CN110510954B - High-strength sprayed concrete for high-ground-temperature tunnel and preparation method thereof - Google Patents
High-strength sprayed concrete for high-ground-temperature tunnel and preparation method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- 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
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/00724—Uses not provided for elsewhere in C04B2111/00 in mining operations, e.g. for backfilling; in making tunnels or galleries
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/34—Non-shrinking or non-cracking materials
- C04B2111/343—Crack resistant materials
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/76—Use at unusual temperatures, e.g. sub-zero
- C04B2111/763—High temperatures
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/10—Mortars, concrete or artificial stone characterised by specific physical values for the viscosity
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/30—Mortars, concrete or artificial stone characterised by specific physical values for heat transfer properties such as thermal insulation values, e.g. R-values
- C04B2201/32—Mortars, concrete or artificial stone characterised by specific physical values for heat transfer properties such as thermal insulation values, e.g. R-values for the thermal conductivity, e.g. K-factors
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- 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
Abstract
The invention discloses a high-strength sprayed concrete for a high-ground-temperature tunnel and a preparation method thereof, wherein the concrete comprises the following raw material components: cement, fly ash, slag powder, sand, coarse aggregate, vitrified micro bubbles, PVA fibers, steel fibers, modified rubber, a water reducing agent, an accelerating agent and water. According to the invention, the low-melting-point water-soluble PVA fiber is adopted, so that after the concrete reaches the fiber melting point, the fiber is melted to form a pore passage, which is convenient for the dissipation of water vapor in the concrete at high temperature, the steam pressure in the concrete is reduced, and the burst risk is reduced; meanwhile, the dissolution of the water-soluble PVA fiber greatly enhances the internal cohesive force of the concrete and avoids the cracking of a cementing surface. Through the mutual matching of the raw materials, the prepared concrete has the characteristics of low heat conductivity coefficient, good impermeability, high interface bonding strength and small later strength loss, the later strength of the sprayed concrete is greatly improved, and the cracking problem of the high-ground-temperature concrete is solved.
Description
Technical Field
The invention belongs to the technical field of concrete, and particularly relates to high-strength sprayed concrete for a high-ground-temperature tunnel and a preparation method thereof.
Background
After the high ground temperature tunnel is excavated, because the temperature of the excavated rock surface is high (more than 80 ℃), the physical properties and the damage form of the concrete are changed after the concrete is sprayed, and the diseases such as low later strength, high rebound rate, uneven strength distribution, concrete cracking and the like of the concrete are often caused.
Due to the migration of water molecules in the condensation process of the high ground temperature concrete, the compactness of the interior of the concrete is uneven, and the concrete cracks along the cementing surface and near the cementing surface under different normal stresses and temperatures. Cracking along the bond surface is one of the most common types of concrete failure.
Disclosure of Invention
In order to solve the problems, the invention aims to provide high-strength shotcrete for a high-ground-temperature tunnel and a preparation method thereof. The obtained concrete has the characteristics of low heat conductivity coefficient, good impermeability, high interface bonding strength and small later strength loss, greatly improves the later strength of the sprayed concrete, and solves the cracking problem of the high-ground-temperature concrete.
In order to achieve the above object, the present invention adopts the following technical solutions.
The high-strength shotcrete for the high-ground-temperature tunnel comprises the following raw material components: the concrete comprises a cementing material, sand, coarse aggregate, vitrified micro bubbles, polyvinyl alcohol (PVA) fiber, steel fiber, modified rubber, a water reducing agent, an accelerating agent and water; wherein the cementing material is cement, fly ash and slag powder.
Further, the dosage of the raw materials is as follows: 1m3The raw materials comprise the following components in parts by mass: 450-500 kg of a cementing material, 600-650 kg of sand, 460-490 kg of coarse aggregate, 100-120 kg of vitrified micro bubbles, 1-2 kg of PVA fiber, 35-40 kg of steel fiber, 28-32 kg of modified rubber, 0.8% of a water reducing agent by mass and 5% of an accelerating agent by mass, wherein the mass ratio of water to the cementing material is 0.45; the cementing material comprises the following raw materials in percentage by mass: 70% of cement, 15% of fly ash and 15% of slag powder.
