CN115180883B - Sprayed concrete and preparation method thereof - Google Patents
Sprayed concrete and preparation method thereof Download PDFInfo
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- CN115180883B CN115180883B CN202210724593.0A CN202210724593A CN115180883B CN 115180883 B CN115180883 B CN 115180883B CN 202210724593 A CN202210724593 A CN 202210724593A CN 115180883 B CN115180883 B CN 115180883B
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- 239000011378 shotcrete Substances 0.000 title claims abstract description 143
- 238000002360 preparation method Methods 0.000 title claims abstract description 16
- 239000004575 stone Substances 0.000 claims abstract description 130
- 239000000843 powder Substances 0.000 claims abstract description 79
- 235000017166 Bambusa arundinacea Nutrition 0.000 claims abstract description 77
- 235000017491 Bambusa tulda Nutrition 0.000 claims abstract description 77
- 241001330002 Bambuseae Species 0.000 claims abstract description 77
- 235000015334 Phyllostachys viridis Nutrition 0.000 claims abstract description 77
- 239000011425 bamboo Substances 0.000 claims abstract description 77
- 239000011384 asphalt concrete Substances 0.000 claims abstract description 72
- 239000004568 cement Substances 0.000 claims abstract description 55
- 239000011343 solid material Substances 0.000 claims abstract description 54
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 46
- 235000019738 Limestone Nutrition 0.000 claims abstract description 45
- 239000006028 limestone Substances 0.000 claims abstract description 45
- 239000002699 waste material Substances 0.000 claims abstract description 45
- 239000004567 concrete Substances 0.000 claims abstract description 44
- 239000002002 slurry Substances 0.000 claims abstract description 42
- 239000004115 Sodium Silicate Substances 0.000 claims abstract description 41
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims abstract description 41
- 229910052911 sodium silicate Inorganic materials 0.000 claims abstract description 41
- 239000002994 raw material Substances 0.000 claims abstract description 13
- -1 accelerator Substances 0.000 claims abstract description 8
- 239000010426 asphalt Substances 0.000 claims description 50
- 239000002245 particle Substances 0.000 claims description 35
- 239000000839 emulsion Substances 0.000 claims description 31
- 239000011268 mixed slurry Substances 0.000 claims description 31
- 238000002156 mixing Methods 0.000 claims description 25
- 238000005507 spraying Methods 0.000 claims description 20
- 239000004576 sand Substances 0.000 claims description 17
- 238000002791 soaking Methods 0.000 claims description 17
- 239000002904 solvent Substances 0.000 claims description 16
- 239000000243 solution Substances 0.000 claims description 14
- 238000000034 method Methods 0.000 claims description 12
- 238000012216 screening Methods 0.000 claims description 10
- 229920000642 polymer Polymers 0.000 claims description 9
- XSTXAVWGXDQKEL-UHFFFAOYSA-N Trichloroethylene Chemical group ClC=C(Cl)Cl XSTXAVWGXDQKEL-UHFFFAOYSA-N 0.000 claims description 7
- 239000007921 spray Substances 0.000 claims description 7
- UBOXGVDOUJQMTN-UHFFFAOYSA-N trichloroethylene Natural products ClCC(Cl)Cl UBOXGVDOUJQMTN-UHFFFAOYSA-N 0.000 claims description 7
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 claims description 6
- OCKPCBLVNKHBMX-UHFFFAOYSA-N butylbenzene Chemical compound CCCCC1=CC=CC=C1 OCKPCBLVNKHBMX-UHFFFAOYSA-N 0.000 claims description 6
- 239000011259 mixed solution Substances 0.000 claims description 6
- 238000005345 coagulation Methods 0.000 claims description 5
- 230000015271 coagulation Effects 0.000 claims description 5
- 229920002689 polyvinyl acetate Polymers 0.000 claims description 5
- 239000011118 polyvinyl acetate Substances 0.000 claims description 5
- 229920001328 Polyvinylidene chloride Polymers 0.000 claims description 3
- 239000002131 composite material Substances 0.000 claims description 3
- 229920002635 polyurethane Polymers 0.000 claims description 3
- 239000004814 polyurethane Substances 0.000 claims description 3
- 239000005033 polyvinylidene chloride Substances 0.000 claims description 3
- 238000010276 construction Methods 0.000 abstract description 55
- 239000000463 material Substances 0.000 abstract description 24
- 238000004064 recycling Methods 0.000 abstract description 9
- 230000002349 favourable effect Effects 0.000 abstract description 2
- 239000000203 mixture Substances 0.000 description 31
- 239000010410 layer Substances 0.000 description 27
- 239000007787 solid Substances 0.000 description 9
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical group [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 8
- 230000008929 regeneration Effects 0.000 description 8
- 238000011069 regeneration method Methods 0.000 description 8
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- 239000000047 product Substances 0.000 description 5
- 240000009132 Sagittaria sagittifolia Species 0.000 description 4
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- 229910000019 calcium carbonate Inorganic materials 0.000 description 4
- 230000017525 heat dissipation Effects 0.000 description 4
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- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- 241000196324 Embryophyta Species 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
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- 229920001971 elastomer Polymers 0.000 description 3
- 238000011049 filling Methods 0.000 description 3
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- 229910052500 inorganic mineral Inorganic materials 0.000 description 3
- 239000011707 mineral Substances 0.000 description 3
- 229920003023 plastic Polymers 0.000 description 3
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- 238000004062 sedimentation Methods 0.000 description 3
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- 238000007711 solidification Methods 0.000 description 3
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
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- 230000009286 beneficial effect Effects 0.000 description 2
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 241000238631 Hexapoda Species 0.000 description 1
- 241000282320 Panthera leo Species 0.000 description 1
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- 229910052742 iron Inorganic materials 0.000 description 1
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Classifications
-
- 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
-
- 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
- C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B14/02—Granular materials, e.g. microballoons
- C04B14/26—Carbonates
- C04B14/28—Carbonates of calcium
-
- 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
- C04B18/16—Waste materials; Refuse from building or ceramic industry
-
- 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
- C04B18/18—Waste materials; Refuse organic
- C04B18/24—Vegetable refuse, e.g. rice husks, maize-ear refuse; Cellulosic materials, e.g. paper, cork
- C04B18/26—Wood, e.g. sawdust, wood shavings
- C04B18/265—Wood, e.g. sawdust, wood shavings from specific species, e.g. birch
-
- 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
- C04B2111/00017—Aspects relating to the protection of the environment
-
- 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
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Structural Engineering (AREA)
- Materials Engineering (AREA)
- Civil Engineering (AREA)
- Organic Chemistry (AREA)
- Environmental & Geological Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Wood Science & Technology (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
The application discloses sprayed concrete and a preparation method thereof, wherein the sprayed concrete comprises the following raw materials: cement, limestone powder, bamboo chips, recycled stone, accelerator, sodium silicate powder and water, wherein the mass ratio of the cement to the limestone powder to the bamboo chips to the recycled stone to the accelerator is 1:0.1759 to 0.1771:0.0024 to 0.0029:4.2616 to 4.3569:0.1166 to 0.1187:0.1401 to 0.1424:0.5426 to 0.5532. The sprayed concrete provided by the application improves the recycling rate of the solid materials of the waste asphalt concrete; the rebound rate is reduced compared with that of the traditional concrete, so that the engineering quality can be effectively improved, and the materials can be saved; the slurry quantity is improved to a certain extent, which is favorable for the trowelling construction of the surface and improves the surface evenness of the sprayed concrete layer.
