A robust ultra-high performance concrete and a preparation method and application thereof

Abstract

This invention relates to a robust ultra-high performance concrete (UHPC), its preparation method, and its application, and relates to the field of concrete technology. Through optimized combination of core materials and regulation with a specialized polycarboxylate superplasticizer, this UHPC achieves a spread of no less than 600 mm, a minimum 2-hour workability loss of 0 mm, an initial setting time exceeding 6 hours, a final setting time exceeding 8 hours, a compressive strength exceeding 170 MPa after 28 days of standard curing, and a flexural strength exceeding 25 MPa, achieving a synergistic effect of excellent and robust workability and ultra-high strength.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, and specifically to a robust ultra-high performance concrete, its preparation method, and its applications. Background Technology

[0002] As buildings increasingly move towards higher heights and larger spans, higher demands are being placed on concrete, the most crucial component of buildings. To meet the needs of modern building development, concrete has gradually transitioned from ordinary concrete and high-performance concrete to ultra-high-performance concrete (UHPC). Since its introduction, UHPC has received widespread attention due to its advantages such as high strength, lightweight, and high toughness, leading to its increasingly wide range of applications.

[0003] The UHPC design process follows the closest packing design theory and eliminates coarse aggregates, which determines from the design source that UHPC has a high cementitious material content compared to ordinary concrete. The high cementitious material content, especially the high dosage of silica fume, is the source of UHPC strength, but it also brings negative effects, such as viscous UHPC paste, easy surface drying, and significant workability loss. Conventional methods involve adjusting the setting time of the water-reducing agent or increasing its dosage, but these operations cause strength loss in UHPC, especially under standard curing conditions, where the strength loss is more pronounced. Furthermore, excessive water-reducing agent dosage can also cause the paste to become viscous, which is detrimental to later construction.

[0004] Ordinary polycarboxylate superplasticizers are designed with a normal water-cement ratio (0.3-0.4). In the extremely low water-cement ratio environment of UHPC (Ultra-High Performance Concrete), the limited mixing water is competed for by a large number of powder particles, requiring the superplasticizer to provide stronger dispersing force to release the trapped water. This results in ineffective dispersion of ultrafine powders such as cement and silica fume, leading to extremely high slurry viscosity, poor fluidity, and difficulty in achieving self-compacting effects. Even with increased dosage, a saturation point is often encountered, beyond which fluidity no longer increases, and excessive air bubbles may even be introduced, reducing the later-stage hardening performance of the concrete. To address this issue, engineers have conducted numerous research studies. Among them, the patent "Ultra-High Performance Polycarboxylate Superplasticizer for UHPC and its Preparation Method" (patent number CN120349113A) proposes improving the dispersibility, impermeability, and fluidity of the superplasticizer by introducing nano-silica, ultrasonic dispersion technology, and low-temperature vacuum dehydration process. However, while this patent maintains UHPC workability, its strength is relatively low, all below 100 MPa, and strictly speaking, it does not fall within the UHPC category. The patent "A Concrete-Type UHPC Admixture" (patent number: CN120247448A) proposes a synergistic effect of modified water-reducing agent, slump retainer, and defoamer to achieve high workability and strength of UHPC. However, in the same patent example, the compressive strength after standard curing for 28 days is only about 130 MPa, which is relatively low.

[0005] Based on the above-mentioned problems, this patent proposes a highly workable and robust method for preparing ultra-high strength and high performance concrete. Through a close-packed mix design, a quaternary cementitious material system is formed, consisting of cement, fly ash microspheres, silica fume, and metakaolin, laying the foundation for rapid strength growth in UHPC. Simultaneously, a specialized water-reducing agent is developed, comprising a polycarboxylate polymer as the main agent, a slow-release slump-retaining component, a viscosity-reducing component, and an antifoaming component. The polycarboxylate polymer as the main agent is prepared through four steps: chain initiation, chain propagation, chain termination, neutralization, and post-treatment, enhancing the adsorption stability of the water-reducing agent molecules on cement particles, particularly its adsorption capacity in the presence of silica fume. The slow-release slump-retaining component has a pH-Ca... 2+ The dual-response mechanism intelligently adjusts its release rate and dispersion behavior according to the actual progress of cement hydration. This specialized water-reducing agent effectively reduces the viscosity of UHPC and maintains its workability for a long time, while having minimal impact on the UHPC hydration process, thus synergistically improving UHPC workability and high strength. Summary of the Invention

