A tunnel engineering shotcrete rebound reducing agent and preparation method thereof

Abstract

This invention provides a rebound reducer for shotcrete used in tunnel engineering and its preparation method. The raw materials of the rebound reducer for shotcrete used in tunnel engineering of this invention have the following mass fractions: 10-15% thickening component, 10-15% nano-active mineral component, 5-10% reinforcing component, 1-2% suspension stabilizing component, 2-3% water-retaining component, 2-3% workability adjusting component, and the remainder being water. The rebound reducer for shotcrete used in tunnel engineering is used at 3-5% of the cementitious material. This rebound reducer can effectively reduce the rebound rate of shotcrete, making it less than 15%, and can significantly improve the compactness of concrete, while enhancing its cohesiveness and fluidity, meeting the construction requirements of shotcrete in tunnel engineering, and maintaining the workability and durability of concrete.

Description

Technical Field

[0001] The invention belongs to the field of auxiliary agents for building materials, and specifically relates to a rebound reducing agent for shotcrete in tunnel engineering and a preparation method thereof. Background Art

[0002] At present, China is the country with the largest number of tunnels and underground projects in the world, the largest scale, the most complex structural forms and geological conditions, and the fastest development of construction technology. However, there are many problems in the operation of tunnels, among which tunnel cracking and water leakage are the most serious hazards to the project, and the quality of shotcrete construction is the key to its prevention.

[0003] As the bearing structure and waterproof structure of the railway tunnel, the design of the shotcrete structure of the tunnel project must meet the requirements of mechanical properties and density. During the construction of shotcrete in the tunnel project, it is generally adopted to pour the concrete in layers on both sides, horizontally symmetrically and fully vibrate to ensure the integrity of the structure. However, since the secondary lining is a thin-walled structure, the reinforcement is very dense when the surrounding rock is poor, and the construction space is limited, it is easy to over-vibrate or miss vibration in some parts, which has an adverse effect on the strength and density of the local concrete. In particular, improper vibration at the location of the tunnel arch waist and arch top can easily cause longitudinal tension cracks under the greater surrounding rock pressure, causing tunnel leakage and endangering the safety of the structure.

[0004] To solve this problem, vibration-free concrete can be designed and applied to the secondary lining of the tunnel. It can be cast and formed in one time during construction, which can not only improve the density and durability of the tunnel concrete, but also save vibration equipment, energy and personnel, shorten the pouring time and speed up the construction progress. Vibration-free concrete has good fluidity, anti-segregation and filling properties, and has high requirements for raw materials, especially the quality of coarse and fine aggregates. When preparing vibration-free concrete, hard, clean, and well-graded zone II river sand should be used as fine aggregate; coarse aggregate should be continuous graded stone with a maximum particle size of no more than 20mm, and needle-like particles should not exceed 8%. In actual production, it is difficult to obtain high-quality coarse and fine aggregates that fully meet the requirements, and it is difficult to prepare concrete that meets the vibration-free requirements by optimizing the mix ratio alone. In addition, the water-cement ratio of medium and low-grade vibration-free concrete is large, the amount of cementitious materials used is large, and the shrinkage is large, which is not conducive to the crack resistance and leakage prevention of tunnel shotcrete.

[0005] Therefore, it is necessary to develop a rebound reducing agent for shotcrete in tunnel engineering. The rebound adjusting agent can effectively reduce the shrinkage of concrete and significantly improve the strength and density of concrete; at the same time, it can enhance the cohesion and fluidity of concrete, meet the construction requirements of shotcrete in tunnel engineering, and maintain the construction performance and durability of concrete. The invention of the rebound adjusting agent is of great significance to improving the working environment of shotcrete in tunnel engineering, solving the construction problems of the secondary lining structure, and improving the anti-cracking and anti-leakage capabilities of the structure.

