Tunnel lining repair material and preparation method thereof

Abstract

The invention provides a tunnel lining repair material and a preparation method thereof, and relates to the technical field of civil engineering materials and tunnel and underground engineering repair. The key technical problems of workability, volume stability, interface bonding and the like of a geopolymer material in tunnel repair are successfully solved through scientific proportioning design and composite use of functional admixtures, and the tunnel lining repair material has the outstanding characteristics of early strength, high strength, micro-expansion, high bonding strength, excellent durability and the like; meanwhile, carbon emission reduction is realized, and the material is an ideal material for green repair of old tunnels.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of civil engineering materials and tunnel and underground engineering repair technology, in particular to a tunnel lining repair material and a preparation method thereof. BACKGROUND

[0002] Old tunnel lining often has diseases such as insufficient strength, cracking and spalling, and needs to be cut off and recast. Traditional repair often uses ordinary Portland cement-based concrete or mortar. However, cement has high carbon emissions, weak bonding interface performance with old concrete, and problems such as large shrinkage and easy cracking. Geopolymer, as a green cementitious material prepared by alkali activation of industrial solid waste (such as fly ash and slag), has the advantages of low carbon, early strength and corrosion resistance, but its application in tunnel lining repair faces challenges such as workability adjustment, volume stability control and cooperation with old concrete. Therefore, we have made improvements and propose a tunnel lining repair material and a preparation method thereof. SUMMARY

[0003] The present application provides a tunnel lining repair material, and the weight ratio of each component is: Fly ash: 100 parts; Steel slag powder: 20-50 parts; Alkali activator: the alkali activator is 8%-15% of the total mass of fly ash and steel slag powder in terms of NaO equivalent; Fine aggregate: 150%-250% of the total mass of fly ash and steel slag powder; Water: adjust the water-binder ratio to 0.30-0.45 as needed; Functional admixture: including 1%-3% of micro-expansion agent, 0.2%-0.5% of water reducing agent and 0.1%-0.3% of retarder.

[0004] As a preferred technical solution of the present application, the alkali activator is a composite solution of water glass solution with a water glass modulus of 1.5-2.2 and sodium hydroxide.

[0005] As a preferred technical solution of the present application, the micro-expansion agent uses calcium sulphoaluminate expansion agent, the water reducing agent uses polycarboxylic acid water reducing agent, and the retarder uses borate retarder.

[0006] As a preferred technical solution of the present application, the fine aggregate is standard sand with a fineness modulus of 2.4.

[0007] As a preferred technical solution of the present application, the toughness index λ of the tunnel lining repair material is required to be: λ = (ft / fc) x u ≥ 0.02; Wherein, ft is the 28d flexural strength of the material, fc is the 28d compressive strength of the material, and u is the ultimate tensile strain of the material.

[0008] A preparation method of a tunnel lining repair material, comprising the following steps: Dry mixing: dry mixing fly ash, steel slag powder and fine aggregate in a mixer to mix uniformly; Alkaline solution preparation and cooling: dissolving water glass solution and sodium hydroxide solid in part of the mixing water, stirring until clear, and cooling to room temperature; Wet mixing: adding alkaline activator solution, remaining mixing water and functional admixture into the dry mixture, and stirring forcibly until forming a uniform and flowable mortar or concrete mixture.

[0009] As a preferred technical solution of the present application, the dry mixing step is dry mixing in the mixer for 1-2 minutes.

[0010] As a preferred technical solution of the present application, the forcibly stirring time is 3-5 minutes.

[0011] As a preferred technical solution of the present application, in the alkaline solution preparation and cooling step, the dissolution temperature of sodium hydroxide solid is controlled at 60-80℃, and the stirring rate is 300-500r / min.

[0012] As a preferred technical solution of the present application, in the alkaline solution preparation and cooling step, the temperature Ta of the final alkaline solution, the ambient temperature Te and the initial temperature Tb of the cementitious material need to satisfy: |Ta-(Te+Tb) / 2|≤10°C.

