A preparation process for lightweight lane slabs for underground tunnels based on UHPC

Abstract

The present invention provides a process for preparing a lightweight UHPC-based underground tunnel roadway slab, belonging to the field of building materials technology. The process comprises the following steps: preparing component A from a modified polyacrylate emulsion; mixing a modified polycarboxylate water-reducing agent with sodium silicate and calcium nitrate; pre-wetting coarse ceramic sand and pre-mixing the other components; preparing component B and mixing it with component A to prepare a lightweight UHPC base plate; and adding fine ceramic sand to prepare an anti-slip coating and spraying it. The present invention uses a modified polyacrylate emulsion and ethylene-vinyl acetate copolymer as raw materials to prepare component A. Component B is then prepared using cement, fly ash, and silica fume as gelling materials, and diamond, ceramic sand, a modified water-reducing agent, an expansion agent, and polypropylene fiber as raw materials. Components A and B are compounded, and after casting, curing, and demolding, a lightweight UHPC plate with low shrinkage and high compressive strength is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and in particular to a preparation process of a lightweight lane slab for an underground tunnel based on UHPC. Background Art

[0002] UHPC, or ultra-high performance concrete, refers to a cement-based concrete material with superb mechanical properties, high toughness, ultra-high durability and excellent pouring and forming properties. It is usually made from high-strength and tough materials such as cementitious materials, aggregates, steel or organic fibers.

[0003] Currently, existing UHPC has good mechanical properties and durability due to its low water-binder ratio, lack of coarse aggregate, and the addition of active mineral admixtures. However, it also causes its relatively large shrinkage, which leads to structural deformation and cracking, reducing the stability and durability of the structure. In addition, when using UHPC to make underground tunnel driveway slabs, since UHPC usually uses fine aggregate as raw material, its surface is relatively smooth. Therefore, when the road surface is wet, the tires of underground working vehicles are prone to slipping, which will cause safety hazards and affect the normal operation of the vehicles.

[0004] Therefore, we proposed a preparation process for UHPC-based lightweight lane slabs for underground tunnels with low shrinkage and anti-slip properties. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a preparation process for lightweight lane slabs of underground tunnels based on UHPC.

[0006] A preparation process for a lightweight lane slab for an underground tunnel based on UHPC comprises the following steps:

[0007] S1: Modify polyacrylate emulsion and prepare component A

[0008] A composite modifier is prepared by mixing hydroxyl-containing polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dilaurate, and then modifying a polyacrylate emulsion, and then mixing it with ethylene-vinyl acetate copolymer to obtain component A;

[0009] S2: Sodium silicate and calcium nitrate mixed modified polycarboxylate water reducer

[0010] Sodium silicate, calcium nitrate and deionized water are mixed to prepare a mixed solution, a polycarboxylate water reducer is prepared to prepare a polycarboxylate water reducer solution, and the mixed solution is pumped into the polycarboxylate water reducer solution to carry out a modification reaction to obtain a modified water reducer;

[0011] S3: Pre-wet the coarse sand and pre-mix the other components

[0012] The coarse ceramic sand is pre-wetted, and then cement, fly ash, silica fume and diamond are mixed into a first premix, and then magnesia powder is prepared by calcining magnesia ore, and the magnesium oxide powder, ettringite expansion agent and polypropylene fiber are ball-milled and mixed into a second premix;

[0013] S4: Prepare component B and mix component A to prepare lightweight UHPC substrate

[0014] The first premix, the second premix, the modified water-reducing agent, the pre-wetted ceramic sand, water and component A are fully mixed into a concrete slurry, and a lightweight UHPC substrate is obtained through pouring, curing and demoulding.

[0015] S5: Add fine ceramic sand to prepare anti-slip coating and spray it

[0016] The polyurethane resin and the polyester resin are fully mixed, and then a thixotropic agent, a filler, an antioxidant, a dispersant, a defoaming agent, a leveling agent, a diluent, a curing agent and fine ceramic sand are added to prepare an anti-slip coating, which is then sprayed on the surface of the above-mentioned lightweight UHPC substrate to obtain a lightweight driveway board.

[0017] Furthermore, the modified polyacrylate emulsion of step S1 is used to prepare component A, which specifically includes the following steps:

[0018] S1.1: Add hydroxyl-containing polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dilaurate into a blender at a mass ratio of 90-100:3-5:1 until a gravity sensor in the blender detects that the gravity in the blender no longer increases, and the gravity sensor sends a signal to the controller;

[0019] S1.2: After receiving the signal from the gravity sensor, the controller controls the stirrer to stir at a rate of 500-600 rpm for 1-2 hours to obtain a composite modifier;

[0020] S1.3: Add the polyacrylate emulsion and the above-mentioned composite modifier to the high-speed disperser at a volume ratio of 10-12:1 until the liquid level sensor in the high-speed disperser detects that the liquid level in the high-speed emulsifier no longer rises, and the liquid level sensor sends a signal to the controller;

[0021] S1.4: After receiving the signal from the liquid level sensor, the controller controls the high-speed disperser to disperse at high speed for 30-40 minutes to modify the polyacrylate emulsion.

[0022] S1.5: Add ethylene-vinyl acetate copolymer into a high-speed disperser at a mass ratio of 1-2:1, and disperse and mix it with the above-mentioned modified polyacrylate emulsion at high speed to obtain component A.

[0023] Furthermore, the sodium silicate and calcium nitrate mixed modified polycarboxylate water-reducing agent in step S2 specifically includes the following steps:

[0024] S2.1: Add sodium silicate, calcium nitrate, and deionized water in a mass ratio of 5-7:1:1-2 into a mixing tank, stir to dissolve, and mix evenly to obtain a mixed solution;

[0025] S2.2: Disperse the polycarboxylate superplasticizer in water to prepare a polycarboxylate superplasticizer solution with a mass fraction of 6-8%;

[0026] S2.3: Pour the polycarboxylate water-reducing agent solution into the reactor and add sodium hydroxide solution to adjust the pH to 8-9;

[0027] S2.4: Turn on the heater and stirrer in the reactor, heat the reactor to 70-80°C using the heater, and stir the reactor at a rate of 200-300 rpm using the stirrer;

[0028] S2.5: Nitrogen is introduced into the heated polycarboxylate superplasticizer solution via an air pump. Simultaneously, the mixed solution is pumped into the reactor at a constant speed via a hydraulic pump, and the reaction is carried out while heating and stirring.