Description
Technical Field
The application relates to the technical field of concrete, in particular to sprayed concrete and a preparation method thereof.
Background
The sprayed concrete is a concrete which is formed by utilizing air compression or other power by means of a spraying machine, mixing materials matched according to a certain proportion, conveying the mixing materials through a pipeline, spraying the mixing materials onto a sprayed surface at a high speed, and solidifying and hardening the mixing materials.
In the traditional sprayed concrete, when the sprayed mixture sprayed by the sprayer and the side wall of the foundation pit are impacted by the sprayed surface, the rebound rate of the splashed mixture which is not adhered to the side wall of the foundation pit is generally 17-25%, which is larger than the specified requirement in 7.5.3 th item of the existing standard (JGJ/T372) of the technical rule for spraying concrete, the rebound rate of the horizontal sprayed concrete mixture is not larger than 15%, the material waste is caused, and the engineering construction cost is increased; after the spraying operation, the sprayed concrete layer falls off, is not compact, has low strength, has small slurry amount of sprayed concrete slurry and poor adhesiveness due to long setting time of the sprayed concrete, and is difficult to trowelle on the surface of the sprayed concrete layer.
Disclosure of Invention
The application provides sprayed concrete and a preparation method thereof, which are used for solving the technical problems of high sprayed rebound rate, poor sprayed concrete engineering quality and difficult sprayed concrete surface trowelling construction of the traditional sprayed concrete.
According to an embodiment of one aspect of the present application, there is provided a shotcrete comprising raw materials of the following composition: cement, limestone powder, bamboo chips, recycled stone, accelerator, sodium silicate powder and water, wherein the mass ratio of the cement to the limestone powder to the bamboo chips to the recycled stone to the accelerator is 1:0.1759 to 0.1771:0.0024 to 0.0029:4.2616 to 4.3569:0.1166 to 0.1187:0.1401 to 0.1424:0.5426 to 0.5532 of the total weight of the composite,
the regenerated stone is formed by crushing, soaking, centrifugally separating and screening waste asphalt concrete solid materials, and comprises regenerated stone A and regenerated stone B, wherein the particle size of the regenerated stone A is 0-4.75 mm; the particle size of the regenerated stone B is 4.75-15 mm.
Further, the specific surface area of the limestone powder is 420-440 m 2 Per kg, the density is 2.7-2.8 g/cm 3 。
Further, the preparation method of the bamboo chips comprises the following steps: the preparation method comprises the steps of forming the arrowhead bamboo sawdust into primary bamboo sawdust with the granularity of 25-35 meshes, and then soaking the primary bamboo sawdust with polymer emulsion to obtain the bamboo sawdust, wherein the polymer emulsion comprises polyvinyl acetate emulsion, EVA emulsion, acrylic ester emulsion, styrene emulsion, butylbenzene emulsion, polyvinylidene chloride emulsion and polyurethane emulsion.
Further, the density of the Sagittaria sagittifolia is 650-750 kg/m 3 。
Further, the initial setting time of the accelerator is 2.0-3.0 min, and the final setting time is 7.0-8.0 min.
Further, the modulus of the sodium silicate powder is 2.2-2.4.
Further, the waste asphalt concrete solid material is soaked, centrifugally separated and screened, and comprises:
the waste asphalt concrete solid material is crushed, soaked, centrifugally separated and screened, and the method comprises the following steps:
s1, mechanically crushing the waste asphalt concrete solid material into particles with the particle size of 0-15 mm;
s2, soaking the waste asphalt concrete solid material with the particle size of 0-15 mm by a solvent so that asphalt in the waste asphalt concrete solid material is dissolved in the solvent to obtain a mixed solution;
s3, centrifugally separating the mixed solution to obtain an asphalt solution and stone;
and S4, screening the stone to obtain the regenerated stone A and the regenerated stone B.
Further, the solvent is trichloroethylene.
Further, the mass ratio of the regenerated stone A to the regenerated stone B is 1: (0.7857-0.8518).
According to another aspect of the present application, there is also provided a method of preparing shotcrete, comprising the steps of:
(1) Mixing cement, regenerated stone, limestone powder, bamboo scraps and water to form mixed slurry;
(2) Adding an accelerator and sodium silicate powder into the mixed slurry to form a spray concrete slurry;
(3) And spraying the concrete slurry on a sprayed surface, and forming concrete after coagulation.
The application has the following beneficial effects:
the sprayed concrete contains the regenerated stone, so that the recycling rate of the solid materials of the waste asphalt concrete is improved, soft slurry is formed by mixing limestone powder, bamboo chips, cement and water, the regenerated stone is wrapped and filled tightly, and the compression strength of the sprayed concrete is improved except for the gaps among the skeletons formed by mixing the regenerated stone; besides meeting the engineering use requirements, the compressive strength of the concrete can also increase the slurry amount of the sprayed concrete, improve the cohesiveness of the sprayed concrete, be favorable for trowelling construction of the surface of the sprayed concrete and improve the surface evenness of the sprayed concrete. Meanwhile, the total surface area of the sprayed concrete aggregate is increased, the air content in the sprayed concrete is increased, tiny bubbles play a role of balls in the sprayed concrete, so that the slump of the sprayed concrete is improved, the cohesion of the sprayed concrete is increased by the increased bubbles, the bubbles are adhered to solid particles, the sinking and water flowing of the solid particles are reduced, bleeding channels are blocked, the bleeding quantity of the sprayed concrete is reduced, the segregation of the sprayed concrete is improved, and the spraying rebound rate of the sprayed concrete is reduced.
Detailed Description
In order to make the objects, technical solutions and advantageous technical effects of the present application clearer, the present application will be further described in detail with reference to examples. It should be understood that the examples described in this specification are for the purpose of illustrating the application only and are not intended to limit the application.
For simplicity, only a few numerical ranges are explicitly disclosed herein. However, any lower limit may be combined with any upper limit to form a range not explicitly recited; and any lower limit may be combined with any other lower limit to form a range not explicitly recited, and any upper limit may be combined with any other upper limit to form a range not explicitly recited. Furthermore, each point or individual value between the endpoints of the range is included within the range, although not explicitly recited. Thus, each point or individual value may be combined as a lower or upper limit on itself with any other point or individual value or with other lower or upper limit to form a range that is not explicitly recited.
In the description herein, unless otherwise indicated, "above" and "below" are intended to include the present number, "one or more" means two or more, and "one or more" means two or more.
In the construction of the main body structure of the underground station of the urban rail transit engineering, the existing asphalt concrete pavement layer of the urban road is broken, and tens of thousands of tons of waste asphalt concrete solid materials can be produced. The general disposal mode of the existing waste asphalt concrete solid material is as follows: and (5) open-air disposal and construction waste disposal in a construction waste disposal field. The outdoor disposal not only occupies land resources for a long time and a large area, but also causes environmental pollution and water source to the periphery of the disposal field, so that the soil is deteriorated; the construction waste disposal site is required to be constructed in suburban areas, so that huge construction waste disposal cost and waste asphalt concrete solid material abandoned transportation cost can be generated for construction enterprises, and the construction cost is increased intangibly.
