Anti-cracking and rebound-reducing tunnel sprayed concrete and preparation and use method of anti-cracking and rebound-reducing tunnel sprayed concrete

Abstract

The invention belongs to the technical field of building materials, and discloses anti-cracking and rebound-reducing tunnel shotcrete and a preparation and use method thereof.The tunnel shotcrete is prepared from, by mass, 135-195 parts of water, 300-350 parts of Portland cement with the strength grade not lower than 42.5, 50-100 parts of F-class I-grade fly ash and 815-905 parts of machine-made sand with the fineness modulus of 2.5-2.8. The concrete is prepared from the following raw materials in parts by weight: 855-925 parts of 5-10mm continuous graded broken stone, 2-4 parts of a polycarboxylic acid type water reducing agent with the water reducing rate of more than 25%, 13-22 parts of an alkali-free accelerator, 5-8 parts of an anti-cracking component and 3-5 parts of a rebound reducing component. Wherein the anti-cracking component is a composition of sodium alginate and nano silicon dioxide, and the resilience reducing component is a composition of nanocrystalline cellulose, Ti2C, methyl anyl alcohol and fatty acid macrogol ester. The tunnel shotcrete disclosed by the invention has the advantages that the cracking resistance and the springback resistance of the tunnel shotcrete are remarkably enhanced through the effects of forming a gel network, in-situ reinforcing a nano material and the like played by the anti-cracking component and the springback reducing component.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to a crack-resistant and rebound-reducing shotcrete for tunnels and its preparation and use methods. Background Art

[0002] During the tunnel construction process, in order to prevent dangerous situations such as surrounding rock loosening, shotcrete is needed to support the surrounding rock.

[0003] In recent years, with the expansion of highway and railway construction into mountainous areas, plateaus and other places, tunnels have gradually developed in the direction of deep burial and long length, but this has led to a series of problems such as extreme heat and humidity, and the maximum rock temperature in the tunnel can reach up to 80°C. After the tunnel is excavated, due to the influence of a large temperature difference, the shotcrete is extremely prone to shrinkage cracking; in addition, due to the use of spraying technology, the rebound rate of the shotcrete during the construction process is high, resulting in a large amount of waste. Based on this, those skilled in the art need a tunnel shotcrete with high crack resistance and low rebound characteristics. Summary of the Invention

[0004] The purpose of the present invention is to provide a crack-resistant and rebound-reducing shotcrete for tunnels and its preparation and use methods according to the deficiencies of the above-mentioned prior art. The crack-resistant and rebound-reducing shotcrete for tunnels significantly enhances the performance of the tunnel shotcrete in resisting cracking and rebound through the formation of a gel network and the in-situ strengthening effect of nanomaterials by the crack-resistant component and the rebound-reducing component.

[0005] The purpose of the present invention is achieved by the following technical solutions: A crack-resistant and rebound-reducing shotcrete for tunnels, the shotcrete for tunnels comprises the following components in parts by mass: 135 - 195 parts of water, 300 - 350 parts of Portland cement with a strength grade not lower than 42.5, 50 - 100 parts of Class F Grade I fly ash, 815 - 905 parts of manufactured sand with a fineness modulus of 2.5 - 2.8, 855 - 925 parts of 5 - 10 mm continuously graded crushed stone, 2 - 4 parts of polycarboxylate-based water reducer with a water reduction rate greater than 25%, 13 - 22 parts of alkali-free accelerator, 5 - 8 parts of crack-resistant component, 3 - 5 parts of rebound-reducing component; wherein, the crack-resistant component is a composition of sodium alginate and nano-silica, and the rebound-reducing component is a composition of nanocrystalline cellulose, Ti2C, methyl pentanol and fatty acid polyethylene glycol ester.

[0006] The mass ratio of sodium alginate to nano-silica in the crack-resistant component is 1:1.

[0007] The mass ratio of nanocrystalline cellulose, Ti2C, methyl pentanol and fatty acid polyethylene glycol ester in the rebound-reducing component is 2:1:0.1:0.1.

[0008] The alkali-free accelerating agent is a composition of aluminum sulfate and organic amine, and the mass ratio of aluminum sulfate to organic amine is 65:8.