[0029] S2.6: After the mixed solution is completely added, add dilute nitric acid solution to the reactor to adjust the pH to 10-12, and continue stirring for 18-20 hours. After filtering, the modified water reducer is obtained.

[0030] Furthermore, the step S3 of pre-wetting the coarse ceramic sand and pre-mixing other components specifically includes the following steps:

[0031] S3.1: Add coarse ceramic sand to water, mix evenly, and fully pre-wet to obtain pre-wet ceramic sand;

[0032] S3.2: Add cement, fly ash, silica fume and diamond in a mass ratio of 6-8:2-3:1-2:0.3-0.5 into a first mixer and stir thoroughly to obtain a first premix;

[0033] S3.3: Place the magnesite in a calcining furnace and calcine it at 800-1000°C for 1-2 hours. After cooling to room temperature, grind it to obtain magnesium oxide powder.

[0034] S3.4: Add magnesium oxide powder, ettringite expansion agent and polypropylene fiber into a ball mill at a mass ratio of 2-3:1:1, ball mill for 1-2 hours, and mix evenly to obtain a second premix.

[0035] Furthermore, step S4 of preparing component B and mixing component A to prepare a lightweight UHPC substrate specifically includes the following steps:

[0036] S4.1: Add the second premix prepared in step S3.4, the modified water-reducing agent prepared in step S2.6, the pre-wetted ceramic sand prepared in step S3.1, and 50-60% water into a concrete mixer and stir until thoroughly mixed.

[0037] S4.2: Add the first premix prepared in step S3.2 and the remaining water into a concrete mixer and continue stirring until uniformly mixed to obtain component B;

[0038] S4.3: Add component A prepared in step S1.5 to component B and continue stirring to mix evenly to obtain a concrete slurry;

[0039] S4.4: Pour the concrete slurry into the mold and pour it. Then, connect a vibrator to the outer wall of the mold to vibrate the concrete slurry in the mold at a high frequency and a small amplitude.

[0040] S4.5: Curing for 16-22 days at a temperature of 18-20°C and a humidity of 94-98%. After demolding, a lightweight UHPC substrate is obtained.

[0041] Furthermore, step S5 of adding fine ceramic sand to prepare the anti-slip coating and spraying it specifically includes the following steps:

[0042] S5.1: Add polyurethane resin and polyester resin to the paint mixing tank and stir at a rate of 1200-1300 rpm for 1-2 hours to ensure thorough and uniform mixing;

[0043] S5.2: Add the thixotropic agent, filler, antioxidant, dispersant, defoamer, leveling agent, and 60-70% of the diluent to the paint mixing tank. Adjust the stirring speed to 1800-2000 rpm and continue stirring for 30-40 minutes to obtain the third premix.

[0044] S5.3: Pour the third premix into a grinder and grind for 20-30 minutes. Then add the remaining diluent into the grinder and stir evenly to obtain a mixed slurry.

[0045] S5.4: Pour the mixed slurry back into the paint tank, add the curing agent and fine ceramic sand into the paint tank, and stir thoroughly to obtain the anti-slip coating;

[0046] S5.5: Evenly spray the anti-slip coating onto the upper surface of the UHPC substrate using a spray gun. After curing, a single-layer coating is formed on the upper surface of the UHPC substrate.

[0047] S5.6: A layer of anti-slip coating is evenly sprayed on the surface of the above single-layer coating again. After curing, a composite coating is formed on the upper surface of the UHPC substrate to obtain a lightweight driveway board.

[0048] Furthermore, component B includes 450-550 parts of the first premix, 50-60 parts of the second premix, 20-30 parts of a modified water-reducing agent, 150-180 parts of pre-wetted ceramic sand and 180-200 parts of water, and the mass ratio of component A to component B is 1:80-90.

[0049] Furthermore, the anti-slip coating includes 70-80 parts of polyurethane resin, 50-60 parts of polyester resin, 3-5 parts of thixotropic agent, 8-10 parts of filler, 1-2 parts of antioxidant, 2-3 parts of dispersant, 1-2 parts of defoaming agent, 1-2 parts of leveling agent, 30-40 parts of diluent, 6-8 parts of curing agent and 20-28 parts of fine ceramic sand.

[0050] Furthermore, the particle size of the coarse pottery sand is 2-4 mm.

[0051] Furthermore, the particle size of the fine ceramic sand is 300-360 μm.

[0052] Compared with the prior art, the present invention has at least the following beneficial effects:

[0053] 1. The present invention uses a modified polyacrylate emulsion and ethylene-vinyl acetate copolymer as raw materials to prepare component A, and then uses cement, fly ash, and silica fume as gelling materials, and combines diamond, ceramic sand, a modified water-reducing agent, an expansion agent, and polypropylene fiber as raw materials to prepare component B. After compounding components A and B, and then undergoing casting, curing, and demolding, a lightweight UHPC board with low shrinkage and high compressive strength can be obtained. Specifically, the polyacrylate emulsion is first modified with a mixed modifier prepared using hydroxyl-containing polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dilaurate as raw materials, and the modified polyacrylate emulsion is then mixed, compounded, and incorporated into concrete. The two can produce a synergistic effect, effectively improving the shrinkage problem of the concrete and improving the compressive strength of the prepared driveway slab.

