CN114620981A - Sprayed concrete and preparation method and application thereof - Google Patents
Sprayed concrete and preparation method and application thereof Download PDFInfo
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- CN114620981A CN114620981A CN202210164817.7A CN202210164817A CN114620981A CN 114620981 A CN114620981 A CN 114620981A CN 202210164817 A CN202210164817 A CN 202210164817A CN 114620981 A CN114620981 A CN 114620981A
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- 239000011378 shotcrete Substances 0.000 title claims abstract description 77
- 238000002360 preparation method Methods 0.000 title claims description 14
- 239000004567 concrete Substances 0.000 claims abstract description 65
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 41
- 239000000843 powder Substances 0.000 claims abstract description 38
- 239000004568 cement Substances 0.000 claims abstract description 29
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 26
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 25
- 239000004576 sand Substances 0.000 claims abstract description 23
- 239000013078 crystal Substances 0.000 claims abstract description 21
- 239000002245 particle Substances 0.000 claims abstract description 15
- 238000010276 construction Methods 0.000 claims abstract description 12
- 239000004575 stone Substances 0.000 claims abstract description 9
- 239000002994 raw material Substances 0.000 claims abstract description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 29
- 238000003756 stirring Methods 0.000 claims description 19
- 238000002156 mixing Methods 0.000 claims description 17
- 239000002002 slurry Substances 0.000 claims description 13
- 238000000034 method Methods 0.000 claims description 12
- 239000000203 mixture Substances 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 10
- 238000005507 spraying Methods 0.000 claims description 7
- 239000010881 fly ash Substances 0.000 claims description 5
- 239000002893 slag Substances 0.000 claims description 5
- 239000002131 composite material Substances 0.000 claims description 4
- 239000000377 silicon dioxide Substances 0.000 claims description 4
- 239000002253 acid Substances 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 3
- 235000019738 Limestone Nutrition 0.000 claims description 2
- 239000006028 limestone Substances 0.000 claims description 2
- 230000008929 regeneration Effects 0.000 claims 1
- 238000011069 regeneration method Methods 0.000 claims 1
- -1 admixture Substances 0.000 abstract description 4
- 230000000996 additive effect Effects 0.000 abstract description 3
- 239000000654 additive Substances 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 20
- 239000007921 spray Substances 0.000 description 8
- 239000002699 waste material Substances 0.000 description 7
- 229910052799 carbon Inorganic materials 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 238000010998 test method Methods 0.000 description 3
- 239000011398 Portland cement Substances 0.000 description 2
- 239000012190 activator Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000000378 calcium silicate Substances 0.000 description 2
- 229910052918 calcium silicate Inorganic materials 0.000 description 2
- CJZGTCYPCWQAJB-UHFFFAOYSA-L calcium stearate Chemical compound [Ca+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O CJZGTCYPCWQAJB-UHFFFAOYSA-L 0.000 description 2
- 235000013539 calcium stearate Nutrition 0.000 description 2
- 239000008116 calcium stearate Substances 0.000 description 2
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 229910052602 gypsum Inorganic materials 0.000 description 2
- 239000010440 gypsum Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000004566 building material Substances 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000009970 fire resistant effect Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 229910021487 silica fume Inorganic materials 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
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
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D20/00—Setting anchoring-bolts
- E21D20/02—Setting anchoring-bolts with provisions for grouting
- E21D20/021—Grouting with inorganic components, e.g. cement
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00034—Physico-chemical characteristics of the mixtures
- C04B2111/00146—Sprayable or pumpable mixtures
- C04B2111/00155—Sprayable, i.e. concrete-like, materials able to be shaped by spraying instead of by casting, e.g. gunite
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Structural Engineering (AREA)
- Inorganic Chemistry (AREA)
- Ceramic Engineering (AREA)
- Mining & Mineral Resources (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
- Lining And Supports For Tunnels (AREA)
Abstract
The invention provides a shotcrete, comprising: the concrete early strength admixture comprises cement, recycled concrete micro powder, admixture, medium sand, gravel, water reducing agent, nano seed crystal early strength agent, accelerating agent and water, wherein the specific surface area of the recycled concrete micro powder is 400m2/kg～800m2(iv) kg; the fineness modulus of the medium sand is 2.3-3.0; the particle size of the crushed stone is 5-10 mm; through the matching use of the raw materials with different grain diameters and the action of the additive, the shotcrete provided by the invention has the strength meeting the construction requirements and low resilience rate on the premise of saving the cement consumption.