[0006] Chinese patent CN 108863148 A discloses a viscosity modifier for self-compacting concrete. The modifier described in the patent can increase the cohesiveness of the concrete paste without affecting the fluidity of the concrete, and prevent the segregation and bleeding of the self-compacting concrete. However, the modifier described in the patent cannot solve the shrinkage of the vibration-free concrete during the hardening process, and cannot play a role in inhibiting shrinkage cracking. Summary of the invention

[0007] The purpose of the present invention is to provide a tunnel engineering shotcrete rebound reducing agent in view of the problems existing in the prior art. While meeting the fluidity and filling requirements of the tunnel engineering shotcrete, the agent increases its cohesiveness and water retention, so that its shotcrete rebound rate is less than 15%, which can effectively reduce the rebound rate of the shotcrete and significantly improve the compactness of the concrete, meet the construction requirements of the tunnel engineering shotcrete, and maintain the construction performance and durability of the concrete.

[0008] The technical solution of the present invention:

[0009] A tunnel engineering shotcrete rebound reducing agent, the concrete rebound reducing agent comprising the following components in percentage by mass:

[0010] 10-15% viscosity increasing component;

[0011] Nano-active mineral components 10-15%;

[0012] Reinforcement component 5-10%;

[0013] Suspended stabilizing component 1-2%;

[0014] Water retention component 2-3%;

[0015] Workability adjustment component 2-3%;

[0016] The balance is water.

[0017] Preferably, the viscosity-increasing component comprises the following components in percentage by mass: 15-20% of a polyether macromonomer, 25-30% of an active small monomer, 0.5-1% of a catalyst, and 3-5% of an initiator.

[0018] Further preferably, the polyether macromonomer is methyl allyl alcohol polyoxyethylene ether, isopentanol polyoxyethylene ether, ethoxy vinyl polyethylene glycol ether or hydroxybutyl vinyl polyethylene glycol ether or a combination thereof, and the number average molecular weight thereof is 2400-4000.

[0019] Further preferably, the reactive small monomer is acrylic acid, methacrylic acid, acrylamide, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, fumaric acid or maleic anhydride or a combination thereof.

[0020] Further preferably, the catalyst is ferrous sulfate, ferrous chloride or cuprous chloride or a combination thereof.

[0021] Further preferably, the initiator is hydrogen peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, azobisisobutylamidine hydrochloride, azobisisobutylimidazoline hydrochloride or azobiscyanovaleric acid or a combination thereof.

[0022] Further preferably, the synthesis method of the viscosity-increasing component is:

[0023] 1) Add water to the reaction kettle, add the polyether macromonomer under stirring to make it completely dissolved, then add the active small monomer, stir evenly, add liquid alkali, adjust the pH value of the mixed solution to 7, and heat;

[0024] 2) Add the catalyst and start to drop the initiator solution into the reactor, increase the temperature, keep the temperature to continue the reaction, add the remaining water into the reactor, stir evenly, cool to room temperature, and obtain the viscosity-increasing component.

[0025] Further preferably, in step 1), heating to 45-55° C.;

[0026] In the step 2), the initiator solution is dripped in 1 hour; the temperature is raised to 75-85° C. and the temperature is kept to continue the reaction for 3-5 hours.

[0027] Preferably, the nano-active mineral component is water-soluble nano-silicon dioxide or nano-aluminum oxide or a combination thereof.

[0028] The reinforcing component is diethanolamine, triethanolamine, calcium formate or sodium thiocyanate or a combination thereof.

[0029] The suspension stabilizing component is SP80, TW80 or TW60 or a combination thereof.

[0030] The water-retaining component is cellulose ether, maltodextrin, Weinland gum, Brunei gum or xanthan gum or a combination thereof.

[0031] The workability adjusting component is sodium tripolyphosphate, sodium hexametaphosphate, sodium thiosulfate or sodium citrate or a combination thereof.