In addition, the shortage of sand and stone materials is also a problem to be solved in the construction of underground stations of urban rail transit engineering. If the sand and stone materials are transported by remote borrowing, the mountain is required to be opened in suburbs of the city to take the stones, so that the land is desertified, natural resources are destroyed, the construction cost is increased, and the construction period is prolonged.
The waste asphalt concrete solid material, the current regeneration technology in China is as follows: the plant mix thermal regeneration, the on-site thermal regeneration, the plant mix cold regeneration and the on-site cold regeneration are all 4 kinds: a large amount of asphalt smoke is generated in the regeneration process to pollute the environment; in the production process, the defect that the temperature of the waste sand aggregates is too high to avoid that the waste asphalt is burnt, so that the discharging temperature of the reclaimed asphalt mixture is low and the paving construction quality is poor is overcome.
In order to actively respond to the 'pushing green development' proposed by the nation, promoting the harmonious symbiosis of people and nature, and constructing an ecological civilization system; the green low-carbon development is accelerated, the environmental quality is continuously improved, the quality and the stability of an ecological system are improved, the resource utilization efficiency is comprehensively improved, the green construction demonstration project is promoted in engineering construction, the green construction work is actively developed, the innovation is conquered, and the practical use is realized, so that the recycling rate of the construction waste generated in the construction meets the specified requirement. Therefore, how to save land and materials, green and low carbon, economically and reasonably recycle the waste asphalt concrete solid materials is an unavoidable problem for urban rail transit engineering construction.
An embodiment of the first aspect of the present application provides a shotcrete comprising the following raw materials: cement, limestone powder, bamboo chips, recycled stone, accelerator, sodium silicate powder and water, wherein the mass ratio of the cement to the limestone powder to the bamboo chips to the recycled stone to the accelerator is 1:0.1759 to 0.1771:0.0024 to 0.0029:4.2616 to 4.3569:0.1166 to 0.1187:0.1401 to 0.1424:0.5426 to 0.5532 of the total weight of the composite,
the regenerated stone is formed by crushing, soaking, centrifugally separating and screening waste asphalt concrete solid materials, and comprises regenerated stone A and regenerated stone B, wherein the particle size of the regenerated stone A is 0-4.75 mm; the particle size of the regenerated stone B is 4.75-15 mm.
The sprayed concrete contains regenerated stone, so that the recycling rate of the waste asphalt concrete solid material is improved, soft slurry is formed by mixing limestone powder, bamboo chips, cement and water, the regenerated stone A and the regenerated stone B are wrapped and filled tightly, the space between the frameworks which is formed by mixing the regenerated stone A and the regenerated stone B is improved, the compressive strength of the sprayed concrete is enabled to meet the engineering use requirement, the slurry amount of the sprayed concrete is increased, the cohesiveness of the sprayed concrete is improved, the trowelling construction of the surface of the sprayed concrete is facilitated, and the surface flatness of the sprayed concrete is improved. Meanwhile, the total surface area of the sprayed concrete aggregate is increased, the air content in the sprayed concrete is increased, tiny bubbles play a role of balls in the sprayed concrete, so that the slump of the sprayed concrete is improved, the fluidity of the sprayed concrete mixed slurry is improved, the sprayed concrete mixed slurry can flow smoothly rapidly when conveyed through a pipeline, a conveying pipeline is not blocked, the increased bubbles can increase the cohesive force of the sprayed concrete, the bubbles are adhered to solid particles, the sinking and water flowing of the solid particles are reduced, a bleeding channel is blocked, the bleeding amount of the sprayed concrete is reduced, the segregation of the sprayed concrete is improved, and the spraying rebound rate of the sprayed concrete is reduced.
According to the specification of the technical Specification for shotcrete application (JGJ/T372) of the standard Table 3.2.3, the cumulative screen residue of 16mm of the side length of the square-hole screen in the grain composition range of the aggregate is 0% (namely, the passing rate is 100%), and the grain diameter of the aggregate for shotcrete is 0-15 mm. After the waste asphalt concrete solid material is mechanically crushed, the grain composition of the stone is in a poor composition state, and the stone is required to be screened into fine regenerated stone A with the grain diameter of 0-4.75 mm and coarse regenerated stone B with the grain diameter of 4.75-15 mm by a square-hole screen with the grain diameter of 4.75 mm. Mixing the fine regenerated stone A and the coarse regenerated stone B according to a specific proportion and stirring the mixture into continuous graded regenerated stone with the particle size of 0-15 mm. Besides meeting the continuous grading requirement of the stones for the sprayed concrete, the strength and the workability of the sprayed concrete can be improved, the sprayed construction operation on the construction site is facilitated, and the phenomenon that the sprayed concrete mixed slurry blocks the conveying pipeline is avoided. In the mixing of the sprayed concrete mixed slurry, bamboo scraps are used as filling aids to improve the grain composition of the regenerated stone and fill gaps among dense regenerated stone skeletons, so that the skeleton stability is enhanced, and the strength of the concrete is further improved; mixing cement and water, forming cement mixed slurry with bamboo scraps and fine regenerated stone A, filling gaps among the coarse regenerated stone B and adhering the coarse regenerated stone B; limestone powder with approximately spherical particles and more fine particles is doped, the limestone powder has a ball function between cement particles with approximately plate-shaped particles, block-shaped particles and more large particles, gaps among cement are filled, water in the gaps of the cement is reduced, more free water is formed and mixed with cement mixed slurry to form slurry of large-flow soft cement slurry, coarse regenerated stone B is wrapped, and gaps among dense regenerated stone frameworks are filled. A part of free water in the slurry of the soft cement slurry has hydration effect with cement, and limestone powder has low activity and basically does not have chemical reaction with water, so that more free water is combined with accelerator and sodium silicate powder to enable the accelerator and the sodium silicate powder to be rapidly dissolved, and the accelerator and the sodium silicate powder are combined with mixed slurry to form sprayed concrete slurry and enable the sprayed concrete slurry to be rapidly solidified to form concrete.
The recycled stone for sprayed concrete is mixed and blended into continuously graded recycled stone according to a specific proportion by the fine recycled stone A and the coarse recycled stone B, and cement, water and an accelerator are mixed to form concrete; bamboo scraps are doped to improve the grain composition of the regenerated stone and fill gaps among the dense regenerated stone skeletons, so that the skeleton stability is enhanced, and the strength of the concrete is further improved; the limestone powder is doped to fill gaps among cement, water used for cement gaps is reduced, more free water and cement mixed slurry are formed and mixed to form large-flow soft cement slurry, a part of soft cement slurry is wrapped with coarse regenerated stone B and fills gaps among dense regenerated stone frames, the rest soft cement slurry is adhered to the surface of the coarse regenerated stone B, fluidity of sprayed concrete is increased, slump of sprayed concrete is improved, and further, the mixed slurry can flow smoothly and rapidly during pipeline conveying and does not block conveying pipelines.
