A highly ductile cementitious material made from tunnel muck sand and powder for shotcreting construction of tunnels with large surrounding rock deformation

Abstract

The present invention discloses a slag sand powder high-toughness cement-based material for shotcreting construction of tunnels with large surrounding rock deformation and a preparation method thereof, belonging to the field of building materials. The raw materials are: 600-1000 parts of portland cement, 300-600 parts of slag sand powder, 50-100 parts of micro energy-consuming components, 20-60 parts of meso energy-consuming components, 60-100 parts of accelerator, 2-5 parts of working performance regulating material, and 350-500 parts of water. The high-toughness cement-based material prepared by the present invention uses hard rock waste slag sand powder to replace the ultrafine quartz sand in traditional materials, and uses meso energy-consuming components plus micro energy-consuming components as toughening and energy-absorbing components. The obtained high-toughness cement-based material has high static ductility, good durability, and low comprehensive cost. At the same time, it provides a way for the reuse of waste slag, and has broad application prospects in tunnels with large surrounding rock deformation in extremely complex stress fields of railways and highways, outer protective layers of large temperature difference cycle bridge piers, and bridge deck pavements.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to a highly ductile cement-based material made of tunnel muck sand powder for shotcreting construction of tunnels with large surrounding rock deformation. Background Art

[0002] With the advancement of infrastructure construction such as railways and highways in China towards the central and western regions and high-altitude and difficult mountainous areas, the control of tunnel disasters under high in-situ stress has become a key technical problem affecting project quality and construction progress. The surrounding rock in the hard rock section under high in-situ stress stores a large amount of elastic energy. When the rock mass is excavated and damaged, the effect of the structural plane is significantly reduced, showing phenomena such as rib spalling, buckling, slab cracking, and rockburst, triggering engineering accidents such as tunnel collapse, TBM jamming, and yield fracture of steel arch frames, and posing a serious threat to the safe service of tunnels. High in-situ stress hard rock can ensure the stability of the surrounding rock through stress release means such as drilling and pre-blasting, or can also be reinforced by using a support method with energy absorption capacity. For tunnels with large surrounding rock deformation, controlling the surrounding rock deformation within the allowable range and adopting the method of "yielding support", and using the high ductility of tunnel concrete and actively deforming to release the energy of the surrounding rock under in-situ stress are effective ways to solve the large deformation of tunnel surrounding rock under high in-situ stress. Steel fiber shotcrete and high-performance polypropylene fiber-reinforced shotcrete have become widely used primary support materials due to their high strength grade and high ductility energy absorption. However, for extremely complex stress fields with frequent crustal activities, the deformation of tunnel surrounding rock under high in-situ stress is even greater, and there is an urgent need for highly ductile cement-based materials to replace traditional shotcrete as the primary support material for tunnels.

[0003] Traditional highly ductile cement-based materials use cement, admixtures, fine aggregates, fibers, and admixtures as raw materials. Their ultimate tensile strain is not less than 0.5%, and they show multi-crack cracking characteristics under tensile stress, also known as engineered cementitious composites (ECC) or strain-hardening cementitious composites (SHCC). Traditional ECC relies on clean ultra-fine quartz sand (maximum particle size less than 0.3 mm) as the aggregate and uses polyethylene fiber (PE) or polyvinyl alcohol fiber (PVA) as the toughening component, with relatively high requirements for raw materials. In the central and western regions and high-altitude and difficult mountainous areas, it is difficult to purchase and transport ultra-fine quartz sand and fly ash, resulting in a relatively high cost of highly ductile cement-based materials prepared by conventional technologies and making it difficult to meet the needs of large-scale use in tunnels with large surrounding rock deformation in extremely complex stress fields.

[0004] Application CN 115477518 A discloses a sprayable ultra-high ductility cement-based composite material and its preparation method and application. It uses cement, fly ash, calcined clay, limestone, and calcined magnesia as cementitious materials and quartz sand as the aggregate, with diverse material sources and difficult to apply in extremely complex stress fields.