[0054] 2. The present invention can prepare an anti-slip coating by compounding a polyurethane resin and a polyester resin, and then adding fine ceramic sand and other additives. The anti-slip coating is evenly sprayed on the surface of a lightweight UHPC substrate and dried to form a film to form an anti-slip coating. The anti-slip coating can not only firmly adhere to the surface of the substrate, but also give the substrate good anti-slip performance. Even when the surface is wet, the tires are not likely to slip, thereby ensuring the safe and smooth progress of underground operations.

[0055] 3. The present invention can play an internal curing role by fully pre-wetting the coarse pottery sand before adding it to the concrete, reducing the autogenous shrinkage and drying shrinkage of the concrete. In addition, the pre-wetted coarse pottery sand can cooperate with the magnesium oxide powder and the ettringite expansion agent to reduce the autogenous shrinkage effect, thereby achieving the purpose of significantly improving the shrinkage reduction effect.

[0056] 4. The present invention can improve the strength of concrete and inhibit the autogenous shrinkage and drying shrinkage of concrete by adding polypropylene fibers with strong restraint and bridging effects. At the same time, polypropylene fibers have a good synergistic effect with magnesium oxide powder and ettringite expansion agent. The combined addition of the three can have a good restraint effect, thereby further improving the shrinkage reduction effect and compressive strength of concrete.

[0057] 5. The present invention prepares sodium silicate and calcium nitrate into a mixed solution, and then uses the mixed solution to modify the polycarboxylate water-reducing agent, so that it can not only reduce the water consumption of the concrete slurry, but also improve the rheological properties of the concrete slurry, shorten the hydration time, and produce a large amount of hydration products to fill the microscopic pores, thereby reducing the macropore content and increasing the nanopore content, thereby further improving the shrinkage reduction performance and compressive strength of the lane slab. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable one skilled in the relevant art to make and use the present disclosure.

[0059] Figure 1 This is a process flow chart for preparing a lightweight lane slab for an underground tunnel based on UHPC, as used in an embodiment of the present invention;

[0060] Figure 2 The following is a summary table of performance test results of Examples 1-3 and Comparative Examples 1-5 of the present invention. DETAILED DESCRIPTION

[0061] The following describes in detail a preparation process of a lightweight lane slab for an underground tunnel based on UHPC provided by the present invention in conjunction with the accompanying drawings and specific embodiments.

[0062] Example 1

[0063] A preparation process for lightweight lane slabs for underground tunnels based on UHPC, such as Figure 1 and Figure 2 As shown, the following steps are included:

[0064] S1: Modify polyacrylate emulsion and prepare component A

[0065] Hydroxyl-containing polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dilaurate are added together in a mass ratio of 90:3:1 to a blender, until a gravity sensor in the blender detects that the gravity in the blender no longer increases, the gravity sensor sends a signal to a controller, and after receiving the signal from the gravity sensor, the controller controls the blender to stir at a rate of 500 r / min for 1 hour to obtain a composite modifier, and then polyacrylate emulsion and the composite modifier are added together in a volume ratio of 10:1 to a high-speed disperser, until a liquid level sensor in the high-speed disperser detects that the liquid level in the high-speed emulsifier no longer rises, the liquid level sensor sends a signal to the controller, and after receiving the signal from the liquid level sensor, the controller controls the high-speed disperser to disperse at high speed for 30 minutes to perform modification to obtain a modified polyacrylate emulsion, and then ethylene-vinyl acetate copolymer is added to the high-speed disperser at a mass ratio of 80% of the modified polyacrylate emulsion, and dispersed and mixed with the modified polyacrylate emulsion at high speed to obtain component A;

[0066] S2: Sodium silicate and calcium nitrate mixed modified polycarboxylate water reducer

[0067] Sodium silicate, calcium nitrate and deionized water are added to a mixing tank in a mass ratio of 5:1:1, stirred to dissolve, and evenly mixed to obtain a mixed solution. The polycarboxylate water-reducer is then dispersed in water to prepare a polycarboxylate water-reducer solution with a mass fraction of 6%. The polycarboxylate water-reducer solution is then poured into a reactor, and sodium hydroxide solution is added to adjust the pH to 8. Subsequently, the heater and stirrer in the reactor are turned on, and the heater is heated at a temperature of 70° C., and stirred at a rate of 200 r / min by the stirrer. Nitrogen is then introduced into the heated polycarboxylate water-reducer solution by an air pump, and the mixed solution is uniformly pumped into the reactor by a hydraulic pump. The reaction is carried out while heating and stirring until the mixed solution is completely added. Dilute nitric acid solution is added to the reactor to adjust the pH to 10, and stirring is continued for 18 hours. After filtering, a modified water-reducer is obtained;

[0068] S3: Pre-wet the coarse sand and pre-mix the other components

[0069] Coarse pottery sand with a particle size of 2 mm is added to water, mixed evenly, and fully pre-wetted to obtain pre-wet pottery sand, and then cement, fly ash, silica fume and diamond are added together in a mass ratio of 6:2:1:0.3 into a first mixer, and fully stirred and mixed to obtain a first premix, and then magnesite is placed in a calcining furnace and calcined at a temperature of 800°C for 1 hour. After cooling to room temperature with the furnace, it is ground to obtain magnesium oxide powder, and finally, magnesium oxide powder, ettringite expansion agent and polypropylene fiber are added together in a mass ratio of 2:1:1 into a ball mill, ball milled for 1 hour, and evenly mixed to obtain a second premix;

[0070] S4: Prepare component B and mix component A to prepare lightweight UHPC substrate

[0071] 50 parts of the second premix, 20 parts of the modified water-reducing agent, 150 parts of pre-wetted ceramic sand and 95 parts of water were added to a concrete mixer and stirred. After being fully and evenly mixed, 450 parts of the first premix and the remaining water were added to the concrete mixer and stirred. After being evenly mixed, component B was obtained. Component A was then added to component B at a mass ratio of component A: component B = 1:80. The mixture was stirred and evenly mixed to obtain a concrete slurry. Subsequently, the concrete slurry was injected into a mold for pouring. A vibrator was then connected to the outer wall of the mold to perform high-frequency micro-vibration on the concrete slurry in the mold. Finally, the mold was cured for 16 days at a temperature of 18° C. and a humidity of 94%. After demolding, a lightweight UHPC substrate was obtained.

