CN115324349A - Construction method for mass concrete of linear accelerator - Google Patents
Construction method for mass concrete of linear accelerator Download PDFInfo
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- CN115324349A CN115324349A CN202210729754.5A CN202210729754A CN115324349A CN 115324349 A CN115324349 A CN 115324349A CN 202210729754 A CN202210729754 A CN 202210729754A CN 115324349 A CN115324349 A CN 115324349A
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G21/00—Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
- E04G21/02—Conveying or working-up concrete or similar masses able to be heaped or cast
- E04G21/04—Devices for both conveying and distributing
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B18/04—Waste materials; Refuse
- C04B18/06—Combustion residues, e.g. purification products of smoke, fumes or exhaust gases
- C04B18/08—Flue dust, i.e. fly ash
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G21/00—Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G21/00—Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
- E04G21/02—Conveying or working-up concrete or similar masses able to be heaped or cast
- E04G21/06—Solidifying concrete, e.g. by application of vacuum before hardening
- E04G21/063—Solidifying concrete, e.g. by application of vacuum before hardening making use of vibrating or jolting tools
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- Environmental & Geological Engineering (AREA)
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- On-Site Construction Work That Accompanies The Preparation And Application Of Concrete (AREA)
Abstract
The invention discloses a construction method of mass concrete of a linear accelerator, relating to the technical field of building construction; the method comprises the following steps: step one, preprocessing, determining elevation, installing reinforcing steel bars and erecting a template; step two, concrete is poured in layers, concrete inclined surfaces are poured in layers, vibration is carried out through a vibrating rod in the pouring process, secondary vibration is carried out before the concrete is initially set, and finally surface treatment is carried out on the concrete of the foundation bottom plate; and step three, curing the large-volume concrete, and after the large-volume concrete is poured, covering and re-heating the large-volume concrete. The invention reduces the concrete shrinkage, improves the ultimate tensile strength of the concrete, and effectively controls the occurrence and development of harmful cracks.
Description
Technical Field
The invention relates to the technical field of building construction, in particular to a construction method of mass concrete of a linear accelerator.
Background
Radiation can be generated during the operation of the linear accelerator, and in order to shield the radiation of the linear accelerator, large-volume concrete needs to be arranged for isolation; the linear accelerator has high radiation protection requirements, and after the main body is poured, the main body cracks are detected by environmental evaluation, and construction cold joints cannot occur; in order to meet the special requirement that concrete has radiation shielding performance, the radiation-proof concrete firstly needs to meet the design requirements of compactness and crack control. The compactness of concrete is mainly related to the mix proportion, the reasonable proportion, the gradation of coarse and fine aggregates and the selected raw materials can finally determine the compactness, the radiation-proof concrete puts high requirements on crack control, especially the generation of through cracks can not be caused, and the radiation-proof concrete mainly depends on the proportion of the raw materials, the field construction and the later maintenance; therefore, in order to ensure the construction quality and the radiation shielding effect of the radiation-proof mass concrete, the pouring measures and the maintenance after pouring of the mass concrete become very important.
Disclosure of Invention
The invention aims to provide a construction method of large-volume concrete of a linear accelerator, which aims to solve the problems in the prior art, reduce the shrinkage of the concrete, improve the ultimate tensile strength of the concrete and effectively control the occurrence and development of harmful cracks.
In order to achieve the purpose, the invention provides the following scheme:
the invention provides a construction method of mass concrete of a linear accelerator, which comprises the following steps:
step one, preprocessing, determining elevation, installing reinforcing steel bars and erecting a template;
step two, concrete is poured in layers, concrete inclined surfaces are poured in layers, vibration is carried out through a vibrating rod in the pouring process, secondary vibration is carried out before the concrete is initially set, and finally surface treatment is carried out on the concrete of the foundation bottom plate;
and step three, curing the mass concrete, and covering and rewarming the mass concrete after the mass concrete is poured.