Description
Technical Field
The invention relates to the technical field of building materials, in particular to sprayed concrete and a preparation method and application thereof.
Background
The sprayed concrete is formed by conveying a prepared mixture through a pipeline by using a spraying machine with the aid of compressed air and spraying the mixture onto a sprayed surface at a high speed for condensation and hardening. It can be with carrying, mix, casting and smashing integration construction as an organic whole. The sprayed concrete is simple in construction process, unique in effect, economical and applicable, and wide in application, and is widely applied to the civil engineering fields of lining support tunnels, thin-wall structure engineering, geotechnical engineering, underground engineering, restoration and reinforcement engineering, fire-resistant engineering and the like.
At present, the shotcrete has the problems of low early strength, high resilience rate, serious waste and the like, and more requirements are provided for the shotcrete along with the requirements of anchor-shotcrete supporting engineering improvement, the requirements of energy conservation and consumption reduction, the urgent need for improvement of field operation environment and the like. The shotcrete for reinforcing the supports in tunnel engineering has been developed from the initial temporary support to the permanent support structure, and new requirements are made on the performance of the shotcrete.
Therefore, in order to solve the existing problems, a shotcrete is urgently needed, which has high early strength and low rebound rate, can reduce the cement consumption, saves energy, reduces consumption, reduces carbon, protects environment and accords with the national sustainable development strategy.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides shotcrete and a preparation method and application thereof.
In a first aspect, the invention provides shotcrete, which comprises the following raw materials in parts by weight:
as a specific embodiment of the present invention, based on 100 parts by mass of cement, the other components are more preferably:
5-20 parts of recycled concrete micro powder, preferably 8-15 parts;
5-50 parts of admixture, preferably 8-30 parts;
the content of the medium sand is 100-500 parts, preferably 150-300 parts;
1-3 parts of a water reducing agent;
4-10 parts of a nano seed crystal early strength agent;
6-9 parts of an accelerator.
As a specific embodiment of the present inventionThe apparent density of the shotcrete particles is 2300kg/m3～2500kg/m3Preferably 2400kg/m3～2450kg/m3(ii) a The 8-hour compressive strength is more than 10MPa, the 24-hour compressive strength is more than 15MPa, and the 28-day compressive strength is more than 30 MPa.
As a specific embodiment of the present invention, the cement is ordinary portland cement.
As a specific embodiment of the present invention, the recycled concrete fine powder has a specific surface area of 400m2/kg～800m2/kg。
As a specific embodiment of the present invention, the recycled concrete micropowder can be obtained from a commercially available source, or can be prepared by a method comprising the steps of: when preparing the recycled concrete particles, the recycled concrete particles which do not meet the requirement of the particle size range of the invention are put into a ball mill for grinding to prepare the recycled concrete particles with the specific surface area of 400m2/kg～800m2Per kg recycled concrete micropowder.
The specific surface area range of the recycled concrete micro powder is 400m2/kg～800m2Per kg, its cost performance is higher than 800m2The increase of the production cost per kg is larger and is less than 400m2The/kg is not beneficial to the exertion of the particle effect. This is because the specific surface area of the admixtures is generally greater than 400m2Perkg, cement typically 350m2/kg～380m2Per kg, the specific surface area range of the recycled concrete micro powder is 400m2/kg～800m2The grain function of the three components and the activity function of the admixture can be well exerted.
As a specific embodiment of the present invention, the special admixture is an early strength composite admixture, preferably a mixture of at least two of fly ash, granulated blast furnace slag powder, silica powder, limestone powder and an activator, and more preferably a mixture of fly ash, granulated blast furnace slag powder, silica powder and an activator. The main components of the exciting agent are gypsum and calcium stearate.