[0072] S5: Add fine ceramic sand to prepare anti-slip coating and spray it

[0073] 70 parts of polyurethane resin and 50 parts of polyester resin are added to the paint mixing tank together, stirred at a rate of 1200r / min for 1h to be fully and evenly mixed, then 3 parts of thixotropic agent, 8 parts of filler, 1 part of antioxidant, 2 parts of dispersant, 1 part of defoamer, 1 part of leveling agent and 19 parts of diluent are added to the paint mixing tank together, the stirring rate is adjusted to 1800r / min, and stirring is continued for 30min to obtain a third premix, and then the third premix is ​​poured into a grinder and ground for 20min, and then the remaining diluent is added to the grinder. After uniform stirring and mixing, a mixed slurry is obtained, and the mixed slurry is poured back into the paint tank. Then, 6 parts of curing agent and 20 parts of fine ceramic sand with a particle size of 300 μm are added to the paint mixing tank, and the mixture is fully stirred and mixed to obtain an anti-slip coating. Finally, the anti-slip coating is evenly sprayed on the upper surface of the above-mentioned UHPC substrate through a spray gun. After curing, a single-layer coating is formed on the upper surface of the UHPC substrate. Then, a layer of anti-slip coating is evenly sprayed on the surface of the single-layer coating again. After curing, a composite coating is formed on the upper surface of the UHPC substrate to obtain a lightweight driveway board.

[0074] Performance testing:

[0075] First, according to the requirements of GBT50082-2009 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete", the shrinkage deformation was tested using the contact method. The shrinkage test used the above concrete slurry and a 100mm×100mm×400mm prism specimen. The results showed that the concrete slurry shrank by about 312×10 -6 mm;

[0076] Secondly, the mechanical properties of the concrete slurry were tested in accordance with the relevant requirements of GB / T31387-2015 "Reactive Powder Concrete". The compressive test used a 100mm×100mm×100mm cubic specimen. The results showed that the 28d compressive strength was approximately 131.4MPa.

[0077] Finally, in accordance with GB / T10006-2021, a friction coefficient tester was used to test the maximum static friction coefficient between the anti-slip coating on the surface of the lightweight driveway board and the rubber surface in water. The results showed that the maximum static friction coefficient of the anti-slip coating in wet state was approximately 1.2.

[0078] Example 2

[0079] A preparation process for lightweight lane slabs for underground tunnels based on UHPC, such as Figure 1 and Figure 2 As shown, the following steps are included:

[0080] S1: Modify polyacrylate emulsion and prepare component A

[0081] Hydroxyl-containing polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dilaurate are added together in a mass ratio of 95:4:1 to a blender, until a gravity sensor in the blender detects that the gravity in the blender no longer increases, the gravity sensor sends a signal to a controller, and after receiving the signal from the gravity sensor, the controller controls the blender to stir at a rate of 550 r / min for 1.5 hours to obtain a composite modifier, and then polyacrylate emulsion and the composite modifier are added together in a volume ratio of 11:1 to a high-speed disperser, until a liquid level sensor in the high-speed disperser detects that the liquid level in the high-speed emulsifier no longer rises, the liquid level sensor sends a signal to the controller, and after receiving the signal from the liquid level sensor, the controller controls the high-speed disperser to disperse at high speed for 35 minutes to perform modification to obtain a modified polyacrylate emulsion, and then ethylene-vinyl acetate copolymer is added to the high-speed disperser at a mass ratio of 90% of the modified polyacrylate emulsion, and dispersed and mixed with the modified polyacrylate emulsion at high speed to obtain component A;

[0082] S2: Sodium silicate and calcium nitrate mixed modified polycarboxylate water reducer

[0083] Sodium silicate, calcium nitrate and deionized water are added to a mixing tank in a mass ratio of 6:1:1, stirred to dissolve, and evenly mixed to obtain a mixed solution. The polycarboxylate water-reducer is then dispersed in water to prepare a polycarboxylate water-reducer solution with a mass fraction of 7%. The polycarboxylate water-reducer solution is then poured into a reactor, and sodium hydroxide solution is added to adjust the pH to 8.5. Subsequently, the heater and stirrer in the reactor are turned on, and the heater is heated at a temperature of 75° C., and the stirrer is stirred at a rate of 250 r / min. Nitrogen is then introduced into the heated polycarboxylate water-reducer solution through an air pump, and the mixed solution is uniformly pumped into the reactor through a hydraulic pump. The reaction is carried out while heating and stirring until the mixed solution is completely added. Dilute nitric acid solution is added to the reactor to adjust the pH to 11, and stirring is continued for 19 hours. After filtering, a modified water-reducer is obtained;

[0084] S3: Pre-wet the coarse sand and pre-mix the other components

[0085] Coarse pottery sand with a particle size of 3 mm is added to water, mixed evenly, and fully pre-wetted to obtain pre-wet pottery sand, and then cement, fly ash, silica fume and diamond are added together in a mass ratio of 7:2:1:0.4 into a first mixer, and fully stirred and mixed to obtain a first premix, and then magnesite is placed in a calcining furnace and calcined at a temperature of 900°C for 1.5 hours. After cooling to room temperature with the furnace, it is ground to obtain magnesium oxide powder, and finally, magnesium oxide powder, ettringite expansion agent and polypropylene fiber are added together in a mass ratio of 2.5:1:1 into a ball mill, ball milled for 1.5 hours, and evenly mixed to obtain a second premix;

[0086] S4: Prepare component B and mix component A to prepare lightweight UHPC substrate

[0087] 55 parts of the second premix, 25 parts of the modified water-reducing agent, 165 parts of pre-wetted ceramic sand and 100 parts of water were added to a concrete mixer and stirred. After being fully and evenly mixed, 500 parts of the first premix and the remaining water were added to the concrete mixer and stirred. After being evenly mixed, component B was obtained. Component A was then added to component B at a mass ratio of component A: component B = 1:85. The mixture was stirred and evenly mixed to obtain a concrete slurry. Subsequently, the concrete slurry was injected into a mold for pouring. A vibrator was then connected to the outer wall of the mold to perform high-frequency micro-vibration on the concrete slurry in the mold. Finally, the mold was cured for 19 days at a temperature of 19° C. and a humidity of 96%. After demolding, a lightweight UHPC substrate was obtained.