[0005] Patent Application CN 110981404 A discloses a ultra-high ductility cementitious material for repair and strengthening, which proposes a mixture ratio of ultra-high ductility cementitious material, in which nano-particles, micro-capsules, PVA fibers or PE fibers are used. The material components are relatively complex, the comprehensive cost is relatively high, and the adaptability to on-site spraying construction is insufficient.

[0006] Patent Application CN 114634338 A discloses a high-ductility cementitious composite material made of desert aeolian sand and its preparation method, which discloses a method for preparing high-ductility material using aeolian sand, making full use of the aeolian sand resources in the desert. However, its forming method is vibration forming, which does not meet the requirements of tunnel spraying construction.

[0007] Patent Application CN 115448647 A discloses a high-ductility recycled powder geopolymer-based repair and strengthening material and its preparation method, which uses geopolymer as a repair and strengthening material to realize the secondary utilization of recycled sand powder. However, the setting time of geopolymer materials is too fast and its curing requirements are relatively high, and it is easy to crack during on-site spraying construction, and there may be problems of insufficient durability.

[0008] As can be seen from the above, although there are currently many high-toughness cementitious materials, most of them have complex material compositions, high costs, and difficult construction performance control. There is still a lack of high-toughness and high-durability cementitious materials suitable for spraying construction of surrounding rock large-deformation tunnels in extremely complex stress fields. On the other hand, according to the provisions of "Mechanism Sand for Railway Concrete" (Q / CR 865), hard rock cavern slag (uniaxial saturated compressive strength of the parent rock is greater than 30 MPa but less than 60 MPa) cannot be used for the production of ballast, crushed stone for concrete, and mechanism sand. Abandoning the hard rock cavern slag not only occupies a large amount of land resources, causes damage to the ecological environment, but also easily induces secondary disasters such as landslides.

[0009] In view of the lack of high-quality raw materials in difficult areas, using hard rock tunnel cavern slag to produce cavern slag sand powder and thus prepare high-toughness cementitious materials to achieve "taking from the tunnel and using in the tunnel" is not only a beneficial method to solve the resource utilization of waste cavern slag, but also of great significance for improving the support capacity of surrounding rock large-deformation tunnels.

[0010] Therefore, it is an urgent technical problem for those skilled in the art to provide a cavern slag sand powder high-toughness cementitious material for spraying construction of surrounding rock large-deformation tunnels using hard rock cavern slag as raw material. Summary of the Invention

[0011] In view of this, the present invention provides a cavern slag sand powder high-toughness cementitious material for spraying construction of surrounding rock large-deformation tunnels.

[0012] In order to achieve the above object, the present invention adopts the following technical solutions:

[0013] A highly ductile cementitious material made of tunnel muck sand powder for shotcrete construction of tunnels with large surrounding rock deformation, comprising the following raw materials in parts by weight: 600 - 1000 parts of portland cement, 300 - 600 parts of tunnel muck sand powder, 50 - 100 parts of micro energy-consuming components, 20 - 60 parts of meso energy-consuming components, 60 - 100 parts of accelerator, 2 - 5 parts of workability regulating materials, and 350 - 500 parts of water.

[0014] Furthermore, the parent rock of the tunnel muck sand powder is hard rock, and the uniaxial saturated compressive strength of the hard rock is 30 - 60 MPa.

[0015] Even further, the particle size of the tunnel muck sand powder is less than 2.36 mm, the crushing index is less than 10%, and the MB value is less than 1.0 g / kg.

[0016] The beneficial effect of adopting the above further scheme is that: the present invention uses hard rock tunnel muck sand powder to replace the commonly used ultra-fine quartz sand in traditional highly ductile cementitious materials, without using mineral admixtures such as fly ash, with a simple raw material composition. At the same time, it solves the problem that the saturated compressive strength of hard rock is insufficient and cannot be used as coarse and fine aggregates for concrete, improves the resource utilization rate of waste tunnel muck, and the prepared shotcrete highly ductile cementitious material is used for shotcrete construction of tunnels with large surrounding rock deformation, realizing the "taking from the tunnel and using in the tunnel" of tunnel muck.