The bamboo scraps have crack resistance, shearing resistance and performance of assisting in improving compactness, and are not influenced by heat generated by mixing cement and water in the hardening stage of sprayed concrete. The three-dimensional disordered distribution of the bamboo scraps weakens the plastic shrinkage of the sprayed concrete, reduces shrinkage cracks and cracks during initial setting of the sprayed concrete, improves the early cracking resistance of the sprayed concrete, and improves the durability of the sprayed concrete.
The limestone powder is an auxiliary cementing material, has the gelation effect, and can promote the solidification of sprayed concrete together with an accelerator and sodium silicate powder, shorten the initial setting time and the final setting time, and enable the sprayed concrete mixture to be quickly coagulated and molded after spraying construction so as to accelerate the supporting effect on the sprayed surface.
The method provided by the application can be used for timely disposing asphalt concrete solid materials which are discarded in open air for a long time and a large area, reducing land occupation resources, avoiding pollution to the environment and water sources and deteriorating the soil; the construction waste disposal site is avoided from being constructed in suburban areas, and the disposal cost of thousands tons of waste asphalt concrete solid materials and the transportation cost outside the construction site are saved for construction enterprises; the defects of low discharging temperature and poor paving construction quality of the regenerated asphalt mixture in the production process are overcome, and the environment is polluted by asphalt smoke generated in the regeneration process of the waste asphalt concrete solid material; in the construction of an underground station of urban rail transit engineering, waste asphalt concrete solid materials are processed into recycled materials meeting engineering construction requirements, and the recycled materials replace part of engineering construction materials, so that the technical defects existing in the prior art of shotcrete are overcome, construction material investment is saved, construction cost is reduced, the demand for gravel building materials and the outer borrowing and transportation cost thereof are reduced, the construction cost is reduced, the construction period is shortened, mountain-opening and stone-taking are reduced, and natural resources are protected; the waste asphalt concrete solid material can be recycled on site, so that waste is changed into valuable, and the recycling rate of the waste asphalt concrete solid material is improved; the construction process is simple and convenient to operate and convenient to widely use.
In the embodiment of the application, the specific surface area of the limestone powder is 420-440 m 2 Per kg, the density is 2.7-2.8 g/cm 3 。
In some embodiments, limestone powder is used as the fine powder produced during the production of crushed stone and machine-made sand, and has a specific surface area of 430m 2 Per kg, density 2.71g/cm 3 The main component is calcium carbonate (CaCO) 3 ) The limestone powder which is qualified by quality inspection is prepared and stored on site for no more than 5 days, is piled up according to classification and storage bins, and is marked and protected from rainwater and moisture.
The limestone powder has approximately spherical particles and more fine particles, the larger the specific surface area is, the smaller the fineness is, the lower the porosity of the concrete mixed by the limestone powder is, the lower the air content in the concrete is, and the compressive strength of the concrete is improved, but a plurality of tiny bubbles and the ball function thereof are absent in the concrete, so that the workability of concrete mixture is reduced, the bleeding rate is increased, the concrete is isolated, the fluidity of mixed slurry in pipeline transportation is reduced, the pipeline is blocked, and the jet rebound rate of the sprayed concrete is increased. Conversely, the compression strength of the sprayed concrete is reduced.
The specific surface area of limestone powder is selected to be larger than that of ordinary Portland cement (the limestone powder particles are smaller than that of ordinary Portland cement), so that the limestone powder is easy to fill gaps among cements. In the implementation, the limestone powder raw material with the specific surface area larger than that of the ordinary Portland cement and the density smaller than that of the ordinary Portland cement is properly selected, so that the working performance and the compressive strength requirements of the sprayed concrete can be met. If the specific surface area and density of limestone powder are too large or too small, the working performance or compressive strength of the sprayed concrete is affected.
The limestone powder has the gelation effect, and the limestone powder, the accelerator and the sodium silicate powder can promote the solidification of sprayed concrete, shorten the initial setting time and the final setting time, and enable the sprayed concrete mixture to be quickly coagulated and molded after spraying construction so as to accelerate the supporting effect on the sprayed surface.
In an embodiment of the application, the preparation method of the bamboo chips comprises the following steps: the preparation method comprises the steps of forming the arrowhead bamboo sawdust into primary bamboo sawdust with the granularity of 25-35 meshes, and then soaking the primary bamboo sawdust with polymer emulsion to obtain the bamboo sawdust, wherein the polymer emulsion comprises polyvinyl acetate emulsion, EVA emulsion, acrylic ester emulsion, styrene emulsion, butylbenzene emulsion, polyvinylidene chloride emulsion and polyurethane emulsion.
In the embodiment of the application, the density of the Sagittaria sagittifolia is 650-750 kg/m 3 。
The bamboo chip particle size is 30 meshes, the corresponding particle size is less than or equal to 0.6mm, the particle grading of the fine regenerated stone A can be improved, the regenerated stone mixture grading of the fine regenerated stone A and the coarse regenerated stone B which are mixed and mixed according to a specific proportion reaches the optimal state, and the compression strength of the sprayed concrete is improved.
The larger the number of bamboo scraps, the smaller the granularity, and the smaller the number of bamboo scraps, the larger the granularity. If the bamboo scraps have smaller granularity, the bamboo scraps are easy to agglomerate and difficult to disperse, and in order to meet the workability of sprayed concrete, the unit water consumption of the sprayed concrete needs to be increased, so that the compressive strength of the sprayed concrete is reduced; if the grain size of the bamboo chips is larger, the early cracking resistance and flexural tensile strength of the sprayed concrete can be improved, but the grain composition of the fine recycled stone A and the recycled stone mixture composition of the fine recycled stone A and the coarse recycled stone B which are mixed and mixed according to a specific proportion cannot be improved, and the compression strength of the sprayed concrete cannot be improved.
The embodiment adopts the Sagittaria Sagittifolia, because the Sagittaria Sagittifolia is strong bamboo or old bamboo over 3 years, the density is 650-750 kg/m < 3 >, the stalk is thick and high in straightness, the fiber is fine and smooth, the toughness is strong, the propagation and growth are fast, the growth area is wide, and the raw materials are easy to obtain.
In some embodiments, the bamboo scraps are natural organic fibers with clean outer surfaces, green and environment-friendly bamboo with strong toughness of bamboo stalk fibers for more than 3 years, the bamboo scraps are formed by saw dust on the bamboo stalks, the granularity of the bamboo scraps is 30 meshes, and the density of the bamboo scraps is 720kg/m 3 . The bamboo scraps are materials which are processed at any time and used at any time, after the bamboo scraps are processed, the fiber reinforcement and toughening effects of the bamboo scraps are prevented, the bamboo scraps are not weakened in the soaking process of cement slurry alkaline solution, the bamboo scraps are soaked in LLA type polyvinyl acetate emulsion solution with the mass concentration of 10% for at least 24 hours, the bamboo scraps are drained to be in a natural drying state, a layer of compact polymer emulsion protective film is formed on the surface layer of the bamboo scraps, the on-site material preparation and storage time is not more than 5 days, the bamboo scraps are stacked in a classified manner according to classification, and the bamboo scraps are marked, rainwater-proof, moisture-proof and insect corrosion-proof storage management is carried out.
