CN111485716A - Application of waste concrete large aggregate in concrete structure construction - Google Patents
Application of waste concrete large aggregate in concrete structure construction Download PDFInfo
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- CN111485716A CN111485716A CN202010284485.7A CN202010284485A CN111485716A CN 111485716 A CN111485716 A CN 111485716A CN 202010284485 A CN202010284485 A CN 202010284485A CN 111485716 A CN111485716 A CN 111485716A
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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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- 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
- C04B28/006—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 mineral polymers, e.g. geopolymers of the Davidovits type
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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
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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
- C04B28/06—Aluminous cements
- C04B28/065—Calcium aluminosulfate cements, e.g. cements hydrating into ettringite
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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
- C04B28/08—Slag cements
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C3/00—Structural elongated elements designed for load-supporting
- E04C3/02—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces
- E04C3/20—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of concrete or other stone-like material, e.g. with reinforcements or tensioning members
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C3/00—Structural elongated elements designed for load-supporting
- E04C3/30—Columns; Pillars; Struts
- E04C3/34—Columns; Pillars; Struts of concrete other stone-like material, with or without permanent form elements, with or without internal or external reinforcement, e.g. metal coverings
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- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding
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- 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
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Abstract
The invention discloses an application of waste concrete large aggregate in concrete structure construction, wherein the concrete structure construction specifically refers to the construction of a precast beam, a precast column or a precast composite beam; the large aggregate of the waste concrete is recycled large aggregate concrete which can be mixed and poured, and each cubic of the recycled large aggregate concrete comprises 900kg of recycled large aggregate, 300kg of cementing material, 650kg of coarse aggregate 550, 650kg of fine aggregate 550, 0-5kg of water reducing agent and 140kg of water 110. The invention solves the problem of uneven distribution of the large aggregate caused by the blocking of the stirrups during pouring, improves the forming compactness and the structural strength and enlarges the application range of the waste concrete.
Description
Technical Field
The invention relates to application of waste concrete large aggregate in concrete structure construction, and belongs to the field of building construction.
Background
With the rapid promotion of urbanization in China, the scale of infrastructure construction is continuously enlarged, and a large number of old buildings need to be dismantled and rebuilt. The annual production of construction waste in China reaches 35 hundred million tons, and 18 hundred million tons of construction waste are removed only, so that the production reaches a peak value by 2020. Waste concrete is the most important of building waste, and how to treat the waste concrete becomes a problem to be solved urgently.
At present, the main treatment measure of the waste concrete is to directly crush the waste concrete into single stones (with nominal particle size of 5-30mm) to be used as concrete coarse aggregates, soft mortar layers are adhered to the surfaces of the regenerated coarse aggregates, the strength of the old mortar layers is far lower than that of the stones and the natural aggregates, the surfaces of the old mortar layers are rough, the water absorption rate is high, the basic performance of the old mortar layers is greatly different from that of the natural coarse aggregates, and the old mortar layers can only be applied to roadbed pavements, non-bearing structures and low-grade products.
The problems associated with crushing waste concrete into recycled coarse aggregate can be avoided if the waste concrete is crushed into rock. The block stone with large particle size is a concrete block, the mechanical property of the block stone is basically the same as that of the original concrete, a sparse and soft mortar layer does not exist on the surface, and the defects of poor mechanical property, high water absorption and the like caused by adhesion of a regenerated coarse aggregate to the mortar layer are avoided. However, the rock blocks are large in size, and the construction method of rock-fill grouting or rock-burying is generally adopted and is applied to large-size concrete projects such as dams. Most of the projects are in remote mountainous areas, stone materials are mostly obtained by digging mountains on the spot, waste concrete mainly comes from urban building garbage, the waste concrete is crushed into rock blocks, and the rock blocks are transported to the remote mountainous areas from cities, so that the method is obviously an irreparable method.