As a specific embodiment of the invention, according to T/CCES6004-2021 functional composite admixture for concrete, the fineness of the admixture is not more than 12%, the fluidity ratio is not less than 90%, and the 1d compressive strength ratio is not less than 110%;
as a specific embodiment of the invention, the modulus of fineness of the medium sand is 2.3-3.0; the silt content of the medium sand is less than 3.0%, preferably less than 1.5%, and more preferably less than 1.0%.
In a specific embodiment of the present invention, the fineness modulus of the medium sand is preferably 2.5 to 2.8, and more preferably 2.5 to 2.6.
As a specific embodiment of the invention, the crushed stone is in 5-10 mm particle size continuous gradation; the mud content of the crushed stone is below 1 percent, and preferably below 0.5 percent.
As a specific embodiment of the invention, the water reducing agent is a polycarboxylic acid water reducing agent; the water reducing rate of the water reducing agent is more than 25%, preferably 30%, the concrete slump loss is less than 50mm, preferably less than 30mm within 2h, and the mixing amount is 1-3%, preferably 2% of the total amount of cement, recycled concrete micropowder and special admixture. In actual production, the cement, the recycled concrete micropowder and the special admixture are combined into a gelled material.
As a specific implementation mode of the invention, the nano seed crystal early strength agent is nano calcium silicate hydrate particles, the particle size range is 40 nm-200 nm, and the 1d compressive strength ratio is not less than 120%.
As a specific embodiment of the invention, the accelerator is a liquid alkali-free accelerator, the 6h strength of the accelerator is not lower than 1MPa, and the 1d strength of the accelerator is not lower than 10 MPa.
The above raw materials in the present invention may be prepared by themselves or may be obtained commercially, and the present invention is not particularly limited thereto.
In a second aspect, the invention provides a preparation method of the shotcrete, which comprises the steps of mixing and stirring cement, recycled concrete micro powder, admixture, medium sand, broken stone, water reducing agent, nano seed crystal early strength agent, water and accelerating agent to obtain the shotcrete; preferably, the method comprises the following steps:
s1: mixing and stirring cement, recycled concrete micro powder, admixture, medium sand and gravel to obtain a mixed material;
s2: adding water, a water reducing agent and a nano seed crystal early strength agent into the mixed material obtained in the step S1 to prepare slurry;
s3: and adding an accelerator into the slurry obtained in the step S2 to prepare the shotcrete.
As a specific embodiment of the present invention, the method further includes S4: construction is carried out by using a spraying device.
In a third aspect, the invention provides application of the shotcrete in the field of underground engineering anchor-jet support and geotechnical slope anchor-jet support construction.
As a specific embodiment of the invention, the underground engineering anchor-jet support construction comprises, but is not limited to, mine roadways, traffic tunnels, hydraulic tunnels and various caverns.
Compared with the prior art, the invention has the beneficial effects that:
1. the shotcrete provided by the invention has the advantages that the strength and the low resilience rate which meet the construction requirements are realized through the synergistic effect of different powder materials, the matching of raw materials with different particle sizes and the early strength and the accelerating agent effect of the additive.
2. In the embodiment of the invention, the waste concrete is recycled with high added value, the special admixture is added to improve the early strength and improve the workability of the concrete, the nano seed crystal early strength agent is added to improve the early strength, the later strength is not reduced, and the rebound rate is reduced, so that the provided sprayed concrete has the strength meeting the construction requirement and low rebound rate, and the permanent support function is realized.
3. The sprayed concrete of the invention is doped with part of recycled concrete micro powder, thus realizing the recycling of the high added value of the concrete building wastes, fully exerting the additive effect of the admixture, reducing the cement consumption, improving the early strength, reducing the rebound rate, saving energy, materials and carbon, and conforming to the national sustainable development strategy.
Detailed Description
The present invention is further illustrated by the following examples, which are not to be construed as limiting the invention in any way.