[0009] A preparation and use method of any of the crack-resistant and rebound-reducing tunnel shotcrete involves the following steps: S1: Weigh water and the rebound-reducing component by mass, pour the rebound-reducing component into the water, place a 40 kHz ultrasonic vibrator into the water, and ultrasonically vibrate for 15 minutes to obtain dispersion liquid I. S2: Weigh the polycarboxylate superplasticizer by mass and place it into dispersion liquid I, and continue to ultrasonically vibrate for 10 minutes to obtain dispersion liquid II. S3: Weigh Portland cement, fly ash, and the crack-resistant component by mass, and then place them into a mixer and stir for 5 minutes. S4: Weigh manufactured sand and crushed stone by mass, place them into the mixer in step S3, and continue to stir for 3 minutes. S5: Pour the dispersion liquid II obtained in step S2 into the mixer and continue to stir for 5 minutes to prepare the shotcrete mixture. S6: During use, send the shotcrete mixture to the nozzle through a delivery pipe, and add an alkali-free accelerating agent at the nozzle to form shotcrete and spray it onto the construction surface.

[0010] The advantages of the present invention are: (1) Using sodium alginate and nano-silica as crack-resistant agent components, sodium alginate will form a cross-linked network gel in cement, which can significantly resist the shrinkage after the hardening of concrete; nano-silica has the effect of improving the tensile strength of concrete and can resist higher tensile stress to inhibit the generation of cracks; the dual effects of sodium alginate and nano-silica make the shotcrete have higher crack-resistant performance.

[0011] (2) Using nanocrystalline cellulose and Ti2C as the rebound-reducing components, nanocrystalline cellulose is a nanofibrous material, which can effectively connect the products microscopically and prevent shedding; Ti2C is an accordion-shaped nanoparticle material, which can adjust the viscosity of concrete; both materials start from the micro-structure of the material to solve the problem of shotcrete rebound. Under the combined action of the two, the rebound rate of the shotcrete is significantly reduced. Specific embodiments

[0012] The following further details the features and other related features of the present invention through examples for the understanding of those skilled in the same industry: Example 1: This example specifically relates to a crack-resistant and rebound-reducing tunnel shotcrete, and the tunnel shotcrete includes the following components in parts by mass: 135 parts of water, 300 parts of portland cement with a strength grade not lower than 42.5, 50 parts of class I fly ash of F type, 815 parts of manufactured sand with a fineness modulus of 2.5, 925 parts of 5mm continuous gradation crushed stone, 4 parts of polycarboxylate superplasticizer with a water reducing rate greater than 25%, 22 parts of alkali-free accelerating agent, 5 parts of crack resistance component, 5 parts of rebound reduction component.

[0013] Among them, the crack resistance component is a composition of sodium alginate and nano-silica, and the mass ratio of sodium alginate to nano-silica is 1:1. The rebound reduction component is a composition of nanocrystalline cellulose, Ti2C, methyl pentanol and fatty acid polyethylene glycol ester, and the mass ratio of the four is 2:1:0.1:0.1. The alkali-free accelerating agent is a composition of aluminum sulfate and organic amine, and the mass ratio of aluminum sulfate to organic amine is 65:8.

[0014] The preparation and use method of the crack resistance and rebound reduction tunnel shotcrete in this example includes the following steps: S1: Weigh water and the rebound reduction component by mass, pour the rebound reduction component into the water, put a 40kHz ultrasonic vibrator into the water, and vibrate ultrasonically for 15 minutes to obtain dispersion liquid I.

[0015] S2: Weigh the polycarboxylate superplasticizer by mass and put it into dispersion liquid I, and continue to vibrate ultrasonically for 10 minutes to obtain dispersion liquid II.

[0016] S3: Weigh portland cement, fly ash and the crack resistance component by mass, and then put them into a mixer and stir for 5 minutes.

[0017] S4: Weigh manufactured sand and crushed stone by mass, put them into the mixer in step S3, and continue to stir for 3 minutes.

[0018] S5: Pour the dispersion liquid II obtained in step S2 into the mixer, and continue to stir for 5 minutes to prepare the shotcrete mixture.

[0019] S6: During use, send the shotcrete mixture to the nozzle through a conveying pipe, add an alkali-free accelerating agent at the nozzle to form shotcrete and spray it onto the construction surface, and calculate the rebound rate and the total cracking area on the unit construction surface.