[0017] Furthermore, the micro energy-consuming components are calcium carbonate whiskers and / or calcium sulfate whiskers;

[0018] The beneficial effect of adopting the above further scheme is that: the micro energy-consuming components of the present invention are a mixture of calcium carbonate whiskers and calcium sulfate whiskers, with a relatively small particle size, which can play a certain nucleation role during the cement hydration process, improving the early strength of the cementitious material. At the same time, the micro energy-consuming components can fill the voids of the cementitious material, increasing the density of the cementitious material and improving the durability of the material.

[0019] And the whiskers in the micro energy-consuming components have a length of 30 - 50 μm and an aspect ratio of 20 - 40.

[0020] Furthermore, the meso energy-consuming components are any two or three mixtures of polyvinyl alcohol fibers, basalt fibers, and alkali-resistant glass fibers.

[0021] The beneficial effect of adopting the above further scheme is that: the meso energy-consuming components used in the present invention are a mixture of two or three of PVA, BF, and GF. By utilizing the low tensile strength, high fracture elongation rate of PVA fibers, and the high tensile strength and medium fracture elongation rate of BF and GF fibers, the synergy of tensile strength and fracture elongation rate of the meso energy-consuming components is achieved, enhancing the toughness of the cementitious material.

[0022] Furthermore, the fiber filaments of the mesoscopic energy-dissipating component have a length of 8 - 30 mm, a length-to-diameter ratio of 200 - 2000, and a fracture elongation rate greater than 3%.

[0023] Preferably, the mesoscopic energy-dissipating component is obtained by mixing polyvinyl alcohol fiber, basalt fiber, and alkali-resistant glass fiber in a mass ratio of 20% - 40%: 20% - 80%: 20% - 80%.

[0024] The beneficial effect of adopting the above further scheme is as follows: In the present invention, nanocrystalline whiskers and hybrid fibers are used as energy-dissipating components. When the initial support of the tunnel deforms under high in-situ stress, firstly, relying on the strengthening and crack-inhibiting effects of the microscopic energy-dissipating components, the generation of microcracks in the cement-based material is reduced. As the deformation increases, relying on the bridging effect of the mesoscopic energy-dissipating components, multi-crack cracking of the cement-based material is achieved, and the initial cracking strength and ultimate strain of the cement-based material are improved, thereby playing a toughening and strengthening role at both the mesoscopic and microscopic scales.

[0025] Further, the working performance regulating material is a viscosity-reducing polycarboxylate water reducer with a water reduction rate greater than 30%.

[0026] Further, the accelerator is an alkali-free accelerator, and the final setting time of the neat paste of the alkali-free accelerator is less than 5 min, and the 90-day compressive strength retention rate is greater than 105%.

[0027] The present invention also provides a preparation method of the above-mentioned high-toughness cement-based material with tunnel slag sand powder for spraying construction of surrounding rock with large deformation, including the following steps:

[0028] (1) Add portland cement, tunnel slag sand powder, and microscopic energy-dissipating components to a mixer and dry mix for 2 - 3 min;

[0029] (2) Add the working performance regulating material and 90% of the water;

[0030] (3) Add the mesoscopic energy-dissipating components and the remaining water, and quickly stir for 3 - 5 min;

[0031] (4) Add the accelerator to obtain the high-toughness cement-based material with tunnel slag sand powder for spraying construction of surrounding rock with large deformation.