Further, the coarse aggregate is crushed stone.
Furthermore, the particle size of the vitrified micro bubbles is 1-2 mm.
Furthermore, the melting point of the PVA fiber is 70-80 ℃.
Furthermore, the diameter of the steel fiber is 0.8-1.0 mm, the length of the steel fiber is 45-50 mm, and the tensile strength is not less than 600 MPa.
Further, the cement is ordinary portland cement, the fly ash is I-grade fly ash, and the specific surface area of the slag powder is 450m2/kg。
Further, the modified rubber is prepared by modifying rubber powder by using sodium silicate through a sol-gel method; the mass ratio of the sodium silicate to the rubber powder is (0.06-0.08) to 1.
Furthermore, the particle size of the rubber powder is 80-100 meshes.
Further, the water reducing agent is a polycarboxylic acid type water reducing agent.
Further, the accelerator is a liquid accelerator.
(II) a preparation method of high-strength shotcrete for a high-ground-temperature tunnel, which comprises the following steps:
step 1, adding sodium silicate into warm water to be fully dissolved to obtain sodium silicate sol; adding rubber powder into the sodium silicate sol, stirring and mixing for 2 hours, and standing for 2 hours to obtain the rubber powder;
step 2, stirring and mixing cement, slag powder, fly ash, sand, coarse aggregate, vitrified micro bubbles, a water reducing agent and water to obtain a base material; adding the modified rubber, the steel fiber and the PVA fiber into the base material, and strongly stirring until the materials are uniformly mixed to obtain a concrete primary product;
and 3, after the rock surface is pretreated, spraying the concrete primary product to the pretreated rock surface through a spraying pipeline, mixing the concrete primary product with an accelerator at the outlet of the spraying pipeline to form high-strength sprayed concrete for a high-ground-temperature tunnel, forming concrete support on the rock surface, and then curing by adopting water glass.
Further, in the step 1, the temperature of the warm water is 40-50 ℃.
Further, in step 3, the pretreatment is: firstly, grinding and cleaning a rock surface to increase the friction force of the rock surface; and then the polished rock surface is subjected to water spraying and wetting treatment.
Further, in the step 3, the spraying amount of the accelerator accounts for 1.8-2.2% of the spraying amount of the concrete primary product.
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the invention, the low-melting-point water-soluble PVA fiber is adopted, so that after the concrete reaches the fiber melting point, the fiber is melted to form a pore passage, which is convenient for the dissipation of water vapor in the concrete at high temperature, and the steam pressure in the concrete is reduced, thereby greatly reducing the burst risk; meanwhile, the dissolution of the water-soluble PVA fiber greatly enhances the internal cohesive force of the concrete and avoids the cracking of a cementing surface.
(2) The invention adopts the double-fiber doping of the PVA fiber and the steel fiber to enhance the strength of the concrete at low temperature, the steel fiber is enhanced to play a main role along with the dissolution of the PVA fiber at high temperature, and the dissolved PVA provides a bridging effect for the steel fiber, can play a role in preventing crack propagation and greatly enhances the later strength of the concrete.
(3) The invention adopts the modified rubber and the vitrified micro bubbles to form double-doped heat insulation, so that the crystal arrays of inorganic non-metallic raw materials in concrete are disordered, a heat flow channel is damaged, and the heat conductivity is greatly reduced. The rubber component is not directly doped, but is added after being modified by the sodium silicate, so that the rubber modified by the sodium silicate can be well combined with the concrete, the problem of uneven mixing caused by large specific gravity difference between the rubber and the concrete is solved, and the influence of the addition of rubber materials on the later strength of the concrete is avoided.
(4) According to the invention, due to the addition of the PVA fiber and the modified rubber, the water migration of the concrete is reduced when the concrete is heated, the high-temperature falling-off phenomenon of the concrete is relieved, the concrete is uniformly hydrated, and the later strength loss rate is reduced.