[0032] The method for preparing a tunnel engineering shotcrete rebound reducing agent comprises adding a nano-active mineral component, a reinforcing component, a suspension stabilizing component, a water retaining component and a workability adjusting component to a viscosity enhancing agent mother solution, and stirring for 25-35 minutes to obtain the tunnel engineering shotcrete rebound reducing agent.

[0033] The present invention has the following beneficial effects:

[0034] 1. The added viscosity-increasing component can improve the cohesiveness and water retention of concrete, improve the segregation and water seepage of shotcrete in tunnel engineering under large flow state during pumping construction, and to a certain extent avoid the high rebound rate of shotcrete caused by poor workability of concrete due to unreasonable sand and gravel grading.

[0035] 2. The added nano-active mineral components can play an active effect, improve the composition of cementitious materials in cement paste, optimize the microstructure of concrete, and at the same time play a micro-aggregate effect, improve the workability of concrete, make the particle grading more perfect, fill each other, reduce the void ratio, increase the packing density, help improve the workability of concrete, and prevent the occurrence of segregation and water seepage, further reducing the rebound rate of concrete spraying.

[0036] 3. The added reinforcing components can increase the compressive and flexural strength of concrete, and improve the mechanical properties and durability of shotcrete in tunnel engineering under large flow conditions during pumping construction.

[0037] 4. The added suspension stabilizing components can improve the uniformity of the liquid, allowing it to be evenly dispersed in the concrete, thereby improving the practicality of the product.

[0038] 5. The added water-retaining components can increase the plasticity of concrete, ensure that the concrete has good fluidity, and improve the workability retention performance of shotcrete in tunnel engineering.

[0039] 6. The added workability adjusting components can improve the workability and encapsulation of concrete, increase the density of concrete, and further reduce the rebound rate of shotcrete.

[0040] 7. The present invention can simplify the construction process, improve labor productivity, speed up the construction progress, improve the construction environment, reduce engineering costs and other technical benefits. DETAILED DESCRIPTION

[0041] The following will be combined with the specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] The synthesis method of the viscosity-increasing component used in Examples 1-7 is:

[0043] 1) Add water to a reaction kettle, add 17% ethoxy vinyl polyglycol ether under stirring to completely dissolve it, then add 18% acrylic acid and 8% maleic anhydride, stir evenly, add liquid alkali, adjust the pH value of the mixed solution to 7, and heat;

[0044] 2) Add 0.7% ferrous sulfate, and begin to drop 4% azobisisobutylamidine hydrochloride into the reactor, raise the temperature, keep the temperature to continue the reaction, add the remaining water into the reactor, stir evenly, and cool to room temperature to obtain a viscosity-increasing component.

[0045] Further preferably, in step 1), heating to 50° C.

[0046] In the step 2), the azobisisobutylamidine hydrochloride solution was dripped over 1 hour; the temperature was raised to 78° C. and the temperature was kept to continue the reaction for 4 hours.

[0047] Example 1

[0048] A tunnel engineering shotcrete rebound reducing agent is composed of 12% of viscosity increasing masterbatch, 12% of nanometer active silicon dioxide, 7% of triethanolamine, 1% of SP80, 2% of Brunei rubber, 2% of sodium tripolyphosphate and 64% of water in percentage by mass.

[0049] Example 2

[0050] A tunnel engineering shotcrete rebound reducing agent is composed of 15% viscosity increasing masterbatch, 10% nano alumina, 6% diethanolamine, 1.5% TW80, 2.5% maltodextrin, 2.5% sodium hexametaphosphate and 62.5% water in percentage by mass.

[0051] Example 3

[0052] A tunnel engineering shotcrete rebound reducing agent is composed of 10% viscosity increasing masterbatch, 13% nano alumina, 9% sodium thiocyanate, 2% TW60, 2.0% cellulose ether, 3% sodium thiosulfate and 61% water in percentage by mass.

[0053] Example 4

[0054] A tunnel engineering shotcrete rebound reducing agent is composed of 14% viscosity increasing masterbatch, 11% nano silicon dioxide, 5% calcium formate, 1.5% TW80, 2.0% Wenlun glue, 2.5% sodium hexametaphosphate and 64% water in percentage by mass.

