Calcium springback inhibitor for sprayed concrete as well as preparation method and application of calcium springback inhibitor

Abstract

The invention discloses a calcium rebound inhibitor for sprayed concrete as well as a preparation method and application of the calcium rebound inhibitor. The calcium rebound inhibitor is prepared by taking a ternary calcium calcined compound and inorganic coagulant calcium salt as core samples and alkanolamine ester compounds as a shell and adopting a physical coating process. The calcium springback inhibitor for the sprayed concrete can be independently used for the sprayed concrete and can also be jointly used for the sprayed concrete with a mineral admixture or a rheology modification component, a springback material of the sprayed concrete can be fully recycled, springback loss of the sprayed concrete in the spraying process is remarkably reduced under the condition of no negative influence on setting and hardening, and the service life of the sprayed concrete is prolonged. The early volume shrinkage of the sprayed concrete material is reduced, the early deformation of weak surrounding rock is restrained, the preparation process is green and low-carbon, and the performance adaptability is wide.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete admixtures, and in particular relates to a calcium rebound inhibitor for shotcrete and a preparation method and application thereof. Background Art

[0002] Shotcrete is a special type of concrete developed from mining, tunnel support and slope reinforcement. It can adhere well to the surface of surrounding rock with poor self-stability and large loose deformation without formwork and specific wind pressure conditions, achieving the initial support effect of controlling the relaxation and deformation of surrounding rock. However, affected by internal and external construction factors such as fluctuations in aggregate quality, high-dosage cementitious material composition, rapid hydration and hardening characteristics, and special spraying technology, shotcrete usually exhibits a high rebound material loss problem. The measured average rebound material fluctuates between 20-40%, and the rebound material is concentrated on both sides of the arch bottom and the arch top area. The high spray rebound loss problem seriously increases the construction costs of tunnel lining structure, such as manpower, equipment, machinery, and construction progress. In addition, the generated spray rebound material has a significant decrease in cementitious activity under the accelerated early hydration, and cannot be used again without treatment, which invisibly increases the cost of slag removal and landfill.

[0003] How to effectively reduce the rebound rate of shotcrete has become an important branch of research on low-carbonization of concrete materials. After realizing that conventional improvement methods such as optimizing the shotcrete process and increasing material costs (such as increasing the amount of cement and using a higher amount of alkali-free accelerator) are difficult to meet the technical needs of reducing the rebound loss of shotcrete under adverse geological conditions such as over-excavation, water seepage, and soft rock, many engineering practitioners and product developers have realized that the development of rebound-reducing products with specific functional properties has become a research hotspot. However, the development of this technology is still not mature enough, and there are many problems that need to be solved urgently as follows: The first problem is the significant influence on setting and hardening: Some rebound-reducing shotcrete materials add a certain amount of high-alumina or sulfoaluminate rapid-hardening cement to accelerate the early hydration rate and strength development of shotcrete, or introduce organic macromolecule thickeners, clay minerals, copolymer emulsions or latex powders to improve the cohesiveness of shotcrete slurry, so as to enhance the cohesiveness between shotcrete and surrounding rock. However, when adding the above-mentioned rebound-reducing materials in the plastic stage of shotcrete, on the one hand, the rapid-hardening cementitious system or the introduction of organic macromolecule thickeners will increase the fluidity loss of the shotcrete mixture, resulting in problems such as excessive shotcrete pump pressure, pump blockage or difficult material discharge. On the other hand, copolymer emulsions or latex powders and clay minerals have a strong retarding effect on the early hydration of cement mineral phases, affecting the effectiveness of the essential materials of the accelerator and being unfavorable for shotcrete construction. Chinese Patent CN114920491A discloses a rebound-reducing shotcrete admixture and its preparation method, which incorporates 30-50% rapid-hardening cement and introduces cellulose-based thickeners, both of which will affect the workability of the shotcrete mixture. Chinese Patent CN115626792A discloses a rebound inhibitor for shotcrete, which includes an interface bonding component of epoxy resin emulsion and a rheology regulating component composed of cellulose ether and redispersible latex powder, both of which will affect the early setting and hardening effect of shotcrete. Korean Patent KR101252962B1 discloses a shotcrete composition containing rapid-setting high-alumina cement, which also adopts the design of portland cement, high-alumina cement and rapid-setting cement in the cementitious system.

[0004] The second problem is the significant influence on mechanical strength: Some rebound-reducing materials incorporate more low-hydration-activity mineral admixtures to achieve functions such as dispersion and loading of organic components, or introduce alkali metal inorganic salts to increase the early hydration and hardening strength. However, too many low-activity mineral admixtures easily lead to slow early mechanical strength development of shotcrete with low early strength itself, thus affecting its early restraint effect on soft surrounding rock. At the same time, while alkali metal inorganic salts increase the early hydration and hardening strength, they have a greater impact on the later strength of shotcrete and will exacerbate the risk of alkali-aggregate reaction. Chinese Patent CN115490480A discloses a low-rebound shotcrete containing biological glue and its preparation and application method. The components incorporate 18-27% low-activity mineral admixtures such as mineral powder and fly ash, and lack compounds or components for early activity excitation, which will cause a decrease in the early strength of shotcrete and affect the support effect; Chinese Patent CN115536300A discloses a functional admixture for shotcrete and its preparation method and application, including three components with a mass ratio of 3~5:8~10:5. Among them, 50-80% of the second component, magnesium sulfate and sodium silicate, are used as chemical activators to increase the early strength of concrete. However, introducing too many alkali metal salts will affect its later strength and service durability.

[0005] The third problem is that the components are complex and difficult to produce or measure: some rebound-reducing materials introduce expensive raw materials, add complex organic or inorganic components, or the preparation method is relatively complicated to achieve comprehensive performance improvement, which causes many inconveniences to the market application, industrial production and use and measurement of the materials. Chinese patent CN115849764A discloses a shotcrete admixture and its preparation method and application, including 8-15 parts of redispersible copolymer powder, 10-20 parts of early strength enhancer, 40-60 parts of composite mineral micropowder, 0.5-3 parts of modified composite fiber, 0.1-1.5 parts of water reducer, and 0.05-0.5 parts of polyamide wax powder, but the raw materials such as silicon carbide nanopowder as composite mineral micropowder, CaAl-layered double metal hydroxide as early strength enhancer, composite fiber modified by 2-morpholineethanesulfonic acid / acetic acid solution, and polyamide wax powder are relatively high in market price, have few sources and are not easy to prepare; Chinese patent CN116161 893A discloses a method for preparing a cross-linking monomer for preparing high early strength and low rebound concrete. The technical idea is to add 0.1-0.3 parts of a reducing agent and 5-15 parts of a cross-linking monomer to 0.5-2 parts of a water-reducing agent to prepare a water-reducing mixture, and add 0.3-2 parts of an initiator to 6-12 parts of an accelerator to prepare a quick-setting mixture. The monomers containing multiple saturated double bonds are cross-linked under the action of the initiator to achieve the rebound reduction effect. The cross-linking monomer and the initiator are fed separately and are difficult to measure accurately during the on-site construction process. The initiator is one or more of sodium persulfate, potassium persulfate, ammonium persulfate and potassium hydrogen persulfate, which will affect the performance of the accelerator and cause undesirable precipitation.