[0013] Compared with the prior art, the present application has the following beneficial effects: In the scheme of the present application: 1. The present application successfully solves the key technical problems of workability, volume stability and interface bonding of geopolymer materials in tunnel repair through scientific proportioning design and composite use of functional admixtures, and the tunnel lining repair material has the outstanding characteristics of early strength, high strength, micro-expansion, high bonding strength and excellent durability, etc., and realizes carbon emission reduction, which is an ideal material for green repair of old tunnels; 2. Early strength and high strength: geopolymer has fast reaction speed and high early strength, which can shorten the demolding and curing period; 3. Micro-expansion: the introduced micro-expansion agent can compensate the shrinkage of geopolymer materials, and even produce moderate expansion, so that the new cast material is tightly combined with the old lining interface to prevent shrinkage cracks; 4. High bonding strength: the cementitious properties of geopolymer and the micro-expansion effect jointly act to make the interface with the old concrete have a bonding strength far exceeding that of ordinary cement-based materials; 5. Good durability: the chemical corrosion resistance is better than that of ordinary concrete, and it is suitable for tunnel harsh environment; 6. Workability controllable: through the use of composite admixtures, the problems of rapid setting and large loss of fluidity commonly existing in geopolymer materials are solved, meeting the requirements of on-site pouring and pumping construction. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The mixing ratio diagram of the tunnel lining repair material provided in the application is provided; Figure 2 The stirring performance test result diagram of the tunnel lining repair material provided in the application is provided; Figure 3 The mechanical property development law diagram of the tunnel lining repair material provided in the application is provided; Figure 4 The durability and interface performance diagram of the tunnel lining repair material provided in the application is provided; Figure 5 The carbon emission comparative analysis diagram of the tunnel lining repair material provided in the application is provided. DETAILED DESCRIPTION

[0015] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should fall within the scope of protection of the present application.

[0016] It should be noted that the embodiments in the present application and the features and technical solutions in the embodiments can be combined with each other without conflict.

[0017] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0018] Embodiment 1, please refer to Figure 1 A tunnel lining repair material, the weight ratio of each component is: Fly ash: 100 parts, fly ash as the main aluminosilicate precursor; Steel slag powder: 30 parts, steel slag powder as a supplementary cementitious component and providing iron phase, improving toughness and wear resistance; Alkali activator: the alkali activator is 8%-15% of the total mass of fly ash and steel slag powder in terms of NaO equivalent, to activate activity, the alkali activator is a composite solution of water glass solution with a modulus of 1.5-2.2 and sodium hydroxide; in this embodiment, a water glass solution with a modulus of 1.8 is specifically used, the fraction is 40, and sodium hydroxide is used in solid form, the fraction is 8 parts; Fine aggregate: 150%-250% of the total mass of fly ash and steel slag powder; the fine aggregate is standard sand with a fineness modulus of 2.4, and the specific quantity in this embodiment is 260 parts; Water: adjust the water-binder ratio to 0.36 as needed to ensure good fluidity; Functional admixture: including 1%-3% of micro-expansion agent, 0.2%-0.5% of water reducing agent, and 0.1%-0.3% of retarder; in this embodiment, the quantity of water reducing agent is specifically 0.35 parts, the quantity of micro-expansion agent is specifically 2.5 parts, and the quantity of buffer is specifically 0.2 parts.

[0019] Embodiment 2, please refer to Figure 1 A tunnel lining repair material, the weight ratio of each component is: Fly ash: 100 parts, which serves as the main aluminosilicate precursor; Steel slag powder: 45 parts, which serves as a supplementary cementitious component and provides iron phase to improve toughness and wear resistance; Alkali activator: the alkali activator is an equivalent of NaO, accounting for 8%-15% of the total mass of fly ash and steel slag powder, to activate activity; the alkali activator is a composite solution of water glass solution with a modulus of 1.5-2.2 and sodium hydroxide; in this embodiment, a water glass solution with a modulus of 1.8 is specifically used, with a quantity of 45 parts, and sodium hydroxide is used in solid form, with a quantity of 10 parts; Fine aggregate: 150%-250% of the total mass of fly ash and steel slag powder; the fine aggregate is standard sand with a fineness modulus of 2.4, and the specific quantity in this embodiment is 290 parts; Water: adjust the water-binder ratio to 0.34 as needed to ensure good fluidity; Functional admixture: including 1%-3% of micro-expansion agent, 0.2%-0.5% of water reducing agent, and 0.1%-0.3% of retarder; in this embodiment, the quantity of water reducing agent is specifically 0.4 parts, the quantity of micro-expansion agent is specifically 2.0 parts, and the quantity of buffer is specifically 0.15 parts.