[0055] Example 5

[0056] A tunnel engineering shotcrete rebound reducing agent is composed of 13% viscosity increasing masterbatch, 15% nano alumina, 10% diethanolamine, 1.5% SP80, 2.0% xanthan gum, 3% sodium tripolyphosphate and 55.5% water in percentage by mass.

[0057] Example 6

[0058] A tunnel engineering shotcrete rebound reducing agent is composed of 11% viscosity increasing masterbatch, 14% nano silicon dioxide, 8% sodium thiocyanate, 1.5% TW60, 3% maltodextrin, 2% sodium hexametaphosphate and 60.5% water in percentage by mass.

[0059] Example 7

[0060] A tunnel engineering shotcrete rebound reducing agent is composed of 13% viscosity increasing masterbatch, 13% nano silicon dioxide, 8% triethanolamine, 1.5% TW80, 3.0% maltodextrin, 2.5% sodium citrate and 59% water in percentage by mass.

[0061] The rebound reducing agent prepared in the above embodiment is used in shotcrete, and the concrete mix ratio is shown in the following table: Shotcrete mix ratio (kg / m 3 )

[0062] Table 1

[0063]

[0064] Table 2

[0065]

[0066]

[0067] It can be seen from Table 2 above that the rebound reducing agent of the present invention can meet various index requirements when added to shotcrete. The fluidity, slump retention and rebound rate of Examples 1-7 are greatly improved compared with the blank example, and the compressive strength of Examples 1-7 is greatly increased compared with the blank example.

[0068] Example 8

[0069] The catalyst in the viscosity-increasing component is ferrous chloride, and the rest is the same as in Example 1.

[0070] Comparative Example 1

[0071] The catalyst in the viscosity-increasing component is sulfuric acid, and the rest is the same as in Example 1.

[0072] Example 9

[0073] Based on Example 1, step 1) heating to 55° C., and the rest are the same as Example 1.

[0074] Comparative Example 2

[0075] Based on Example 1, step 1) heating to 40° C., and the rest are the same as Example 1.

[0076] Comparative Example 3

[0077] Based on Example 1, step 1) heating to 60° C., and the rest are the same as Example 1.

[0078] Example 10

[0079] Based on Example 1, step 2) the temperature was raised to 85° C. and the reaction was continued for 5 h. The rest was the same as in Example 1.

[0080] Comparative Example 4

[0081] Based on Example 1, step 2) the temperature was raised to 70° C. and the reaction was continued for 5 h. The rest was the same as in Example 1.

[0082] Comparative Example 5

[0083] Based on Example 1, step 2) the temperature was raised to 90° C. and the reaction was continued for 5 h. The rest was the same as Example 1.

[0084] Table 3

[0085]

[0086]

[0087] It can be seen from Example 1, Example 8 and Comparative Example 1 that changing the catalyst in the viscosity-increasing component has a great influence on the fluidity, collapse retention performance, concrete rebound rate, compressive strength, etc. of the concrete. The rebound rate of the concrete is greatly increased, the compressive strength is significantly reduced, and the comprehensive performance is far worse than that of Example 1 and Example 8. This may be because the catalytic efficiency of the added sulfuric acid catalyst in the system is low, and it cannot effectively catalyze the reaction to proceed completely. The conversion rate of the target product during the reaction is low, resulting in poor viscosity-increasing performance of the final product.