(5) In order to prevent the water loss in the curing process, the water glass is used for curing, and the water glass reacts with calcium hydroxide generated by hydration of cement to generate calcium silicate gel so as to prevent the water loss in the curing process.
Detailed Description
The embodiments and effects of the present invention are described in further detail below.
The high-strength shotcrete for the high-ground-temperature tunnel comprises the following raw materials in percentage by weight: the cement is grade P.042.5 ordinary portland cement of Yao Bai cement Limited in Xian Lantian, the accelerator is XJ-SN type liquid accelerator of novel building materials Limited in Henan, the water reducing agent is a poly carboxylic acid water reducing agent of type (1) of novel building materials Limited in Henan, the fly ash is grade I fly ash, and the density of slag powder is 2.88g/m37d activity coefficient 95%, 28d activity coefficient 107%, specific surface area 450m2Per kg; the sand is river sand, and the fineness modulus is 2.7; the steel fiber adopts a wave-shaped corrugated type, and the specification is as follows: the diameter is 0.95mm, the length is 50mm, and the tensile strength is more than or equal to 600 MPa; the PVA fiber is water-soluble explosion-proof PVA fiber; the particle size of the vitrified micro bubbles is 1mm, and the volume density is 100kg/m 3; the granularity of the rubber powder is 80 meshes, and the volume density is 350kg/m 3.
Example 1
A preparation method of high-strength shotcrete for a high-ground-temperature tunnel comprises the following raw materials in parts by weight:
1m3the raw materials comprise the following components in parts by mass: 350kg of cement, 75kg of fly ash, 75kg of slag powder, 483kg of broken stone, 650kg of sand, 225kg of water, 100kg of vitrified micro bubbles, 1kg of PVA fiber, 40kg of steel fiber, 31.5kg of modified rubber, 4kg of water reducing agent and 25kg of accelerating agent.
The preparation method is implemented according to the following steps:
step 1, adding 6kg of sodium silicate into 50L of warm water with the temperature of 40 ℃ for full dissolution to obtain sodium silicate sol; adding 94kg of rubber powder into the sodium silicate sol, stirring and mixing for 2 hours, and standing for 2 hours to obtain modified rubber;
step 2, stirring and mixing cement, slag powder, fly ash, sand, coarse aggregate, vitrified micro bubbles, a water reducing agent and water to obtain a base material; adding the modified rubber, the steel fiber and the PVA fiber into the base material, and strongly stirring until the materials are uniformly mixed to obtain a concrete primary product;
step 3, polishing and cleaning the rock surface to increase the friction force of the rock surface; then, performing water spraying and wetting treatment on the polished rock surface; spraying the concrete primary product to the pretreated rock surface through a spraying pipeline, mixing the concrete primary product with an accelerating agent at the outlet of the spraying pipeline to form high-strength spraying concrete for the high-ground-temperature tunnel, forming a concrete support on the rock surface, and then curing by adopting water glass; wherein the spraying amount of the accelerator accounts for 2% of the spraying amount of the concrete primary product.
Example 2
A preparation method of high-strength shotcrete for a high-ground-temperature tunnel comprises the following raw materials in parts by weight:
1m3the raw materials comprise the following components in parts by mass: 315kg of cement, 67.5kg of fly ash, 67.5kg of slag powder, 480kg of broken stone, 630kg of sand, 202.5kg of water, 100kg of vitrified micro bubbles, 1kg of PVA fiber, 35kg of steel fiber, 30kg of modified rubber, 3.6kg of water reducing agent and 22.5kg of accelerating agent.