If the waste concrete block stone is crushed into the recycled large aggregate with the size fraction range of 20-60mm, the concrete prepared from the waste concrete block stone can be mixed and poured like common concrete, so that the aims of treating and utilizing the waste concrete in the city on site are fulfilled. Meanwhile, the particle size of the recycled large aggregate is larger than the particle size range of the recycled coarse aggregate, and the defects of poor mechanical property and high water absorption rate caused by the adhesion of the recycled coarse aggregate to a mortar layer are overcome.
The maximum particle size of the concrete coarse aggregate is limited by the structure type and the density of the reinforcing bars. The stirrup spacing in the column/beam end stirrup encryption area needs to meet the requirements of shear bearing capacity and construction, GB50010-2010 concrete structure design Specification specifies that the construction requirements are that the smaller value of 6 times and 100mm of the diameter of the longitudinal steel bar is taken at the first level of the earthquake-resistant grade, the smaller value of 8 times and 100mm of the diameter of the longitudinal steel bar is taken at the second level, the smaller value of 8 times and 150mm (column root 100mm) of the diameter of the longitudinal steel bar is taken at the third level, and the smaller value of 8 times and 150mm (column root 100mm) of the diameter of the longitudinal steel bar is taken at the fourth level. In practical engineering, in order to meet the requirement of shear resistance, the spacing between the stirrups can be as low as 50-100mm, and the clear distance between the stirrups is smaller. The maximum grain size of the fresh concrete coarse aggregate is not larger than 3/4 of the net distance of the reinforcing steel bars according to the specification. Obviously, when the hoops in the dense area are densely configured, the maximum particle size of the recycled large aggregate cannot meet the requirement of smoothly passing through the hoops in the dense area.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides the application of the waste concrete large aggregate in the concrete structure construction, and solves the problems that the waste concrete is reused in engineering and the aggregate of the large aggregate concrete is blocked by the stirrups in the actual pouring process.
In order to achieve the purpose, the invention adopts the application of the waste concrete large aggregate in the construction of a concrete structure, wherein the concrete structure construction specifically refers to the construction of a precast beam, a precast column or a precast composite beam;
the large aggregate of the waste concrete is recycled large aggregate concrete which can be mixed and poured, and each cubic of the recycled large aggregate concrete comprises 900kg of recycled large aggregate, 300kg of cementing material, 650kg of coarse aggregate 550, 650kg of fine aggregate 550, 0-5kg of water reducing agent and 140kg of water 110.
As an improvement, the recycled large aggregate is a large aggregate which is obtained by crushing waste concrete into 20-60mm continuous gradation, wherein the recycled large aggregates with the particle size ranges of 20-30mm, 30-40mm, 40-50mm and 50-60mm respectively account for 20-30%.
As an improvement, the cementing material adopts any one of general portland cement, alkali slag, geopolymer cement and sulphoaluminate cement.
As an improvement, the construction of the prefabricated composite beam by using the waste concrete large aggregate comprises the following steps:
1) firstly, assembling and erecting a U-shaped permanent template;
2) binding longitudinal bars and stirrups in the permanent template to form a steel reinforcement framework, wherein the stirrups comprise common closed stirrups used in a non-encryption area, and U-shaped stirrups and common closed stirrups alternately used in an encryption area;
3) mixing the recycled large aggregate concrete, pouring the recycled large aggregate concrete into the permanent formwork, wherein the pouring depth is the height of the formwork, and vibrating and compacting the recycled large aggregate concrete;
4) the U-shaped stirrup is sealed by a tie bar to form a sealed stirrup ring;
5) and curing the large aggregate concrete precast composite beam to a specified age to obtain a finished product.
As an improvement, the height of the reinforcement cage in the step 2) is 50-100mm higher than that of the side plate of the permanent template; the thickness of the permanent formwork is equal to the thickness of the designed protective layer of the concrete beam.