[0088] S5: Add fine ceramic sand to prepare anti-slip coating and spray it

[0089] 75 parts of polyurethane resin and 55 parts of polyester resin were added to the paint mixing tank and stirred at a rate of 1250 r / min for 1.5 hours to mix thoroughly and evenly. Then 4 parts of thixotropic agent, 9 parts of filler, 1 part of antioxidant, 2 parts of dispersant, 1 part of defoamer, 1 part of leveling agent and 25 parts of diluent were added to the paint mixing tank and the stirring rate was adjusted to 1900 r / min. The stirring was continued for 35 minutes to obtain a third premix. The third premix was then poured into a grinder and ground for 25 minutes. The remaining diluent was then added to the grinder. , after uniform stirring and mixing, a mixed slurry is obtained, and the mixed slurry is poured back into the paint tank, and then 7 parts of curing agent and 24 parts of fine ceramic sand with a particle size of 330 μm are added to the paint mixing tank, and after sufficient stirring and mixing, an anti-slip coating is obtained. Finally, the anti-slip coating is evenly sprayed on the upper surface of the above-mentioned UHPC substrate through a spray gun. After curing, a single-layer coating is formed on the upper surface of the UHPC substrate, and then a layer of anti-slip coating is evenly sprayed on the surface of the single-layer coating again. After curing, a composite coating is formed on the upper surface of the UHPC substrate to obtain a lightweight driveway board.

[0090] Performance testing:

[0091] First, according to the requirements of GBT50082-2009 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete", the shrinkage deformation was tested using the contact method. The shrinkage test used the above concrete slurry and a 100mm×100mm×400mm prism specimen. The results showed that the concrete slurry shrank by about 314×10 -6 mm;

[0092] Secondly, the mechanical properties of the concrete slurry were tested in accordance with the relevant requirements of GB / T31387-2015 "Reactive Powder Concrete". The compressive test used a 100mm×100mm×100mm cubic specimen. The results showed that the 28d compressive strength was approximately 131.5MPa.

[0093] Finally, in accordance with GB / T10006-2021, a friction coefficient tester was used to test the maximum static friction coefficient between the anti-slip coating on the surface of the lightweight driveway board and the rubber surface in water. The results showed that the maximum static friction coefficient of the anti-slip coating in wet state was approximately 1.2.

[0094] Example 3

[0095] A preparation process for lightweight lane slabs for underground tunnels based on UHPC, such as Figure 1 and Figure 2 As shown, the following steps are included:

[0096] S1: Modify polyacrylate emulsion and prepare component A

[0097] Hydroxyl-containing polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dilaurate are added together in a mass ratio of 100:5:1 into a blender, until a gravity sensor in the blender detects that the gravity in the blender no longer increases, the gravity sensor sends a signal to a controller, and after receiving the signal from the gravity sensor, the controller controls the blender to stir at a rate of 600 r / min for 2 hours to obtain a composite modifier, and then polyacrylate emulsion and the composite modifier are added together in a volume ratio of 12:1 into a high-speed disperser, until a liquid level sensor in the high-speed disperser detects that the liquid level in the high-speed emulsifier no longer rises, the liquid level sensor sends a signal to the controller, and after receiving the signal from the liquid level sensor, the controller controls the high-speed disperser to disperse at high speed for 40 minutes to perform modification to obtain a modified polyacrylate emulsion, and then ethylene-vinyl acetate copolymer is added into the high-speed disperser at a mass ratio of 100% of the modified polyacrylate emulsion, and dispersed and mixed with the modified polyacrylate emulsion at high speed to obtain component A;

[0098] S2: Sodium silicate and calcium nitrate mixed modified polycarboxylate water reducer

[0099] Sodium silicate, calcium nitrate and deionized water are added to a mixing tank in a mass ratio of 7:1:2, stirred to dissolve, and evenly mixed to obtain a mixed solution. The polycarboxylate water-reducer is then dispersed in water to prepare a polycarboxylate water-reducer solution with a mass fraction of 8%. The polycarboxylate water-reducer solution is then poured into a reactor, and sodium hydroxide solution is added to adjust the pH to 9. Subsequently, the heater and stirrer in the reactor are turned on, and the heater is heated at a temperature of 80° C., and the stirrer is stirred at a rate of 300 r / min. Nitrogen is then introduced into the heated polycarboxylate water-reducer solution through an air pump, and the mixed solution is uniformly pumped into the reactor through a hydraulic pump. The reaction is carried out while heating and stirring until the mixed solution is completely added. Dilute nitric acid solution is added to the reactor to adjust the pH to 12, and stirring is continued for 20 hours. After filtering, a modified water-reducer is obtained;

[0100] S3: Pre-wet the coarse sand and pre-mix the other components

[0101] Coarse pottery sand with a particle size of 4 mm is added to water, mixed evenly, and fully pre-wetted to obtain pre-wet pottery sand, and then cement, fly ash, silica fume and diamond are added together in a mass ratio of 8:3:2:0.5 into a first mixer, and fully stirred and mixed to obtain a first premix, and then magnesite is placed in a calcining furnace and calcined at a temperature of 1000° C. for 2 hours. After cooling to room temperature with the furnace, it is ground to obtain magnesium oxide powder, and finally, magnesium oxide powder, ettringite expansion agent and polypropylene fiber are added together in a mass ratio of 3:1:1 into a ball mill, ball-milled for 2 hours, and evenly mixed to obtain a second premix;