[0020] In order to compare the crack resistance performance and rebound rate of the shotcrete in this example, a control example 1 of shotcrete was prepared. The samples of control example 1 without adding the crack resistance component and the rebound reduction component were used as a group, and their preparation and use methods were the same as those of example 1. The components of control example 1 are as follows: 135 parts of water, 300 parts of portland cement with a strength grade not lower than 42.5, 50 parts of class I fly ash of F type, 815 parts of manufactured sand with a fineness modulus of 2.5, 925 parts of 5mm continuous gradation crushed stone, 4 parts of polycarboxylate superplasticizer with a water reducing rate greater than 25%, 22 parts of alkali-free accelerating agent.

[0021] Example 2: This example specifically relates to a crack-resistant and rebound-reducing tunnel shotcrete. The tunnel shotcrete comprises the following components in parts by mass: 155 parts of water, 320 parts of Portland cement with a strength grade not lower than 42.5, 50 parts of Class F Grade I fly ash, 905 parts of manufactured sand with a fineness modulus of 2.5, 855 parts of 5 mm continuous graded crushed stone, 3 parts of polycarboxylate-based water reducer with a water reduction rate greater than 25%, 13 parts of alkali-free accelerator, 8 parts of crack-resistant component, and 3 parts of rebound-reducing component.

[0022] Among them, the crack-resistant component is a composition of sodium alginate and nano-silica, and the mass ratio of sodium alginate to nano-silica is 1:1. The rebound-reducing component is a composition of nanocrystalline cellulose, Ti2C, methyl pentanol, and fatty acid polyethylene glycol ester, and the mass ratio of the four is 2:1:0.1:0.1. The alkali-free accelerator is a composition of aluminum sulfate and organic amine, and the mass ratio of aluminum sulfate to organic amine is 65:8.

[0023] In this example, the preparation and use method of the crack-resistant and rebound-reducing tunnel shotcrete are the same as those in Example 1.

[0024] In order to compare the crack resistance and rebound rate of the shotcrete in this example, a control example 2 of the shotcrete was prepared. The specimens without adding the crack-resistant component and the rebound-reducing component were used as a group, and their preparation and use methods were the same as those in Example 1. The components of control example 2 are as follows: 155 parts of water, 320 parts of Portland cement with a strength grade not lower than 42.5, 50 parts of Class F Grade I fly ash, 905 parts of manufactured sand with a fineness modulus of 2.5, 855 parts of 5 mm continuous graded crushed stone, 3 parts of polycarboxylate-based water reducer with a water reduction rate greater than 25%, and 13 parts of alkali-free accelerator.

[0025] Example 3: This example specifically relates to a crack-resistant and rebound-reducing tunnel shotcrete. The tunnel shotcrete comprises the following components in parts by mass: 195 parts of water, 350 parts of Portland cement with a strength grade not lower than 42.5, 100 parts of Class F Grade I fly ash, 850 parts of manufactured sand with a fineness modulus of 2.5, 900 parts of 5 mm continuous graded crushed stone, 2 parts of polycarboxylate-based water reducer with a water reduction rate greater than 25%, 18 parts of alkali-free accelerator, 6 parts of crack-resistant component, and 4 parts of rebound-reducing component.

[0026] Among them, the crack-resistant component is a composition of sodium alginate and nano-silica, and the mass ratio of sodium alginate to nano-silica is 1:1. The rebound-reducing component is a composition of nanocrystalline cellulose, Ti2C, methyl pentanol, and fatty acid polyethylene glycol ester, and the mass ratio of the four is 2:1:0.1:0.1. The alkali-free accelerator is a composition of aluminum sulfate and organic amine, and the mass ratio of aluminum sulfate to organic amine is 65:8.

[0027] In this embodiment, the preparation and usage method of the crack-resistant and rebound-reducing tunnel shotcrete are the same as those in Embodiment 1.

[0028] In order to compare the crack resistance and rebound rate of the shotcrete in this embodiment, a control example 3 of shotcrete is prepared. The specimens without adding crack-resistant components and rebound-reducing components are used as a group, and their preparation and usage methods are the same as those in Embodiment 1. The components of Control Example 3 are as follows: 195 parts of water, 350 parts of Portland cement with a strength grade not lower than 42.5, 100 parts of Class F Grade I fly ash, 850 parts of manufactured sand with a fineness modulus of 2.5, 900 parts of 5mm continuous gradation crushed stone, 2 parts of polycarboxylic acid-based water reducer with a water reduction rate greater than 25%, and 18 parts of alkali-free accelerating agent.