As an improvement, the waste concrete large aggregate is used for the construction of a prefabricated column, and the method comprises the following steps:
1) firstly, erecting a U-shaped permanent template;
2) binding longitudinal bars and stirrups in the permanent template to form a steel reinforcement framework, wherein the stirrups comprise common closed stirrups used in a non-encryption area, and U-shaped stirrups and common closed stirrups alternately used in an encryption area;
3) mixing the recycled large aggregate concrete, pouring the recycled large aggregate concrete to the upper limb of a common closed stirrup, and vibrating and compacting;
4) the U-shaped stirrup is sealed by a tie bar to form a sealed stirrup ring;
5) continuously pouring common commercial concrete into the permanent formwork to the height of the formwork, and vibrating and compacting for forming;
6) and curing the large aggregate concrete precast column to a specified age to obtain a finished product.
As an improvement, the thickness of the permanent formwork in the step 1) and the height of the side plate of the permanent formwork above the steel reinforcement framework are both equal to the thickness of the designed protective layer of the concrete column.
As an improvement, the waste concrete large aggregate is used for the construction of precast beams and comprises the following steps:
1) firstly, erecting a U-shaped permanent template;
2) binding longitudinal bars and stirrups in the permanent template to form a steel reinforcement framework, wherein the stirrups comprise common closed stirrups used in a non-encryption area, and U-shaped stirrups and common closed stirrups alternately used in an encryption area;
3) mixing the recycled large aggregate concrete, pouring the recycled large aggregate concrete to the upper limb of a common closed stirrup, and vibrating and compacting;
4) the U-shaped stirrup is sealed by a tie bar to form a sealed stirrup ring;
5) pouring common commercial concrete into the permanent formwork to the height of the formwork, and vibrating and compacting;
6) and curing the large aggregate concrete precast beam to a specified age to obtain a finished product.
As an improvement, the thickness of the permanent formwork in the step 1) and the height of the permanent formwork side plate higher than the steel reinforcement framework are equal to the thickness of the designed protective layer of the concrete beam.
Compared with the prior art, the invention has the beneficial effects that:
1) the pouring quality is ensured by the structural form of the permanent template and the local U-shaped stirrups
The invention provides a novel structure of a U-shaped permanent template and a local U-shaped stirrup, wherein a common closed stirrup is adopted in a non-encryption area, and the U-shaped stirrup and the common closed stirrup in an encryption area are alternately used. The accessible interval of aggregate has been increased under the condition of not expanding the stirrup interval, fundamentally solved when big aggregate concrete pouring, the aggregate is blockked the column end concrete strength reduction problem that leads to.
2) The recycled large aggregate has high mechanical strength and low water absorption
The invention takes the recycled large aggregate with 20-60mm continuous gradation as the large framework of the concrete, the large aggregate has the same mechanical strength as the original concrete matrix, and the surface of the large aggregate does not have a soft mortar layer, thereby solving the problems of high water absorption and poor mechanical property caused by crushing the waste concrete into the recycled coarse aggregate adhered mortar layer.
3) Can be mixed and poured like common concrete
The recycled large aggregate is a waste concrete block with various properties the same as that of a concrete matrix before crushing, the particle size of the recycled large aggregate is far smaller than that of the rock, the recycled large aggregate can be mixed and poured into recycled large aggregate concrete with the strength grade equivalent to that of the original waste concrete, the recycled large aggregate is applied to different fields of road paving, bridge construction, fabricated concrete and the like, and the problem that the rock concrete cannot be mixed and poured like common concrete is solved.
