filling in winter shall meet the following requirements: Q) Ice and snow and thermal insulation materials on the base shall be removed before filling; (2) Frozen soil shall not be used for filling within 1m of the surface layer of fill slope; (3) The frozen soil block in the filler shall be evenly distributed and compacted layer by layer, and its content shall meet the design requirements.
If it is necessary to construct in winter, the construction method shall be determined after technical and economic comparison.
The water brought in by aggregates and the water in antifreeze solution shall be deducted from the mixing water.
How is the compressive strength of winter concrete specified? (1) The concrete prepared with Portland cement or ordinary Portland cement is 30% of the standard value of designed concrete strength.
█ What are the ways to add concrete admixtures in winter? (1) For concrete poured in winter, it is better to use chlorine free salt antifreeze, and for concrete with high frost resistance requirements, it is better to use air entraining agent or air entraining water reducing agent.
The measuring position of the temperature measuring element shall be 20mm below the structure surface.
(6) Before concrete pouring, a 150mm long (10mm diameter) white iron pipe shall be made in advance, and both ends shall be sealed with adhesive tape.
█ What are the special features of concrete curing in winter construction? ⑴ It is strictly prohibited to water when curing under negative temperature and the exposed surface must be covered.
How to arrange the temperature measuring hole of concrete for winter construction that is not less than 3mino█ left in the temperature measuring hole? (1) The temperature measuring hole is generally set at the representative structural part and the part with large temperature change and easy cooling.
(4) The outlet temperature of concrete mixture should not be lower than 10 ° C, and the molding temperature should not be lower than 5 ° CO █ What are the requirements for winter concrete pouring? ⑴ Ice, snow and dirt on the formwork shall be removed before concrete pouring.
The plowing depth should be determined according to the local climate conditions, generally not less than 30cm.
█ Concrete structure engineering 1.
The hole depth shall be 1/3 of the wall thickness, and shall not be less than 10cm.
Each room with an area of no more than 20 dishes can be provided with a temperature measuring hole, which is perpendicular to the plate surface and has a depth of 1/3 to 1/2 of the plate thickness.
(3) Formwork and insulation shall not be removed until the concrete has cooled to 5 ° C.
(2) The concrete prepared with slag Portland cement shall be 40% of the designed concrete strength standard value, but the concrete not greater than C10 shall not be less than 5.0N/m 2.
What should we pay attention to during winter construction? Let me talk with you.
(4) The aggregate used for concrete must be clean and free of ice, snow and other frozen substances and minerals that are easy to crack.
(2) The cement strength grade shall not be lower than 32.5, the minimum cement consumption shall not be less than 300kg/m3, and the water cement ratio shall not be greater than 0.6.
(2) The water cement ratio of concrete shall be strictly controlled.
The thickness of each layer of soil paved in winter filling shall be reduced by 20%~25% compared with that in normal temperature construction, and the reserved settlement shall be appropriately increased compared with that in normal temperature construction.
(4) When the temperature difference between the concrete and the outside is greater than 20 ° C, the concrete surface after formwork removal shall be temporarily covered to cool it slowly.
(3) Before mixing, the mixer shall be flushed with hot water or steam, and the mixing time shall be 1.5 times of the mixing time at room temperature.
(8) The temperature measurement can be stopped after the concrete reaches the freezing critical strength.
█ Instructions for earthwork excavation: When the anti freezing method is used for earthwork excavation, the insulation material can be used to cover or the topsoil can be plowed and scarified before freezing.
(4) When the wall thickness is 20cm or less, a temperature measuring hole shall be set on one side, and the hole depth shall be 1/2 of the wall thickness; When the wall thickness is greater than 20cm, temperature measuring holes shall be set on both sides.
█ Instructions for backfilling in winter construction 1.
(3) During physical temperature measurement, the temperature measuring element shall be isolated from the external temperature by taking measures.
█ What should be paid attention to in winter concrete temperature measurement? (1) The weather temperature is measured 4 times every day and night at 8 o’clock, 12 o’clock, 16 o’clock and 20 o’clock respectively, and the temperature is recorded.
(2) The temperature measuring hole on the beam shall be perpendicular to the axis of the beam, and the hole depth shall be 1/3 to 1/2 of the beam height.
2.
The key to earthwork construction in winter is backfilling.
Anti freezing measures shall be taken after filling and before ground construction.
The temperature measuring hole shall form a 30 ° inclination angle with the plate surface.
During pouring, the temperature measuring pipe shall be placed according to the layout of temperature measuring hole drawn in advance.
Large area wall temperature measuring holes shall be arranged at a spacing of no more than 5m in both vertical and horizontal directions; When the area of each wall is less than 20itf, a temperature measuring hole can be set on each surface.
█ What are the requirements for concrete mixing in winter construction? (1) The preparation of antifreeze solution and the dosage of antifreeze shall comply with the relevant provisions of the current national standards.
How to prepare concrete for winter construction? Q) For the preparation of concrete for winter construction, Portland cement or ordinary Portland cement shall be preferred.
(5) Active aggregate shall not be mixed in the concrete containing potassium and sodium ion antifreeze.
The filling under the ground layer shall not contain frozen soil blocks.
⑵ The containers for transporting and pouring concrete shall be provided with thermal insulation measures.
Before construction, it is required to plan carefully and make preparations for continuous construction.
(2) When plain concrete is used, the chloride content shall not be greater than 3% of the cement weight.
█ Can earthwork be constructed in winter? Yes, but not.
(2) The initial curing temperature of concrete shall not be lower than the specified temperature of antifreeze, and insulation measures shall be taken immediately when the specified temperature is not reached..