[0006] The fourth problem is the neglect of the durability of shotcrete: shotcrete is usually designed with a higher cement content and a larger water-cement ratio material component. Therefore, the material usually exhibits a higher tendency of late drying shrinkage, which leads to a greater risk of late cracking of shotcrete, inducing durability problems such as a decrease in the bearing capacity of the primary support structure and increased water seepage and dissolution. However, simply introducing polymer rheology-modified materials into some rebound-reducing materials cannot improve the above-mentioned durability problems, and the adaptability of existing chemical shrinkage reducers or inorganic expansion and shrinkage components in shotcrete is still unknown.

[0007] Therefore, how to provide a rebound suppression material for shotcrete that has a wide preparation source, strong rebound reduction effect, good adaptability to concrete, can make secondary solid waste use of shotcrete rebound materials and has better early crack resistance improvement is an engineering and technical problem that needs to be solved urgently for technical personnel in this field. Summary of the invention

[0008] In view of the problems in the prior art that the setting and hardening of the rebound-reducing material have a great negative impact, the mechanical strength in the early and later stages decreases, the components are complex and difficult to produce and measure, etc., and the technical requirements for low-carbon and high-durability such as the high cost and difficulty of disposing of the sprayed rebound waste and the low improvement amplitude of the early crack resistance ability, the present invention provides a calcium-based rebound inhibitor for shotcrete, a preparation method thereof and an application.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions: A calcium-based rebound inhibitor for shotcrete is composed of a shell A and a core sample B. The shell A is coated on the surface of the core sample B, and the mass ratio of the shell A to the core sample B is 1:10 - 20; The shell A is a compound of alkanolamine ester, the relative molecular mass of the compound of alkanolamine ester is less than 1000, and the hydrolysis temperature is 20 - 80 °C; The core sample B is composed of a ternary calcium calcined mineral and an inorganic coagulant calcium salt. The mass ratio of the ternary calcium calcined mineral to the inorganic coagulant calcium salt is (95 - 75):(5 - 25); the ternary calcium calcined mineral is prepared by a light burning process from limestone, clay minerals and sprayed rebound material, and the mass ratio of limestone, clay minerals and sprayed rebound material is (30 - 50):(20 - 40):(10 - 50), and the temperature of the light burning process is 850 - 1200 °C.

[0010] Further, the compound of alkanolamine ester is an ester compound of diethanolamine or an ester compound of triethanolamine.

[0011] Furthermore, the compound of alkanolamine ester is selected from triethanolamine acrylate, triethanolamine stearate, triethanolamine propionate, triethanolamine methyl propionate, triethanolamine acetate, triethanolamine oleate, diethanolamine acetate or diethanolamine oleate.

[0012] Further, the light burning process is selected from a shaft kiln process, a suspension kiln process or a rotary kiln process, and preferably a suspension kiln process.

[0013] Further, the calcium carbonate content in the limestone is greater than 90%.

[0014] Further, the clay minerals are selected from kaolin, bentonite, montmorillonite, illite or chlorite, and preferably kaolin.

[0015] Further, the sprayed rebound material is the concrete material obtained by spraying, rebounding and falling, and collecting the dry-process shotcrete, wet-process shotcrete or wet-process shotcrete.

[0016] Further, the inorganic coagulant calcium salt is selected from calcium sulfoaluminate, calcium hydroxide, calcium formate, calcium nitrate or calcium sulfate.

[0017] The preparation method of the above calcium rebound inhibitor adopts a physical coating process, including the following steps: Add ternary calcium calcined minerals and inorganic coagulation-promoting calcium salts into a suspension container, start an air flow or a dispersion medium to fully disperse the materials, and form a stable dispersed fluidized bed bottom layer or an air flow layer; introduce an alkanolamine ester compound into the liquid phase pipeline, and complete the preparation at a specific process temperature and operating time.

[0018] Furthermore, the physical coating process is a fluidized bed process or a spray drying process, preferably a fluidized bed process; the process temperature is 85-105°C, and the process time is 1.5-3 h.

[0019] The calcium rebound inhibitor of the present invention has a specific surface area of 150-300 m 2 / kg, and the alkali content is less than 1%.

[0020] The calcium rebound inhibitor of the present invention is applicable to shotcrete neat cement, shotcrete mortar, plain shotcrete, fiber shotcrete, and shotcrete ultra-high performance concrete, and is more applicable to fiber shotcrete. During use, according to the shotcrete construction method, add the calcium rebound inhibitor during the mixing process of cement paste, mortar or concrete, and the dosage accounts for 5-20% of the total mass of the binder.

[0021] A liquid calcium rebound inhibitor is composed of the above calcium rebound inhibitor and water. The amount of water is 40-60% of the total mass of the liquid calcium rebound inhibitor, and the dosage of the calcium rebound inhibitor is not less than 40% of the total mass of the liquid calcium rebound inhibitor. The calcium rebound inhibitor is used to prepare the liquid calcium rebound inhibitor, which can effectively reduce the pumping and metering difficulty of the calcium rebound inhibitor and improve the dispersion effect.

[0022] A rebound suppression composition for shotcrete includes the above liquid calcium rebound inhibitor and an auxiliary rebound suppression component. The mass ratio of the liquid calcium rebound inhibitor to the auxiliary rebound suppression component is (85-95):(5-15); The auxiliary rebound suppression component is selected from mineral admixtures and / or rheology modification components; The mineral admixture is selected from fly ash, slag powder, silica fume, steel slag powder or metakaolin, and its function is to provide auxiliary cementitious action and improve the rheological properties of the concrete paste; The rheological modification component is selected from organic thickeners and / or redispersible latex powders. The organic thickener is selected from amide organic compounds, methyl cellulose ethers, hydroxyethyl cellulose ethers, hydroxypropyl cellulose ethers, maltodextrin, xanthan gum or gellan gum; the amide organic compound is selected from polyacrylamide, N-methylolacrylamide, dimethylformamide or cyclopropylamide; the redispersible latex powder is selected from vinyl propionate polymer latex powder, pure acrylic copolymer latex powder, styrene-acrylate copolymer latex powder, vinyl acetate-vinyl versatate copolymer latex powder, vinyl acetate-ethylene copolymer latex powder or vinyl acetate-vinyl chloride-acrylate copolymer latex powder, and its function is to improve the rheological viscosity of the concrete paste and its bonding and adhesion to the rock mass or the sprayed surface.

[0023] The calcium-based rebound inhibitor of the present invention is compounded with other auxiliary rebound-reducing components, which can effectively improve the rheological properties of the shotcrete and its bonding and adhesion effects between the concrete and the rock mass or the sprayed surface during the spraying process. In particular, the use of a liquid calcium-based rebound inhibitor and auxiliary rebound-reducing components further enhances the effect of reducing the shotcrete rebound rate and the spraying quality.