Optionally, in the first step, the elevation control of the main building is used as an elevation control basis; adopting a rectangular external control method, taking a main building control point as a basis, establishing a rectangular control net, and bouncing the rectangular control net on a foundation bottom plate by using ink with a distance of 0.5 m outwards from the same side, and taking the rectangular control net as a basis for plane axis control and construction paying-off; the reinforcing steel bars are erected in a binding or mechanical connection mode; the erection template comprises the installation of a shear wall template, the checking and adjusting of the verticality and the flatness of the shear wall template, the reinforcement of the shear wall template, the acceptance of the shear wall template, the installation of a top plate support system, the installation of a top plate template and the acceptance of the top plate template.
Optionally, in the second step, vibrating rods are respectively arranged at the discharging point, the toe of the slope and the middle part of the slope, and in the pouring process, the end parts of the vibrating rods are inserted into the next layer of concrete by 50mm; in the vibrating process, the vibrating rod is pulled up and down, and the quick-inserting and the slow-pulling are performed, so that the up-and-down vibration is uniform.
Optionally, when the surface treatment is performed on the foundation bottom plate concrete, firstly, the foundation bottom plate concrete is compacted by using a coal prying plate according to the surface elevation, and a long scraper is used for leveling; secondly, before initial setting, rolling and flattening for a plurality of times by using an iron roller; and finally, before final setting, using a wooden trowel to beat, compact and level so as to close the concrete shrinkage crack.
Optionally, the coarse aggregate in the cast concrete is broken stone with the grain diameter of 1-2.5cm, the crushing index of less than 10%, the content of needle-shaped particles of less than 10% and the mud content of less than 1.0%; the fine aggregate is river sand with fineness modulus of 2.6-3.0 and mud content less than or equal to 2%; adding fly ash as an additive; the swelling agent is mixed, and the water-cement ratio is controlled to be 0.4.
Optionally, in the third step, after the large-volume concrete is poured, covering and curing the large-volume concrete, wherein the curing time is not less than 14d; maintaining under the condition of negative temperature, not watering, completely covering the surface of the outer leakage, keeping the environmental temperature not lower than 5 ℃ during the standing period, finishing the pouring for 4-6 h, and heating the concrete after final setting, wherein the heating speed is not more than 10 ℃/h, and the cooling speed is not more than 2 ℃/d; the internal temperature of the concrete does not exceed 60 ℃ in the constant temperature period, and the constant temperature curing time is determined through tests according to the requirements of the demolding strength of the component, the mixing proportion condition of the concrete and the environmental conditions; and determining the heat preservation maintenance time according to the temperature measurement result, controlling the cooling rate, and dismantling and preserving heat when the surface temperature and the atmospheric temperature are not more than 20 ℃.
Optionally, the method further comprises measuring the temperature of the large-volume concrete, wherein a plurality of temperature measuring points are respectively arranged at the wall body and the top plate, the temperature of the concrete casting is monitored at any time, the temperature rise value of the concrete casting is not more than 50 ℃, the temperature difference of the inner surface of the concrete casting is not more than 25 ℃, and the temperature reduction rate of the concrete casting is not more than 2.0 ℃/d.
Compared with the prior art, the invention achieves the following technical effects:
according to the construction method of the large-volume concrete of the linear accelerator, provided by the invention, the concrete is doped with additives such as the fly ash and the expanding agent, so that the effects of improving the strength and the compactness are achieved on the premise of ensuring the fluidity required by construction, and the use of the high-efficiency additives in the concrete can weaken the exothermic peak value of hydration heat of cement in the concrete, reduce the internal early temperature rise of the concrete, facilitate shrinkage resistance and crack prevention, and avoid the cold joint problem during the construction of the large-volume concrete, so that the leakage problem caused by the cold joint is avoided.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a schematic view of the present invention for the layered placement of concrete;
FIG. 2 is a schematic diagram of a slant for layered placement of concrete according to the present invention;
FIG. 3 is a schematic view of the vibrator bar arrangement of the present invention;
FIG. 4 is a schematic view of the present invention showing layered vibration;
FIG. 5 is a schematic view of the arrangement of the temperature measuring points of the wall body according to the present invention;
FIG. 6 is a plan view of the temperature measuring point of the top plate from-3.3 to-1.5 in the invention;
FIG. 7 is a schematic view of the plan arrangement of the temperature measuring points of the top plate of the invention from-1.5 to-0.4;
description of reference numerals: 1-first pouring, 2-second pouring, 3-third pouring, 4-fourth pouring, 5-fifth pouring and 6-vibrating rod.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a construction method of large-volume concrete of a linear accelerator, which aims to solve the problems in the prior art, reduce the shrinkage of the concrete, improve the ultimate tensile strength of the concrete and effectively control the occurrence and development of harmful cracks.