[0029] Embodiment 4: This embodiment specifically relates to a crack-resistant and rebound-reducing tunnel shotcrete, which includes the following components in parts by mass: 165 parts of water, 330 parts of Portland cement with a strength grade not lower than 42.5, 70 parts of Class F Grade I fly ash, 900 parts of manufactured sand with a fineness modulus of 2.5, 870 parts of 5mm continuous gradation crushed stone, 3.5 parts of polycarboxylic acid-based water reducer with a water reduction rate greater than 25%, 15 parts of alkali-free accelerating agent, 5 parts of crack-resistant components, and 4.5 parts of rebound-reducing components.

[0030] Among them, the crack-resistant component is a composition of sodium alginate and nano-silica, and the mass ratio of sodium alginate to nano-silica is 1:1. The rebound-reducing component is a composition of nanocrystalline cellulose, Ti2C, methyl pentanol, and fatty acid polyethylene glycol ester, and the mass ratio of the four is 2:1:0.1:0.1. The alkali-free accelerating agent is a composition of aluminum sulfate and organic amine, and the mass ratio of aluminum sulfate to organic amine is 65:8.

[0031] In this embodiment, the preparation and usage method of the crack-resistant and rebound-reducing tunnel shotcrete are the same as those in Embodiment 1.

[0032] In order to compare the crack resistance and rebound rate of the shotcrete in this embodiment, a control example 4 of shotcrete is prepared. The specimens without adding crack-resistant components and rebound-reducing components are used as a group, and their preparation and usage methods are the same as those in Embodiment 1. The components of Control Example 4 are as follows: 165 parts of water, 330 parts of Portland cement with a strength grade not lower than 42.5, 70 parts of Class F Grade I fly ash, 900 parts of manufactured sand with a fineness modulus of 2.5, 870 parts of 5mm continuous gradation crushed stone, 3.5 parts of polycarboxylic acid-based water reducer with a water reduction rate greater than 25%, and 15 parts of alkali-free accelerating agent.

[0033] The specific sources of the raw materials used in Embodiments 1, 2, 3, 4 and Control Examples 1, 2, 3, 4 are as follows: Portland cement: Anhui Conch Group Co., Ltd., Conch brand, 50KG / bag, M32.5.

[0034] Mechanism sand: Anhui Conch Group Co., Ltd., Conch brand, bulk, fineness modulus 2.5.

[0035] Graded crushed stone: Anhui Conch Group Co., Ltd., Conch brand, bulk, 5mm continuous graded crushed stone.

[0036] Fly ash: Lingshou County Yongshun Mineral Products Processing Factory, Yongshun brand, 50KG / bag, Class F Grade I fly ash.

[0037] Polycarboxylate superplasticizer: Beijing Dechang Weiye Construction Engineering Technology Co., Ltd., Dechang Weiye brand, 25KG / bag, water reduction rate 30%.

[0038] Alkali-free accelerating agent: Shandong Kunsheng Chemical Co., Ltd., Kunsheng Chemical brand, 1300KG / barrel, liquid, customized product based on the mass ratio of aluminum sulfate and organic amine; among them, the organic amine is formamide (CH3NO) belonging to amides.

[0039] Anti-cracking component: The mass ratio of sodium alginate and nano-silica is 1:1, and it is mixed by construction workers based on the mass ratio. Among them, sodium alginate comes from Lianyungang Tiantian Algae Industry Co., Ltd., Tiantian brand, 25KG / bag, product execution standard: GB1886.243-2016; nano-silica comes from type 380 of AEROSIL brand, CAS No. 112945-52-5, 10KG / bag.