[0024] The preparation method of the above-mentioned rebound-inhibiting composition for shotcrete includes the following steps: (1) Prepare the calcium-based rebound inhibitor; (2) According to the material ratio setting, first add water, start heating, and after the temperature rises to 45-60 °C, add the auxiliary rebound-reducing components while stirring within 30-60 minutes. The stirring rate is 500-1000 r / min, and the total stirring time is 1-1.5 h; (3) Start cooling. After the temperature drops to 30 °C, add the calcium-based rebound inhibitor, and keep stirring for 1.5-3.0 h to obtain the rebound-inhibiting composition for shotcrete. The stirring rate is 300-500 r / min.

[0025] When the above-mentioned rebound-inhibiting composition for shotcrete is used, according to the wet shotcrete construction method, the rebound-inhibiting composition is added to the shotcrete mixture and dispersed sufficiently. The incorporation amount accounts for 10-30% of the total mass of the cementitious materials.

[0026] The present invention innovatively uses a ternary calcium calcined compound and an inorganic coagulation-promoting calcium salt as the core sample, and a alkanolamine ester compound as the shell to prepare a calcium-based rebound inhibitor by a physical coating process, and further compound it with other auxiliary rebound-reducing components to prepare a rebound-inhibiting composition for shotcrete.

[0027] Compared with the prior art, the present invention has the following beneficial effects: (1) It has no negative impact on setting and hardening, and significantly improves the spraying quality. The calcium-based rebound inhibitor of the present invention uses alkanolamine ester compounds as the shell. After being initially added to the concrete mixture, it is gradually hydrolyzed under the influence of cement lye to produce alkanolamine and corresponding organic salts, which have no adverse effects on the workability and setting and hardening properties of cement-based materials. As the mixing, transportation, and spraying processes proceed, the core sample components mainly composed of ternary calcium calcined compounds and inorganic coagulant calcium salts are released and participate in cement hydration, accelerating the dissolution and hydration of cement mineral phases, enriching calcium-containing hydration products such as early ettringite and hydrated calcium silicate, accelerating the setting and hardening of concrete, reducing the rebound loss during spraying, and increasing the early strength. When compounded with auxiliary rebound-reducing components to prepare a spraying concrete rebound inhibition composition, it can simultaneously improve the rheological properties of the slurry, increase the viscosity of the slurry and the interfacial bonding properties, promote cement setting and hardening, and jointly achieve improving the bonding effect between spraying concrete and soft rock masses and increasing the thickness of the first spraying under conditions such as overexcavation and water seepage. Using the calcium-based rebound inhibitor of the present invention to prepare spraying concrete can achieve no slump workability loss in 3 hours, a spraying rebound rate of less than 10%, a first spraying thickness of up to more than 100 mm, a bonding strength with the surrounding rock greater than 1.0 MPa, a 7-day compressive strength ratio greater than 135%, and a 28-day compressive strength ratio greater than 120%, greatly reducing the time-consuming of the primary support construction process and the material cost loss; (2) Green and low-carbon preparation, wide adaptability in use and performance. The calcium-based rebound inhibitor of the present invention uses limestone, clay minerals, and spraying rebound materials to prepare ternary calcium calcined minerals. During the light burning process, limestone and clay minerals are decomposed at high temperature to reactivate the spraying rebound materials with low cementitious properties, forming a ternary calcium-based active cementitious material composed of calcined calcium oxide - calcined clay - activated spraying rebound materials, which can fully recycle and utilize the waste spraying rebound materials, realizing green and low-carbon preparation. The calcined products formed under a stable calcination process have stable properties and good adaptability to calcium-based cementitious materials such as cement. Moreover, the calcium-based rebound inhibitor can be fed in powder or liquid form according to the transportation and feeding scenarios, with simple use and convenient metering; (3) Low risk of early shrinkage cracking and good durability. The calcium-based rebound inhibitor of the present invention makes full use of the mutual hydration effects between ternary calcium calcined minerals, cement mineral phases, accelerators and other components, and through the combined synergistic effects of auxiliary rebound-reducing components, can form good filling of the pores inside the spraying concrete and at the interface between it and the rock mass. And through the early micro-expansion characteristics of the calcined by-product calcium oxide, it can reduce the early volume shrinkage of the spraying concrete material, realizing an electric flux of less than 1000 C for the spraying concrete in 56 days, a dry shrinkage deformation of less than 150 με for the spraying concrete in 7 days, and a restricted expansion rate of more than 0.050% for the 7-day water-cured spraying concrete, which has a good effect on restraining the early deformation of soft surrounding rock. Specific embodiments

[0028] The preferred embodiments of the present invention will be described in detail below in conjunction with the embodiments. It should be understood that the following embodiments are given only for the purpose of illustration and are not used to limit the scope of the present invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from the purpose and spirit of the present invention.

[0029] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods.

[0030] Unless otherwise specified, the materials, reagents, etc. used in the following examples can all be obtained from commercial channels.

[0031] Example I-1 / 3: A calcium rebound inhibitor, adopting a shell-core structure, with different ratios and materials of ternary calcium minerals, the same as inorganic coagulant calcium salts.

[0032] Example I-1 A calcium rebound inhibitor is prepared by the following steps: (1) Selection of shell A: Select an alkanolamine ester compound as shell A, preferably an ester compound of diethanolamine, more preferably diethanolamine acetate; the relative molecular mass of the diethanolamine acetate is 245.4, and the hydrolysis temperature is 25 °C; (2) Preparation of core sample B: Prepare ternary calcium calcined minerals by a light calcination process of raw material grinding, high-temperature calcination, cooling, and clinker grinding of limestone, clay minerals, and sprayed rebound material according to the set material ratio, calcination method, and calcination temperature, and mix the ternary calcium calcined minerals and the inorganic coagulant calcium salt composition evenly according to the set ratio to obtain core sample B. Among them, the mass ratio of limestone, clay minerals, and sprayed rebound material is 30:20:50; the light calcination process is selected as the rotary kiln process, and the calcination temperature is 1200 °C; the calcium carbonate content of the limestone is 91%, the clay mineral is montmorillonite, and the sprayed rebound material is the concrete material obtained by spraying, rebounding, and collecting dry-process sprayed concrete; the mass ratio of the ternary calcium calcined minerals to the inorganic coagulant calcium salt is 75:25; the inorganic coagulant calcium salt is calcium formate; (3) Preparation by physical coating process: Add core sample B to a suspension container, start the air flow or dispersion medium to fully disperse the material to form a stable dispersed fluidized bed bottom layer or air flow layer; introduce shell A into the liquid phase pipeline, and complete the preparation of the calcium rebound inhibitor at a specific process temperature and running time; the physical coating process is the fluidized bed process, the process temperature is 85 °C, and the running time is 1.5 h. The mass ratio of shell A to core sample B is 1:10.