In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, the present invention is described in detail with reference to the accompanying drawings and the detailed description thereof.
The invention provides a construction method of mass concrete of a linear accelerator, which comprises the following steps:
step one, preprocessing, determining elevation, installing reinforcing steel bars and erecting a template;
and step two, concrete is poured in layers, concrete inclined surfaces are poured in layers, vibration is carried out through a vibrating rod in the pouring process, secondary vibration is carried out before the concrete is initially set, and finally surface treatment is carried out on the concrete of the foundation bottom plate, wherein cement slurry on the surface of the large-volume concrete of the bottom plate is thick and needs to be carefully treated. The concrete surface treatment achieves three-fold three-plane. Firstly, compacting by using a coal prying plate according to the surface elevation, and leveling by using a long scraper; secondly, before initial setting, rolling and flattening for a plurality of times by using an iron roller; finally, before final setting, a wooden trowel is used for patting, compacting and leveling so as to close the concrete shrinkage crack;
step three, curing the large-volume concrete, and after the large-volume concrete is poured, covering and re-heating the large-volume concrete; in order to ensure that newly poured concrete has proper hardening conditions and prevent cracks from being generated due to dry shrinkage in the early stage, after the pouring of the large-volume concrete of the bottom plate is finished, covering and curing are carried out on the large-volume concrete of the bottom plate, and the curing time is not less than 14d; maintaining under the condition of negative temperature, not watering, completely covering the surface of the leakage, not exposing, keeping the environmental temperature to be not lower than 5 ℃ during the static stop period, finishing the pouring for 4-6 h, and heating after the concrete is finally solidified, wherein the heating speed is not more than 10 ℃/h, and the cooling speed is not more than 2 ℃/d; the internal temperature of the concrete is not more than 60 ℃ in the constant temperature period, the maximum temperature is not more than 65 ℃, and the constant temperature curing time is determined by tests according to the requirements of the demolding strength of the component, the mixing proportion of the concrete, the environmental conditions and the like; and determining the heat preservation and maintenance time according to the temperature measurement result, controlling the cooling rate, and dismantling and preserving heat when the surface temperature and the atmospheric temperature are not more than 20 ℃.
Specifically, the method further comprises the steps of manufacturing a large-volume concrete test piece and measuring the temperature:
the manufacturing steps of the large-volume concrete test piece comprise the steps of checking a test mould, cleaning and brushing the test mould, and brushing a layer of mineral grease on the inner layer of the test mould. Vibrating and molding; wherein the vibration molding comprises the following steps of,
1) When the vibration table is adopted for vibration, the concrete mixture is once loaded into the test mold, and a spatula is used for inserting and tamping along the inner wall of the test mold during loading, and the mixture is slightly abundant. During vibration, the test mold is prevented from freely jumping on a vibration table, the test mold is vibrated until the surface layer presents cement paste, and redundant concrete is scraped and smoothed by a spatula;
2) After the test piece is formed, smearing the surface of the concrete within 1 to 2 hours before the concrete is initially set, and smearing the surface along a die orifice;
3) Covering the molded test piece with wet cloth or plastic cloth, standing for 1d (but not more than 2 d) in a room at 20 +/-5 ℃, and then demolding and numbering;
4) And (4) after the mold is removed, placing the test pieces into an on-site standard curing room for curing, wherein the distance between the test pieces is kept to be 10-20 mm, and avoiding directly spraying the test pieces with water.
