CN115385629A - Sprayed concrete for reducing resilience rate of dry spraying concrete and construction process thereof - Google Patents
Sprayed concrete for reducing resilience rate of dry spraying concrete and construction process thereof Download PDFInfo
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- CN115385629A CN115385629A CN202211028900.8A CN202211028900A CN115385629A CN 115385629 A CN115385629 A CN 115385629A CN 202211028900 A CN202211028900 A CN 202211028900A CN 115385629 A CN115385629 A CN 115385629A
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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
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D15/00—Handling building or like materials for hydraulic engineering or foundations
- E02D15/02—Handling of bulk concrete specially for foundation or hydraulic engineering purposes
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
- E21D11/105—Transport or application of concrete specially adapted for the lining of tunnels or galleries ; Backfilling the space between main building element and the surrounding rock, e.g. with concrete
-
- 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
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00034—Physico-chemical characteristics of the mixtures
- C04B2111/00146—Sprayable or pumpable mixtures
- C04B2111/00155—Sprayable, i.e. concrete-like, materials able to be shaped by spraying instead of by casting, e.g. gunite
-
- 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
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/20—Mortars, concrete or artificial stone characterised by specific physical values for the density
-
- 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
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
-
- 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
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
- C04B2201/52—High compression strength concretes, i.e. with a compression strength higher than about 55 N/mm2, e.g. reactive powder concrete [RPC]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Abstract
The utility model provides a reduce shotcrete and construction technology of dry blasting method concrete rebound rate, belongs to tunnel engineering construction technical field, can solve the concrete dry blasting work progress, because of taking place the waste of the material that causes of kick-backing and increasing dust concentration scheduling problem, the shotcrete mix proportion is cement: sand: breaking stone: water: the accelerator = 1.73. The invention also provides a sprayed concrete construction process based on the mixing ratio, and by adopting the sprayed concrete mixing ratio and the construction process, the spraying and mixing operation is carried out on the primary support of the tunnel by adopting a dry spraying machine, so that the rebound rate of the sprayed concrete is obviously reduced, the spraying and mixing quality is better, the spraying cost and the later stage spray supplementing process are saved, the construction efficiency is improved, and the economic benefit is better.
Description
Technical Field
The invention belongs to the technical field of tunnel engineering construction, and particularly relates to sprayed concrete for reducing the resilience rate of dry spraying concrete and a construction process thereof.
Background
The concrete is sprayed by a concrete sprayer, and the concrete mixture mixed with the additive is mixed with high-pressure water by utilizing compressed air or other power, sprayed onto a sprayed surface through a nozzle, and rapidly condensed and hardened to form a new concrete reinforcing and reinforcing material. The physical components and the structure of the sprayed concrete are basically consistent with those of common concrete, but the sprayed concrete is widely applied to supporting engineering of underground chambers such as highway tunnels, railway tunnels, water conservancy projects, mines and the like at present due to the advantages of convenient and quick construction, low construction cost and the like.
The concrete spraying construction is divided into three processes of dry spraying, wet spraying and wet spraying according to the process flow. The dry spraying method is that cement and aggregate are evenly stirred according to a certain proportion, the mixture is formed into material beams by a nozzle through compressed air after entering a spraying machine, the material beams are pushed to a sprayed working surface at a high speed, and mixing water is added through a water ring of the nozzle; the wet spraying method is characterized in that a proper amount of water is added into a mixture in advance, an accelerator is added when the mixture enters a spraying machine, sufficient water is supplemented, and compressed air is used for pushing a material beam formed by a nozzle of a hose to a sprayed working surface at a high speed; the wet spraying method sprays the concrete mixture which is mixed by adding water according to the mixing proportion onto the sprayed working surface. At present, wet spraying construction technology is mostly adopted in tunnel engineering, but dry spraying construction technology is adopted in some engineering with special requirements.