Drawings
FIG. 1 is a schematic structural diagram of a prefabricated composite beam according to the present invention;
FIG. 2 is a schematic cross-sectional view of a precast composite beam of the present invention;
FIG. 3 is a schematic view illustrating the forming of the prefabricated composite beam according to the present invention;
FIG. 4 is a schematic structural view of a precast column of the present invention;
FIG. 5 is a schematic cross-sectional view of a precast column of the present invention;
FIG. 6 is a schematic view of a first pour of the precast column of the present invention;
FIG. 7 is a schematic view of the prefabricated column of the present invention after completion of casting;
fig. 8 is a schematic perspective view of a precast beam according to the present invention;
FIG. 9 is a schematic cross-sectional view of a precast beam of the present invention;
FIG. 10 is a schematic view of a first casting of the precast beam of the present invention;
FIG. 11 is a schematic view of the completion of the casting of the precast beam according to the present invention;
in the figure: 1. the method comprises the following steps of (1) an encryption area, 2) a permanent template, 3, a common closed type stirrup, 4, a U-shaped stirrup, 5, a erection rib, 6, a longitudinal rib, 7 and a tie rib.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below. It should be understood, however, that the description herein of specific embodiments is only intended to illustrate the invention and not to limit the scope of the invention.
Example 1
As shown in fig. 1 to 3, a construction method of a precast composite beam made of waste concrete and large aggregate comprises the following steps:
1) firstly, assembling and erecting a U-shaped permanent template 2; the thickness of the permanent template is equal to the thickness of the designed protective layer of the concrete beam;
2) binding frame vertical bars 5, longitudinal bars 6 and stirrups in the permanent template to form a steel reinforcement framework, wherein the height of the steel reinforcement framework is 80mm higher than that of a side plate of the permanent template (the specific height is determined according to the required lap joint length of the superposed beam steel bars), and the stirrups comprise common closed stirrups 3 used in a non-encryption area, and U-shaped stirrups 4 and common closed stirrups 3 alternately used in an encryption area 1;
3) and (3) casting molding: mixing the recycled large aggregate concrete, pouring the recycled large aggregate concrete into the permanent formwork, wherein the pouring depth is the height of the formwork, and vibrating and compacting the recycled large aggregate concrete; each cube of the castable large aggregate concrete can be mixed and poured, and comprises 700kg of the castable large aggregate, 200kg of cementing material, 550kg of coarse aggregate, 550kg of fine aggregate and 110kg of water, wherein the cementing material adopts general portland cement;
the recycled large aggregate is a large aggregate which is obtained by crushing waste concrete into 20-60mm continuous gradation, wherein the recycled large aggregates with the particle size ranges of 20-30mm, 30-40mm, 40-50mm and 50-60mm respectively account for 25 percent;
4) the U-shaped stirrup is closed by a tie bar 7 to form a closed stirrup ring;
5) and curing the large aggregate concrete precast composite beam to a specified age to obtain a finished product.
Comparative example 1
Except for recycled large aggregate, the method for prefabricating the composite beam and other raw materials in the comparative example are the same as those in the examples, and the concrete mixing ratio is as follows: the coarse aggregate is graded crushed stone with the thickness of 5-31.5mm (the mixing amount is 1050 kg/m)3) (ii) a The fine aggregate is river sand (mixing amount is 750 kg/m)3) (ii) a The cementing material is P.O42.5 ordinary portland cement (the mixing amount is 400 kg/m)3) (ii) a Water (mixing amount 160 kg/m)3) (ii) a Polycarboxylic acid high-efficiency water reducing agent (mixing amount is 4 kg/m)3). The concrete prepared in this comparative example has the workability, slump and compressive strength test results shown in Table 1.
In the embodiment of the invention and the comparative example, the preparation and maintenance of each group of concrete are respectively carried out according to GB/T50080-2002 Standard of methods for testing the Performance of the mixture of ordinary concrete and GB/T50081-2002 Standard of methods for testing the mechanical Performance of ordinary concrete, and the workability, slump and the compressive strength of the concrete of corresponding age of the fresh concrete are measured as shown in Table 1.
TABLE 1 concrete Properties of examples and comparative examples
As can be seen from Table 1, the recycled large aggregate concrete which can be mixed and poured and is used by the invention has good workability, can be mixed and poured for construction like common concrete, and has better mechanical properties than the common concrete. Therefore, the performance of the recycled large aggregate concrete can fully meet the construction performance requirement of the prefabricated composite beam.