The treated bamboo scraps have a protective film of high molecular latex on the surface, so that the bamboo scraps have the property of easy heat dissipation, thereby improving the heat dissipation property of sprayed concrete and reducing the generation of cracks. And because the three-dimensional disorderly distribution of the bamboo scraps weakens the plastic shrinkage of the sprayed concrete, shrinkage cracks and cracks during initial setting of the sprayed concrete are reduced, the early cracking resistance of the sprayed concrete is improved, and the durability of the sprayed concrete is improved.
In the hardening stage of the sprayed concrete, a large amount of heat is generated by mixing cement and water, so that the internal temperature of the sprayed concrete greatly exceeds the external temperature, and larger temperature stress is caused, thereby directly causing cracks to be generated on the surface of the sprayed concrete. However, as the bamboo scraps are soaked in LLA type polyvinyl acetate emulsion solution with the mass concentration of 10% for 24 hours, a layer of compact polymer emulsion protective film is formed on the surfaces of the bamboo scraps, so that the bamboo scraps are prevented from being contacted with cement; in a large amount of heat generated by mixing cement and water, most of the heat is directly contacted with sprayed concrete, and the rest of the small residual heat can influence bamboo scraps, so that the performances of cracking resistance, shearing resistance and auxiliary improvement of compactness of the bamboo scraps are not greatly influenced and changed. In addition, the protective film of the polymer latex has the property of easy heat dissipation, so that the heat dissipation property of sprayed concrete is improved, and the generation of cracks is reduced. And because the three-dimensional disorderly distribution of the bamboo scraps weakens the plastic shrinkage of the sprayed concrete, shrinkage cracks and cracks during initial setting of the sprayed concrete are reduced, the early cracking resistance of the sprayed concrete is improved, and the durability of the sprayed concrete is improved.
In the embodiment of the application, the initial setting time of the accelerator is 2.0-3.0 min, and the final setting time is 7.0-8.0 min. The initial setting time of the first-grade accelerator according to the accelerator for shotcrete (JC 477-2005) is less than or equal to 3.0min. Too short a setting time is inconvenient for construction operations and requires a fast operation speed; the setting time is too long, the concrete is slow to form and easy to fall off. The final setting time of the first-grade accelerator according to the accelerator for shotcrete (JC 477-2005) is less than or equal to 8.0min. Too short a setting time is inconvenient for construction operations and requires a fast operation speed; the setting time is too long, the concrete is slow to form and easy to fall off.
The sprayed concrete without the accelerator has longer setting time, and is easy to cause the defects of falling off, non-compactness and high rebound rate of the sprayed concrete layer. After the accelerator is doped, cement and sodium carbonate are made to react with gypsum in cement in alkaline liquid fast to make the gypsum lose its retarding effect and form many crystals, so that the concrete has fast setting and early strength effects. The accelerator for sprayed concrete is divided into first-class products and qualified products. And the first grade product with shorter setting time is selected, so that the setting and forming of concrete are accelerated, and the technical problems of falling off, incompact and high rebound rate of the sprayed concrete layer are reduced.
In some embodiments, the accelerator is a DS-1 type accelerator with an initial set time of 3min and a final set time of 8min.
In an embodiment of the application, the sodium silicate powder has a modulus of 2.2 to 2.4. According to the standard of the industrial instant powdered sodium silicate (HGT 4315-2012): the modulus of the I grade product is 1.9-2.1, and the modulus of the II grade product is 2.2-2.4. And II, the like can meet the construction requirement.
In some embodiments, the sodium silicate powder is a Luan brand industrial instant powdered sodium silicate having a modulus of 2.32.
The sodium silicate powder is added into concrete as an accelerator to play a role in rapid coagulation. The concrete doped with the sodium silicate powder has good physical properties, higher compressive strength, tensile strength and better corrosion resistance.
After the mixed slurry is combined with the accelerator and the sodium silicate powder at the discharge port of the conveying pipeline of the sprayer, the accelerator and the sodium silicate powder are quickly dissolved by free water in the slurry amount of the soft cement slurry to form an alkaline aqueous solution, and the alkaline aqueous solution is uniformly dispersed and mixed with limestone powder, bamboo chips and cement powdery materials to promote the concrete sprayed on the sprayed surface to be quickly solidified. The mixed slurry is quickly solidified and early strength is formed by adding the accelerator, but the adhesiveness of the mixed slurry is not strong, and after adding the sodium silicate powder, the solidification time of the mixed slurry is continuously shortened, the mixed slurry has strong adhesiveness, the adhesive force of the sprayed concrete is enhanced, and the spray rebound rate of the sprayed concrete is reduced.
The modulus is an important parameter of sodium silicate, the modulus is 1, warm water can dissolve solid instant powdery sodium silicate at normal times, hot water is needed to dissolve the solid instant powdery sodium silicate when the modulus is increased, and steam with the pressure of more than 4 atmospheres is needed to dissolve the solid instant powdery sodium silicate when the modulus is more than 3. The solid instant powdery sodium silicate with low modulus is more soluble in water, more crystal components, poorer binding capacity, increased modulus, increased colloid components, increased binding capacity, higher modulus, higher viscosity of the solid instant powdery sodium silicate and more indissolvable water.
In the embodiment, the sodium silicate powder of grade II with the modulus of 2.2-2.4 is selected, so that the free water in the slurry amount of the soft cement slurry is easy to dissolve, and the sprayed concrete mixed slurry has adhesiveness, thereby reducing the spraying rebound rate of the sprayed concrete. The sodium silicate powder of class I with the modulus of 1.9-2.1 is easy to dissolve in water, but has less colloid component and poor adhesiveness of the sprayed concrete mixed slurry.
In an embodiment of the present application, the crushing, soaking, centrifugal separation and screening of the waste asphalt concrete solid material comprises:
s1, mechanically crushing the waste asphalt concrete solid material into particles with the particle size of 0-15 mm;
s2, soaking the waste asphalt concrete solid material with the particle size of 0-15 mm by a solvent so that asphalt in the waste asphalt concrete solid material is dissolved in the solvent to obtain a mixed solution;
s3, centrifugally separating the mixed solution to obtain an asphalt solution and stone;
and S4, screening the stone to obtain the regenerated stone A and the regenerated stone B.
In some embodiments, after step S3, an asphalt solution and stone are obtained, wherein the asphalt solution is darker; repeating S2 and S3 until the obtained asphalt solution becomes clear light yellow, and then entering S4 to obtain the regenerated stone A and the regenerated stone B.
In some embodiments, the solvent is trichloroethylene. The trichloroethylene is used as a solvent, and asphalt concrete solid materials are required to be immersed, so that the solvent surface is 100-150 mm higher than the top surface of the asphalt concrete solid materials. The first soaking time is 30min, and the second soaking time and the subsequent soaking time are 3-5 min. Trichloroethylene is an excellent solvent, has the characteristics of incombustibility, low boiling point and low toxicity, and is a good substitute for benzene and gasoline. Because it does not burn, it has no corrosion to metal and strong dissolving power. After the asphalt is dissolved, the asphalt content remaining on the surface of the reclaimed stone is only about 0.4%. And compared with the residual asphalt with the asphalt dissolved by other solvents, the residual asphalt has the lowest content and is clean.