In the dry spraying construction, due to the limitation of a spraying process and a spraying manipulator, the rebound can be avoided in the concrete spraying construction process, the rebound rate of the sprayed concrete is 35-40% under the general condition, the great waste is caused, the dust concentration is increased, and the health of constructors is harmed. Therefore, in the dry spraying construction process, the control of the rebound rate is a key technical problem in construction.
Disclosure of Invention
The invention provides sprayed concrete for reducing the resilience rate of dry-spraying concrete and a construction process thereof, aiming at the problems of material waste, dust concentration increase and the like caused by resilience in the dry-spraying construction process of concrete.
The invention adopts the following technical scheme:
the shotcrete for reducing the rebound rate of the concrete by the dry spraying method comprises cement, sand, gravel, water and an accelerating agent, wherein the mass ratio of the cement to the sand to the gravel to the water to the accelerating agent is 1.73.
Further, the cement is ordinary portland cement.
Furthermore, the sand is grade II sand, and the fineness modulus is 2.8.
Furthermore, the particle size of the crushed stone is 5-10mm.
A construction process of sprayed concrete for reducing the rebound rate of concrete by a dry spraying method comprises the following steps:
step one, preparing concrete according to the mixing ratio of each component;
secondly, before the spraying construction, the constructor inspects and processes the sprayed rock surface;
thirdly, checking mechanical equipment, checking the equipment of machines and tools and pipelines such as wind, water, electricity and the like before the concrete spraying construction, positioning a dry spraying machine, and performing trial operation;
fourthly, spraying concrete by a dry spraying method for construction:
(1) the concrete spraying operation is sequentially carried out by segmentation, fragmentation and layering, the spraying sequence is from bottom to top, the length of the segmentation is not more than 6m, the low-lying part is approximately sprayed during spraying, and then the layering and reciprocating spraying are sequentially carried out from bottom to top;
(2) when the sprayed concrete is constructed in a segmented mode, an inclined plane is reserved in the last time of concrete spraying, the width of the inclined plane is 200-300 mm, and the concrete is sprayed after the inclined plane is washed and wetted by pressure water;
(3) the spraying in pieces is carried out from bottom to top, the concrete between the steel frames and the wall surface is sprayed firstly, then the concrete between the two steel frames is sprayed, the side wall spraying concrete is sprayed upwards from the wall feet, and the rebound cannot wrap the final spraying layer;
(4) when the layered spraying is carried out, the later layer of spraying is carried out after the former layer of concrete is finally set, if the spraying is carried out after the final setting is carried out for 1h, wind and water are firstly used for cleaning the surface of the sprayed layer, the thickness of the once sprayed concrete is determined by the fact that the sprayed concrete does not slide and fall, the cohesive force and the cohesive force of the sprayed concrete can not be influenced due to too large thickness, the rebound quantity can not be increased due to too thin thickness, the thickness of the once sprayed concrete of the side wall is controlled to be 7-10 cm, the arch part is controlled to be 5-6 cm, and the thickness of the sprayed layer is kept uniform;
(5) when the top is sprayed with concrete, in order to avoid the falling phenomenon, the interval time of two times is preferably 2-4 h, the spraying speed is proper so as to be beneficial to the compaction of the concrete, the wind pressure is overlarge, the spraying speed is increased, and the rebound is increased; wind pressure undersize, the jet velocity undersize, the compaction is little, and the concrete intensity is spouted in the influence, consequently will notice after the start and observe the wind pressure, and the initial wind pressure reaches 0.5MPa after, could begin to operate to according to nozzle ejection of compact condition adjustment wind pressure, general work wind pressure: the side wall is 0.3-0.5 MPa, and the arch part is 0.4-0.65 MPa;
(6) when in spraying, the nozzle and the sprayed surface are kept at a proper distance, the spraying angle is as close to 90 degrees as possible, so that the maximum compaction and the minimum rebound are obtained, and the distance between the nozzle and the sprayed surface is preferably 1.5-2.0 m; the nozzle should continuously and slowly move transversely and circularly, a circle is pressed for a half circle, and the annular ring drawn by a spraying hand is 40-60 cm transversely and 15-20 cm high; if the sprayed surface is covered by the steel frame and the steel bar mesh, the nozzle can be slightly deflected, but is not smaller than 70 degrees, if the angle between the nozzle and the sprayed surface is large, concrete materials can roll on the sprayed surface, an uneven wavy sprayed surface is generated, the rebound quantity is increased, and the quality of sprayed concrete is influenced;
fifthly, detecting the rebound rate of the sprayed concrete;
sixthly, spraying concrete for curing;
and seventhly, inspecting the quality of the sprayed concrete.