Example 2
A construction method for a waste concrete large aggregate prefabricated composite beam comprises the following steps:
1) firstly, assembling and erecting a U-shaped permanent template 2; the thickness of the permanent template is equal to the thickness of the designed protective layer of the concrete beam;
2) binding frame vertical bars 5, longitudinal bars 6 and stirrups in the permanent template to form a steel reinforcement framework, wherein the height of the steel reinforcement framework is 60mm higher than that of a side plate of the permanent template, and the stirrups comprise common closed stirrups 3 used in a non-encryption area, U-shaped stirrups 4 and common closed stirrups 3 alternately used in an encryption area 1;
3) and (3) casting molding: mixing the recycled large aggregate concrete, pouring the recycled large aggregate concrete into the permanent formwork, wherein the pouring depth is the height of the formwork, and vibrating and compacting the recycled large aggregate concrete; each cube of the castable large aggregate concrete can be mixed and poured, and comprises 900kg of the recycled large aggregate, 300kg of cementing material, 650kg of coarse aggregate, 650kg of fine aggregate, 5kg of water reducing agent and 140kg of water, wherein the cementing material adopts general purpose portland cement;
the recycled large aggregate is a large aggregate which is obtained by crushing waste concrete into 20-60mm continuous gradation, wherein the recycled large aggregates with the particle size ranges of 20-30mm, 30-40mm, 40-50mm and 50-60mm respectively account for 25 percent;
4) the U-shaped stirrup is closed by a tie bar 7 to form a closed stirrup ring;
5) and curing the large aggregate concrete precast composite beam to a specified age to obtain a finished product.
Example 3
A construction method for a waste concrete large aggregate prefabricated composite beam comprises the following steps:
1) firstly, assembling and erecting a U-shaped permanent template 2; the thickness of the permanent template is equal to the thickness of the designed protective layer of the concrete beam;
2) binding frame vertical bars 5, longitudinal bars 6 and stirrups in the permanent template to form a steel reinforcement framework, wherein the height of the steel reinforcement framework is 100mm higher than that of a side plate of the permanent template, and the stirrups comprise common closed stirrups 3 used in a non-encryption area, U-shaped stirrups 4 and common closed stirrups 3 alternately used in an encryption area 1;
3) and (3) casting molding: mixing the recycled large aggregate concrete, pouring the recycled large aggregate concrete into the permanent formwork, wherein the pouring depth is the height of the formwork, and vibrating and compacting the recycled large aggregate concrete; each cubic meter of the castable large aggregate concrete can be mixed and poured, and the concrete comprises 800kg of the castable large aggregate, 250kg of cementing material, 600kg of coarse aggregate, 600kg of fine aggregate, 3kg of water reducing agent and 120kg of water, wherein the cementing material adopts general alkali slag;
the recycled large aggregate is a large aggregate which is obtained by crushing waste concrete into 20-60mm continuous gradation, wherein the recycled large aggregates with the particle size ranges of 20-30mm, 30-40mm, 40-50mm and 50-60mm respectively account for 25 percent;
4) the U-shaped stirrup is closed by a tie bar 7 to form a closed stirrup ring;
5) and curing the large aggregate concrete precast composite beam to a specified age to obtain a finished product.