In the embodiment of the application, the mass ratio of the regenerated stone A to the regenerated stone B is 1: (0.7857-0.8518).
The grain diameter of the regenerated stone A is 0-4.75 mm and the grain diameter of the regenerated stone B is 4.75-15 mm and is coarse aggregate, and the sand ratio of the mass of the fine aggregate to the sum of the mass of the fine aggregate is the sand ratio. The mass ratio of the regenerated stone A to the regenerated stone B is 1:0.7857, the corresponding sand rate is 56%; the mass ratio of the regenerated stone A to the regenerated stone B is 1:0.8518, corresponding to a sand ratio of 54%. The mass ratio of the regenerated stone a to the regenerated stone B is therefore 1: the sand ratio of (0.7857-0.8518) is 54-56%.
An embodiment of the second aspect of the present application provides a method for preparing shotcrete, comprising the steps of:
(1) Mixing cement, regenerated stone, limestone powder, bamboo scraps and water to form mixed slurry;
(2) Adding an accelerator and sodium silicate powder into the mixed slurry to form a spray concrete slurry;
(3) And spraying the concrete slurry on a sprayed surface, and forming concrete after coagulation.
The preparation method of the sprayed concrete is simple in process, and can be used for preparing the sprayed concrete according to the embodiment of the first aspect of the application, and the prepared sprayed concrete is low in spraying rebound rate, high in strength and stable in system.
Examples
The present disclosure is more particularly described in the following examples that are intended as illustrations only, since various modifications and changes within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages, and ratios reported in the examples below are by weight, and all reagents used in the examples are commercially available or were obtained synthetically according to conventional methods and can be used directly without further treatment, as well as the instruments used in the examples.
Example 1
S1: preparation work before breaking.
Taking an underground station of an urban rail transit engineering and the top road restoration construction thereof as an example, before the regeneration application, the preparation work before the breaking of the existing urban road asphalt concrete pavement layer is completed is needed, and the working contents comprise:
s101: the pavement layer of asphalt concrete for the existing urban road is subjected to field investigation, design and construction data collection, and especially asphalt variety specification, oil-stone ratio (which refers to the mass percent of asphalt and mineral aggregate in the mixture), variety, specification and characteristics of asphalt concrete constituent materials and the like are collected.
S102: through the field investigation, collection design and construction data, can acquire: the road asphalt concrete pavement layer is a hot-mix asphalt concrete pavement with a 40 mm-thick fine-grain ARAC-13C rubber asphalt upper layer, a 60 mm-thick medium-grain AC-20C road petroleum asphalt middle layer and a 80 mm-thick coarse-grain AC-25C road petroleum asphalt lower layer. The broken stone, stone chips and mineral powder are all limestone, the fine-grain type upper layer asphalt is rubber asphalt, and the middle-grain type middle-surface layer asphalt and the coarse-grain type lower layer asphalt are all 70 # A grade road petroleum asphalt. The blending proportion (in mass percent) of the asphalt mixture of the road asphalt concrete pavement layer is shown in table 1.
The regenerated stone A with the particle size of 0-4.75 mm and the regenerated stone B with the particle size of 4.75-15 mm, which are prepared by mechanical crushing, soaking, centrifugal separation and screening, are mixed with newly-doped cement, limestone powder, bamboo chips, accelerator, sodium silicate powder and mixing water according to a specific mass ratio to form environment-friendly sprayed concrete, and the environment-friendly sprayed concrete is applied to a baffle plate layer between foundation pit supporting structures of underground stations.
Table 1 asphalt mixture blending ratio (in mass%) of asphalt concrete pavement layer
S2: and (5) breaking and recycling asphalt concrete solid materials.
After the construction of the urban road central dividing belt, the removal of evergreen plants in the motor vehicle lane and non-motor vehicle lane dividing belt, the dredging of urban road traffic, the closure of the surrounding barrier of the underground station construction area and the like is finished, the asphalt concrete pavement layer in the underground station main body structure construction area is broken. The mist gun machine is arranged in the breaking operation area for sprinkling water at regular time to prevent dust from polluting air, and the safety warning area for the breaking operation of the excavator is arranged in the breaking operation area.
S201: and (5) breaking the operation. The excavator is adopted to strictly carry out the breaking operation in the daytime according to the safety operation regulations for breaking the pavement of the excavator, and the breaking operation is strictly forbidden at night. The breaking operation route of the excavator and the transportation route of the broken asphalt concrete solid materials are in opposite directions, and at least a distance of 30-50 m is kept between the breaking operation point of the excavator and the loading and transporting operation point of the asphalt concrete solid materials, so that broken stones are prevented from splashing around to hurt personnel due to too strong stress when the excavator breaks the pavement.
S202: and (5) the requirement on the granularity of the solid material. During the construction of asphalt concrete pavement layers, firstly breaking the fine grain type upper layer with the thickness of 40mm, and then breaking the middle grain type middle surface layer with the thickness of 60mm and the coarse grain type lower layer with the thickness of 80mm to the top surface of the cement stabilized base. The granularity of the asphalt concrete solid material after being broken is less than or equal to 100mm, so that the asphalt in the asphalt concrete can be separated from mineral aggregate. And (3) crushing asphalt concrete solid materials with the granularity of more than 100mm into particles with the granularity of less than or equal to 100mm again or repeatedly by adopting an excavator.
S203: and (5) recycling and sorting stacking. Because asphalt on the upper layer of the fine-grained asphalt concrete is rubber asphalt, the broken asphalt concrete solid material must be transported to a designated place for processing recycled materials; because the middle-grain asphalt concrete middle surface layer and the coarse-grain asphalt concrete lower surface layer asphalt are 70 # A grade road petroleum asphalt, the breaking of the middle-grain asphalt concrete middle surface layer and the coarse-grain asphalt concrete lower surface layer can be simultaneously broken, and the broken asphalt concrete solid materials need to be transported to a recycled material processing appointed place.
The fine-grain asphalt concrete upper layer asphalt concrete solid material, the middle-grain asphalt concrete middle-surface layer and the coarse-grain asphalt concrete lower layer asphalt concrete solid material are stacked in a classified manner at a designated place for processing the recycled materials, and the exposed asphalt concrete solid material is covered by a green net respectively to prevent dust emission.
S3: and (5) processing and manufacturing the regenerated material.
The day before the recycled materials are processed and manufactured, the recycled and piled waste asphalt concrete solid materials are washed by clean high-pressure water, dust and soil on the surfaces of the waste asphalt concrete solid materials are removed, and the waste asphalt concrete solid materials are drained to be in a dry state. The washed sewage is discharged to a sedimentation tank through drainage facilities around a regenerated material processing field, and is discharged to an urban sewage pipe network after sedimentation, and the sedimentation tank is cleaned up by special persons at regular intervals.
1. Crushing processing
The medium-grain and coarse-grain waste asphalt concrete solid materials are mechanically crushed and processed into particles with the grain size of 0-15 mm.