The method also comprises a temperature measurement step, wherein due to the radiation protection requirement, the cold water pipe is not allowed to be arranged inside, the engineering adopts an external heat-preservation maintenance mode, and a temperature sensor is adopted for measuring the temperature; the temperature rise value of the concrete casting is not more than 50 ℃, the inside temperature difference (equivalent temperature without concrete shrinkage) of the concrete casting is not more than 25 ℃, and the cooling rate of the concrete casting is not more than 2.0 ℃/d; for the temperature control of mass concrete, three characteristic values are mainly considered: the mold-entering temperature, the highest temperature and the curing temperature.
Arranging temperature measuring points: as shown in fig. 5, 6 and 7, 4 temperature measuring points are arranged on the top plate of the linear accelerator along the pouring direction of the concrete, the first temperature measuring point is within 50mm of the surface of the pouring body, the fourth temperature measuring point is within 50mm above the bottom surface of the pouring body, and the distance between the pouring directions of the rest temperature measuring points is not less than 500mm. The temperature measuring point is reliably fixed and avoids the steel bars; the protection is strengthened and the damage is prevented. The wall body part is respectively provided with a temperature measuring point at the positions of-6.5 m and-4.7 m for measuring the position, and the horizontal distance is 5m. -3.3-1.5 m top plate, each side is provided with a measuring position in the middle and each corner is provided with a measuring position. -1.5-0.4 m top plate, four positioning parts are respectively arranged at four corners, and one positioning part is arranged at the middle of each side in the length direction. In the above positioning, one measuring point is respectively arranged at 500mm of the concrete surface layer, the middle of the concrete and 500mm of the concrete bottom layer.
Further preferably, in the preprocessing step, the elevation control basis of the project is the main building control elevation. The plane axis control adopts a rectangular external control method, a rectangular control net is established based on a main building control point, ink bullets are used for bouncing on a foundation bottom plate by a distance of 0.5 m outwards from the same side, and a red triangular mark is made and is used as the basis for plane axis control and construction paying-off. When the reinforcing steel bar is installed: HRB 40014's reinforcing bar adopts the ligature overlap joint, HRB40016, HRB40020, HRB 40025's reinforcing bar adopts mechanical connection, to the reinforcing bar that adopts mechanical connection, adds the diameter and the length of strict control silk head and the complete of silk head man-hour, and single silk head minimum 10 silk, encloses silk rear end and polish and level and smooth, between the multilayer reinforcing bar net piece, except setting up the drag hook according to the design, HRB40025@600 both way arrangement is established to the wall muscle, as: wall thickness control, template reinforcement, wall reinforcing steel bar protective layer thickness control and wall mesh reinforcing steel bar layer interval control; HRB40025@600mm is arranged in the top plate in a longitudinal and transverse mode to control the plate thickness. The length of the additional rib is respectively equal to the thickness of the wall and the thickness of the plate. When the template is erected, the thickness of the wall body of the machine room is 1800mm, 3000mm and 1400mm; the thickness of the top plate of the machine room is 1800mm and 2900mm; the height of the wall body is 4500mm.
Procedure for template set up: the installation of shear wall template, the straightness that hangs down of shear wall template, the inspection and the adjustment of roughness, the reinforcement of shear wall template, the acceptance of shear wall template, the installation of roof support system, roof template installation, roof template acceptance of examination. Before the construction of the template, the positioning lines of the shear wall are popped out of the bottom plate, and then HRB40025 steel bars are arranged at the position which is 20mm away from the plate surface and is 600mm away from the plate surface so as to prevent the bottom of the template from moving inwards when the template is reinforced.