[0032] The beneficial effect of the present invention is as follows: The high-toughness cement-based material prepared by the present invention uses hard rock waste tunnel slag sand powder to replace the ultra-fine quartz sand used in traditional high-toughness cement-based materials, and uses the mesoscopic energy-dissipating component + microscopic energy-dissipating component as the toughening and energy-absorbing components. The prepared high-toughness cement-based material has the advantages of high static ductility, good durability, and low comprehensive cost, and moreover, provides a way for the reuse of waste tunnel slag, and has broad application prospects in tunnels with large deformation of surrounding rock under extremely complex stress fields of railways and highways, outer protective layers of large-temperature-difference cycle bridge piers, and bridge deck pavings. Detailed implementation manners

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] Embodiment 1

[0035] The slag sand powder high-toughness cement-based material for shotcrete construction of surrounding rock with large deformation, the raw materials and the dosage of 1m 3 The dosage of the high-toughness materials is as follows:

[0036] Portland cement: Beijing Jinyu P·O 42.5 cement meeting the requirements of GB / 175-2007, with a dosage of 800 kg;

[0037] Slag sand powder: Dolomite with a uniaxial saturated compressive strength of the parent rock of 49.7 MPa, the maximum particle size of the sand powder is 2.36 mm, the crushing index is 8.5%, and the MB value is 0.8 g / kg, with a dosage of 500 kg;

[0038] Workability regulation material: PCEA-1 viscosity-reducing polycarboxylate water reducer produced by Jiangsu Sobute New Materials Co., Ltd., with a water reduction rate of 32% and a solid content of 40%, and a dosage of 3.2 kg;

[0039] Microscopic energy-consuming component: Calcium carbonate whiskers with a length of 30 μm and a diameter of 1 μm produced by Lingshou County Tuyun Mineral Products Processing Factory, with a dosage of 30 kg, and calcium sulfate whiskers with a length of 40 μm and a diameter of 1.2 μm produced by Hebei Ruijiang Metals Co., Ltd., with a dosage of 40 kg;

[0040] Mesoscopic energy-consuming component: Polyvinyl alcohol fibers with a length of 12 mm and a diameter of 39 μm produced by Shanghai Yingjia Industrial Development Co., Ltd., with a fracture elongation rate of 7.5%, and a dosage of 15 kg; Alkali-resistant glass fibers with a length of 12 mm and a diameter of 14 μm produced by Shandong Hengtai New Materials Technology Co., Ltd., with a fracture elongation rate of 3.5%, and a dosage of 35 kg;

[0041] Alkali-free accelerating agent: ZTSN-1 alkali-free accelerating agent produced by Anhui Zhongtie Engineering Materials Technology Co., Ltd., with a net paste setting time of 3.5 minutes and a 90d compressive strength retention rate of 108%, and a dosage of 80 kg;

[0042] Water: Ordinary tap water, with a dosage of 400 kg.

[0043] Embodiment 2

[0044] The slag sand powder high-toughness cement-based material for shotcreting construction of tunnels with large surrounding rock deformation, raw materials and 1m 3 The dosage of high-toughness materials is as follows:

[0045] Portland cement: Beijing Jinyu P·O 52.5 cement meeting the requirements of GB / 175-2007, with a dosage of 700 kg;

[0046] Slag sand powder: Marble with a uniaxial saturated compressive strength of the parent rock of 42.5 MPa, the maximum particle size of the sand powder is 0.6 mm, the crushing index is 6.5%, and the MB value is 0.9 g / kg, with a dosage of 550 kg;

[0047] Workability regulating material: ZTPCE-1 viscosity-reducing polycarboxylate water reducer produced by Anhui Zhongtie Engineering Materials Technology Co., Ltd., with a water reduction rate of 35% and a solid content of 20%, with a dosage of 4.2 kg;

[0048] Microscopic energy-consuming component: Calcium carbonate whiskers with a length of 18 μm and a diameter of 0.5 μm produced by Tuyun Mineral Products Processing Factory in Lingshou County, with a dosage of 40 kg, and calcium sulfate whiskers with a length of 40 μm and a diameter of 1 μm produced by Hebei Ruijiang Metals Co., Ltd., with a dosage of 50 kg;