2. And (5) centrifugal separation.
According to the technical requirements of a centrifugal extractor in the current standard of highway engineering asphalt and asphalt mixture test procedure (JTG E20-2011T 0722-1993), the centrifugal separator with a capacity of 750L and a cover container, a rotating speed of not less than 3000r/min, and a filtrate outlet is improved and manufactured. The container cover and the container are sealed by oil-resistant filter paper, and the filtrate flows out from the outlet after being discharged through the filter paper and is collected in the recovery container. The instrument installation must be stable and firm, and workplaces must be provided with good ventilation facilities.
(1) Putting the asphalt concrete solid material into a metal container with the volume of 1000L, injecting trichloroethylene solvent into the metal container, enabling the solvent surface to be 100-150 mm higher than the top surface of the asphalt concrete solid material, soaking for 30min, and stirring the asphalt concrete solid material by using an iron rod to fully dissolve asphalt.
(2) Taking out asphalt concrete solid material and solution with the volume of 450-550L from the metal container, pouring the asphalt concrete solid material and the solution into a centrifugal separator, filling filter paper on the edge of the centrifugal separator, and capping and fastening; and an asphalt recovery container is arranged at the filtrate outlet of the centrifugal separator, and the upper opening is sealed to prevent the effluent from being scattered in a mist form.
(3) Starting the centrifugal machine, gradually increasing the rotating speed to 3000r/min, injecting the asphalt solution into the asphalt recycling container through the discharge port, and stopping the machine after outflow is stopped.
(4) Adding new trichloroethylene solvent into the hole of the upper cover of the container to immerse the asphalt concrete solid material to be 100-150 mm higher than the top surface, and soaking for 3-5 min; the centrifuge is started again to allow the asphalt solution to be injected into the asphalt recycling container through the discharge port.
(5) The above operation was repeated several times until the flowing asphalt solution became clear pale yellow.
(6) And (5) removing the upper cover of the container and discharging the stones.
3. And (5) screening.
The stones are respectively obtained through screening by a square hole sieve with the diameter of 4.75 mm: regenerated stone A with the particle size of 0-4.75 mm and regenerated stone B with the particle size of 4.75-15 mm.
4, residual asphalt content inspection.
1500g of stone is extracted from the regenerated stone A and the regenerated stone B respectively, and the residual asphalt content in the regenerated stone is checked according to the test method of Highway engineering asphalt and asphalt mixture test procedure (JTG E20-2011T 0722-1993). The residual asphalt content was examined to be 0.4% and 0.3%, respectively.
S4: and (3) preparing sprayed concrete.
The raw materials are provided according to the following mass ratio:
(1) Cement, limestone powder, bamboo scraps, recycled stone (comprising recycled stone A and recycled stone B in a mass ratio of 1:0.7857), accelerator, sodium silicate powder and water in a mass ratio of 1:0.1759:0.0024:4.2616:0.1166:0.1401:0.5426, sand ratio was 56%.
Wherein, the cement adopts red lion brand P.O42.5 ordinary Portland cement, and the quality meets the technical requirement of P.O42.5 in the general Portland cement (GB 175) standard. The limestone powder adopts fine powder produced in the process of producing broken stone and machine-made sand, has specific surface area of 430m2/kg and density of 2.71g/cm3, and contains calcium carbonate (CaCO) as main component 3 ). The bamboo scraps are natural organic fibers with clean outer surfaces, are green and environment-friendly, have strong toughness for more than 3 years, are formed by saw dust on the bamboo stalks, have the granularity of 30 meshes and have the density of 720kg/m 3 . The accelerator adopts DS-1 accelerator, and the initial setting time of the accelerator3min, and final setting time of 8min, wherein the quality meets the specified requirements in the quick setting agent for shotcrete (JC 477); the sodium silicate powder adopts Luan brand industrial instant powdery sodium silicate with the modulus of 2.32.
(2) Mixing cement, regenerated stone, limestone powder, bamboo scraps and water to form mixed slurry.
(3) And adding an accelerator and sodium silicate powder into the mixed slurry to form the spray concrete slurry.
(4) And spraying the concrete slurry to the side wall of a baffle construction area between foundation pit supporting structure piles of the underground station, and forming concrete after condensation.
Example 2
The raw materials are provided according to the following mass ratio:
(1) Cement, limestone powder, bamboo scraps, recycled stone (comprising recycled stone A and recycled stone B in a mass ratio of 1:0.8182), accelerator, sodium silicate powder and water in a mass ratio of 1:0.1765:0.0026:4.3092:0.1176:0.1412:0.5479, sand ratio 55%.
(2) Mixing cement, regenerated stone, limestone powder, bamboo scraps and water to form mixed slurry.
(3) And adding an accelerator and sodium silicate powder into the mixed slurry to form the spray concrete slurry.
(4) And spraying the concrete slurry onto the side wall of a baffle construction area between piles of the foundation pit supporting structure of the underground station, and condensing to form concrete, wherein the construction conditions and the technological parameters are the same as those of the embodiment 1, and the raw materials are the same as those of the embodiment 1.
Example 3
The raw materials are provided according to the following mass ratio:
(1) Cement, limestone powder, bamboo scraps, recycled stone (comprising recycled stone A and recycled stone B in a mass ratio of 1:0.8518), accelerator, sodium silicate powder and water in a mass ratio of 1:0.1771:0.0029:4.3569:0.1187:0.1424:0.5532, sand ratio was 54%.
(2) Mixing cement, regenerated stone, limestone powder, bamboo scraps and water to form mixed slurry.
(3) And adding an accelerator and sodium silicate powder into the mixed slurry to form the spray concrete slurry.
(4) And spraying the concrete slurry onto the side wall of a baffle construction area between piles of the foundation pit supporting structure of the underground station, and condensing to form concrete, wherein the construction conditions and the technological parameters are the same as those of the embodiment 1, and the raw materials are the same as those of the embodiment 1.
Comparative example 1
The preparation method of the sprayed concrete comprises the following steps:
(1) The raw materials are provided according to the following mass ratio: the mass ratio of cement to fine aggregate to coarse aggregate to accelerator to mixing water is 1:2.0150:1.6486:0.1000:0.4545, the mass ratio of fine aggregate to coarse aggregate is 1:0.8182, and the sand ratio is 55%. Wherein, the fine aggregate adopts natural sand with fineness modulus of 2.6; the coarse aggregate adopts limestone broken stone with the particle size of 4.75-10 mm; the remaining raw materials were the same as in example 1.
(2) Mixing cement, fine aggregate, coarse aggregate and water to form mixed slurry.
(3) And adding an accelerator into the mixed slurry to form the sprayed concrete slurry.
(4) The concrete slurry is sprayed on the side wall of a baffle construction area between foundation pit supporting structure piles of an underground station, and concrete is formed after the concrete slurry is condensed (the construction conditions and the technological parameters are the same as those in the embodiment 1).
The rebound rate and the compressive strength of the sprayed concrete were measured according to the test method of the rebound rate, the test method of the sprayed concrete test piece and the test method of the compressive strength in the standard of the application technical code of sprayed concrete (JGJ/T372), respectively, and the setting time of the sprayed concrete was measured according to the test method of T0527-2005 in the standard of the test code of highway engineering Cement and cement concrete (JTG 3420), and the sprayed concrete prepared in examples 1 to 3 and comparative example 1 was measured, and the measurement results are shown in Table 2.