-7.8 — 5.7m single-sided die: the side plates adopt 15mm thick plywood secondary keels, 40mm multiplied by 80mm wood squares are combined into one, the main keels are phi 48mm multiplied by 2.7mm double steel pipes, the inclined struts adopt 10# I-steel and are divided into an upper channel and a lower channel with the positions of 200mm, 600mm, 1100mm and 1700mm respectively, and the horizontal distance of the inclined struts is 800mm. A common template: 3000mm wall, 15mm thick plywood is adopted to the curb plate, and the secondary joist is 40mm 80mm flitch interval 120mm, and the main joist is 400mm of two steel pipe vertical spacing 400mm of 48mm 2.7mm of phi, adopts M20 split bolt horizontal spacing 400mm.1800mm wall, 15mm thick plywood is adopted to the curb plate, and the secondary joist is 40mm 80mm flitch interval 120mm, and the distance 500mm about the main joist is two steel pipes of 48mm 2.7mm phi, adopts M20 split bolt horizontal spacing 500mm. Because of the wall body is thicker, be not suitable for the reinforced concrete internal stay, adopt HRB40025 reinforcing bar interval 600mm two-way arrangement, reinforcing bar length is the wall thickness, welds electrically on the vertical reinforcing bar of wall body, still can play each layer reinforcing bar net piece interval of interval and the effect of guaranteeing outer reinforcing bar net piece protective layer thickness. In order to prevent the concrete structure from being affected by corrosion caused by long-time exposure of the inner supporting head of the steel bar, after the template is disassembled, the exposed steel bar head is manually removed by 30mm, the steel bar head is cut off by oxygen welding, rust-proof paint is dotted on the steel bar head, and the steel bar head is sealed by high-grade cement mortar.
After the construction of the foundation slab is completed, elastic lines are divided and designed according to the design area on the foundation slab according to the scheme design, then paddings are placed according to the intersection points of the elastic lines, and vertical rods are erected; the setting height of the foot sweeping rod and the step pitch of the horizontal rod are strictly set up according to the design of a scheme; the support system setting sequence is as follows: from inside to outside, from bottom to top; the tightening torque of each fastener is controlled to be 45-60N.m.
In order to ensure the construction quality and safety of the linear accelerator, in the embodiment, the pouring is divided into 5 times, the concrete pouring of the foundation bottom plate adopts 'inclined plane layering, thin layer pouring, sequential propulsion and one-time in-place', the concrete inclined plane layering pouring is shown in the figure, vibrating rods are respectively arranged at the top of a slope, in the slope and at the top of the slope, the concrete is guaranteed to be vibrated compactly and does not leak vibration, and during construction, in order to enable the concrete to be vibrated compactly, improve the compactness and the tensile strength of the concrete and reduce the shrinkage deformation, 3 vibrating rods 6 are arranged at the discharge port of the concrete pump, and each vibrating rod is arranged in three ways, as shown in fig. 3 and fig. 4. The first path is arranged at a discharging point to enable the concrete to form a natural flowing slope, the second path is arranged at a toe to ensure the lower part of the concrete to be compact, the third path is arranged in the middle of an inclined plane, and each point on the inclined plane needs to strictly control the vibration time, the moving distance and the insertion depth. The insertion points can be uniformly arranged according to a determinant and a staggered mode, the distance between the insertion points is 1.2 times of the action radius of the vibrator, and the distance between the vibrator and the template is half of the action radius of the vibrator; the end part of the vibrator is inserted into the next layer of concrete by 50mm to be integrated; when the vibrating rod is operated, the fast inserting and slow pulling are required, if the slow inserting is carried out, the surface concrete is tamped firstly, so that the lower concrete is separated, if the slow inserting is carried out, a cavity is formed after the vibrating rod is pulled out, the requirement of compaction cannot be met, and the vibrating rod is pulled up and down in the vibrating process and uniformly vibrates up and down; the vibration time of each insertion point is generally 20 s-30 s, and the concrete surface is horizontal without sinking, bubbles and mortar floating on the surface. The concrete adopts a secondary feeding method and secondary vibration, surface accumulated water is timely drained after pouring, a water collecting pit and an elevator foundation pit can be utilized to enable bleeding to flow into the water collecting pit in a centralized manner, most of the bleeding is drained by a flexible shaft pump, early maintenance is strengthened, and the tensile strength and the elastic modulus of the concrete at the early stage or the corresponding age are improved; the secondary vibration is the best method and the necessary way for solving the sinking crack of the concrete in the construction process, the secondary vibration is carried out before the initial setting of the concrete, the intermittent time of the secondary vibration is 40 to 60 minutes, the secondary vibration can be properly prolonged in the concrete added with the retarder and controlled within the range of 1.5 to 2.5 hours, but the unfavorable phenomena of over-vibration, vibrator touch on a template and the like are prevented.