Further, the treatment of the sprayed rock surface in the second step comprises the following steps:
generally, the rock surface uses high-pressure water to wash floating dust and rock debris on the sprayed rock surface; when the rock surface is easy to deliquesce and argillization when meeting water, blowing the rock surface clean by high-pressure wind; if the surface is a muddy or sandy rock surface, hanging a fine reinforcing mesh;
furthermore, the meshes of the fine steel bar mesh are not more than 20 multiplied by 20mm, the wire diameter is preferably less than 3mm, and the fine steel bar mesh is fixed by using annular steel bars and anchor bolts or steel frames to be closely attached to a sprayed surface so as to improve the adhesive force of sprayed concrete and set a mark for controlling the thickness of the sprayed concrete.
Furthermore, the mark for controlling the thickness of the sprayed concrete adopts an embedded steel bar head as a mark, or an iron wire with the length 5cm greater than the designed thickness is inserted during spraying, and one iron wire is arranged every 1-2 m.
Further, the device check in the third step includes: (1) the conveying pipe can bear the pressure of more than 0.8MPa and has good wear resistance; (2) good ventilation and lighting conditions in the operation area are ensured; (3) the ambient temperature of the spraying operation must not be lower than 5 ℃.
Further, the detection method of the rebound resilience in the fifth step is as follows: the steel plate is paved on the ground before the concrete is sprayed on site, after the concrete is sprayed, the size of the ground material is calculated by measuring the length, width and height of the concrete falling on the steel plate, the total volume of the sprayed concrete is recorded during spraying, and then the rebound rate of the sprayed concrete = the volume of the ground material/the total volume of the sprayed concrete multiplied by 100% is calculated according to the following formula.
And further, curing the sprayed concrete in the sixth step to fully hydrate the cement, reducing and preventing shrinkage cracks, starting watering curing 2 hours after the sprayed concrete is finally set, wherein the curing time and the watering frequency depend on the variety of the cement and the air humidity, the curing time is not less than 14 days under any condition, and the water spraying curing is not required when the air temperature is lower than +5 ℃.
Furthermore, the sprayed concrete quality inspection in the seventh step is to inspect the surface of the sprayed concrete in time, and the surface of the concrete should be flat and compact without cracks, falling off, leaking, exposing ribs, hollowing and leaking water, and the reinforcing steel bars of the anchor rod head are not exposed.
The invention has the following beneficial effects:
the raw materials related to the mixing proportion of the shotcrete are easy to obtain, special additives are not needed, the rebound rate of the shotcrete for the preliminary tunnel support can be reduced to about 25% only by utilizing the existing raw materials through adjusting the mixing proportion, the rebound rate can be reduced by 25% -29% compared with the rebound rate of the shotcrete by the existing dry spraying method, the problem of high rebound rate of the traditional dry spraying concrete can be greatly improved, the spraying cost and the later stage spray supplementing process are saved, the spraying quality is ensured, the construction efficiency is improved, and the economic benefit and the social benefit are obvious.
Detailed Description
The technical scheme of the invention is further elaborated by combining specific implementation examples.