In each example of the invention, the specific reagents used were as follows:
the cement is ordinary portland cement with the brand number of P.O42.5, and the manufacturer is a limited liability company of Beijing cement factory;
the recycled concrete micropowder is prepared by sorting, crushing and screening the waste concrete demolished objects, and then grinding the waste concrete particles by a ball mill to obtain the recycled concrete micropowder with the specific surface area of 400-600 m2Per kg recycled concrete micropowder;
the special admixture is prepared by mixing I-grade and II-grade fly ash of the Huaneng power plant, granulated high slag powder of Tangshanlinglong S95 grade, silica fume, gypsum and calcium stearate according to the mixing ratio of 1:1:0.05: 0.03;
medium sand with fineness modulus of 2.5, commercially available, parturient Laiscui;
5-10 mm of broken stone, which is sold in the market and dense in the producing area;
the water reducing agent is a polycarboxylic acid high-performance water reducing agent with the model number of JW-11X, and the manufacturer comprises: shanxi Jiawei New materials Co;
nano seed crystal early strength agent, patent product, patent number ZL201510422642.5, model JW-43, manufacturer: shanxi Jiawei new materials Co., Ltd, the components in each embodiment of the invention are: nano-sized calcium silicate hydrate particles;
the accelerator is a sulphoaluminate alkali-free liquid accelerator with the model JW-18, and is manufactured by: shanxi Jiawei New materials Co.
In each embodiment of the invention, the test method is as follows:
the apparent density of the concrete particles is tested and evaluated according to GB50080-2016 'test method for the performance of common concrete mixtures';
the concrete compressive strength is tested and evaluated according to GB50081-2019 test method standards for concrete physical and mechanical properties;
the strength of the accelerator is evaluated according to GB/T35159-2017 accelerator for sprayed concrete;
the specific surface area is tested and evaluated according to the standard of T/CCES6004-2021 functional composite admixture for concrete;
the rebound rate of sprayed concrete refers to horizontal sprayingElasticity, spraying 2400kg (1 m) on the sidewall3) Concrete, collecting and measuring the weight of concrete falling on the ground, wherein the rebound rate is the ratio of the weight of the concrete falling on the ground to the weight of the sprayed concrete;
weighing with an electronic scale to 0.1 kg;
the spraying equipment was a concrete wet sprayer model number GHP16G, gunn engineering equipment, Inc. of Henan province.
Example 1
The embodiment provides a shotcrete and a preparation method thereof, and the concrete details are as follows:
s1: adding 300kg of P.O42.5 cement, 40kg of recycled concrete micro powder, 60kg of admixture, 752kg of medium sand and 1038kg of macadam into a stirrer, and fully stirring and uniformly mixing;
s2: adding 160kg of water, 24kg of nano seed crystal early strength agent and 6kg of water reducing agent into the stirrer, and stirring into uniform slurry;
s3: and adding 28kg of accelerator, and quickly forming to obtain the sprayed concrete.
The shotcrete obtained in example 1 was found to have a compressive strength of 12.1MPa at 8 hours, 18.2MPa at 1d and 43.8MPa at 28 d. The rebound resilience is 4.5% when the test spray is matched with the above formula.
Example 2
The embodiment provides a shotcrete and a preparation method thereof, and the concrete details are as follows:
s1: adding 360kg of P.O42.5 cement, 50kg of recycled concrete micro powder, 90kg of admixture, 688kg of medium sand and 1032kg of gravel into a stirrer, and fully stirring and uniformly mixing;
s2: adding 150kg of water, 30kg of nano seed crystal early strength agent and 12kg of water reducing agent into the stirrer, and stirring into uniform slurry;
s3: and adding 40kg of accelerator, and quickly forming to obtain the sprayed concrete.
The shotcrete obtained in example 2 was tested to have a compressive strength of 14.8MPa at 8h, 20.4MPa at 1d and 66.5MPa at 28 d. The rebound resilience of the test spray is 3.5 percent.
Example 3
The embodiment provides a shotcrete and a preparation method thereof, and the concrete details are as follows:
s1: adding 225kg of P.O42.5 cement, 30kg of recycled concrete micro powder, 45kg of admixture, 869kg of medium sand and 1021kg of gravel into a stirrer, and fully stirring and uniformly mixing;
s2: then 160kg of water, 21kg of nano seed crystal early strength agent and 6kg of water reducing agent are added into the stirrer and stirred into uniform slurry;
s3: then adding 21kg of accelerator, and quickly forming to obtain the sprayed concrete.