[0033] Example I-2 A calcium rebound inhibitor is prepared by the following steps: (1)Selection of Shell A: Select alkanolamine ester compounds as Shell A, preferably ester compounds of triethanolamine, and more preferably triethanolamine acrylate; the relative molecular mass of the triethanolamine acrylate is 221.3, and the hydrolysis temperature is 80°C; (2)Preparation of Core Sample B: Prepare ternary calcium calcined minerals by the light calcination process of raw material grinding, high-temperature calcination, cooling, and clinker grinding of limestone, clay minerals, and sprayed rebound material according to the set material ratio, calcination method, and calcination temperature, and mix the ternary calcium calcined minerals and inorganic coagulation-promoting calcium salts evenly according to the set ratio to obtain Core Sample B. Among them, the mass ratio of limestone, clay minerals, and sprayed rebound material is 50:40:10; the light calcination process is selected as the suspension kiln process, and the calcination temperature is 850°C; the calcium carbonate content of the limestone is 93%, the clay mineral is kaolin, and the sprayed rebound material is the concrete material collected after spraying, rebounding, and falling of wet-process sprayed concrete; the mass ratio of the ternary calcium calcined minerals to the inorganic coagulation-promoting calcium salt is 75:25; the inorganic coagulation-promoting calcium salt is calcium formate; (3)Preparation by physical coating process: Add Core Sample B to a suspension container, turn on the air flow or dispersion medium to fully disperse the material to form a stable dispersed fluidized bed bottom layer or air flow layer; introduce Shell A into the liquid phase pipeline, and complete the preparation of the calcium-based rebound inhibitor at a specific process temperature and running time; the physical coating process is the spray drying process, the process temperature is 105°C, and the running time is 3 h. The mass ratio of Shell A to Core Sample B is 1:20.

[0034] Example Ⅰ-3 A calcium-based rebound inhibitor is prepared by the following steps: (1)Selection of Shell A: Select alkanolamine ester compounds as Shell A, preferably ester compounds of triethanolamine, and more preferably triethanolamine acetate; the relative molecular mass of the triethanolamine acetate is 275.3, and the hydrolysis temperature is 50°C; (2)Preparation of Core Sample B: Prepare ternary calcium calcined minerals by the light calcination process of raw material grinding, high-temperature calcination, cooling, and clinker grinding of limestone, clay minerals, and sprayed rebound material according to the set material ratio, calcination method, and calcination temperature, and mix the ternary calcium calcined minerals and inorganic coagulation-promoting calcium salts evenly according to the set ratio to obtain Core Sample B. Among them, the mass ratio of limestone, clay minerals, and sprayed rebound material is 40:30:30; the light calcination process is selected as the suspension kiln process, and the calcination temperature is 950°C; the calcium carbonate content of the limestone is 95%, the clay mineral is illite, and the sprayed rebound material is the concrete material collected after spraying, rebounding, and falling of wet-process sprayed concrete; the mass ratio of the ternary calcium calcined minerals to the inorganic coagulation-promoting calcium salt is 75:25; the inorganic coagulation-promoting calcium salt is calcium formate; (3) Preparation by physical coating process: Add core sample B into the suspension container, turn on the air flow or dispersion medium to fully disperse the materials, and form a stable dispersed fluidized bed bottom layer or air flow layer; Introduce shell A into the liquid phase pipeline, and complete the preparation of the calcium-based rebound inhibitor at a specific process temperature and running time; The physical coating process is a spray drying process, the process temperature is 90 °C, and the running time is 2 h. The mass ratio of shell A to core sample B is 1:15.

[0035] Example I-4 / 5: A calcium-based rebound inhibitor, the same as above, with the type and ratio of inorganic coagulant calcium salts changed.

[0036] Example I-4 A calcium-based rebound inhibitor The materials and preparation steps of this example are the same as those of Example I-1, except that the mass ratio of ternary calcium calcined minerals to inorganic coagulant calcium salts is 95:5, and the inorganic coagulant calcium salt is calcium nitrate.

[0037] Example I-5 A calcium-based rebound inhibitor The materials and preparation steps of this example are the same as those of Example I-1, except that the mass ratio of ternary calcium calcined minerals to inorganic coagulant calcium salts is 80:20, and the inorganic coagulant calcium salt is calcium sulfoaluminate.

[0038] Comparative Example I-1 A calcium-containing rebound inhibitor The materials and ratios used in this example are the same as those in Example I, but each component is simply compounded, and the structure of the shell-core sample is protected. Specifically: The materials and preparation steps of shell A and core sample B are the same as those of Example I-3, but the physical coating process is not used, and only mixing is carried out evenly.

[0039] Comparative Example I-2 A calcium-based rebound inhibitor This example adopts the structure of shell-core sample, the shell is ethyl acetate, and the core sample material and ratio remain unchanged, protecting the alkano-lamine ester compounds and the difficulty of alkaline hydrolysis.

[0040] Specifically: The materials, preparation and physical coating process of core sample B are the same as those of Example I-3, but shell A is selected as ethyl acetate, and the relative molecular mass of ethyl acetate is 88.11, and the hydrolysis temperature is 65 °C.

[0041] Comparative Example I-3 A calcium-based rebound inhibitor This example adopts the structure of shell-core sample, the core sample is pure limestone calcined, and other materials and ratios are the same as those in Example I, protecting the ternary calcium calcined mineral components.

[0042] Specifically: The materials, preparation, and physical coating process of the shell A are the same as those in Example I-3, but the core sample B is composed of lightly burned limestone and inorganic coagulation-promoting calcium salts, and the composition ratio and types of inorganic coagulation-promoting calcium salts are the same as those in Example I-3.

[0043] Comparative Example I-4 A calcium-based rebound inhibitor This example adopts a shell-core sample structure, and the core sample is calcined from the sprayed rebound material. The other materials and ratios are the same as those in Example I, and it protects the method for activating the gelling activity of the sprayed rebound material.

[0044] Specifically: The materials, preparation, and physical coating process of the shell A are the same as those in Example I-3, but the core sample B is composed of lightly burned sprayed rebound material and inorganic coagulation-promoting calcium salts, and the composition ratio, types of inorganic coagulation-promoting calcium salts, and sprayed rebound material are the same as those in Example I-3.

[0045] Comparative Example I-5 A calcium-based rebound inhibitor This example has no inorganic coagulation-promoting calcium salts, and the other materials and ratios are the same as those in Example I, protecting the synergistic coagulation-promoting effect of the inorganic coagulation-promoting calcium salts.

[0046] Specifically: The materials, preparation, and physical coating process of the shell A are the same as those in Example I-3, but the core sample B is 100% ternary calcium-based calcined minerals, and the material types and ratios are the same as those in Example I-3.

[0047] Example II-1 / 2: A liquid calcium-based rebound inhibitor, the end-point values of the proportion of water.

[0048] Example II-1 A liquid calcium-based rebound inhibitor is prepared by the following steps: (1) Preparation of the calcium-based rebound inhibitor: The same as in Example I-1; (2) Mix the calcium-based rebound inhibitor and water thoroughly according to a set ratio, and the set ratio is water:calcium-based rebound inhibitor = 40:60.