Example 4
As shown in fig. 4 to 7, a construction method of a recycled large aggregate concrete precast column includes the following steps:
1) erecting a U-shaped permanent template 2 outside the designed column structure, wherein the thickness of the permanent template 2 and the height of a side plate of the permanent template, which is higher than the steel reinforcement framework, are equal to the thickness of a designed protective layer of the concrete column;
2) binding a steel bar framework: binding longitudinal bars 5 and stirrups according to design requirements, using a common closed type stirrup 3 in a non-encryption area, and alternately using a U-shaped stirrup 4 and the common closed type stirrup 3 in a stirrup encryption area 1;
3) pouring for one time: mixing and pouring the recycled large aggregate concrete to the upper limbs of stirrups, vibrating and compacting, wherein each cubic can be mixed and poured into the recycled large aggregate concrete, and the recycled large aggregate concrete comprises 150kg of large aggregates with the particle size of 20-30mm, 200kg of large aggregates with the particle size of 30-40mm, 200kg of large aggregates with the particle size of 40-50mm, 200kg of large aggregates with the particle size of 50-60mm, 600kg of graded broken stones with the particle size of 5-31.5mm, 625kg of river sand with the fineness modulus of 2.75, 250kg of P.O42.5 ordinary portland cement, 115kg of water and 5kg of polycarboxylic acid high-efficiency water reducing agent, wherein the recycled large aggregates are formed by crushing waste concrete with the original concrete strength grade of C40, and the preparation method of the recycled large aggregate concrete comprises the following steps: adding graded broken stone, river sand, portland cement, a polycarboxylic acid high-efficiency water reducing agent and water into a stirrer to be stirred to prepare large-fluidity concrete, and then adding a regenerated large aggregate to be stirred to obtain the regenerated large aggregate concrete capable of being cast; the experimental results of the workability, slump and compressive strength of the recycled large-aggregate concrete prepared in the embodiment are shown in table 2; pouring the mixture into the upper limb of a common closed stirrup 3 after mixing, and vibrating and compacting for forming;
4) the U-shaped hoop is closed: the U-shaped stirrup 4 is sealed by a tie bar 7 to form a sealed stirrup ring;
5) secondary pouring: pouring common commercial concrete into the template to the height of the template, and vibrating and compacting;
6) and (5) maintenance: and curing the large aggregate concrete precast column to a specified age to obtain a finished product.
Comparative example 4
Except for recycled large aggregate, other raw materials, the method for processing the prefabricated column and the embodiment are the same, and the concrete mixing ratio is as follows: the coarse aggregate is graded crushed stone with the thickness of 5-31.5mm (the mixing amount is 1050 kg/m)3) (ii) a The fine aggregate is river sand (mixing amount is 750 kg/m)3) (ii) a The cementing material is P.O42.5 ordinary portland cement (the mixing amount is 400 kg/m)3) (ii) a Water (mixing amount 160 kg/m)3) (ii) a Polycarboxylic acid high-efficiency water reducing agent (mixing amount is 4 kg/m)3). The concrete prepared in the comparative example has the workability, slump and compressive strength test results shown in Table 2.
In the embodiment of the invention and the comparative example, the preparation and maintenance of each group of concrete are respectively carried out according to GB/T50080-2002 Standard for testing the Performance of the mixture of ordinary concrete and GB/T50081-2002 Standard for testing the mechanical Performance of ordinary concrete, and the workability, slump and the compressive strength of the concrete of corresponding age of the fresh concrete are measured as shown in Table 2.
TABLE 2 concrete Properties of examples and comparative examples
As can be seen from Table 2, the recycled large aggregate concrete which can be mixed and poured and is used by the invention has good workability, can be mixed and poured for construction like common concrete, and has better mechanical properties than the common concrete. Therefore, the performance of the recycled large aggregate concrete can fully meet the construction performance requirement of the prefabricated column.