[0040] Rebound reduction component: The mass ratio of nanocrystalline cellulose, Ti2C, methyl pentanol and fatty acid polyethylene glycol ester is 2:1:0.1:0.1, and it is mixed by construction workers based on the mass ratio. Among them, nanocrystalline cellulose comes from Nanjing Tianlu Nano Technology Co., Ltd., Tianlu Nano brand, 1kg / bottle, cellulose nanocrystal TL-003; Ti2C comes from Suzhou Kaifa New Materials Technology Co., Ltd., Kaifa brand, 50ml / bottle, CAS No. 12316-56-2; methyl pentanol comes from Jiangsu Runfeng Synthetic Technology Co., Ltd., Runfeng Synthetic brand, 25KG / barrel, CAS No. 227456-27-1; fatty acid polyethylene glycol ester comes from Jiangsu Hai'an Petrochemical Factory, Haishihua brand, 200kg / barrel, polyethylene glycol fatty acid ester.

[0041] Compare the rebound rates and the results of the unit cracking area of Example 1, Control Example 1, Example 2, Control Example 2, Example 3, Control Example 3, Example 4, and Control Example 4. As shown in the following table, it can be found that for the anti-cracking performance, after adding the anti-cracking component, the cracking area per unit construction surface drops sharply, from several hundred mm 2 / m2 Reduced to more than a dozen millimeters 2 / m 2 , the anti-cracking performance has been significantly improved; after adding the component for reducing rebound, the rebound rate is reduced to less than 4%, significantly lower than the rebound rate of 20 - 25% of the control group.

[0042]

[0043] It should be noted that the test method for the cracking area on the unit construction surface is carried out according to the early anti-cracking test in Chapter 9 of GB / T 50082 - 2009 "Test Methods for Long-term Performance and Durability of Ordinary Concrete", and the test method for the rebound rate is carried out according to JGJ / T 23 - 2011 "Technical Specification for Testing Concrete Compressive Strength by Rebound Method".

Claims

1. A crack-resistant and rebound-reducing tunnel shotcrete, characterized in that: The tunnel shotcrete comprises the following components in parts by mass: 135-195 parts of water, 300-350 parts of silicate cement with a strength grade not less than 42.5, 50-100 parts of Class F Grade I fly ash, 815-905 parts of machine-made sand with a fineness modulus of 2.5-2.8, 855-925 parts of 5-10 mm continuously graded crushed stone, 2-4 parts of a polycarboxylic acid type water reducer with a water reduction rate greater than 25%, 13-22 parts of an alkali-free quick-setting agent, 5-8 parts of an anti-cracking component, and 3-5 parts of a rebound reducing component; wherein the anti-cracking component is a composition of sodium alginate and nano-silicon dioxide, and the rebound reducing component is a composition of nanocrystalline cellulose, Ti2C, methylpentanol and fatty acid polyethylene glycol ester.

2. The anti-cracking and rebound-reducing tunnel shotcrete according to claim 1 is characterized in that: The mass ratio of sodium alginate to nano silicon dioxide in the anti-cracking component is 1:

1.

3. The anti-cracking and rebound-reducing tunnel shotcrete according to claim 1 is characterized in that: The mass ratio of nanocrystalline cellulose, Ti2C, methylpentanol and fatty acid polyethylene glycol ester in the resilience reducing component is 2:1:0.1:0.

1.

4. The anti-cracking and rebound-reducing tunnel shotcrete according to claim 1 is characterized in that: The alkali-free quick-setting agent is a composition of aluminum sulfate and organic amine, and the mass ratio of aluminum sulfate to organic amine is 65:

8.

5. A method for preparing and using the anti-cracking and rebound-reducing tunnel shotcrete according to any one of claims 1 to 4, characterized in that: The preparation and use method comprises the following steps: S1: Weigh water and a resilience reducing component by mass, pour the resilience reducing component into the water, put a 40 kHz ultrasonic vibration rod into the water, and perform ultrasonic vibration for 15 minutes to obtain a dispersion I; S2: Weigh the polycarboxylate water reducer by mass and put it into dispersion I, and continue ultrasonic vibration for 10 minutes to obtain dispersion II; S3: Weigh the silicate cement, fly ash and anti-cracking components by mass, and then put them into a mixer and stir for 5 minutes; S4: Weigh the machine-made sand and gravel by mass, put them into the mixer in step S3, and continue stirring for 3 minutes; S5: Pour the dispersion II obtained in step S2 into a mixer and continue stirring for 5 minutes to prepare a shotcrete mixture; S6: When in use, the shotcrete mixture is delivered to the nozzle through a delivery pipe, and an alkali-free quick-setting agent is added at the nozzle to form shotcrete to be sprayed onto the construction surface.

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