Table 2 results of performance tests of examples and comparative examples
| Project | Rebound Rate (%) | Initial setting time (min) | Final setting time (min) | Compressive Strength (M Pa) |
| Example 1 | 13.2 | 2.5 | 4.0 | Average value 29.8 |
| Example 2 | 13.5 | 3.0 | 5.5 | Average value 29.4 |
| Example 3 | 14.2 | 3.6 | 6.2 | Average value 28.2 |
| Comparative example 1 | 18.5 | 4.5 | 9.2 | Average value 27.8 |
As can be seen from Table 1, the compression strength of the sprayed concrete of the example is improved by 0.4-2.0 MPa, and the rebound rate is reduced by 23-29%; the initial setting time is shortened by 1-2 min, and the final setting time is shortened by 3-5 min. The amount of the sprayed concrete slurry in the examples consisted of cement, limestone powder, bamboo dust, recycled stone a, accelerator, sodium silicate powder and water, while the amount of the sprayed concrete slurry in the comparative examples consisted of cement, sand, accelerator, mix water. Compared with the sprayed concrete slurry of the comparative example, the embodiment improves the sprayed concrete slurry by 2-4%, is beneficial to trowelling construction of the surface of the sprayed concrete, improves the surface evenness of the sprayed concrete, reduces the spraying rebound rate of the sprayed concrete by 23-29%, effectively improves the engineering quality and saves the materials.
In the comparative example 1, when the spraying operation is performed, after the mixture sprayed by the spraying machine is impacted by the sprayed surface on the side wall of the foundation pit, the rebound rate of the splashed mixture which is not adhered to the side wall of the foundation pit is 17-25%, which is larger than the specified requirement in the 7.5.3 th "rebound rate of the horizontal sprayed concrete mixture is not larger than 15%" of the current standard "sprayed concrete application technical Specification (JGJ/T372"), thereby causing material waste and increasing engineering construction cost; after the spraying operation, the sprayed concrete layer is fallen off, not compact and low in strength due to long coagulation time of the sprayed concrete, the sprayed concrete slurry is small in slurry quantity and poor in adhesiveness, the surface of the sprayed concrete layer is difficult to trowelle, and the technical defects of uneven surface are caused.
While the application has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the application, and in particular, the technical features set forth in the various embodiments may be combined in any manner so long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.
Claims (6)
1. The sprayed concrete is characterized by comprising the following raw materials in parts by weight: cement, limestone powder, bamboo chips, recycled stone, accelerator, sodium silicate powder and water, wherein the mass ratio of the cement to the limestone powder to the bamboo chips to the recycled stone to the accelerator is 1:0.1759 to 0.1771:0.0024 to 0.0029:4.2616 to 4.3569:0.1166 to 0.1187:0.1401 to 0.1424:0.5426 to 0.5532 of the total weight of the composite,
the regenerated stone is formed by crushing, soaking, centrifugally separating and screening waste asphalt concrete solid materials, and comprises regenerated stone A and regenerated stone B, wherein the particle size of the regenerated stone A is 0-4.75 mm; the particle size of the regenerated stone B is 4.75-15 mm, and the mass ratio of the regenerated stone A to the regenerated stone B is 1: (0.7857-0.8518); the modulus of the sodium silicate powder is 2.2-2.4; the limestone powder adopts fine powder produced in the process of producing broken stone and machine-made sand, and the specific surface area of the limestone powder is 420-440 m 2 Per kg, the density is 2.7-2.8 g/cm 3 ；
The preparation method of the sprayed concrete comprises the following steps:
(1) Mixing cement, regenerated stone, limestone powder, bamboo scraps and water to form mixed slurry;
(2) Adding an accelerator and sodium silicate powder into the mixed slurry to form a spray concrete slurry;
(3) And spraying the concrete slurry on a sprayed surface, and forming concrete after coagulation.
2. The shotcrete according to claim 1, wherein the method of producing the bamboo chips comprises: the preparation method comprises the steps of forming the arrowhead bamboo sawdust into primary bamboo sawdust with the granularity of 25-35 meshes, and then soaking the primary bamboo sawdust with polymer emulsion to obtain the bamboo sawdust, wherein the polymer emulsion comprises polyvinyl acetate emulsion, EVA emulsion, acrylic ester emulsion, styrene emulsion, butylbenzene emulsion, polyvinylidene chloride emulsion and polyurethane emulsion.
3. The shotcrete according to claim 2, wherein the density of the arrowhead is 650-750 kg/m 3 。
4. The shotcrete according to claim 1, wherein the initial setting time of the accelerator is 2.0 to 3.0min and the final setting time is 7.0 to 8.0min.
5. The shotcrete according to claim 1, wherein the waste asphalt concrete solid material is crushed, soaked, centrifugally separated and sieved comprising:
s1, mechanically crushing the waste asphalt concrete solid material into particles with the particle size of 0-15 mm;
s2, soaking the waste asphalt concrete solid material with the particle size of 0-15 mm by a solvent so that asphalt in the waste asphalt concrete solid material is dissolved in the solvent to obtain a mixed solution;
s3, centrifugally separating the mixed solution to obtain an asphalt solution and stone;
and S4, screening the stone to obtain the regenerated stone A and the regenerated stone B.
6. The shotcrete of claim 5, wherein the solvent is trichloroethylene.
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| CN108793935A (en) * | 2018-08-25 | 2018-11-13 | 北京建工新型建材有限责任公司 | Prefabricated siccative gunite concrete |
| CN109437706A (en) * | 2018-12-27 | 2019-03-08 | 中交公局第三工程有限公司 | A kind of gunite concrete and its preparation method and application |
| CN113699851A (en) * | 2021-09-14 | 2021-11-26 | 山东交通学院 | Waste asphalt pavement material crushing, screening and recycling system and screening and recycling method |
| CN113929379A (en) * | 2021-09-17 | 2022-01-14 | 中建五局土木工程有限公司 | Bamboo concrete and preparation method thereof and pavement paving construction method of bamboo concrete |
| CN114620981A (en) * | 2022-02-23 | 2022-06-14 | 山西佳维新材料股份有限公司 | Sprayed concrete and preparation method and application thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108793935A (en) * | 2018-08-25 | 2018-11-13 | 北京建工新型建材有限责任公司 | Prefabricated siccative gunite concrete |
| CN109437706A (en) * | 2018-12-27 | 2019-03-08 | 中交公局第三工程有限公司 | A kind of gunite concrete and its preparation method and application |
| CN113699851A (en) * | 2021-09-14 | 2021-11-26 | 山东交通学院 | Waste asphalt pavement material crushing, screening and recycling system and screening and recycling method |
| CN113929379A (en) * | 2021-09-17 | 2022-01-14 | 中建五局土木工程有限公司 | Bamboo concrete and preparation method thereof and pavement paving construction method of bamboo concrete |
| CN114620981A (en) * | 2022-02-23 | 2022-06-14 | 山西佳维新材料股份有限公司 | Sprayed concrete and preparation method and application thereof |
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