The preparation method is implemented according to the following steps:
step 1, adding 6kg of sodium silicate into 50L of warm water with the temperature of 40 ℃ for full dissolution to obtain sodium silicate sol; adding 94kg of rubber powder into the sodium silicate sol, stirring and mixing for 2 hours, and standing for 2 hours to obtain modified rubber;
step 2, stirring and mixing cement, slag powder, fly ash, sand, coarse aggregate, vitrified micro bubbles, a water reducing agent and water to obtain a base material; adding the modified rubber, the steel fiber and the PVA fiber into the base material, and strongly stirring until the materials are uniformly mixed to obtain a concrete primary product;
step 3, polishing and cleaning the rock surface to increase the friction force of the rock surface; then, performing water spraying and wetting treatment on the polished rock surface; spraying the concrete primary product to the pretreated rock surface through a spraying pipeline, mixing the concrete primary product with an accelerating agent at the outlet of the spraying pipeline to form high-strength spraying concrete for the high-ground-temperature tunnel, forming a concrete support on the rock surface, and then curing by adopting water glass; wherein the spraying amount of the accelerator accounts for 2% of the spraying amount of the concrete primary product.
Comparative example 1
The preparation method of the sprayed concrete comprises the following raw materials in parts by weight:
1m3the raw materials comprise the following components in parts by mass: 350kg of cement, 75kg of fly ash, 75kg of slag powder, 483kg of broken stone, 650kg of sand, 225kg of water, 100kg of vitrified micro bubbles, 1kg of PVA fiber, 40kg of steel fiber, 4kg of water reducing agent and 25kg of accelerating agent.
The preparation method is implemented according to the following steps:
step 1, stirring and mixing cement, slag powder, fly ash, sand, coarse aggregate, vitrified micro bubbles, a water reducing agent and water to obtain a base material; adding the steel fiber and the PVA fiber into the base material, and strongly stirring until the materials are uniformly mixed to obtain a concrete primary product;
step 2, polishing and cleaning the rock surface to increase the friction force of the rock surface; then, performing water spraying and wetting treatment on the polished rock surface; spraying the concrete primary product to the pretreated rock surface through a spraying pipeline, mixing the concrete primary product with an accelerating agent at the outlet of the spraying pipeline to form high-strength spraying concrete for the high-ground-temperature tunnel, forming a concrete support on the rock surface, and then curing by adopting water glass; wherein the spraying amount of the accelerator accounts for 2% of the spraying amount of the concrete primary product.
Comparative example 2
The preparation method of the sprayed concrete comprises the following raw materials in parts by weight:
1m3the raw materials comprise the following components in parts by mass: 350kg of cement, 75kg of fly ash, 75kg of slag powder, 483kg of broken stone, 650kg of sand, 225kg of water, 100kg of vitrified micro bubbles, 31.5kg of modified rubber, 4kg of water reducing agent and 25kg of accelerator.
The preparation method is implemented according to the following steps:
step 1, adding 6kg of sodium silicate into 50L of warm water with the temperature of 40 ℃ for full dissolution to obtain sodium silicate sol; adding 94kg of rubber powder into the sodium silicate sol, stirring and mixing for 2 hours, and standing for 2 hours to obtain modified rubber;
step 2, stirring and mixing cement, slag powder, fly ash, sand, coarse aggregate, vitrified micro bubbles, a water reducing agent and water to obtain a base material; adding the modified rubber into the base material, and stirring strongly until the materials are uniformly mixed to obtain a concrete primary product;
step 3, polishing and cleaning the rock surface to increase the friction force of the rock surface; then, performing water spraying and wetting treatment on the polished rock surface; spraying the concrete primary product to the pretreated rock surface through a spraying pipeline, mixing the concrete primary product with an accelerating agent at the outlet of the spraying pipeline to form high-strength spraying concrete for the high-ground-temperature tunnel, forming a concrete support on the rock surface, and then curing by adopting water glass; wherein the spraying amount of the accelerator accounts for 2% of the spraying amount of the concrete primary product.
Comparative example 3
1m3The raw materials comprise the following components in parts by mass: 350kg of cement, 75kg of fly ash, 75kg of slag powder, 483kg of broken stone, 650kg of sand, 225kg of water, 100kg of vitrified micro bubbles, 40kg of steel fiber, 31.5kg of modified rubber, 4kg of water reducing agent and 25kg of accelerating agent.
