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CN-121992944-A - Concrete pouring method for abrupt cross section

CN121992944ACN 121992944 ACN121992944 ACN 121992944ACN-121992944-A

Abstract

The invention discloses a concrete pouring method with a sudden change section, which optimizes the performance parameters of each layer of concrete according to a section sudden change coefficient K through the integrated process of sudden change section parameterization analysis, concrete mix proportion gradient design, adjustable template support, layered synchronous pouring and intelligent maintenance, optimizes compactness and heat dissipation of a large-section main body layer, improves strength and impermeability of a small-section main body layer, realizes seamless connection and uniform compaction of a sudden change part by matching with flexible template support and ultrasonic auxiliary vibration, and accurately controls temperature and humidity of an intelligent maintenance system to reduce crack risk. The invention obviously improves the bonding strength (more than or equal to 1.5 MPa) and compactness (the void ratio is less than or equal to 2 percent) of the concrete with the abrupt cross section, reduces the crack occurrence rate by more than 85 percent, improves the construction efficiency by 40 percent, and is suitable for the construction of structures such as brackets of industrial plants, variable cross sections of bridge pier columns, high-rise building conversion layers and the like.

Inventors

  • XU GUANGYUN
  • FENG QUN
  • WU LONGFEI

Assignees

  • 中国五冶集团有限公司
  • 五冶集团上海有限公司

Dates

Publication Date
20260508
Application Date
20251231

Claims (10)

  1. 1. The concrete pouring method with the abrupt cross section is characterized by comprising the following steps of: Step S1, parameterized analysis of abrupt cross section Establishing a three-dimensional model with an abrupt cross section through a BIM technology, calculating a cross section abrupt change coefficient K, and dividing a transition joint layer, a large-cross section main body layer and a small-cross section main body layer; step S2, gradient design of concrete mixing proportion The transition joint layer has a water gel ratio of 0.38-0.42, slump of 180-200mm, 0.05-0.1% of polycarboxylic retarder, 28d compressive strength 5-10MPa higher than that of the large-section main body layer, the large-section main body layer has a water gel ratio of 0.43-0.47, slump of 160-180mm, 0.03-0.05% of air entraining agent, and the small-section main body layer has a water gel ratio of 0.35-0.38, slump of 140-160mm, and 5-8% of silica fume is doped; Step S3, adjustable template support The method comprises the steps of adopting a combined steel template, arranging a flexible rubber gasket with the thickness of 5-8mm on a transition joint layer, controlling the verticality deviation of the template to be less than or equal to 3mm/m through a hydraulic jacking system, and sealing a spliced seam by using a water-swelling water stop strip; S4, layered synchronous pouring Firstly pouring a small-section main body layer, synchronously pouring a transition joint layer, and finally pouring a large-section main body layer in a layered pushing manner; Step S5, intelligent maintenance Covering the moisturizing film 4-6 hours after pouring, monitoring the internal temperature by a temperature sensor, starting spraying when the internal and external temperature difference exceeds 25 ℃, maintaining for more than or equal to 14 days, and performing additional steam curing on the transition joint layer.
  2. 2. The method for pouring concrete with abrupt cross sections according to claim 1, wherein in the step S1, the thickness of the transitional joint layer is 0.3-0.5 times of the side length of the small cross section, and in the step S5, the curing condition is 40-50 ℃ and the humidity is more than or equal to 90% and is 3d.
  3. 3. The method according to claim 1, wherein in the step S2, the transition joint layer adopts a double doping technique, and 2-3% of fly ash is doped in addition to retarder.
  4. 4. The method according to claim 1, wherein in step S4, ultrasonic-assisted vibration is applied only to the joint surface of the transition joint layer and the large-section main body layer, and vibration is performed for 30-60S per casting layer.
  5. 5. The method according to claim 1, wherein in step S5, the temperature sensor arrangement pitch is 500-800mm, the monitoring data is transmitted to the control system in real time, and the spray frequency and the steam supply are automatically adjusted.
  6. 6. The method for pouring concrete with abrupt cross sections according to claim 1, wherein in the step S1, when the section abrupt coefficient K is more than or equal to 5, the thickness of the transition joint layer is 0.4-0.5 times of the side length of the small cross section, and reinforcing steel bar meshes with phi of 6-8mm are arranged in the joint layer, and the spacing between the reinforcing steel bar meshes is 100-150mm.
  7. 7. The method for pouring concrete with abrupt cross sections according to claim 1, wherein in the step S2, the silica fume of the main body layer with small cross section adopts nano silica fume, and the specific surface area is more than or equal to 20000m2/kg.
  8. 8. The method according to claim 1, wherein in step S3, the hydraulic jack-up system is equipped with pressure sensors, the side pressure of the formwork is monitored in real time, and the pressure relief adjustment is automatically started when the pressure exceeds 30kN/m 2.
  9. 9. The method for pouring concrete with abrupt cross sections according to claim 1, wherein in the step S4, the pouring height difference between the small-section main body layer and the transition joint layer is controlled to be less than or equal to 100mm during layered synchronous pouring.
  10. 10. The method for pouring concrete with abrupt cross sections according to claim 1, wherein in the step S5, the steam curing adopts a sectional heating mode, the initial heating rate is less than or equal to 10 ℃ per hour, the constant temperature curing is carried out after the temperature reaches 40-50 ℃, and the cooling rate is less than or equal to 8 ℃ per hour at the end.