The method is characterized in that the large-volume concrete is poured by adopting a layering and segmenting method, layering is beneficial to the dissipation of concrete hydrothermal heat, the heat storage amount of each pouring length is reduced, the accumulation of the hydration heat is prevented, and the temperature stress is reduced, as shown in fig. 1 and fig. 2, the arrow direction in the drawing is the concrete pouring direction, and 1 in fig. 2: n is the concrete flowing inclination, and n = 5-10; pouring for the first time 1: raft foundation (-7.8) and upper 300mm guide wall; and 2, casting for the second time: the wall body is arranged at the part (-5.7) with high span and low span, and a single-side formwork is required at the part with high span and low span, and a construction joint is reserved at the part from the safety perspective; and (3) pouring for the third time: the wall body is high and spans to the bottom of the plate (-3.3); fourth pouring 4: the bottom of the top plate is 1.8 m of the top plate surface (-1.5); and fifth pouring 5: the thickness of the other part of the top plate is 2.9 meters (-1.5-0.4). In order to meet the radiation protection requirement, the tongue-and-groove is reserved at the reserving positions of the construction joints so as to effectively control radiation.
In the embodiment, the concrete adopts the coarse aggregate with good gradation, the mud content is strictly controlled, the admixture is added, and the hydrothermal reaction and shrinkage are reduced; furthermore, aggregate with continuous gradation can be adopted, and gravel with good gradation, which has the grain diameter of 1-2.5cm, the crushing index of less than 10 percent, the needle-shaped particle content of less than 10 percent and the mud content of less than 1.0 percent, is selected as the stones; the fine aggregate is medium coarse river sand with fineness modulus of 2.6-3.0 and mud content less than or equal to 2%; the method is characterized in that a certain amount of fly ash is added into mass concrete as an additive, so that the compactness of the concrete can be increased, the cement is mainly generated by hydration heat because the temperature difference is generated by the hydration heat, the hydration heat is reduced as much as possible in order to reduce the temperature difference, the cement with low early hydration heat is adopted in order to reduce the hydration heat, the hydration heat of the cement is reduced as much as possible as the hydration heat of the cement is a function of mineral components and fineness, and the proper mineral composition is mainly selected and the fineness modulus of the cement is adjusted, so that the impermeability of the concrete can be improved, the working degree of the concrete is improved, the final shrinkage value is reduced, the cement consumption is reduced, the internal temperature rise caused by the cement hydration heat of the mass concrete can be reduced, and the temperature crack of the structure is prevented; the concrete is doped with the SY-G type expanding agent, the water cement ratio is controlled to be 0.4, the effect of improving the strength and the compactness is achieved on the premise of ensuring the fluidity of construction requirements, the use of the high-efficiency additive in the concrete can weaken the exothermic peak value of hydration heat of water in the concrete, reduce the early temperature rise in the concrete, facilitate the shrinkage resistance and the crack resistance, avoid the cold joint problem during the construction of large-volume concrete and further avoid the leakage problem caused by the cold joint.
In the description of the present invention, it should be noted that the terms "center", "top", "bottom", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The principle and the implementation mode of the invention are explained by applying a specific example, and the description of the embodiment is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (7)
1. A construction method for mass concrete of a linear accelerator is characterized by comprising the following steps: the method comprises the following steps:
step one, preprocessing, determining elevation, installing reinforcing steel bars and erecting a template;
step two, concrete is poured in layers, concrete inclined surfaces are poured in layers, a vibrating rod is used for vibrating in the pouring process, secondary vibrating is carried out before the concrete is initially set, and finally surface treatment is carried out on the concrete of the base bottom plate;
and step three, curing the large-volume concrete, and after the large-volume concrete is poured, covering and re-heating the large-volume concrete.