The preparation method is implemented according to the following steps:
step 1, adding 6kg of sodium silicate into 50L of warm water with the temperature of 40 ℃ for full dissolution to obtain sodium silicate sol; adding 94kg of rubber powder into the sodium silicate sol, stirring and mixing for 2 hours, and standing for 2 hours to obtain modified rubber;
step 2, stirring and mixing cement, slag powder, fly ash, sand, coarse aggregate, vitrified micro bubbles, a water reducing agent and water to obtain a base material; adding the modified rubber and the steel fiber into the base material, and stirring strongly until the materials are uniformly mixed to obtain a concrete primary product;
step 3, polishing and cleaning the rock surface to increase the friction force of the rock surface; then, performing water spraying and wetting treatment on the polished rock surface; spraying the concrete primary product to the pretreated rock surface through a spraying pipeline, mixing the concrete primary product with an accelerating agent at the outlet of the spraying pipeline to form high-strength spraying concrete for the high-ground-temperature tunnel, forming a concrete support on the rock surface, and then curing by adopting water glass; wherein the spraying amount of the accelerator accounts for 2% of the spraying amount of the concrete primary product.
Comparative example 4
1m3The raw materials comprise the following components in parts by mass: 350kg of cement, 75kg of fly ash, 75kg of slag powder, 483kg of broken stone, 650kg of sand, 225kg of water, 100kg of vitrified micro bubbles, 4kg of water reducing agent and 25kg of accelerating agent.
The preparation method is implemented according to the following steps:
step 1, stirring and mixing cement, slag powder, fly ash, sand, coarse aggregate, vitrified micro bubbles, a water reducing agent and water to obtain a concrete primary product;
step 2, polishing and cleaning the rock surface to increase the friction force of the rock surface; then, performing water spraying and wetting treatment on the polished rock surface; spraying the concrete primary product to the pretreated rock surface through a spraying pipeline, mixing the concrete primary product with an accelerating agent at the outlet of the spraying pipeline to form high-strength spraying concrete for the high-ground-temperature tunnel, forming a concrete support on the rock surface, and then curing by adopting water glass; wherein the spraying amount of the accelerator accounts for 2% of the spraying amount of the concrete primary product.
Sampling concrete which is sprayed in the concrete support maintenance of the concrete in the embodiment 1 and the concrete support maintenance of the concrete in the comparative examples 1-4 for 24h, 7 days and 28 days, and respectively testing the compressive strength, the splitting strength, the breaking strength, the heat conductivity coefficient and the splitting, pulling and bonding strength of the surrounding rock of the concrete in each maintenance time, wherein the testing processes of the compressive strength, the splitting strength and the breaking strength are carried out according to GB-T50081 and 2002 Standard of Experimental methods for mechanical Properties of ordinary concrete; the splitting, pulling and bonding strength with surrounding rock is carried out by adopting a direct pulling method, namely, a pulling device is adopted to directly pull the drilled rock sample sprayed with concrete. The above tests were conducted while controlling the sample temperature at 20 ℃ and 80 ℃ respectively, and the test results at 20 ℃ are shown in table 1 below, in which the thermal conductivity in unit W/(m.k) in table 1.
TABLE 1 test results of mechanical and thermal conductivity at 20 deg.C
As can be seen from Table 1, the method of the present invention has the lowest thermal conductivity compared with other comparative examples, which shows that the addition of the modified rubber of the present invention can greatly improve the thermal insulation performance of concrete. Compared with the comparative example 4, the compressive strength, the splitting strength, the breaking strength and the tensile bonding strength with the dangerous rock of the steel fiber and the PVA fiber are higher than those of other comparative examples, which shows that the concrete prepared by the invention has the best comprehensive performance, can greatly improve the mechanical property of the concrete, and particularly has obvious effect of improving the later strength (28d is strength) of the concrete. Comparing the results of comparative example 3 and example 1, it can be seen that the addition of the PVA fibers in the present invention improves the cleavage strength and the adhesive strength of the concrete, indicating that it can increase the cohesion of the concrete.