Example 5
As shown in fig. 8 to 11, a method for processing a precast beam using a waste concrete large aggregate includes the steps of:
1) firstly, a U-shaped permanent template 2 is erected, and the thickness of the permanent template 2 and the height of a permanent template side plate higher than a steel reinforcement framework are equal to the thickness of a protective layer of a concrete beam;
2) binding longitudinal bars 6 and stirrups in the permanent template 2 to form a steel reinforcement framework, wherein the stirrups comprise common closed stirrups 3 used in a non-encryption area, U-shaped stirrups 4 and common closed stirrups 3 alternately used in a stirrup encryption area 1;
3) mixing the recycled large aggregate concrete, wherein each cubic of the mixed and poured recycled large aggregate concrete comprises 150kg of large aggregates with the particle size of 20-30mm, 200kg of large aggregates with the particle size of 30-40mm, 200kg of large aggregates with the particle size of 40-50mm, 200kg of large aggregates with the particle size of 50-60mm, 600kg of 5-31.5mm graded broken stones, 625kg of river sand with the fineness modulus of 2.75, 250kg of P.O42.5 ordinary portland cement, 115kg of water and 5kg of polycarboxylic acid high-efficiency water reducing agent; the recycled large aggregate concrete is formed by crushing waste concrete with the original concrete strength grade of C40, and the preparation method of the recycled large aggregate concrete comprises the following steps: adding graded broken stone, river sand, portland cement, a polycarboxylic acid high-efficiency water reducing agent and water into a stirrer to be stirred to prepare large-fluidity concrete, and then adding a regenerated large aggregate to be stirred to obtain the regenerated large aggregate concrete capable of being cast; the experimental results of the workability, slump and compressive strength of the recycled large-aggregate concrete prepared in the embodiment are shown in Table 3; pouring the mixture into the upper limb of a common closed stirrup after mixing, and vibrating and compacting for forming;
4) the U-shaped stirrup 4 is sealed by a tie bar 7 to form a sealed stirrup ring;
5) pouring common commercial concrete into the permanent formwork 2 to the height of the formwork, and vibrating and compacting for forming;
6) and curing the stone concrete precast beam to a specified age to obtain a finished product.
Comparative example 5
Except for recycled large aggregate, the other raw materials, the method for processing the precast beam and the embodiment are the same, and the concrete mixing ratio is as follows: the coarse aggregate is graded crushed stone with the thickness of 5-31.5mm (the mixing amount is 1050 kg/m)3) (ii) a The fine aggregate is river sand (mixing amount is 750 kg/m)3) (ii) a The cementing material is P.O42.5 ordinary portland cement (the mixing amount is 400 kg/m)3) (ii) a Water (mixing amount 160 kg/m)3) (ii) a Polycarboxylic acid high-efficiency water reducing agent (mixing amount is 4 kg/m)3). The concrete prepared in this comparative example has the workability, slump and compressive strength test results shown in Table 3.
In the embodiment of the invention and the comparative example, the preparation and maintenance of each group of concrete are respectively carried out according to GB/T50080-2002 Standard for testing the Performance of the mixture of ordinary concrete and GB/T50081-2002 Standard for testing the mechanical Performance of ordinary concrete, and the workability, slump and the compressive strength of the concrete of corresponding age of the fresh concrete are measured as shown in Table 3.
TABLE 3 concrete Properties in examples and comparative examples
As can be seen from Table 3, the recycled large aggregate concrete which can be mixed and poured and is used by the invention has good workability, can be mixed and poured for construction like common concrete, and has better mechanical properties than the common concrete. Therefore, the performance of the recycled large aggregate concrete can fully meet the performance requirement of the precast beam.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents or improvements made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (9)
1. The application of the waste concrete large aggregate in concrete structure construction is characterized in that the concrete structure construction specifically refers to the construction of a precast beam, a precast column or a precast composite beam;
the large aggregate of the waste concrete is recycled large aggregate concrete which can be mixed and poured, and each cubic of the recycled large aggregate concrete comprises 900kg of recycled large aggregate, 300kg of cementing material, 650kg of coarse aggregate 550, 650kg of fine aggregate 550, 0-5kg of water reducing agent and 140kg of water 110.
2. The use of the waste concrete macroaggregate in the construction of concrete structures according to claim 1, wherein the recycled macroaggregate is a macroaggregate obtained by crushing waste concrete into 20-60mm continuous gradation, wherein the recycled macroaggregate having particle sizes ranging from 20-30mm, 30-40mm, 40-50mm and 50-60mm is 20-30% each.