[0020] Embodiment 3, please refer to Figure 1 A tunnel lining repair material, the weight ratio of each component is: Fly ash: 100 parts, which serves as the main aluminosilicate precursor; Steel slag powder: 25 parts, which serves as a supplementary cementitious component and provides iron phase to improve toughness and wear resistance; Alkali activator: The alkali activator, calculated as NaO equivalent, is 8%-15% of the total mass of fly ash and steel slag powder, used to activate activity. The alkali activator is a composite solution of water glass solution with a modulus between 1.5 and 2.2 and sodium hydroxide. In this embodiment, a water glass solution with a modulus of 1.8 is used, with a volume of 38 parts, and solid sodium hydroxide is used, with a volume of 7 parts. Fine aggregate: 150%-250% of the total mass of fly ash and steel slag powder; the fine aggregate is standard sand with a fineness modulus of 2.4, and the specific amount in this embodiment is 50 parts; Water: Adjust the water-to-binder ratio to 0.38 as needed to ensure good flowability; Functional admixtures include 1%-3% micro-expansion agent, 0.2%-0.5% water-reducing agent, and 0.1%-0.3% retarder; in this embodiment, the water-reducing agent is specifically 0.5 parts, the micro-expansion agent is specifically 3.0 parts, and the buffer is specifically 0.25 parts.

[0021] Example 4 further optimizes the tunnel lining repair material provided in the above examples. Specifically, the micro-expansion agent is calcium sulfoaluminate expansion agent, the water-reducing agent is polycarboxylate water-reducing agent, and the retarder is borate retarder. The calcium sulfoaluminate expansion agent has a stable expansion effect and good compatibility with the geopolymer system, enabling precise micro-expansion compensation. The polycarboxylate water-reducing agent has high water-reducing efficiency and low air entrainment, improving material density while ensuring fluidity. The borate retarder has a mild retarding effect, effectively controlling setting time without affecting subsequent strength development. The combination of these three agents makes the functional admixtures more precise and efficient.

[0022] Furthermore, the toughness index λ of the tunnel lining repair material is required to be: λ=(ft / fc)×u≥0.02; Where ft is the 28-day flexural strength (MPa), fc is the 28-day compressive strength (MPa), and u is the ultimate tensile strain (%). The toughness index λ should be no less than 0.02, which is used to characterize the material's crack resistance when subjected to tunnel deformation. The requirement of toughness index λ≥0.02 is clearly defined. By taking into account the 28-day flexural strength, compressive strength, and ultimate tensile strain, it is ensured that the material has sufficient crack resistance, can adapt to the deformation during tunnel operation, and reduce the risk of cracking.

[0023] Experimental data and compatibility of tunnel lining repair materials based on fly ash-steel slag geopolymers Figure 1 As shown; Based on the content of this invention patent, detailed material mixing ratios and corresponding experimental verification data are provided to demonstrate the excellent performance of the repair material. Example 1 uses ratio 1, Example 2 uses ratio 2, and Example 3 uses ratio 3. Na2O equivalent calculation: Formula 1: Na₂O equivalent = (8 + 40 × 0.15) / (100 + 30) × 100% = 10.8%; Formula 2: Na₂O equivalent = (10 + 45 × 0.15) / (100 + 45) × 100% = 11.7%; Ratio 3: Na2O equivalent = (7 + 38 × 0.15) / (100 + 25) × 100% = 10.2%.

[0024] Experimental performance test data: The stirring performance test results are as follows Figure 2 As shown; The development law of mechanical properties is as follows Figure 3 As shown; Durability and interface performance, such as Figure 4 As shown; Carbon emission comparative analysis, such as Figure 5 As shown.

[0025] Mixture ratio 2 has a 3-hour strength of 12.2 MPa, which meets the requirements for rapid repair. Its 1-day strength exceeds 30 MPa, allowing for early demolding and shortening the construction period. Its 3-day strength is 60-70% of the 28-day strength.

[0026] All three formulations exhibited slight expansion characteristics, with expansion rates ranging from 85 to 165 × 10⁻⁻⁻⁶. 6 Within the specified range, it effectively compensates for shrinkage, forms a tight interface with the old concrete, and prevents shrinkage cracks.

[0027] The interfacial bonding strength is outstanding, far exceeding the standard requirement of 2.0 MPa, reaching 3.2 MPa in mix proportion 2, which is 1.5-2 times that of ordinary cement-based materials. The synergistic effect of the geopolymer's gelling properties and micro-expansion effect is evident. It has excellent durability, a permeability grade of P12 or higher, high density, excellent resistance to sulfate corrosion, and a strength retention rate of >90%, making it suitable for humid and corrosive environments in tunnels.

[0028] Recommended application scenarios: Mixture 1 (Standard): Suitable for most tunnel lining repair projects, with balanced overall performance; Formula 2 (early strength type): Suitable for emergency repair projects with tight schedules and requiring rapid traffic reopening; Formula 3 (high fluidity type): Suitable for special working conditions such as complex shape repair and long-distance pumping; Example 5: A method for preparing a tunnel lining repair material, comprising the following steps: Dry mixing: Dry mix fly ash, steel slag powder and fine aggregate in a mixer until evenly mixed; Lye preparation and cooling: Dissolve water glass solution and sodium hydroxide solid in part of mixing water, stir until clear, and cool to room temperature; Wet mixing: Add alkali activator solution, remaining mixing water and functional admixtures to dry mix, and force stir until uniform, flowable mortar or concrete mixture is formed.