The test results at a sample temperature of 80 ℃ are shown in Table 2 below, and the thermal conductivity in Table 2 is represented by W/(m.K).
TABLE 2 test results of mechanical properties and thermal conductivity of samples at 80 deg.C
As can be seen from Table 2, only the cementing surface of the concrete obtained by the invention is not cracked and no micro-cracks or cracks are generated in the concrete under the condition of high temperature of 80 ℃, which shows that the cohesive force of the product of the invention is the best, and compared with the comparative example 4, the product of the invention obviously improves the cohesive force in the concrete and the bonding strength with surrounding rocks.
In conclusion, the invention has good comprehensive mechanical property at room temperature, and particularly has better later strength. Under the condition of high temperature, the sprayed concrete adopts the low-melting-point water-soluble PVA fiber, so that the fiber is melted after the concrete reaches the fiber melting point, a pore passage is formed, the dissipation of water vapor in the concrete at the high temperature is facilitated, the steam pressure in the concrete is reduced, and the bursting risk is greatly reduced; meanwhile, the dissolution of the water-soluble PVA fiber greatly enhances the internal cohesive force of the concrete and avoids the cracking of a cementing surface. The invention adopts the double-fiber doping of the PVA fiber and the steel fiber to enhance the strength of the concrete at low temperature, the steel fiber is enhanced to play a main role along with the dissolution of the PVA fiber at high temperature, and the dissolved PVA provides a bridging effect for the steel fiber, can play a role in preventing crack propagation and greatly enhances the later strength of the concrete.
The invention has high interface bonding strength with concrete, effectively controls the rebound rate of sprayed concrete and reduces the waste of concrete. In a word, the workability, durability, crack resistance and later strength of the sprayed concrete can all meet the design index requirements of the sprayed concrete with 20-85 ℃ heat damage, and an effective way is provided for the field application of the sprayed concrete in the heat damage tunnel.
The rubber powder can be prepared from waste tire rubber, so that waste utilization is realized, and the environmental protection property is good. The method of the present invention is a conventional method unless otherwise specified, and the starting material is commercially available.
The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (8)
1. The high-strength shotcrete for the high-ground-temperature tunnel is characterized by comprising the following raw material components: the concrete comprises a cementing material, sand, coarse aggregate, vitrified micro bubbles, PVA fiber, steel fiber, modified rubber, a water reducing agent, an accelerating agent and water; wherein the cementing material is cement, fly ash and slag powder; the modified rubber is prepared by modifying rubber powder by using sodium silicate through a sol-gel method; the mass ratio of the sodium silicate to the rubber powder is (0.06-0.08) to 1;
the dosage of the raw materials is as follows: 1m3The raw materials comprise the following components in parts by mass: 450-500 kg of a cementing material, 600-650 kg of sand, 460-490 kg of coarse aggregate, 100-120 kg of vitrified micro bubbles, 1-2 kg of PVA fiber, 35-40 kg of steel fiber, 28-32 kg of modified rubber, 0.8% of a water reducing agent by mass and 5% of an accelerating agent by mass, wherein the mass ratio of water to the cementing material is 0.45; the cementing material comprises the following raw materials in percentage by mass: 70% of cement, 15% of fly ash and 15% of slag powder.
2. The high-strength shotcrete for the high-ground-temperature tunnel according to claim 1, wherein the cement is ordinary portland cement, the fly ash is class I fly ash, and the specific surface area of the slag powder is 450m2/kg。
3. A high-strength shotcrete for a high-ground-temperature tunnel according to claim 1, wherein the PVA fiber has a melting point of 70 to 80 ℃.
4. The high-strength shotcrete for the high-ground-temperature tunnel according to claim 1, wherein the steel fibers have a diameter of 0.8 to 1.0mm, a length of 45 to 50mm, and a tensile strength of not less than 600 MPa.