[0049] Mesoscopic energy-consuming component: Polyvinyl alcohol fibers with a length of 12 mm and a diameter of 8 μm produced by Kuraray Co., Ltd. of Japan, with a fracture elongation rate of 8.2%, with a dosage of 15 kg; Alkali-resistant glass fibers with a length of 12 mm and a diameter of 14 μm produced by Shandong Hengtai New Materials Technology Co., Ltd., with a fracture elongation rate of 3.5%, with a dosage of 15 kg; Basalt fibers with a length of 18 mm and a diameter of 10 μm produced by Sichuan Aerospace Tuoda Basalt Fiber Co., Ltd., with a fracture elongation rate of 3.1%, with a dosage of 15 kg;

[0050] Non-alkali quick-setting agent: ZTSN-1 non-alkali quick-setting agent produced by Anhui Zhongtie Engineering Materials Technology Co., Ltd., with a net paste setting time of 3.5 minutes and a 90d compressive strength retention rate of 108%, with a dosage of 100 kg;

[0051] Water: Ordinary tap water, with a dosage of 420 kg.

[0052] Example 3

[0053] The slag sand powder high-toughness cement-based material for shotcreting construction of tunnels with large surrounding rock deformation, raw materials and 1m 3 The dosage of high-toughness materials is as follows:

[0054] Portland cement: Beijing Jinyu P·O 42.5 cement meeting the requirements of GB / 175-2007, with a dosage of 900 kg;

[0055] Hole slag sand powder: Dolomite with a uniaxial saturated compressive strength of the parent rock of 49.7 MPa, the maximum particle size of the sand powder is 1.18 mm, the crushing index is 8.5%, the MB value is 0.6 g / kg, and the dosage is 320 kg;

[0056] Working performance regulating material: PCEA-1 viscosity-reducing polycarboxylate superplasticizer produced by Jiangsu Sobute New Materials Co., Ltd., with a water reduction rate of 35%, a solid content of 20%, and a dosage of 4.7 kg;

[0057] Microscopic energy-consuming components: Calcium carbonate whiskers with a length of 30 μm and a diameter of 1 μm produced by Lingshou County Tuyun Mineral Products Processing Factory, with a dosage of 40 kg, and calcium sulfate whiskers with a length of 40 μm and a diameter of 1.2 μm produced by Hebei Ruijiang Metal Co., Ltd., with a dosage of 60 kg;

[0058] Mesoscopic energy-consuming components: Polyvinyl alcohol fibers with a length of 12 mm and a diameter of 8 μm produced by Kuraray Co., Ltd. of Japan, with a fracture elongation rate of 8.2%, and a dosage of 20 kg; Basalt fibers with a length of 18 mm and a diameter of 10 μm produced by Sichuan Aerospace Tuoda Basalt Fiber Co., Ltd., with a fracture elongation rate of 3.1%, and a dosage of 35 kg;

[0059] Alkali-free accelerator: TKSN-2 alkali-free accelerator produced by China Academy of Railway Sciences Corporation, with a net paste setting time of 3.1 minutes and a 90-day compressive strength retention rate of 110%, and a dosage of 70 kg;

[0060] Water: Ordinary tap water, with a dosage of 470 kg.

[0061] The above-mentioned embodiments 1-3 of the present invention adopt the following steps to prepare a high-toughness cement-based material with hole slag sand powder for spraying construction of tunnels with large surrounding rock deformation:

[0062] (1) Add Portland cement, hole slag sand powder, and microscopic energy-consuming components to a mixer and dry mix for 2-3 minutes;

[0063] (2) Add the working performance regulating material and 90% of the water;

[0064] (3) Add the mesoscopic energy-consuming components and the remaining water, and quickly stir for 3-5 minutes;

[0065] (4) Add the accelerator to obtain a high-toughness cement-based material with hole slag sand powder for spraying construction of tunnels with large surrounding rock deformation.