[0102] S4: Prepare component B and mix component A to prepare lightweight UHPC substrate

[0103] 60 parts of the second premix, 30 parts of the modified water reducer, 180 parts of pre-wetted ceramic sand and 120 parts of water are added to a concrete mixer and stirred. After being fully and evenly mixed, 550 parts of the first premix and the remaining water are added to the concrete mixer and stirred. After being evenly mixed, component B is obtained. Component A is then added to component B at a mass ratio of component A: component B = 1:90. The mixture is stirred and evenly mixed to obtain a concrete slurry. Subsequently, the concrete slurry is injected into a mold for pouring. A vibrator is then connected to the outer wall of the mold to perform high-frequency micro-vibration on the concrete slurry in the mold. Finally, the mold is cured for 22 days at a temperature of 20°C and a humidity of 98%. After demolding, a lightweight UHPC substrate is obtained.

[0104] S5: Add fine ceramic sand to prepare anti-slip coating and spray it

[0105] 80 parts of polyurethane resin and 60 parts of polyester resin were added to the paint mixing tank and stirred at a rate of 1300 r / min for 2 hours to mix thoroughly and evenly. Then 5 parts of thixotropic agent, 10 parts of filler, 2 parts of antioxidant, 3 parts of dispersant, 2 parts of defoamer, 2 parts of leveling agent and 28 parts of diluent were added to the paint mixing tank and the stirring rate was adjusted to 2000 r / min. The stirring was continued for 40 minutes to obtain a third premix. The third premix was then poured into a grinder and ground for 30 minutes. The remaining diluent was then added to the grinder. , after uniform stirring and mixing, a mixed slurry is obtained, and the mixed slurry is poured back into the paint tank, and then 8 parts of curing agent and 28 parts of fine ceramic sand with a particle size of 360 μm are added to the paint mixing tank, and after sufficient stirring and mixing, an anti-slip coating is obtained. Finally, the anti-slip coating is evenly sprayed on the upper surface of the above-mentioned UHPC substrate through a spray gun. After curing, a single-layer coating is formed on the upper surface of the UHPC substrate, and then a layer of anti-slip coating is evenly sprayed on the surface of the single-layer coating again. After curing, a composite coating is formed on the upper surface of the UHPC substrate to obtain a lightweight driveway board.

[0106] Performance testing:

[0107] First, according to the requirements of GBT50082-2009 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete", the shrinkage deformation was tested using the contact method. The shrinkage test used the above concrete slurry and a 100mm×100mm×400mm prism specimen. The results showed that the concrete slurry shrank by about 318×10 -6 mm;

[0108] Secondly, the mechanical properties of the concrete slurry were tested in accordance with the relevant requirements of GB / T31387-2015 "Reactive Powder Concrete". The compressive test used a 100mm×100mm×100mm cubic specimen. The results showed that the 28d compressive strength was approximately 132.3MPa.

[0109] Finally, in accordance with GB / T10006-2021, a friction coefficient tester was used to test the maximum static friction coefficient between the anti-slip coating on the surface of the lightweight driveway board and the rubber surface in water. The results showed that the maximum static friction coefficient of the anti-slip coating in wet state was approximately 1.2.

[0110] Comparative Example 1

[0111] The difference between this comparative example 1 and example 1 is that the step of modifying the polyacrylate emulsion in step S1 is removed, and the modified polyacrylate emulsion is replaced with an equal amount of ethylene-vinyl acetate copolymer, that is, component A is only ethylene-vinyl acetate copolymer, and then the lightweight driveway board is prepared according to the subsequent steps.

[0112] The performance test was performed according to the performance test method in Example 1. Figure 2 As shown in the results, the shrinkage after 56 days is about 478×10 -6 mm, a 28d compressive strength of approximately 118.3 MPa, and a maximum static friction coefficient of the anti-slip coating of approximately 1.2.

[0113] By comparing the test results of Example 1 above, it can be seen that by first modifying the polyacrylate emulsion with a mixed modifier prepared with hydroxyl-containing polydimethylsiloxane, tetraethyl orthosilicate and dibutyltin dilaurate as raw materials, and then mixing the modified polyacrylate emulsion with ethylene-vinyl acetate and incorporating it into concrete, the two can produce a synergistic effect, effectively improving the shrinkage problem of concrete and improving the compressive strength of the prepared driveway slab.

[0114] Comparative Example 2

[0115] The difference between Comparative Example 1 and Example 1 is that step S5 is removed, that is, the anti-slip coating is not sprayed, and the lightweight UHPC substrate is directly used as the lightweight driveway board.

[0116] The performance test was performed according to the performance test method in Example 1. Figure 2 As shown in the results, the shrinkage after 56 days is about 315×10 -6 mm, a 28d compressive strength of approximately 132.1 MPa, and a maximum static friction coefficient of the anti-slip coating of approximately 0.7.

[0117] By comparing the test results of Example 1 above, it can be seen that by compounding a polyurethane resin and a polyester resin and then adding fine ceramic sand and other additives, an anti-slip coating can be prepared. The anti-slip coating is evenly sprayed on the surface of a lightweight UHPC substrate and dried to form a film to form an anti-slip coating. The anti-slip coating can not only firmly adhere to the surface of the substrate, but also enable the substrate to have good anti-slip properties. Even when the surface is wet, the tires are not easy to slip, thereby ensuring the safe and smooth progress of underground operations.

[0118] Comparative Example 3

[0119] The difference between Comparative Example 1 and Example 1 is that the step of pre-wetting the coarse ceramic sand in step S3 is removed, that is, the coarse ceramic sand is not pre-wetted, and dry coarse ceramic sand is directly added to prepare component B.