[0088] It can be seen from Example 1 and Example 9 and Comparative Examples 2-3 that changing the heating temperature of the solution has an impact on the fluidity, collapse protection performance, concrete rebound rate, compressive strength, etc. of the concrete. This may be because when the heating temperature of the solution is too low, the solid matter in the solution fails to fully dissolve, resulting in the failure of the material to fully react chemically during the subsequent chemical reaction. When the heating temperature is too high, the small monomer containing double bonds in the solution is highly active, and some double bonds break or self-polymerize, destroying the performance of the original small monomer, thereby affecting the performance of the final product. By changing the temperature of the catalytic reaction from Example 1 and Example 10 and Comparative Examples 4-5, the fluidity, collapse protection performance, concrete rebound rate, compressive strength, etc. of the concrete have a great impact. This may be because within a certain temperature range, the catalyst can make the chemical reaction proceed well. When the reaction temperature is too low, the catalyst catalytic efficiency is low, the chemical reaction is not fully carried out, and the conversion rate and product performance of the target product are affected. When the reaction temperature is too high, the material reaction is too intense during the chemical reaction, resulting in a large molecular weight and viscosity of the target product, thereby affecting the performance of the product.

[0089] The above are only relatively preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A tunnel engineering shotcrete rebound reducing agent, characterized in that: The concrete resilience reducing agent comprises the following components in percentage by mass: Tackifying component 10-15%; Nano-active mineral components 10-15%; Reinforcement component 5-10%; Suspended stable component 1-2%; Water retention component 2-3%; Workability adjustment component 2-3%; The balance is water; The nano-active mineral component is water-soluble nano-silicon dioxide or nano-aluminum oxide or a combination thereof; The viscosity-increasing component includes the following components in percentage by mass: Polyether macromonomer 15-20%, active small monomer 25-30%, catalyst 0.5-1%, initiator 3-5%; The polyether macromonomer is one of methyl allyl alcohol polyoxyethylene ether, isopentanol polyoxyethylene ether, ethoxy vinyl polyethylene glycol ether, hydroxybutyl vinyl polyethylene glycol ether or a combination thereof, and has a number average molecular weight of 2400-4000; The active small monomer is one of acrylic acid, methacrylic acid, acrylamide, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, fumaric acid, maleic anhydride or a combination thereof; The catalyst is one of ferrous sulfate, ferrous chloride, cuprous chloride or a combination thereof; The synthesis method of the viscosity-increasing component is: 1) Add water to the reactor, add the polyether macromonomer under stirring to make it completely dissolved, then add the active small monomer, stir evenly, add liquid alkali, adjust the pH value of the mixed solution to 7, and heat; 2) Add the catalyst and start to drip the initiator solution into the reactor, increase the temperature, keep the temperature to continue the reaction, add the remaining water into the reactor, stir evenly, cool to room temperature, and obtain the viscosity-increasing component.

2. According to claim 1, a tunnel engineering shotcrete rebound reducing agent, characterized in that: The initiator is one of hydrogen peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, azobisisobutylamidine hydrochloride, azobisisobutylimidazoline hydrochloride, azobiscyanovaleric acid or a combination thereof.

3. According to claim 1, a tunnel engineering shotcrete rebound reducing agent, characterized in that: In the step 1), heating to 45-55°C; In step 2), the initiator solution is dripped in 1 hour; the temperature is raised to 75-85°C, and the temperature is kept to continue the reaction for 3-5 hours.

4. The tunnel engineering shotcrete rebound reducing agent according to claim 1, characterized in that: The reinforcing component is one of diethanolamine, triethanolamine, calcium formate, sodium thiocyanate or a combination thereof; The suspension stabilizing component is one of SP80, TW80, TW60 or a combination thereof; The water-retaining component is one of cellulose ether, maltodextrin, Weinlun gum, Brunei gum, xanthan gum or a combination thereof; The workability adjusting component is one of sodium tripolyphosphate, sodium hexametaphosphate, sodium thiosulfate, sodium citrate or a combination thereof.

5. The method for preparing the tunnel engineering shotcrete rebound reducing agent according to any one of claims 1 to 4, characterized in that: Add nanometer active mineral component, reinforcing component, suspension stabilization component, water retention component and workability adjustment component to the viscosity increasing component, stir for 25-35 minutes, and obtain the tunnel engineering shotcrete rebound reducing agent.

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