2. The construction method of the large-volume concrete of the linear accelerator according to claim 1, characterized in that: in the first step, the elevation control of the main building is used as the elevation control basis; adopting a rectangular external control method, taking a main building control point as a basis, establishing a rectangular control net, and bouncing the rectangular control net on a foundation bottom plate by using ink with a distance of 0.5 m outwards from the same side, and taking the rectangular control net as a basis for plane axis control and construction paying-off; the reinforcing steel bars are erected in a binding or mechanical connection mode; the building of the template comprises the installation of the shear wall template, the checking and adjusting of the verticality and the flatness of the shear wall template, the reinforcement of the shear wall template, the acceptance of the shear wall template, the installation of a top plate support system, the installation of a top plate template and the acceptance of the top plate template.
3. The construction method of the large-volume concrete of the linear accelerator according to claim 1, characterized in that: in the second step, vibrating rods are respectively arranged at the discharging point, the slope toe and the middle part of the inclined plane, and the end parts of the vibrating rods are inserted into the next layer of concrete by 50mm in the pouring process; in the vibrating process, the vibrating rod is pulled up and down, and is inserted quickly and pulled slowly, so that the vibrating rod vibrates uniformly up and down.
4. The construction method of the large-volume concrete of the linear accelerator according to claim 1, characterized in that: when the surface treatment is carried out on the foundation bottom plate concrete, firstly, the foundation bottom plate concrete is compacted by a coal prying plate according to the surface elevation, and a long scraping ruler is used for scraping; secondly, before initial setting, an iron roller is used for rolling for a plurality of times and flattening; and finally, before final setting, using a wooden trowel to beat, compact and level so as to close the concrete shrinkage crack.
5. The construction method of the large-volume concrete of the linear accelerator according to claim 1, characterized in that: the coarse aggregate in the cast concrete is selected from gravels with the grain diameter of 1-2.5cm, the crushing index of less than 10 percent, the needle-shaped particle content of less than 10 percent and the mud content of less than 1.0 percent; the fine aggregate is river sand with fineness modulus of 2.6-3.0 and mud content less than or equal to 2%; adding fly ash as an additive; the expanding agent is mixed, and the water-cement ratio is controlled to be 0.4.
6. The construction method of the large-volume concrete of the linear accelerator according to claim 1, characterized in that: in the third step, after the large-volume concrete is poured, covering and curing the large-volume concrete for not less than 14 days; maintaining under the condition of negative temperature, not watering, completely covering the surface of the outer leakage, keeping the environmental temperature not lower than 5 ℃ during the standing period, finishing the pouring for 4-6 h, and heating the concrete after final setting, wherein the heating speed is not more than 10 ℃/h, and the cooling speed is not more than 2 ℃/d; the internal temperature of the concrete does not exceed 60 ℃ in the constant temperature period, and the constant temperature curing time is determined through tests according to the requirements of the demolding strength of the component, the mixing proportion condition of the concrete and the environmental conditions; and determining the heat preservation maintenance time according to the temperature measurement result, controlling the cooling rate, and dismantling and preserving heat when the surface temperature and the atmospheric temperature are not more than 20 ℃.
7. The construction method of the large-volume concrete of the linear accelerator according to claim 1, characterized in that: the method also comprises the step of measuring the temperature of the large-volume concrete, wherein a plurality of temperature measuring points are respectively arranged on the wall body and the top plate, the temperature of the concrete casting is monitored at any time, the temperature rise value of the concrete casting is not more than 50 ℃, the temperature difference of the inner surface of the concrete casting is not more than 25 ℃, and the temperature reduction rate of the concrete casting is not more than 2.0 ℃/d.
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| CN116117975A (en) * | 2023-02-23 | 2023-05-16 | 中建八局第四建设有限公司 | Large-volume high-strength concrete experimental block template supporting, pouring and cooling method |
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