[0029] Further, in the dry mixing step, the dry mixing time in the mixer is 1-2 minutes.

[0030] Further, the forced stirring time is 3-5 minutes.

[0031] Further, in the lye preparation and cooling step, the dissolution temperature of sodium hydroxide solid is controlled at 60-80℃, and the stirring rate is 300-500 r / min; the 60-80℃ dissolution temperature and 300-500 r / min stirring rate can promote the full dissolution of sodium hydroxide, and improve the activity of lye; Further, in the lye preparation and cooling step, the temperature Ta of the final lye, the ambient temperature Te and the initial temperature Tb of the cementitious material need to meet: |Ta-(Te+Tb) / 2|≤10℃; This temperature control is used to avoid the large temperature difference between the lye and the raw materials when they are in contact, which affects the workability and early hydration reaction; the difference between the lye temperature and the ambient and cementitious material temperature is controlled, which effectively avoids the abnormal early hydration reaction or workability decline caused by the large temperature difference, ensures the stable and controllable performance of the prepared material, and improves the construction quality consistency of the repair project.

[0032] In the present application, unless otherwise clearly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected or communicate with each other; it can be directly connected, or it can be indirectly connected through an intermediate medium, it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0033] Obviously, the above-described embodiments are only some embodiments but not all the embodiments of the present application, the preferred embodiments of the present application are shown in the drawings, but do not limit the patent scope of the present application. The present application can be implemented in many different forms, and conversely, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing specific embodiments, or make equivalent replacements to some technical features therein. Any equivalent structure made by using the content of the present application specification and drawings, directly or indirectly applied to other related technical fields, is also within the patent protection scope of the present application.

Claims

1. A tunnel lining repair material, characterized in that, The weight ratio of each component is as follows: Fly ash: 100 parts; Steel slag powder: 20-50 parts; Alkali activator: The alkali activator, calculated as NaO equivalent, is 8%-15% of the total mass of fly ash and steel slag powder; Fine aggregate: 150%-250% of the total mass of fly ash and steel slag powder; Water: Adjust the water-to-binder ratio to 0.30-0.45 as needed; Functional admixtures include 1%-3% micro-expansion agent, 0.2%-0.5% water-reducing agent, and 0.1%-0.3% retarder.

2. The tunnel lining repair material according to claim 1, characterized in that, The alkaline activator is a composite solution of water glass solution with a modulus between 1.5 and 2.2 and sodium hydroxide.

3. The tunnel lining repair material according to claim 1, characterized in that, The micro-expansion agent is calcium sulfoaluminate expansion agent, the water-reducing agent is polycarboxylate water-reducing agent, and the retarder is borate retarder.

4. The tunnel lining repair material according to claim 1, characterized in that, The fine aggregate is standard sand with a fineness modulus of 2.

4.

5. The tunnel lining repair material according to claim 1, characterized in that, The toughness index λ of tunnel lining repair materials is required to be: λ=(ft / fc)×u≥0.02; Where ft is the 28d flexural strength of the material, fc is the 28d compressive strength of the material, and u is the ultimate tensile strain of the material.

6. A method for preparing a tunnel lining repair material, characterized in that, Includes the following steps: Dry mixing: Dry mix fly ash, steel slag powder and fine aggregate in a mixer until evenly mixed; Preparation and cooling of alkaline solution: Dissolve water glass solution and sodium hydroxide solid in part of the mixing water, stir until clear, and cool to room temperature; Wet mixing: Add the alkali activator solution, remaining mixing water and functional admixtures to the dry mix and forcibly mix until a uniform, fluid mortar or concrete mixture is formed.

7. The method for preparing the tunnel lining repair material according to claim 6, characterized in that, In the dry mixing step, the dry mixing time in the mixer is 1-2 minutes.

8. The method for preparing the tunnel lining repair material according to claim 6, characterized in that, Forced mixing should be performed for 3-5 minutes.

9. The method for preparing the tunnel lining repair material according to claim 6, characterized in that, In the alkaline solution preparation and cooling steps, the dissolution temperature of sodium hydroxide solid is controlled at 60-80℃, and the stirring rate is 300-500 r / min.

10. The method for preparing the tunnel lining repair material according to claim 6, characterized in that, In the alkaline solution preparation and cooling steps, the final alkaline solution temperature Ta, the ambient temperature Te, and the initial temperature Tb of the cementitious material must satisfy the following: |Ta-(Te+Tb) / 2|≤10°C.

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