[0006] To address the aforementioned issues, this invention provides a robust ultra-high performance concrete (UHPC). Through optimized combination of core materials and regulation with a dedicated polycarboxylate superplasticizer, this UHPC exhibits a spread of no less than 600 mm, 0 mm workability loss over 2 hours, initial setting time exceeding 6 hours, final setting time exceeding 8 hours, compressive strength exceeding 170 MPa after 28 days of standard curing, and flexural strength exceeding 25 MPa, achieving a synergistic effect of excellent and robust workability and ultra-high strength.

[0007] This invention provides a robust ultra-high performance concrete, comprising the following raw materials in the indicated weight proportions:

[0008] The raw materials for preparing the polycarboxylate superplasticizer include: polycarboxylate polymer main agent, slow-release slump-retaining component, viscosity-adjusting component, and defoaming component; the weight ratio of the polycarboxylate polymer main agent, slow-release slump-retaining component, viscosity-adjusting component, and defoaming component is (650-850):(120-165):(1.5-2.5):(0.5-1.2).

[0009] In one embodiment, the raw materials for preparing the polycarboxylic acid polymer master agent include: oxidant, reducing agent, reactive monomer, chain transfer agent, and neutralizing agent; The mass ratio of the oxidant, reducing agent, reactant 1, reactant 2, macromonomer, chain transfer agent, and neutralizing agent is (2-3):(0.4-1):(20-30):(4-7):(200-350):(3-5):(40-60). The oxidant includes ammonium persulfate, the reducing agent includes vitamin C, the reactive monomer 1 includes acrylic acid, the reactive monomer 2 includes 2-acrylamide-2-methylpropanesulfonic acid, the macromonomer includes isopentenyl polyoxyethylene ether, the chain transfer agent includes mercaptopropionic acid, and the neutralizing agent includes sodium hydroxide.

[0010] In one embodiment, the raw materials for preparing the sustained-release slump-preserving component include: reactive monomers, chain transfer agents, oxidants, and reducing agents; the reactive monomers include: framework monomers, anchoring monomers, stabilizing monomers, and smart-response monomers. The molar ratio of the skeleton unit, anchoring unit, stabilizing unit, and smart response unit is 1:(0.5-3.5):(0.03-0.3):(0.05-0.5); The chain transfer agent accounts for 0.8% to 1.5% of the mass of the reactant monomer, the oxidant accounts for 0.8% to 1.2% of the mass of the reactant monomer, and the reducing agent accounts for 0.3% to 0.6% of the mass of the reactant monomer.

[0011] In one embodiment, the skeleton monomer includes isopentenyl polyoxyethylene ether, the anchoring monomer includes acrylic acid, the stabilizing monomer includes 2-acrylamide-2-methylpropanesulfonic acid, and the smart responsive monomer includes ethylene glycol acetoacetate methacrylate. The chain transfer agent includes mercaptopropionic acid, the oxidizing agent includes hydrogen peroxide, and the reducing agent includes vitamin C.

[0012] In one embodiment, the viscosity-adjusting component includes at least one of polyethylene glycol and hydroxypropyl methylcellulose; the defoaming component includes at least one of silicone defoamer and polyether defoamer.

[0013] In one embodiment, the cement includes at least one of P.II, P·IIR, and P·O cements with a strength grade ≥52.5; the fly ash microspheres are cenospheres; the silica fume contains ≥95% silica by mass; the metakaolin contains ≥50% silica by mass and has a mesh size ≥400 mesh; The quartz sand includes quartz sand with a fineness modulus of 2.6 to 3.0; The steel fiber is copper-plated steel fiber.