[0049] Example II-2 A liquid calcium-based rebound inhibitor is prepared by the following steps: (1) Preparation of the calcium-based rebound inhibitor: The same as in Example I-1; (2) Mix the calcium-based rebound inhibitor and water thoroughly according to a set ratio, and the set ratio is water:calcium-based rebound inhibitor = 60:40.

[0050] Comparative Example II-1 For the liquid calcium-based rebound inhibitor in this example, the proportion of water exceeds the range.

[0051] (1) Preparation of the calcium-based rebound inhibitor: The same as in Example I-1; (2) Mix the calcium rebound inhibitor and water thoroughly in a set ratio, where the set ratio is water:calcium rebound inhibitor = 80:20.

[0052] Example III-1 / 2: A rebound inhibition composition with different proportion endpoints of auxiliary rebound reduction components.

[0053] Example III-1 A rebound inhibition composition for shotcrete is prepared by the following steps: (1) Preparation of the calcium rebound inhibitor: The same as in Example I-1; (2) According to the material ratio setting, first add water, start heating, and after the temperature rises to 45°C, add the auxiliary rebound reduction components while stirring within 30 - 60 minutes. The stirring rate is 500 r / min, and the total stirring time is 1 h; the ratio of water to the calcium rebound inhibitor is the same as in Example II-1; the mass ratio of the auxiliary rebound reduction components to the liquid calcium rebound inhibitor is 5:95; the auxiliary rebound reduction components are selected from mineral admixtures and rheological modification components. The mineral admixture is selected from fly ash; the rheological modification components are selected from two types of organic thickeners, amide organic compounds and redispersible latex powder, preferably polyacrylamide and ethylene-vinyl acetate copolymer latex powder; (3) Start cooling. After the temperature drops to 30°C, add the calcium rebound inhibitor and keep stirring for 1.5 h to obtain the rebound inhibition composition for shotcrete, with a stirring rate of 300 r / min.

[0054] Example III-2 A rebound inhibition composition for shotcrete is prepared by the following steps: (1) Preparation of the calcium rebound inhibitor: The same as in Example I-1; (2) According to the material ratio setting, first add water, start heating, and after the temperature rises to 60°C, add the auxiliary rebound reduction components while stirring within 30 - 60 minutes. The stirring rate is 1000 r / min, and the total stirring time is 1.5 h; the ratio of water to the calcium rebound inhibitor is the same as in Example II-1; the mass ratio of the auxiliary rebound reduction components to the liquid calcium rebound inhibitor is 15:85; the auxiliary rebound reduction components are selected from mineral admixtures and rheological modification components. The mineral admixture is selected from silica fume; the rheological modification components are selected from two types of organic thickeners and redispersible latex powder. The organic thickener is selected from methyl cellulose ether, and the redispersible latex powder is selected from vinyl propionate polymer latex powder; (3) Start cooling. After the temperature drops to 30°C, add the calcium rebound inhibitor and keep stirring for 1.5 h to obtain the rebound inhibition composition for shotcrete, with a stirring rate of 500 r / min.

[0055] Example III-3 A rebound suppression composition for shotcrete For the rebound suppression composition of this example, there is no rheological modification component in the auxiliary rebound reduction component.

[0056] Specifically: The material ratio, type and preparation sequence are the same as those in Example III-1. The auxiliary rebound reduction component is selected from mineral admixtures, and the type of the mineral admixture is the same as that in Example III-1.

[0057] Examples III-4 / 5: A rebound suppression composition, and the rheological modification component is only an organic thickener or a redispersible latex powder.

[0058] Example III-4 A rebound suppression composition for shotcrete For the materials of this example, the ratio, type and preparation sequence are the same as those in Example III-1. The rheological modification component in the auxiliary rebound reduction component is selected from one kind of organic thickener, and the type of the organic thickener is the same as that in Example III-1.

[0059] Example III-5 A rebound suppression composition for shotcrete For the materials of this example, the ratio, type and preparation sequence are the same as those in Example III-1. The rheological modification component in the auxiliary rebound reduction component is selected from one kind of redispersible latex powder, and the type of the redispersible latex powder is the same as that in Example III-1.

[0060] Comparative Example III-1 A rebound suppression composition for shotcrete The rebound suppression composition of this example is prepared by simply compounding a calcium-based rebound inhibitor and an auxiliary rebound reduction component.

[0061] Specifically: The material ratio and type are the same as those in Example III-1, but the calcium-based rebound inhibitor and the auxiliary rebound reduction component are simply mixed evenly by a physical method.

[0062] Comparative Example III-2 A rebound suppression composition for shotcrete For the rebound suppression composition of this example, the proportion of the auxiliary rebound reduction component exceeds the ratio.

[0063] Specifically: The material type and preparation method are the same as those in Example III-1, but the ratio of the auxiliary rebound reduction component to the calcium-based rebound inhibitor is 20:80.

[0064] Test Example 1 Performance test of cement paste or mortar Replace 5% of cement with a fixed calcium rebound inhibitor or a rebound inhibition composition, select 7% of a liquid alkali-free accelerating admixture, and respectively test the setting time of the accelerating admixture paste with or without the calcium rebound inhibitor or the rebound inhibition composition and the stability of the calcium rebound inhibitor or the rebound inhibition composition with reference to GB35159-2017 <Accelerating Admixture for Shotcrete>; test the total alkali content of the calcium rebound inhibitor or the rebound inhibition composition with reference to GB / T8077-2012 <Test Methods for Homogeneity of Concrete Admixtures>; test the restricted expansion rate and specific surface area of the calcium rebound inhibitor or the rebound inhibition composition with reference to GB / T 23439-2017 Concrete Expansive Agent. The corresponding results are shown in Table 1.

[0065] Table 1 Test Results of Cement Paste or Mortar Properties in Examples and Comparative Examples