[0066] Test example

[0067] The initial setting time of the cement-based materials prepared in Examples 1-3 was tested with reference to the Standard Test Method for Performance of Ordinary Concrete Mixtures (GB / T 50080-2016). When the cement-based materials were cured to the age of 28 days, the initial cracking strength, ultimate tensile strain and compressive strength of the cement-based materials were tested with reference to the Test Method for Mechanical Properties of High Ductility Fiber Reinforced Cementitious Composites (JC / T 2461-2018), the electric flux of the cement-based materials was tested with reference to the Standard Test Method for Long-Term Performance and Durability of Ordinary Concrete (GB / T 50082-2009), and the bond strength between the cement-based materials and concrete was tested with reference to the Technical Specification for Application of Shotcrete (JGJT 372-2016). The results are shown in Table 1.

[0068] Table 1

[0069]

[0070]

[0071] As can be seen from Table 1, the initial cracking strength of the high-toughness cement-based material of the present invention is between 3.5 MPa and 6.2 MPa, the ultimate tensile strain is between 1.9% and 3.4%, and the compressive strength is between 39.7 MPa and 48.8 MPa. It has good toughness and meets the requirements for the initial support deformation of tunnels under the condition of large surrounding rock deformation; the electric flux is less than 1500 C, and the durability performance is good; the bond strength with concrete meets the standard requirements, and it is suitable for shotcrete construction of tunnels with large surrounding rock deformation in complex stress fields, and at the same time has significant economic and environmental benefits.

[0072] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A highly ductile cementitious material made of tunnel muck sand powder for shotcreting construction of tunnels with large surrounding rock deformation, characterized in that, It includes the following raw materials in parts by weight: 600 - 1000 parts of portland cement, 300 - 600 parts of tunnel slag sand powder, 50 - 100 parts of micro energy-consuming components, 20 - 60 parts of meso energy-consuming components, 60 - 100 parts of accelerator, 2 - 5 parts of working performance regulating material, and 350 - 500 parts of water; The parent rock of the tunnel slag sand powder is hard rock, and the uniaxial saturated compressive strength of the hard rock is 30 - 60 MPa. The micro energy-consuming components are calcium carbonate whiskers and / or calcium sulfate whiskers; and the whisker length in the micro energy-consuming components is 30 - 50 μm, and the aspect ratio is 20 - 40. The meso energy-consuming components are obtained by mixing polyvinyl alcohol fiber, basalt fiber and alkali-resistant glass fiber according to the mass ratio of 20% - 40%: 20% - 80%: 20% - 80%.

2. The highly ductile cementitious material made from tunnel muck sand powder for shotcreting construction in tunnels with large surrounding rock deformation according to claim 1, characterized in that, The particle size of the tunnel slag sand powder is less than 2.36 mm, the crushing index is less than 10%, and the MB value is less than 1.0 g / kg.

3. The high-toughness cement-based material made of tunnel muck sand powder for shotcreting construction in tunnels with large surrounding rock deformation according to claim 1, wherein The single fiber length of the fiber used in the meso energy-consuming components is 8 - 30 mm, the aspect ratio is 200 - 2000, and the fracture elongation rate is greater than 3%.

4. The highly ductile cementitious material made from tunnel muck sand powder for shotcreting construction of tunnels with large surrounding rock deformation according to claim 1, wherein, The working performance regulating material is a viscosity-reducing polycarboxylate water reducer with a water reduction rate greater than 30%.

5. The highly ductile cementitious material of crushed rock sand powder for shotcreting construction in tunnels with large surrounding rock deformation according to claim 1, characterized in that, The accelerator is an alkali-free accelerator, and the final setting time of the neat cement of the alkali-free accelerator is less than 5 min, and the 90-day compressive strength retention rate is greater than 105%.

6. The preparation method of the highly ductile cement-based material of tunnel slag sand powder for shotcreting construction of surrounding rock with large deformation according to any one of claims 1-5, characterized in that, It includes the following steps: (1) Add portland cement, tunnel slag sand powder, and micro energy-consuming components to a mixer and dry mix for 2 - 3 min; (2) Add the working performance regulating material and 90% of the water; (3) Add the meso energy-consuming components and the remaining water, and quickly stir for 3 - 5 min; (4) Add the accelerator to obtain a tunnel slag sand powder high-toughness cement-based material for shotcreting construction of surrounding rock large deformation tunnels.

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