The invention relates to a sprayed concrete mix proportion for reducing the resilience rate of concrete by a dry spraying method and a construction process thereof, wherein the sprayed concrete consists of cement, sand, gravel, water and an accelerating agent, and the mix proportion is 1.73.
Wherein, the cement is preferably Portland cement or ordinary Portland cement, and the detection indexes of the physical properties of the cement are as follows:
the sand is II-grade sand, and the detection indexes are as follows:
the coarse aggregate of the sprayed concrete is hard and durable gravel, the aggregate with potential alkali activity is strictly forbidden to be used, the maximum particle size of stones in the sprayed concrete is not more than 10mm, the mud content is not more than 1% by weight, and the mud block content is not more than 0.25%. The gravel detection indexes are as follows:
the accelerating agent is a powder accelerating agent. Before the accelerator is used, a cement compatibility test and a cement paste coagulation effect test are carried out, the mixing amount is strictly controlled, and the initial setting time is required to be not more than 5min, and the final setting time is required to be not more than 10min. The detection indexes of the accelerator for the sprayed concrete are as follows:
the mix proportion of the sprayed concrete needs to entrust qualified detection units to give test reports, and the test reports of the mix proportion of the concrete provided by the invention are as follows:
a sprayed concrete mix proportion for reducing the rebound rate of dry spraying concrete and a construction process thereof mainly comprise the following steps during site construction:
the mixing proportion and the construction process for reducing the rebound rate of the sprayed concrete are suitable for the primary support construction of the dry-spraying tunnel, the excavated rock surface of the tunnel is required to be relatively flat without obvious holes, and if the excavated rock surface is uneven, the sprayed surface is leveled and then construction is carried out. The construction process is operated by a skilled sprayer, the water-cement ratio is strictly controlled in the spraying process, and the spraying quality is ensured.
Step1: before the concrete is sprayed to the primary support of the tunnel for construction, on-site technicians carry out technical and safe bottom crossing on constructors, and after bottom crossing, the constructors configure the concrete which meets the engineering requirements according to the mixing ratio of the concrete;
step2: and (5) inspecting and processing the sprayed rock surface. Before the spraying construction, the constructor inspects and processes the sprayed rock surface, the floating dust and rock debris on the sprayed rock surface can be washed by high-pressure water on the general rock surface, and when the rock surface is easy to deliquesce and argillization when meeting water, the high-pressure air is adopted to blow the rock surface clean. If the surface is a muddy or sandy rock surface, a fine steel bar mesh (the mesh is preferably not more than 20 multiplied by 20mm, and the wire diameter is preferably less than 3 mm) is hung and fixed by using annular steel bars and anchor bolts or steel frames to be closely attached to the sprayed surface so as to improve the adhesive force of sprayed concrete. The mark for controlling the thickness of sprayed concrete is usually embedded steel bar head, and iron wire with length greater than designed thickness by 5cm may be inserted during spraying and installed in each 1-2 m for controlling construction.
Step3: and (6) checking mechanical equipment. Before the concrete spraying construction, the pipeline circuits of machines and tools, wind, water, electricity and the like are checked, the dry spraying machine is in place, and the dry spraying machine is tested to run. (1) The conveying pipe can bear the pressure of more than 0.8MPa and has good wear resistance; (2) good ventilation and lighting conditions in the operation area are ensured; (3) the ambient temperature of the spraying operation must not be lower than 5 ℃.
Step4: and (5) carrying out concrete spraying construction by a dry spraying method.
(1) The concrete spraying operation is sequentially carried out by segmentation, fragmentation and layering, the spraying sequence is from bottom to top, and the length of the segmentation is not more than 6m. When spraying, the low-lying part is roughly sprayed flat, and then the spraying is carried out in a layering and reciprocating manner from bottom to top.
(2) When the sprayed concrete is constructed in sections, an inclined plane is reserved in the last time of concrete spraying, the width of the inclined plane is 200-300 mm, and the concrete is sprayed after the inclined plane is washed and wetted by pressure water.