The shotcrete obtained in example 3 was tested to have a compressive strength of 11.8MPa at 8 hours, 16.4MPa at 1d and 30.2MPa at 28 d. The rebound resilience is 5.0% when the test spray is matched with the above formula.
Example 4
The comparative example provides a shotcrete and a preparation method thereof, and the concrete details are as follows:
s1: adding 360kg of P.O42.5 cement, 80kg of recycled concrete micro powder, 90kg of admixture, 658kg of medium sand and 1032kg of gravel into a stirrer, and fully stirring and uniformly mixing;
s2: adding 160kg of water, 30kg of nano seed crystal early strength agent and 12kg of water reducing agent into the stirrer, and stirring into uniform slurry;
s3: and adding 30kg of accelerator, and quickly forming to obtain the sprayed concrete.
The shotcrete obtained in example 4 was tested to have a compressive strength of 12.2MPa at 8 hours, 17.0MPa at 1d and 60.2MPa at 28 d. The rebound resilience is 8.2% when the mixture is matched with a test spray.
Comparative example 1
The comparative example provides a shotcrete and a preparation method thereof, and the concrete details are as follows:
s1: 340kg of P.O42.5 cement, 120kg of recycled concrete micro powder, 70kg of admixture, 658kg of medium sand and 1032kg of gravel are added into a stirrer to be fully stirred and uniformly mixed;
s2: adding 160kg of water, 30kg of nano seed crystal early strength agent and 14kg of water reducing agent into the stirrer, and stirring into uniform slurry;
s3: and adding 30kg of accelerator, and quickly forming to obtain the sprayed concrete.
The sprayed concrete obtained in the comparative example 1 is detected to have 8.2MPa of compressive strength at 8h, 15.1MPa of compressive strength at 1d and 50.2MPa of compressive strength at 28 d. The rebound resilience is 14.2% when the mixture is matched with the test spray.
Compared with the comparative example 1 and the example 2, the mixing amount of the recycled concrete micro powder is increased by more than 20%, the mixing amount of the water reducing agent is increased, the corresponding strength is reduced, the rebound rate is increased, and the method is uneconomical.
Comparative example 2
The comparative example provides a shotcrete and a preparation method thereof, wherein recycled concrete micro powder is not added, the amount of the recycled concrete micro powder is replaced by cement, and the concrete details are as follows:
s1: 440kg of P.O42.5 cement, 90kg of admixture, 658kg of medium sand and 1032kg of broken stone are added into a stirrer to be fully stirred and uniformly mixed;
s2: adding 160kg of water, 30kg of nano seed crystal early strength agent and 12kg of water reducing agent into the stirrer, and stirring into uniform slurry;
s3: and adding 30kg of accelerator, and quickly forming to obtain the sprayed concrete.
The shotcrete obtained in the comparative example 2 is detected to have a compressive strength of 13.2MPa at 8h, 18.0MPa at 1d and 61.4MPa at 28 d. The rebound resilience of the mixture is 8.0 percent according to the matching test spray.
Compared with the embodiment 2, the recycled concrete micro powder is not added, the corresponding strength is slightly improved, the rebound resilience is slightly reduced, but the cost is greatly improved, and the low-carbon environmental protection is not realized.
Comparative example 3
The comparative example provides a shotcrete and a preparation method thereof, and the concrete details are as follows:
s1: adding 360kg of P.O42.5 cement, 50kg of recycled concrete micro powder, 15kg of admixture, 763kg of medium sand and 1032kg of macadam into a stirrer, and fully stirring and uniformly mixing;
s2: adding 150kg of water, 30kg of nano seed crystal early strength agent and 10kg of water reducing agent into the stirrer, and stirring into uniform slurry;
s3: then adding 34kg of accelerator, and quickly forming to obtain the sprayed concrete.
The sprayed concrete obtained in the comparative example 3 is detected to have the 8h compressive strength of 11.2MPa, the 1d compressive strength of 15.3MPa and the 28d compressive strength of 48.2 MPa. The rebound resilience of the mixture is 10.2 percent according to the matching ratio of the test spraying.
Compared with the comparative example 3 and the example 2, the amount of the special admixture is reduced by less than 5 percent, the corresponding strength is reduced, and the rebound rate is improved.