[0120] The performance test was performed according to the performance test method in Example 1. Figure 2 As shown in the results, the shrinkage after 56 days is about 387×10 -6 mm, a 28d compressive strength of approximately 126.8 MPa, and a maximum static friction coefficient of the anti-slip coating of approximately 1.2.

[0121] Comparing the test results of Example 1 above, it can be seen that the coarse pottery sand is fully pre-wetted before being added to the concrete, which can play a role in internal curing and reduce the autogenous shrinkage and drying shrinkage of the concrete. In addition, the pre-wetted coarse pottery sand can cooperate with the magnesium oxide powder and the ettringite expansion agent to reduce the autogenous shrinkage effect, thereby achieving the purpose of significantly improving the shrinkage reduction effect.

[0122] Comparative Example 4

[0123] The difference between Comparative Example 1 and Example 1 is that the polypropylene fiber in step S3 is removed, that is, no polypropylene fiber is added.

[0124] The performance test was performed according to the performance test method in Example 1. Figure 2 As shown in the results, the shrinkage of 56d is about 423×10 -6 mm, a 28d compressive strength of approximately 115.7 MPa, and a maximum static friction coefficient of the anti-slip coating of approximately 1.2.

[0125] By comparing the test results of Example 1 above, it can be seen that by adding polypropylene fibers with strong restraint and bridging effects, the strength of concrete can be improved, and the autogenous shrinkage and drying shrinkage of concrete can be inhibited. At the same time, polypropylene fibers have a good synergistic effect with magnesium oxide powder and ettringite expansion agent. The combined addition of the three can have a good restraint effect, thereby further improving the shrinkage reduction effect and compressive strength of concrete.

[0126] Comparative Example 5

[0127] The difference between Comparative Example 1 and Example 1 is that step S2 is removed, and the modified water-reducing agent in step S4 is replaced by an equal amount of polycarboxylate water-reducing agent, that is, the polycarboxylate water-reducing agent is not modified.

[0128] The performance test was performed according to the performance test method in Example 1. Figure 2 As shown in the results, the shrinkage of 56d is about 354×10 -6 mm, a 28d compressive strength of approximately 125.6 MPa, and a maximum static friction coefficient of the anti-slip coating of approximately 1.2.

[0129] By comparing the test results of Example 1 above, it can be seen that by preparing sodium silicate and calcium nitrate into a mixed solution and then using the mixed solution to modify the polycarboxylate water-reducing agent, it is possible to not only reduce the water consumption of the concrete slurry, but also improve the rheological properties of the concrete slurry, shorten the hydration time, and produce a large amount of hydration products to fill the microscopic pores, thereby reducing the macropore content and increasing the nanopore content, thereby further improving the shrinkage reduction performance and compressive strength of the lane slab.

[0130] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A process for preparing a lightweight lane slab for an underground tunnel based on UHPC, characterized in that: The steps include: S1: Modify polyacrylate emulsion and prepare component A A composite modifier is prepared by mixing hydroxyl-containing polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dilaurate, and then modifying a polyacrylate emulsion, and then mixing it with ethylene-vinyl acetate copolymer to obtain component A; S2: Sodium silicate and calcium nitrate mixed modified polycarboxylate water reducer Sodium silicate, calcium nitrate and deionized water are mixed to prepare a mixed solution, a polycarboxylate water reducer is prepared to prepare a polycarboxylate water reducer solution, and the mixed solution is pumped into the polycarboxylate water reducer solution to carry out a modification reaction to obtain a modified water reducer; S3: Pre-wet the coarse sand and pre-mix the other components The coarse ceramic sand is pre-wetted, and then cement, fly ash, silica fume and diamond are mixed into a first premix, and then magnesia powder is prepared by calcining magnesia ore, and the magnesium oxide powder, ettringite expansion agent and polypropylene fiber are ball-milled and mixed into a second premix; S4: Prepare component B and mix component A to prepare lightweight UHPC substrate The first premix, the second premix, the modified water-reducing agent, the pre-wetted ceramic sand, water and component A are fully mixed into a concrete slurry, and a lightweight UHPC substrate is obtained through pouring, curing and demoulding. S5: Add fine ceramic sand to prepare anti-slip coating and spray it The polyurethane resin and the polyester resin are fully mixed, and then a thixotropic agent, a filler, an antioxidant, a dispersant, a defoaming agent, a leveling agent, a diluent, a curing agent and fine ceramic sand are added to prepare an anti-slip coating, which is then sprayed on the surface of the above-mentioned lightweight UHPC substrate to obtain a lightweight driveway board.

2. The process for preparing a lightweight lane slab for an underground tunnel based on UHPC according to claim 1, characterized in that: The modified polyacrylate emulsion of step S1 is used to prepare component A, which specifically includes the following steps: S1.1: Add hydroxyl-containing polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dilaurate into a blender at a mass ratio of 90-100:3-5:1 until a gravity sensor in the blender detects that the gravity in the blender no longer increases, and the gravity sensor sends a signal to the controller; S1.2: After receiving the signal from the gravity sensor, the controller controls the stirrer to stir at a rate of 500-600 rpm for 1-2 hours to obtain a composite modifier; S1.3: Add the polyacrylate emulsion and the above-mentioned composite modifier to the high-speed disperser at a volume ratio of 10-12:1 until the liquid level sensor in the high-speed disperser detects that the liquid level in the high-speed emulsifier no longer rises, and the liquid level sensor sends a signal to the controller; S1.4: After receiving the signal from the liquid level sensor, the controller controls the high-speed disperser to disperse at high speed for 30-40 minutes to modify the polyacrylate emulsion. S1.5: Add ethylene-vinyl acetate copolymer into a high-speed disperser and disperse and mix it with the modified polyacrylate emulsion at high speed to obtain component A, wherein the mass ratio of modified polyacrylate emulsion to ethylene-vinyl acetate copolymer is 1-2:

1.