(3) The spraying in pieces is carried out from bottom to top, and the concrete between the steel frames and the wall surface is sprayed firstly, and then the concrete between the two steel frames is sprayed. The side wall shotcrete should be sprayed upward from the footing so that the rebound will not wrap into the final sprayed layer.
(4) When spraying in layers, the spraying of the later layer should be carried out after the final setting of the concrete of the former layer, and if spraying is carried out after 1 hour of final setting, the surface of the sprayed layer should be cleaned by wind and water. The thickness of the once sprayed concrete is determined by the fact that the sprayed concrete does not slide and fall, and the adhesive force and the cohesive force of the sprayed concrete cannot be influenced by too large thickness, and the rebound quantity cannot be increased by too small thickness. The thickness of the side wall sprayed with concrete at one time is controlled to be 7-10 cm, the arch part is controlled to be 5-6 cm, and the thickness of a sprayed layer is kept uniform.
(5) When the concrete is sprayed on the top, the interval time between two times is preferably 2 to 4 hours in order to avoid the falling phenomenon. The spraying speed is appropriate to facilitate the compaction of the concrete. The air pressure is overlarge, the injection speed is increased, and the rebound is increased; the air pressure is too small, the jet velocity is too small, the compaction force is small, and the concrete spraying strength is influenced. Therefore, the air pressure is observed after the machine is started, the operation can be started only when the initial air pressure reaches 0.5MPa, and the air pressure is adjusted according to the discharging condition of the nozzle. General work wind pressure: the side wall is 0.3-0.5 MPa, and the arch part is 0.4-0.65 MPa.
(6) During spraying, the nozzle and the sprayed surface are kept at a proper distance, and the spraying angle is as close to 90 degrees as possible, so that the maximum compaction and the minimum rebound are obtained. The distance between the nozzle and the spraying surface is preferably 1.5-2.0 m; the nozzle should continuously and slowly move transversely and circularly, a circle is pressed for a half circle, and the annular ring drawn by a spraying hand is 40-60 cm transversely and 15-20 cm high; if the sprayed surface is covered by steel frame and reinforcing mesh, the nozzle may be slightly inclined, but it is not smaller than 70 °. If the nozzle with receive the angle size of spouting the face, can form the concrete material and spout the roll on the face by receiving, produce unevenness's wave form and spout the face, increase the rebound volume, the quality of concrete is spouted in the influence.
(7) The mix proportion design of the sprayed concrete is selected by tests according to the properties of raw materials, the technical conditions and the design requirements of the concrete, and the mix proportion design meets the following regulations: the glue-bone ratio is preferably 1 3 。
Step5: and detecting the rebound rate of the sprayed concrete. The steel plate is paved on the ground before the concrete is sprayed on site, after the concrete is sprayed, the size of the ground material is calculated by measuring the length, width and height of the concrete falling on the steel plate, the total volume of the sprayed concrete is recorded during spraying, and then the rebound rate of the sprayed concrete = the volume of the ground material/the total volume of the sprayed concrete multiplied by 100% is calculated according to the following formula. The rebound resilience is reported as follows:
step6: and (5) spraying concrete for curing. In order to fully hydrate the cement and reduce and prevent shrinkage cracks, the spraying and curing are started 2h after the sprayed concrete is finally set. The curing time and the watering frequency depend on the variety of cement and air humidity, and in any case, the curing time is not less than 14d, and the water spraying curing is not required when the temperature is lower than +5 ℃.
Step7: and (5) inspecting the quality of the sprayed concrete. The sprayed concrete surface is inspected in time, the concrete surface is smooth and compact, no crack, drop, leakage, exposed rib, hollow drum and water leakage exist, and the anchor rod head steel bar is not exposed.
The above-mentioned embodiments are only preferred embodiments of the patent of the present invention, and do not constitute a limitation to the present invention, it should be noted that the skilled person in the art can make modifications to the present embodiments without inventive contribution as required after reading the present specification, but shall be protected by patent laws within the scope of the claims of the present invention. Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.