Description

Concrete pouring method for abrupt cross section Technical Field The invention relates to the technical field of concrete pouring, in particular to a concrete pouring method with an abrupt cross section. Background The concrete pouring is a construction process of pouring concrete into a mould until plasticization, is widely applied to civil and architectural engineering, and is generally prepared by adopting P.S42.5slag Portland cement, matching with fine sand, stones with the particle size of 16-30mm, FJ-1 pumping agent and the like, and finishing preparation works such as operator training and the like before construction. In the construction engineering, a concrete structure with an abrupt section (such as bracket, pier column variable section, conversion layer, etc.) has a design that the section size is suddenly increased or reduced due to the stress requirement. The traditional pouring method mainly adopts integral one-time pouring or secondary connection after sectional pouring, but has the technical defects that firstly, the concrete fluidity and the setting time of the upper section and the lower section of the abrupt part are not matched, the bonding strength of the bonding surface is insufficient, cold joints and shrinkage cracks are easy to generate, secondly, the compactness of the concrete with a large section and the concrete with a small section is uneven, the concrete with a small section is easy to form honeycomb pitting surfaces due to insufficient vibration, the temperature cracks are easy to generate due to unsmooth heat dissipation of the large section, thirdly, the rigidity of a template support is insufficient, the stress concentration of the abrupt part is easy to cause the deformation of the template, the structural dimensional precision is influenced, fourthly, the pertinence of curing measures is poor, the moisture evaporation of the bonding surface is too fast, and the crack generation is further aggravated. These problems seriously affect the carrying capacity and durability of the abrupt cross-sectional structure, limiting the application range of the conventional method. Therefore, there is a need for a method of casting concrete with abrupt cross section that can solve the above-mentioned technical drawbacks. Disclosure of Invention Aiming at the problems in the prior art, the invention aims to provide a concrete pouring method with an abrupt cross section, which realizes seamless connection and uniform compaction of concrete at abrupt parts and improves construction quality. The invention adopts the following technical scheme: A concrete pouring method with abrupt cross sections comprises the following steps: Step S1, parameterized analysis of abrupt cross section Establishing a three-dimensional model with an abrupt cross section through a BIM technology, calculating a cross section abrupt change coefficient K, and dividing a transition joint layer, a large-cross section main body layer and a small-cross section main body layer; step S2, gradient design of concrete mixing proportion The transition joint layer has a water gel ratio of 0.38-0.42, slump of 180-200mm, 0.05-0.1% of polycarboxylic retarder, 28d compressive strength 5-10MPa higher than that of the large-section main body layer, the large-section main body layer has a water gel ratio of 0.43-0.47, slump of 160-180mm, 0.03-0.05% of air entraining agent, and the small-section main body layer has a water gel ratio of 0.35-0.38, slump of 140-160mm, and 5-8% of silica fume is doped; Step S3, adjustable template support The method comprises the steps of adopting a combined steel template, arranging a flexible rubber gasket with the thickness of 5-8mm on a transition joint layer, controlling the verticality deviation of the template to be less than or equal to 3mm/m through a hydraulic jacking system, and sealing a spliced seam by using a water-swelling water stop strip; S4, layered synchronous pouring Firstly pouring a small-section main body layer, synchronously pouring a transition joint layer, and finally pouring a large-section main body layer in a layered pushing manner; Step S5, intelligent maintenance Covering the moisturizing film 4-6 hours after pouring, monitoring the internal temperature by a temperature sensor, starting spraying when the internal and external temperature difference exceeds 25 ℃, maintaining for more than or equal to 14 days, and performing additional steam curing on the transition joint layer. Further, in the step S1, the thickness of the transition joint layer is 0.3-0.5 times of the side length of the small section, and in the step S5, the curing condition is that the temperature is 40-50 ℃, the humidity is more than or equal to 90%, and the curing time is 3d. Further, in step S2, the transition joint layer adopts a double doping technology, and 2-3% of fly ash is doped in addition to retarder. Further, in step S4, ultrasonic-assisted vibration is only applied to the joint surface of the