[0014] In one embodiment, the quartz sand has a mud content (by mass) of 0% and a strength loss of ≤8%; the steel fiber has a length of 13.0 mm and an aspect ratio of 60.0.

[0015] The present invention also provides a method for preparing the UHPC, comprising the following steps: mixing cement, fly ash microspheres, silica fume, metakaolin, and quartz sand, stirring, adding water and polycarboxylate superplasticizer, stirring, adding steel fibers, stirring, and obtaining ultra-high performance concrete.

[0016] In one embodiment, the preparation method of the polycarboxylate superplasticizer includes the following steps: preparing a polycarboxylate polymer main agent, preparing a slow-release slump-retaining component, mixing the polycarboxylate polymer main agent and the slow-release slump-retaining component, stirring, adding a viscosity adjusting component, stirring until dissolved, adding an antifoaming component, stirring, adding water, stirring, and obtaining the polycarboxylate superplasticizer. The preparation of the polycarboxylic acid polymer main agent includes: dissolving an oxidant to obtain an oxidant solution, dissolving a reducing agent to obtain a reducing agent solution, dissolving a macromonomer, heating under a protective atmosphere, adding reactant 1 and reactant 2 to obtain a monomer solution; adding and mixing the monomer solution, oxidant solution, and reducing agent solution dropwise to react and obtain a reaction solution, cooling, adding a neutralizing agent, adjusting the pH value, and obtaining the polycarboxylic acid polymer main agent; The preparation of the sustained-release slump-retaining component includes: dissolving the reactant and chain transfer agent in water, adjusting the pH to 5-6 to obtain solution A, dissolving the oxidant in water to obtain solution B, dissolving the reducing agent in water to obtain solution C, adding solutions A, B, and C dropwise to water, reacting under a protective atmosphere, cooling, and neutralizing to a pH of 6.5-7.5 to obtain the sustained-release slump-retaining component.

[0017] In one embodiment, in the step of preparing the polycarboxylic acid polymer main agent, the temperature of the dropwise mixing is 35-60°C and the time is 2.5-3 hours; the temperature of the reaction is 60-65°C and the time is 1-2 hours; and the pH value is adjusted to 6.0-7.5. In the step of preparing the sustained-release slump-preserving component, the dropwise addition time is 3-3.5 h, and the reaction conditions include: temperature 60±2℃, reaction time 1-2 h; the cooling temperature is ≤40℃.

[0018] The present invention also provides a building material, including the aforementioned ultra-high performance concrete.

[0019] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a robust ultra-high performance concrete (UHPC), its preparation method, and its application. On one hand, the UHPC core material is composed of cement, fly ash microspheres, silica fume, and metakaolin, providing a sufficient driving force for rapid strength growth and ensuring rapid strength development. On the other hand, addressing the issue of the high cementitious material content in UHPC leading to a very viscous fresh concrete mix, especially with the presence of large amounts of silica fume, which further exacerbates the workability maintenance problem, this invention proposes a dedicated ultra-high performance polycarboxylate superplasticizer. This polycarboxylate superplasticizer mainly consists of a polycarboxylate polymer, a slow-release slump-retaining component, a viscosity-regulating component, an antifoaming component, and water. The polymer enhances the adsorption stability of the superplasticizer with cement particles, especially its adsorption capacity in the presence of silica fume. Simultaneously, the slow-release slump-retaining component achieves optimal pH and Ca2+ levels. 2+ "The dual-response release mechanism, combined with the presence of viscosity-adjusting components, effectively avoids the problems of excessive viscosity and rapid workability loss in freshly mixed UHPC slurry, while the defoaming component ensures the density of UHPC. Through the optimized combination of core materials and the regulation of special water-reducing agents, UHPC achieves a spread of no less than 600mm, a minimum 2-hour workability loss of 0mm, an initial setting time of over 6 hours, a final setting time of over 8 hours, a compressive strength of over 170MPa after 28 days of standard curing, and a flexural strength of over 25MPa, achieving a synergy of excellent and robust workability and ultra-high strength." Detailed Implementation

[0020] To facilitate understanding of the present invention, a more complete description will be given below with reference to relevant embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] Unless otherwise specified, all reagents, materials, and equipment used in this embodiment are commercially available; unless otherwise specified, all test methods are conventional test methods in this field.