Claims (10)
1. The utility model provides a reduce shotcrete of dry blasting method concrete rebound rate which characterized in that: the shotcrete comprises cement, sand, broken stones, water and an accelerating agent, wherein the mass ratio of the cement to the sand to the broken stones to the water to the accelerating agent is 1.73.
2. The shotcrete for reducing resilience of dry-sprayed concrete according to claim 1, wherein: the cement is ordinary portland cement.
3. The shotcrete for reducing resilience of dry-sprayed concrete according to claim 1, wherein: the sand is grade II sand, and the fineness modulus is 2.8.
4. The shotcrete for reducing resilience of dry-sprayed concrete according to claim 1, wherein: the particle size of the macadam is 5-10mm.
5. A process for constructing shotcrete for reducing the resilience of dry-sprayed concrete according to any one of claims 1 to 4, wherein: the method comprises the following steps:
step one, preparing concrete according to the mixing ratio of each component;
secondly, before the spraying construction, the constructor inspects and processes the sprayed rock surface;
thirdly, checking mechanical equipment, checking the equipment of machines and tools and pipelines such as wind, water, electricity and the like before the concrete spraying construction, positioning a dry spraying machine, and performing trial operation;
fourthly, spraying concrete by a dry spraying method for construction:
(1) the concrete spraying operation is sequentially carried out by segmentation, fragmentation and layering, the spraying sequence is from bottom to top, the length of the segmentation is not more than 6m, the low-lying part is approximately sprayed during spraying, and then the layering and reciprocating spraying are sequentially carried out from bottom to top;
(2) when the sprayed concrete is constructed in a segmented mode, an inclined plane is reserved in the last time of concrete spraying, the width of the inclined plane is 200-300 mm, and the concrete is sprayed after the inclined plane is washed and wetted by pressure water;
(3) the spraying in pieces is carried out from bottom to top, the concrete between the steel frames and the wall surface is sprayed firstly, then the concrete between the two steel frames is sprayed, the side wall spraying concrete is sprayed upwards from the wall foot, and the rebound cannot wrap the final spraying layer;
(4) when spraying in layers, the later layer of spraying is carried out after the former layer of concrete is finally set, if spraying is carried out after 1 hour of final setting, the surface of the sprayed layer is cleaned by wind and water, the thickness of the once sprayed concrete is controlled to be 7-10 cm, the arch part is controlled to be 5-6 cm, and the thickness of the sprayed layer is kept uniform;
(5) when top shotcrete, for avoiding producing the phenomenon of falling, twice interval should be 2 ~ 4h, and after 0.5MPa was reached to originated wind pressure, the start operation to according to nozzle ejection of compact condition adjustment wind pressure, general work wind pressure: the side wall is 0.3-0.5 MPa, and the arch part is 0.4-0.65 MPa;
(6) when in spraying, the distance between the nozzle and the sprayed surface is 1.5-2.0 m, and the spraying angle is as close to 90 degrees as possible, so that the maximum compaction and the minimum rebound are obtained; the nozzle should continuously and slowly move transversely and circularly, a circle is pressed for a half circle, and the annular ring drawn by a spraying hand is 40-60 cm transversely and 15-20 cm high; if the sprayed surface is covered by steel frame and reinforcing mesh, the nozzle can be slightly deflected, but not smaller than 70 degrees;
fifthly, detecting the rebound rate of the sprayed concrete;
sixthly, spraying concrete for curing;
and seventhly, inspecting the quality of the sprayed concrete.