5. The preparation method of the high-strength shotcrete for the high-ground-temperature tunnel is characterized by comprising the following steps of:
step 1, adding sodium silicate into warm water to be fully dissolved to obtain sodium silicate sol; adding rubber powder into the sodium silicate sol, stirring and mixing for 2 hours, and standing for 2 hours to obtain the rubber powder;
step 2, stirring and mixing cement, slag powder, fly ash, sand, coarse aggregate, vitrified micro bubbles, a water reducing agent and water to obtain a base material; adding the modified rubber, the steel fiber and the PVA fiber into the base material, and strongly stirring until the materials are uniformly mixed to obtain a concrete primary product;
and 3, after the rock surface is pretreated, spraying the concrete primary product to the pretreated rock surface through a spraying pipeline, mixing the concrete primary product with an accelerator at the outlet of the spraying pipeline to form high-strength sprayed concrete for a high-ground-temperature tunnel, forming concrete support on the rock surface, and then curing by adopting water glass.
6. A preparation method of a high-strength shotcrete for a high-ground-temperature tunnel according to claim 5, wherein the temperature of the warm water in the step 1 is 40-50 ℃.
7. A preparation method of high-strength shotcrete for high-ground-temperature tunnels according to claim 5, wherein in the step 3, the pretreatment is: firstly, grinding and cleaning a rock surface to increase the friction force of the rock surface; and then the polished rock surface is subjected to water spraying and wetting treatment.
8. A method for preparing high-strength shotcrete for high-ground-temperature tunnels according to claim 5, wherein in the step 3, the spraying amount of the accelerator is 1.8-2.2% of the spraying amount of the concrete primary product.
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| CN110981345B (en) * | 2019-12-17 | 2020-08-04 | 广东省水利水电第三工程局有限公司 | Sprayed concrete and construction method thereof |
| CN111205045B (en) * | 2020-01-13 | 2021-03-09 | 西南交通大学 | Special sprayed concrete material for tunnel high-ground-temperature dry-heat environment |
| CN111606611A (en) * | 2020-06-11 | 2020-09-01 | 陕西拉发纪新材料科技有限公司 | Inorganic high-strength corrosion-resistant spraying material for coal mine tunnel and coating construction process thereof |
| CN113149555A (en) * | 2021-04-21 | 2021-07-23 | 河南省宜居建材科技有限公司 | Sprayed concrete for roadway |
| CN114263479A (en) * | 2021-12-27 | 2022-04-01 | 中国建筑土木建设有限公司 | Device and method for controlling rebound rate of tunnel shotcrete |
| CN114573285A (en) * | 2022-02-22 | 2022-06-03 | 兴宁市龙江建材实业有限公司 | Preparation method of polymer cement mortar with high crack resistance |
| CN116102301A (en) * | 2023-02-07 | 2023-05-12 | 中国铁道科学研究院集团有限公司铁道建筑研究所 | Heat-insulating high-toughness carbonic acid tunnel slag geopolymer shotcrete and preparation method thereof |
| CN116283145A (en) * | 2023-03-14 | 2023-06-23 | 西南交通大学 | High-strength and high-toughness heat-insulation functional sprayed concrete for high-temperature hot water tunnel |
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| CN105060836A (en) * | 2015-08-21 | 2015-11-18 | 成都理工大学 | High-ground-temperature tunnel heat insulation lining concrete and preparation method thereof |
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| KR101923493B1 (en) * | 2018-05-18 | 2018-11-29 | 씨엘엠테크(주) | Mortar Composition with air-entraining agent for Concrete Repair and Concrete Repair Method Using the same |
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| CN105060836A (en) * | 2015-08-21 | 2015-11-18 | 成都理工大学 | High-ground-temperature tunnel heat insulation lining concrete and preparation method thereof |
| CN105367026A (en) * | 2015-12-10 | 2016-03-02 | 张进 | High strength concrete and preparation method thereof |
| CN107721317A (en) * | 2017-11-15 | 2018-02-23 | 东南大学 | Basalt and polyvinyl alcohol mix fiber concrete and preparation method |
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