Comparative example 4
The comparative example provides a shotcrete and a preparation method thereof, and the concrete details are as follows:
s1: adding 360kg of P.O42.5 cement, 50kg of recycled concrete micro powder, 90kg of admixture, 688kg of medium sand and 1032kg of gravel into a stirrer, and fully stirring and uniformly mixing;
s2: adding 150kg of water, 13kg of nano seed crystal early strength agent and 12kg of water reducing agent into the stirrer, and stirring into uniform slurry;
s3: and adding 40kg of accelerator, and quickly forming to obtain the sprayed concrete.
The sprayed concrete obtained in the comparative example 4 is detected to have 5.6MPa of compressive strength at 8h, 10.8MPa of compressive strength at 1d and 55.8MPa of compressive strength at 28 d. The rebound resilience of the test spray is 15.0 percent.
Compared with the comparative example 4 and the example 2, the doping amount of the nano seed crystal early strength agent is reduced by less than 4 percent, the corresponding strength is reduced, and the rebound rate is improved.
Comparative example 5
The present comparative example provides an existing shotcrete and a method for preparing the same, the specific details are as follows:
s1: adding 440kg of P.O42.5 cement, 60kg of recycled concrete micro powder, 688kg of medium sand and 1032kg of macadam into a stirrer, and fully stirring and uniformly mixing;
s2: adding 150kg of water, 30kg of nano seed crystal early strength agent and 12kg of water reducing agent into the stirrer, and stirring into uniform slurry;
s3: and adding 40kg of accelerator, and quickly forming to obtain the sprayed concrete.
The shotcrete obtained in example 2 was tested to have a compressive strength of 2.8MPa at 8h, 6.4MPa at 1d and 40.6MPa at 28 d. The rebound resilience of the test spray is 15.5 percent.
Compared with the concrete prepared by the method in the comparative example 5, the special admixture is not used, so that the cost of the concrete is high, the corresponding strength is greatly reduced, and the rebound resilience is greatly improved.
Application example
The sprayed concrete prepared in the embodiment 2 is applied to the construction supporting engineering of a tunnel of an urban railway, so that the cost is low, the rebound rate is low, the strength is high, the material is saved, the recycled construction waste micro powder is used, and the environmental benefit meets the national strategic direction.
Comparing examples 1-3 with comparative examples 1-5, it can be seen that the strength of the sprayed concrete can be greatly improved and the resilience can be reduced by adding the recycled construction waste micro powder, the special admixture and the nano seed crystal early strength agent. The cement consumption can be reduced, the low carbon and environmental protection are realized, and the sustainable development direction is met.
In conclusion, the sprayed concrete disclosed by the invention has the advantages of early strength, low rebound rate, low cost and the like. The sprayed concrete disclosed by the invention meets the standard requirements of GB50086-2001 anchor rod sprayed concrete support technical specifications, TB/T3275-2018 railway concrete.
Any numerical value mentioned in this specification, if there is only a two unit interval between any lowest value and any highest value, includes all values from the lowest value to the highest value incremented by one unit at a time. For example, if it is stated that the amount of a component, or a value of a process variable such as temperature, pressure, time, etc., is 50 to 90, it is meant in this specification that values of 51 to 89, 52 to 88 … …, and 69 to 71, and 70 to 71, etc., are specifically enumerated. For non-integer values, units of 0.1, 0.01, 0.001, or 0.0001 may be considered as appropriate. These are only some specifically named examples. In a similar manner, all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be disclosed in this application.
It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.
Claims (13)
1. The shotcrete is characterized by comprising the following raw materials in parts by weight:
2. the shotcrete according to claim 1, wherein the cement is, based on 100 parts by mass of the cement:
5-20 parts of recycled concrete micro powder, preferably 8-15 parts; and/or
The content of the medium sand is 100-500 parts, preferably 150-300 parts; and/or
5-50 parts of admixture, preferably 8-30 parts; and/or
1-3 parts of a water reducing agent; and/or
4-10 parts of a nano seed crystal early strength agent; and/or
And 6-9 parts of an accelerator.