[0066] From the basic physical properties of the calcium rebound inhibitor or the rebound inhibition composition for shotcrete described in Table 1, it can be seen that the specific surface area of the calcium rebound inhibitor or the rebound inhibition composition for shotcrete of the present invention is in the range of 150-300 m 2 / kg, the total alkali content is less than 1%, the liquid form meets the requirement that the stability is greater than 28 days, it is green and environmentally friendly, and has good homogeneity. Comparing Example I-3, the product obtained by simply physically mixing the ternary calcined calcium mineral, alkanolamine ester compound and inorganic coagulation-promoting calcium salt in Comparative Example I-1 has a smaller specific surface area and coarser particles, indicating that the calcium rebound inhibitor product with more uniform and finer particles can be obtained by physical coating treatment, which is beneficial to its dispersion and dissolution; in Comparative Example 1-3 and Comparative Example I-4, core sample B was obtained by calcining pure limestone and pure shotcrete rebound material respectively, and the specific surface area of the obtained calcium rebound inhibitor particles is between 120-175 m 2 / kg, indicating that the fineness range of the calcium-based rebound inhibitor prepared from a single calcined mineral system is relatively narrow and the particles are relatively coarse. Comparing Example II-1 with Example II-2, in Comparative Example II-1, a liquid calcium-based rebound inhibitor prepared with more than 60% water showed a layering problem at room temperature after 5 days, indicating that for a liquid calcium-based rebound inhibitor prepared from a calcium-based rebound inhibitor and water, excessive water consumption will lead to a decrease in its stability, which is not conducive to its actual use and metering by extraction. Comparing Example III-1, in Comparative Example III-1, a rebound inhibition composition was prepared by simply mixing and compounding a liquid calcium-based rebound inhibitor and an auxiliary rebound reduction component, and precipitation occurred after 3 days, and the precipitate was mainly the auxiliary rebound reduction component, indicating that the preparation method of the rebound inhibition composition described in the present invention promoted the mutual dispersion and dissolution of the liquid calcium-based rebound inhibitor and the auxiliary rebound reduction component, forming a better physical stable structure and improving its room temperature stability. Comparing Example III-1, in Comparative Example III-2, the rebound inhibition composition obtained with 20% of the auxiliary rebound reduction component also had a room temperature precipitation problem, and the precipitate was also mainly the rheological modification component in the auxiliary rebound reduction component, indicating that the proportion of the auxiliary rebound reduction component in the rebound inhibition composition should not exceed 20%, and the range of 5-15% given in the present invention is more appropriate.

[0067] From the results of the setting time of the neat paste with non-alkali accelerating agent in Table 1, it can be seen that the calcium-based rebound inhibitor or rebound inhibition composition described in the present invention significantly shortens the setting time of the accelerating paste, and the restricted expansion rate at 7-day water curing is greater than 0.050%. This is because the ternary calcium-based calcined minerals and inorganic accelerating calcium salts in the calcium-based rebound inhibitor act together with the non-alkali accelerating agent and cement during the release process, providing abundant calcium ions for the hydration liquid phase, promoting the rapid formation of hydration products such as ettringite skeleton and early hydration calcium silicate, thus shortening the setting time, reducing the tendency of early drying shrinkage, and having a tendency of slight expansion. Comparing with Example I-3, the product prepared by simply physically mixing the ternary calcium-based calcined minerals, alkanolamine ester compounds and inorganic accelerating calcium salts in Comparative Example I-1, the alkanolamine ester compounds are difficult to hydrolyze under the action of acidic non-alkali accelerating agent, and affect the early formation of hydration products such as ettringite and hydration calcium silicate by complexing calcium ions in the hydration liquid phase. Therefore, the effect of shortening the setting time of the system is significantly weakened; in Comparative Example I-2, non-alkanolamine ester compounds are used, and ethyl acetate is used as the shell, and the ethanol or acetic acid monomers released by the alkaline hydrolysis of cement have a strong delaying effect on cement hydration. Therefore, it also affects the effect of the calcium-based rebound inhibitor in shortening the setting time; the products prepared with pure limestone and shotcrete rebound materials as core sample B in Comparative Example I-3 and Comparative Example I-4 also have a decrease in the effect of shortening the setting time, indicating that it is difficult to play a strong role in shortening the setting time with the calcined product calcium oxide as the core sample, and simply calcining the shotcrete rebound material cannot activate its internal gelling properties; Comparative Example I-5 lacks inorganic accelerating calcium salts, and only the ternary calcium-based calcined product cannot provide sufficient calcium salt ions in the early stage of hydration. Therefore, it also affects its effect of shortening the setting time. Comparing with Example II-1, the liquid calcium-based rebound inhibitor prepared with more than 60% proportion of water in Comparative Example II-1 weakens the concentration of the effective calcium-based rebound inhibitor, so it affects its effect of shortening the setting time. Comparing with Example III-1, the rebound inhibition composition prepared by simply compounding and mixing the liquid calcium-based rebound inhibitor and the auxiliary rebound reduction component in Comparative Example III-1, the rheological modification component plays a delaying hydration role when participating in hydration, while the rebound inhibition composition obtained with 20% proportion of the auxiliary rebound reduction component in Comparative Example III-2 also introduces too many rheological modification components, and both of them prolong the final setting time of the neat paste with non-alkali accelerating agent.

[0068] Test Example 2 To test the performance of shotcrete, the benchmark shotcrete mix ratio is set as follows: 450kg cement + 890kg 5-10mm melon stone + 950kg medium river sand + 185kg water per cubic meter. The concrete preparation method is as follows: according to the wet shotcrete construction method, add the calcium rebound inhibitor or the rebound inhibition composition to the shotcrete mixture and fully disperse it, and the amount of the addition accounts for 5-20% of the total mass of the cementitious material; at the mixing station, the concrete except the accelerator is fully stirred and transported to the spraying site, and the liquid alkali-free accelerator is pre-pumped into the accelerator ton barrel storage tank in the wet spraying machine. According to the instrument parameters of the wet spraying machine, the accelerator dosage is set to 7%, and the hourly concrete displacement is selected to be 15-30m 3 The mechanical arm sprayer is used. After the wind pressure is turned on and the sprayed material is stabilized, it is sprayed into a large plate test mold with a specification of 500mm×450 mm×200mm. The test mold is placed in the corner of the wall and forms an angle of 60°~75° with the ground. The spraying distance is maintained at 1.2~1.5 m to avoid excessive friction and impact between the sprayed material and the test mold, resulting in loss of rebound rate. The spray gun is at a vertical angle to the forming surface. After the spraying is completed, the concrete specimen is cured with the mold for 24 hours and then cut into the corresponding test specimen using a rock cutter.

[0069] The influence of calcium rebound inhibitor or rebound inhibition composition on the initial slump and 3h slump loss of shotcrete was tested with reference to GB / T 50080-2016 <Test method for performance of ordinary concrete mixture>; the initial plastic viscosity of the above concrete was tested with Anton Paar concrete rotation viscometer; the 1d / 7d / 28d compressive strength of concrete was tested with reference to GB / T 50081-2019 <Test method for physical and mechanical properties of concrete>; the drying shrinkage deformation, electric flux, and early crack resistance of the above shotcrete were tested with reference to GB / T 50082-2009 <Test method for long-term performance and durability of ordinary concrete>; the inclined shaft of a tunnel with Class IV surrounding rock was selected, the over-excavation depth was 30cm, and the single shot volume was 60 cubic meters. The corresponding shotcrete spraying construction performance (average rebound rate, one-shot thickness, and bonding strength with surrounding rock) was tested. The performance results of shotcrete are summarized in Tables 2 and 3.

[0070] Table 2 Working and mechanical properties test results of shotcrete of embodiment and comparative example

[0071] Note: Except for Example I-1, the dosage of other examples and comparative examples is fixed at 10% of the cementitious material.