3. The process for preparing a lightweight lane slab for an underground tunnel based on UHPC according to claim 2, characterized in that: The sodium silicate and calcium nitrate mixed modified polycarboxylate water-reducing agent in step S2 specifically comprises the following steps: S2.1: Add sodium silicate, calcium nitrate, and deionized water in a mass ratio of 5-7:1:1-2 into a mixing tank, stir to dissolve, and mix evenly to obtain a mixed solution; S2.2: Disperse the polycarboxylate superplasticizer in water to prepare a polycarboxylate superplasticizer solution with a mass fraction of 6-8%; S2.3: Pour the polycarboxylate water-reducing agent solution into the reactor and add sodium hydroxide solution to adjust the pH to 8-9; S2.4: Turn on the heater and stirrer in the reactor, heat the reactor to 70-80°C using the heater, and stir the reactor at a rate of 200-300 rpm using the stirrer; S2.5: Nitrogen is introduced into the heated polycarboxylate superplasticizer solution via an air pump. Simultaneously, the mixed solution is pumped into the reactor at a constant speed via a hydraulic pump, and the reaction is carried out while heating and stirring. S2.6: After all the mixed solution has been added, add dilute nitric acid solution to the reactor to adjust the pH to 10-12, and continue stirring for 18-20 hours. After filtering, the modified water reducer is obtained.

4. The process for preparing a lightweight lane slab for an underground tunnel based on UHPC according to claim 3, characterized in that: Step S3 of pre-wetting the coarse ceramic sand and pre-mixing other components specifically includes the following steps: S3.1: Add coarse ceramic sand to water, mix evenly, and fully pre-wet to obtain pre-wet ceramic sand; S3.2: Add cement, fly ash, silica fume and diamond in a mass ratio of 6-8:2-3:1-2:0.3-0.5 into a first mixer and stir thoroughly to obtain a first premix; S3.3: Place the magnesite in a calcining furnace and calcine it at 800-1000°C for 1-2 hours. After cooling to room temperature, grind it to obtain magnesium oxide powder. S3.4: Add magnesium oxide powder, ettringite expansion agent and polypropylene fiber into a ball mill at a mass ratio of 2-3:1:1, ball mill for 1-2 hours, and mix evenly to obtain a second premix.

5. The process for preparing a lightweight lane slab for an underground tunnel based on UHPC according to claim 4, characterized in that: Step S4 of preparing component B and mixing it with component A to prepare a lightweight UHPC substrate specifically includes the following steps: S4.1: Add the second premix prepared in step S3.4, the modified water-reducing agent prepared in step S2.6, the pre-wetted ceramic sand prepared in step S3.1, and 50-60% water to a concrete mixer and stir until thoroughly mixed. S4.2: Add the first premix prepared in step S3.2 and the remaining water into a concrete mixer and continue stirring until uniformly mixed to obtain component B; S4.3: Add component A prepared in step S1.5 to component B and continue stirring to mix evenly to obtain a concrete slurry; S4.4: Pour the concrete slurry into the mold and pour it. Then, connect a vibrator to the outer wall of the mold to vibrate the concrete slurry in the mold at a high frequency and a small amplitude. S4.5: Curing for 16-22 days at a temperature of 18-20°C and a humidity of 94-98%. After demolding, a lightweight UHPC substrate is obtained.

6. The process for preparing a lightweight lane slab for an underground tunnel based on UHPC according to claim 5, characterized in that: Step S5 of adding fine ceramic sand to prepare the anti-slip coating and spraying it specifically includes the following steps: S5.1: Add polyurethane resin and polyester resin to the paint mixing tank and stir at a rate of 1200-1300 rpm for 1-2 hours to ensure thorough and uniform mixing; S5.2: Add the thixotropic agent, filler, antioxidant, dispersant, defoamer, leveling agent, and 60-70% diluent to the paint mixing tank. Adjust the stirring speed to 1800-2000 rpm and continue stirring for 30-40 minutes to obtain the third premix. S5.3: Pour the third premix into a grinder and grind for 20-30 minutes. Then add the remaining diluent into the grinder and stir evenly to obtain a mixed slurry. S5.4: Pour the mixed slurry back into the paint tank, add the curing agent and fine ceramic sand into the paint tank, and stir thoroughly to obtain the anti-slip coating; S5.5: Evenly spray the anti-slip coating onto the upper surface of the UHPC substrate using a spray gun. After curing, a single-layer coating is formed on the upper surface of the UHPC substrate. S5.6: A layer of anti-slip coating is evenly sprayed on the surface of the above single-layer coating again. After curing, a composite coating is formed on the upper surface of the UHPC substrate to obtain a lightweight driveway board.

7. The process for preparing a lightweight lane slab for an underground tunnel based on UHPC according to claim 5, characterized in that: Component B includes 450-550 parts of the first premix, 50-60 parts of the second premix, 20-30 parts of a modified water reducer, 150-180 parts of pre-wetted pottery sand and 180-200 parts of water, and the mass ratio of component A to component B is 1:80-90.

8. The process for preparing a lightweight lane slab for an underground tunnel based on UHPC according to claim 6, characterized in that: The anti-slip coating comprises 70-80 parts of polyurethane resin, 50-60 parts of polyester resin, 3-5 parts of thixotropic agent, 8-10 parts of filler, 1-2 parts of antioxidant, 2-3 parts of dispersant, 1-2 parts of defoaming agent, 1-2 parts of leveling agent, 30-40 parts of diluent, 6-8 parts of curing agent and 20-28 parts of fine ceramic sand.

9. The process for preparing a lightweight lane slab for an underground tunnel based on UHPC according to claim 4, characterized in that: The particle size of coarse pottery sand is 2-4mm.

10. The process for preparing a lightweight lane slab for an underground tunnel based on UHPC according to claim 6, characterized in that: The particle size of fine ceramic sand is 300-360μm.

Images