6. The construction process of shotcrete for reducing the rebound of dry-shotcrete according to claim 5, wherein: in the second step, the treatment of the sprayed rock surface comprises the following steps:
the general rock surface uses high-pressure water to wash floating dust and rock debris on the sprayed rock surface; when the rock surface is easy to deliquesce and argillization when meeting water, blowing the rock surface clean by high-pressure wind; if the surface is a muddy or sandy rock surface, hanging a fine reinforcing mesh;
the meshes of the fine reinforcing mesh are not more than 20 multiplied by 20mm, the wire diameter is preferably less than 3mm, and the fine reinforcing mesh is fixed by using annular reinforcing steel bars and anchor bolts or steel frames to be closely attached to a sprayed surface so as to improve the adhesive force of sprayed concrete and set a mark for controlling the thickness of the sprayed concrete;
the mark for controlling the thickness of the sprayed concrete adopts an embedded steel bar head as a mark, or an iron wire with the length 5cm greater than the designed thickness is inserted during spraying, and one iron wire is arranged every 1-2 m.
7. The construction process of sprayed concrete for reducing the rebound rate of dry spraying concrete according to claim 5, wherein the construction process comprises the following steps: the device check in the third step comprises: (1) the conveying pipe can bear the pressure of more than 0.8MPa and has good wear resistance; (2) good ventilation and lighting conditions in the operation area are ensured; (3) the ambient temperature of the spraying operation must not be lower than 5 ℃.
8. The construction process of sprayed concrete for reducing the rebound rate of dry spraying concrete according to claim 5, wherein the construction process comprises the following steps: the detection method of the rebound resilience in the fifth step is as follows: the steel plate is paved on the ground before the concrete is sprayed on site, after the concrete is sprayed, the size of the ground material is calculated by measuring the length, width and height of the concrete falling on the steel plate, the total volume of the sprayed concrete is recorded during spraying, and then the rebound rate of the sprayed concrete = the volume of the ground material/the total volume of the sprayed concrete multiplied by 100% is calculated according to the following formula.
9. The construction process of sprayed concrete for reducing the rebound rate of dry spraying concrete according to claim 5, wherein the construction process comprises the following steps: and sixthly, curing the sprayed concrete to fully hydrate the cement, reducing and preventing shrinkage cracks, starting watering curing 2 hours after the sprayed concrete is finally set, wherein the curing time and the watering frequency depend on the variety of the cement and the air humidity, and under any condition, the curing time is not less than 14 days, and the water spraying curing is not required when the air temperature is lower than +5 ℃.
10. The construction process of sprayed concrete for reducing the rebound rate of dry spraying concrete according to claim 5, wherein the construction process comprises the following steps: and seventhly, inspecting the quality of the sprayed concrete, and inspecting the surface of the sprayed concrete in time, wherein the surface of the sprayed concrete is smooth and compact, has no crack, drop, leakage spray, exposed rib, hollow drum and leakage water, and the reinforcing steel bar of the anchor rod head is not exposed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211028900.8A CN115385629A (en) | 2022-08-24 | 2022-08-24 | Sprayed concrete for reducing resilience rate of dry spraying concrete and construction process thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211028900.8A CN115385629A (en) | 2022-08-24 | 2022-08-24 | Sprayed concrete for reducing resilience rate of dry spraying concrete and construction process thereof |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012166993A (en) * | 2011-02-16 | 2012-09-06 | Kyushu Nisshoku Kk | Cement-based solidifying material composition and method for spraying the same |
| CN108046712A (en) * | 2018-01-15 | 2018-05-18 | 中国建筑科学研究院 | High-strength low-resilience-rate sprayed concrete and construction process thereof |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012166993A (en) * | 2011-02-16 | 2012-09-06 | Kyushu Nisshoku Kk | Cement-based solidifying material composition and method for spraying the same |
| CN108046712A (en) * | 2018-01-15 | 2018-05-18 | 中国建筑科学研究院 | High-strength low-resilience-rate sprayed concrete and construction process thereof |
Non-Patent Citations (1)
| Title |
|---|
| 孙俊境;柳文亮;李明达;: "高铁隧道初期支护之湿式喷射混凝土施工探讨" * |
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