[0072] From the test results of the working and mechanical properties of shotcrete in the examples and comparative examples in Table 2, it can be seen that the results of Examples I-1 to I-5 show that the calcium-based rebound inhibitor described in the present invention has little effect on the working performance of shotcrete, but significantly improves the early and late mechanical strengths of shotcrete. The 7-day compressive strength ratio is greater than 135%, and the 28-day compressive strength ratio is greater than 120%. The improvement effect is proportional to its dosage (5-20%); the results of Examples II-1 to II-2 show that after being incorporated in the form of a liquid calcium-based rebound inhibitor with better dispersion effect, the workability of shotcrete is better improved, and it does not affect its improvement effect on the early and late mechanical strengths, and it is applicable to the application scenarios using liquid product metering; the results of Examples III-1 to III-5 show that the rebound inhibition composition prepared from a liquid calcium-based rebound inhibitor and an auxiliary rebound reduction component also has little effect on the workability of shotcrete and improves the early and late strengths, and at the same time improves the cohesiveness of the mixture (the viscosity value increases), which indicates that the rheological modification component and the calcium-based rebound inhibitor have good functional complementarity.

[0073] Comparing with Example I-3, the product prepared by simply physically mixing the ternary calcium calcined mineral, the alkanolamine ester compound and the inorganic coagulant calcium salt in Comparative Example I-1, because the ternary calcium calcined mineral and the inorganic coagulant calcium salt gradually exhibit high hydration activity characteristics when added to the shotcrete mixture, resulting in a large loss of slump workability, significantly increasing the transportation difficulty of the mixture, and the viscosity of the mixture also increases significantly, which also affects its improvement effect on the late mechanical strength; in Comparative Example I-2, a non-alkanolamine ester compound, ethyl acetate as the shell, is incorporated, and the slump workability is lost 3 hours after being incorporated into the shotcrete, and the ethanol or acetic acid monomers released by the alkaline hydrolysis of ethyl acetate in cement have a strong delaying effect on the early hydration of cement, so the 1-day strength of the shotcrete decreases, and the improvement amplitude of the late strength also decreases compared with Comparative Example I-1; in Comparative Examples I-3 and I-4, the products prepared with pure limestone and shotcrete rebound materials as core samples B respectively, the hydration activity of the calcined product calcium oxide as the core sample is not as good as that of the ternary calcium calcined product, and simply calcining the shotcrete rebound materials cannot activate the partially hydrated gel characteristics inside, so the improvement amplitude of the early and late mechanical strengths of the shotcrete is not high; in Comparative Example I-5, the inorganic coagulant calcium salt is lacking, resulting in a lower improvement amplitude of the 1-day strength of the shotcrete than the combined effect of the ternary calcium calcined mineral and the inorganic coagulant calcium salt.

[0074] Comparative Example II-1: The liquid calcium-based rebound inhibitor prepared with more than 60% water in Comparative Example II-1 weakens the concentration of the effective calcium-based rebound inhibitor, thus affecting its enhancement effect on the early and late strengths of shotcrete. Comparative Example III-1: The rebound inhibition composition prepared by simply compounding and mixing the liquid calcium-based rebound inhibitor and the auxiliary rebound-reducing component in Comparative Example III-1 causes the rheological modification component to play the roles of viscosity increase and early hydration delay prematurely during hydration, thus excessively increasing the cohesiveness of shotcrete, which is not conducive to its spraying, and having a strong negative effect on the 1-day strength. While in Comparative Example III-2, the rebound inhibition composition obtained with 20% of the auxiliary rebound-reducing component also introduces too many rheological modification components. Both of them affect their enhancement effects on the early and late strengths of shotcrete.

[0075] Table 3 Test Results of Durability Performance and Spraying Construction Performance of Shotcrete in Examples and Comparative Examples

[0076] Note: Except for Example I-1, the dosages of the remaining examples and comparative examples are fixed at 10% of the cementitious materials.

[0077] From the test results of the durability and spraying construction performance of the shotcrete in Examples and Comparative Examples in Table 3, it can be seen that the results of Examples I-1 to I-5 show that the incorporation of the calcium-based rebound inhibitor described in the present invention significantly reduces the early drying shrinkage tendency of the shotcrete. The dry shrinkage strain value of the shotcrete at 7 days is less than 150 με. By optimizing the early and late hydration processes and refining the hardened pore structure through the material structure characteristics of the shell A-core sample B, the number of cracks and the electric flux value of the shotcrete are significantly reduced, significantly improving the early crack resistance and service durability of the shotcrete. The electric flux at 56 days is less than 1000 C, and the number of cracking cracks is reduced by more than 60% year-on-year. At the same time, the incorporation of the calcium-based rebound inhibitor described in the present invention significantly improves the spraying quality of the shotcrete. The average spraying rebound rate is less than 10%, the bonding strength with the surrounding rock is greater than 1.0 MPa, and the one-time spraying thickness can reach more than 100 mm. The improvement effect on the durability and spraying construction performance of the shotcrete is also proportional to its dosage (5-20%). The results of Examples II-1 to II-2 show that the incorporation in the form of a liquid calcium-based rebound inhibitor with better dispersion effect is more conducive to improving the spraying quality of the shotcrete and does not affect its improvement effect on the crack resistance and service durability. The results of Examples III-1 to III-5 show that the rebound inhibition composition prepared from the liquid calcium-based rebound inhibitor and the auxiliary rebound reduction component can further improve the spraying quality of the shotcrete by optimizing the early and late hydration processes, refining the hardened pores, and improving the cohesiveness of the shotcrete mixture. The average spraying rebound rate can be controlled within 5%, the bonding strength with the surrounding rock is greater than 1.2 MPa, and the one-time spraying thickness can reach more than 140 mm, greatly reducing the time-consuming of the primary support construction process and the material cost loss.

[0078] Comparative Example I-3, the product prepared by the Comparative Example I-1 by simply physically mixing the ternary calcareous calcined mineral, the alkanolamine ester compound and the inorganic coagulant calcium salt. Since the ternary calcareous calcined mineral and the inorganic coagulant calcium salt prematurely exhibit their high hydration activity characteristics, the reduction of the spray rebound rate, the improvement of the early anti-cracking performance and the improvement of the service durability are not obvious. At the same time, the bonding effect with the surrounding rock is affected. The thickness of the first spray is less than 100 mm, only 89 mm, and the bonding strength with the surrounding rock is only 0.88 MPa; the Comparative Example I-2 uses a non-alkanolamine ester compound, ethyl acetate as the shell, and the retarding hydration effect of ethanol or acetic acid monomers released by the alkaline hydrolysis of ethyl acetate in cement affects the hydration activity of the ternary calcareous calcined mineral and the rapid setting and hardening characteristics of the alkali-free accelerator, thereby affecting the improvement of its early anti-cracking ability of the sprayed concrete, and affecting the reduction of the spray rebound rate and the bonding effect with the surrounding rock, and the bonding strength with the surrounding rock is 0.92 MPa; the products prepared by the Comparative Example I-3 or I-4 using pure limestone and spray rebound material as the core sample B respectively. The early and late hydration activities of the core sample using the calcined product calcium oxide are not as good as those of the ternary calcareous calcined product, resulting in a decline in the improvement effect of its service durability, and the reduction of the spray rebound rate of the sprayed concrete is not obvious. And simply calcining the spray rebound material cannot activate the partially hydrated gel characteristics inside it, and the effect of refining pores is poor. The spray rebound rate is close to the reference group, reaching 18.8%, and the electric flux and the number of cracking cracks of the concrete do not decrease significantly. Therefore, using a single limestone or spray rebound material cannot achieve the effect of ternary composite calcination, affecting its improvement effect in the setting and hardening of sprayed concrete, spray quality, early anti-cracking performance and service durability; the Comparative Example I-5 lacks the inorganic coagulant calcium salt, so it affects the improvement effect of its spray quality, especially the reduction of the spray rebound rate of the sprayed concrete and the increase of the thickness of the first spray.