3. The use of the waste concrete macroaggregate in the construction of concrete structures according to claim 1, wherein the cementitious material is any one of general portland cement, alkali slag, geopolymer cement, and sulphoaluminate cement.
4. The use of the waste concrete macroaggregate in the construction of concrete structures according to claim 1, wherein the waste concrete macroaggregate is used for the construction of prefabricated composite beams, and comprises the following steps:
1) firstly, assembling and erecting a U-shaped permanent template;
2) binding longitudinal bars and stirrups in the permanent template to form a steel reinforcement framework, wherein the stirrups comprise common closed stirrups used in a non-encryption area, and U-shaped stirrups and common closed stirrups alternately used in an encryption area;
3) mixing the recycled large aggregate concrete, pouring the recycled large aggregate concrete into the permanent formwork, wherein the pouring depth is the height of the formwork, and vibrating and compacting the recycled large aggregate concrete;
4) the U-shaped stirrup is sealed by a tie bar to form a sealed stirrup ring;
5) and curing the large aggregate concrete precast composite beam to a specified age to obtain a finished product.
5. The use of the waste concrete large aggregate in the construction of concrete structures according to claim 4, wherein the height of the reinforcement cage in the step 2) is 50-100mm higher than that of the side plate of the permanent formwork; the thickness of the permanent formwork is equal to the thickness of the designed protective layer of the concrete beam.
6. The use of the waste concrete macroaggregate in the construction of concrete structures according to claim 1, wherein the waste concrete macroaggregate is used for the construction of prefabricated columns, and comprises the following steps:
1) firstly, erecting a U-shaped permanent template;
2) binding longitudinal bars and stirrups in the permanent template to form a steel reinforcement framework, wherein the stirrups comprise common closed stirrups used in a non-encryption area, and U-shaped stirrups and common closed stirrups alternately used in an encryption area;
3) mixing the recycled large aggregate concrete, pouring the recycled large aggregate concrete to the upper limb of a common closed stirrup, and vibrating and compacting;
4) the U-shaped stirrup is sealed by a tie bar to form a sealed stirrup ring;
5) continuously pouring common commercial concrete into the permanent formwork to the height of the formwork, and vibrating and compacting for forming;
6) and curing the large aggregate concrete precast column to a specified age to obtain a finished product.
7. The use of the waste concrete large aggregate in the construction of concrete structures according to claim 6, wherein the thickness of the permanent formwork and the height of the side plate of the permanent formwork above the steel reinforcement cage in the step 1) are equal to the designed protective layer thickness of the concrete column.
8. The use of the waste concrete macroaggregate according to claim 1 in the construction of concrete structures, wherein the waste concrete macroaggregate is used for the construction of precast beams, comprising the steps of:
1) firstly, erecting a U-shaped permanent template;
2) binding longitudinal bars and stirrups in the permanent template to form a steel reinforcement framework, wherein the stirrups comprise common closed stirrups used in a non-encryption area, and U-shaped stirrups and common closed stirrups alternately used in an encryption area;
3) mixing the recycled large aggregate concrete, pouring the recycled large aggregate concrete to the upper limb of a common closed stirrup, and vibrating and compacting;
4) the U-shaped stirrup is sealed by a tie bar to form a sealed stirrup ring;
5) pouring common commercial concrete into the permanent formwork to the height of the formwork, and vibrating and compacting;
6) and curing the large aggregate concrete precast beam to a specified age to obtain a finished product.
9. The use of the waste concrete large aggregate in the construction of concrete structures according to claim 8, wherein the thickness of the permanent form in step 1) and the height of the permanent form side plate above the steel reinforcement cage are equal to the designed protective layer thickness of the concrete beam.
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| CN114718245A (en) * | 2022-04-22 | 2022-07-08 | 华南理工大学 | Recycled block/aggregate concrete prefabricated superposed beam and construction method thereof |
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