3. Shotcrete as claimed in claim 1 or claim 2, wherein the shotcrete particles have an apparent density of 2300kg/m3～2500kg/m3Preferably 2400kg/m3～2450kg/m3(ii) a The 8-hour compressive strength is more than 10MPa, the 24-hour compressive strength is more than 15MPa, and the 28-day compressive strength is more than 30 MPa.
4. Shotcrete according to any one of claims 1-3, wherein the regeneration is performedThe specific surface area of the concrete micro powder is 400m2/kg～800m2/kg。
5. The shotcrete according to any one of claims 1 to 4, wherein the admixture is an early strength type composite admixture, preferably a mixture of at least two of fly ash, granulated blast furnace slag powder, silica powder, limestone powder and an excitant, more preferably a mixture of fly ash, granulated blast furnace slag powder, silica powder and excitant in a proportion of (0-30): (0-50): (0 to 10) and (0.05 to 0.25).
6. The shotcrete according to any one of claims 1-5, wherein the natural medium sand fineness modulus is 2.3-3.0; the mud content of the natural medium sand is less than 3.0%, preferably less than 1.5%, and more preferably less than 1.0%.
7. The shotcrete of any one of claims 1-6, wherein the crushed stone is a 5-10 mm grain size continuous grade; the mud content of the macadam is below 1%, preferably below 0.5%.
8. The shotcrete of any one of claims 1-7, wherein the water reducing agent is a polycarboxylic acid water reducing agent; the water reducing rate of the water reducing agent is more than 25%, preferably 30%, the concrete slump loss is less than 50mm, preferably less than 30mm within 2h, and the mixing amount is 1-3%, preferably 2% of the total amount of cement, recycled concrete micropowder and special admixture.
9. The shotcrete of any one of claims 1 to 8, wherein the nano-seed early strength agent has a 1d compressive strength ratio of not less than 120%.
10. The shotcrete according to any one of claims 1 to 9, wherein the accelerator is a liquid alkali-free accelerator having a 6h strength of not less than 1MPa and a 1d strength of not less than 10 MPa.
11. A method for preparing shotcrete according to any one of claims 1 to 10, wherein the shotcrete is obtained by mixing and stirring cement, recycled concrete micropowder, admixture, medium sand, crushed stone, water reducing agent, nano seed crystal early strength agent, water and accelerator; preferably, the method comprises the following steps:
s1: mixing and stirring the cement, the recycled concrete micro powder, the admixture, the medium sand and the crushed stone to obtain a mixed material;
s2: adding the water, the water reducing agent and the nano seed crystal early strength agent into the mixed material obtained in the step S1 to prepare slurry;
s3: and adding the accelerator into the slurry obtained in the step S2 to prepare the shotcrete.
12. The shotcrete preparation method of claim 11, further comprising S4: construction is carried out by using a spraying device.
13. Use of the shotcrete according to any one of claims 1 to 10 or the shotcrete produced by the method according to claim 11 or 12 in the field of anchor-shotcrete support in underground works and anchor-shotcrete support in geotechnical slopes.
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| CN116621489A (en) * | 2023-07-24 | 2023-08-22 | 石家庄市长安育才建材有限公司 | Sprayed concrete admixture |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115180883A (en) * | 2022-06-23 | 2022-10-14 | 中建五局土木工程有限公司 | Sprayed concrete and preparation method thereof |
| CN115180883B (en) * | 2022-06-23 | 2023-10-31 | 中建五局土木工程有限公司 | Sprayed concrete and preparation method thereof |
| CN115536302A (en) * | 2022-11-07 | 2022-12-30 | 贵州天威建材科技有限责任公司 | Silicomanganese slag-based super early-strength shotcrete admixture and shotcrete |
| CN115536302B (en) * | 2022-11-07 | 2023-09-12 | 贵州天威建材科技有限责任公司 | Silicon-manganese slag-based super-early-strength sprayed concrete admixture and sprayed concrete |
| CN116621489A (en) * | 2023-07-24 | 2023-08-22 | 石家庄市长安育才建材有限公司 | Sprayed concrete admixture |
| CN116621489B (en) * | 2023-07-24 | 2023-10-27 | 石家庄市长安育才建材有限公司 | Sprayed concrete admixture |
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