[0079] Comparative Example II-1, the liquid calcium rebound inhibitor prepared by the Comparative Example II-1 using more than 60% water weakens the concentration of the effective calcium rebound inhibitor, so it affects its reduction effect on the early anti-cracking performance and spray rebound rate of the sprayed concrete. Comparative Example III-1, the rebound inhibition composition prepared by the Comparative Example III-1 by simply compounding and mixing the liquid calcium rebound inhibitor and the auxiliary rebound reduction component. When participating in hydration, the rheological modification component prematurely exhibits the thickening and retarding early hydration effects, so the cohesiveness of the sprayed concrete is excessively increased, resulting in a small decline in its spray rebound rate, and affecting the improvement of its early anti-cracking performance and the improvement of its bonding strength with the surrounding rock; while the Comparative Example III-2 uses the rebound inhibition composition obtained with 20% of the auxiliary rebound reduction component, which also introduces too many rheological modification components, both of which affect the improvement of its early anti-cracking performance of the sprayed concrete and its bonding strength with the surrounding rock.

[0080] Although the present invention has been described in detail above with general descriptions, specific embodiments and experiments, modifications or improvements can be made to it based on the present invention, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. A calcium rebound inhibitor for shotcrete, characterized in that: It consists of a shell A and a core sample B, wherein the shell A is coated on the surface of the core sample B, and the mass ratio of the shell A to the core sample B is 1: 10-20; The shell A is an alkanolamine ester compound, the relative molecular mass of the alkanolamine ester compound is less than 1000, and the hydrolysis temperature is 20-80°C; The core sample B is composed of a ternary calcine calcined mineral and an inorganic coagulant calcium salt, and the mass ratio of the ternary calcine calcined mineral to the inorganic coagulant calcium salt is (95-75):(5-25); the ternary calcine calcined mineral is prepared by a light-burning process of limestone, clay mineral and shot-rebound material, and the mass ratio of the limestone, clay mineral and shot-rebound material is (30-50):(20-40):(10-50), and the temperature of the light-burning process is 850-1200°C.

2. The calcium rebound inhibitor for shotcrete according to claim 1, characterized in that: The alkanolamine ester compound is an ester compound of diethanolamine or an ester compound of triethanolamine, selected from triethanolamine acrylate, triethanolamine stearate, triethanolamine propionate, triethanolamine methylpropionate, triethanolamine acetate, triethanolamine oleate, diethanolamine acetate or diethanolamine oleate.

3. The calcium rebound inhibitor for shotcrete according to claim 1, characterized in that: The light firing process is selected from a vertical kiln process, a suspension kiln process or a rotary kiln process.

4. The calcium rebound inhibitor for shotcrete according to claim 1, characterized in that: The calcium carbonate content of the limestone is greater than 90%; the clay mineral is selected from kaolin, bentonite, montmorillonite, illite or chlorite; the shotcrete rebound material is a concrete material obtained by spraying, rebounding, and collecting dry shotcrete, tidal shotcrete or wet shotcrete.

5. The calcium rebound inhibitor for shotcrete according to claim 1, characterized in that: The inorganic coagulant-accelerating calcium salt is selected from calcium sulfoaluminate, calcium hydroxide, calcium formate, calcium nitrate or calcium sulfate.

6. The method for preparing the calcium rebound inhibitor for shotcrete according to any one of claims 1 to 5, characterized in that: The physical coating process includes the following steps: The ternary calcium calcined mineral and inorganic coagulant calcium salt are added to a suspension container, and the air flow or dispersion medium is turned on to fully disperse the materials to form a stable dispersed fluidized bed bottom layer or air flow layer; the alkanolamine ester compound is introduced into the liquid phase pipeline to complete the preparation under specific process temperature and operation time.

7. A liquid calcium rebound inhibitor for shotcrete, characterized in that: It is composed of the calcium rebound inhibitor for shotcrete according to any one of claims 1 to 5 and water, the amount of water is 40-60% of the total mass of the liquid calcium rebound inhibitor for shotcrete, and the amount of the calcium rebound inhibitor for shotcrete is not less than 40% of the total mass of the liquid calcium rebound inhibitor for shotcrete.

8. A rebound suppression composition for shotcrete, characterized in that: The liquid calcium rebound inhibitor for shotcrete and the auxiliary rebound reducing component according to claim 7 are included, wherein the mass ratio of the liquid calcium rebound inhibitor for shotcrete to the auxiliary rebound reducing component is (85-95): (5-15); The auxiliary rebound reducing component is selected from mineral admixtures and / or rheology modifying components; The mineral admixture is selected from fly ash, slag powder, silica fume, steel slag powder or metakaolin; The rheology-modifying component is selected from an organic thickener and / or a redispersible latex powder, wherein the organic thickener is selected from an amide organic matter, methyl cellulose ether, hydroxyethyl cellulose ether, hydroxypropyl cellulose ether, maltodextrin, xanthan gum or gellan gum; the amide organic matter is selected from polyacrylamide, N-hydroxymethyl acrylamide, dimethylformamide or cyclopropamide; the redispersible latex powder is selected from vinyl propionate polymer latex powder, pure acrylic acid copolymer latex powder, styrene-acrylate copolymer latex powder, vinyl acetate-versatate vinyl copolymer latex powder, vinyl acetate-ethylene copolymer latex powder or vinyl acetate-vinyl chloride-acrylate copolymer latex powder.

9. The method for preparing the rebound suppression composition for shotcrete according to claim 8, characterized in that: The steps include: (1) Preparation of calcium rebound inhibitor; (2) Add water according to the material ratio, turn on the heating and wait until the temperature rises to 45-60°C, add the auxiliary rebound reducing component while stirring for 30-60 minutes, the stirring rate is 500-1000r / min, and the total stirring time is 1-1.5h; (3) Start cooling, add the calcium rebound inhibitor after the temperature drops to 30°C, keep stirring for 1.5-3.0 hours to obtain the rebound inhibiting composition for shotcrete, and stir at a rate of 300-500 r / min.

10. A shotcrete, characterized in that: The invention comprises a cementitious material and an admixture, wherein the admixture is the calcium rebound inhibitor for shotcrete according to any one of claims 1 to 5, the liquid calcium rebound inhibitor for shotcrete according to claim 7, or the rebound suppression composition for shotcrete according to claim 8.

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