[0023] Example 1 A UHPC based on polycarboxylate superplasticizer and its preparation method.

[0024] The specific preparation method of this UHPC is as follows: I. Preparation of polycarboxylate superplasticizer.

[0025] The polycarboxylate superplasticizer mainly comprises a polycarboxylate polymer, a slow-release slump-preserving component, a viscosity-regulating component, and an antifoaming component. The aforementioned polycarboxylate polymer is a terpolymer formed by free radical copolymerization of unsaturated polyether macromonomers, unsaturated hydroxy acid monomers, and sulfonic acid functional monomers in aqueous solution. The reaction process is divided into four stages.

[0026] Phase 1: Chain Trigger The goal of this stage is to generate enough free radicals to initiate the polymerization reaction. The reaction temperature is controlled between 25-35℃, and the pH value is controlled between 5-7. The reaction process is as follows: (a) Oxidative decomposition: Ammonium persulfate decomposes upon heating, producing primary free radicals.

[0027] (b) Reducing agent effect: Vitamin C reacts with oxidants or their decomposition products to form redox reactions, generating more active free radicals. This reaction can be carried out at lower temperatures and is more efficient.

[0028]

[0029] (c) Initiation of monomer: The generated sulfate anion radical attacks the double bond of the monomer, forming a monomer radical. The reaction is as follows:

[0030] Phase Two: Chain Growth The monomer radical undergoes successive addition reactions with other monomer molecules, resulting in rapid polymer chain growth. The reaction conditions are as follows: (a) Temperature: 35-60℃.

[0031] (b) Key step - Monomer addition: Mix AA, AMPS and some chain transfer agent, and add them separately, synchronously and slowly to the aqueous solution of macromonomer (TPEG) along with the initiator solution (i.e., the monomer radicals generated in steps a, b and c of stage one).

[0032] (c) Stirring: Stir at medium to high speed to ensure uniform mixing and prevent local overheating or excessive monomer concentration.

[0033] Overall reaction equation: In the presence of a free radical initiator (i.e., monomer free radicals generated in steps a, b, and c of stage 1), the three monomers form a random copolymer through free radical copolymerization. The overall reaction can be expressed as: -

[0034] Where: M aa Represents the acrylic acid unit: -CH2-CH(COOH)- Mamps represents the AMPS unit: -CH2-CH(C(O)NH-C(CH3)2-CH2-SO3H) - Mp represents the TPEG macromonomer unit: -CH2-CH(CH2-(OCH2CH2) n -OH) - x, y, and z represent the molar ratios of each monomer, and the sequence is randomly distributed.

[0035] Chain growth response mechanism: The general formula for chain growth steps is: Where P· is the growing chain radical and M is any monomer, the chain growth process reaction formula is as follows:

[0036] This step primarily achieves the formation of double bonds between acrylic acid radicals (from chain growth) and AMPS monomers, forming new AMPS units, with the radicals transferring to the AMPS units.

[0037] Reaction of growth chain free radicals with TPEG macromonomers:

[0038] This process mainly involves AMPS radicals attacking the double bonds of TPEG monomers to form new TPEG units, with the radicals then transferring to the TPEG units.

[0039] The reaction of growth chain free radicals with acrylic acid monomers:

[0040] The reaction primarily enables TPEG radicals to attack the double bonds of acrylic acid monomers, forming new acrylic acid units, and then the radicals transfer to the acrylic acid units.

[0041] Phase 3: Chain Termination This stage mainly involves the meeting of two growing polymer chain free radicals, which then stop the chain growth through coupling termination.

[0042] Reaction conditions: After all materials have been added dropwise, continue to maintain the temperature at 60-65℃ for 1-2 hours to allow the remaining monomers and initiators to react fully, thereby improving monomer conversion and reducing the free monomer content in the product. The reaction formula is as follows:

[0043] The complete reaction equation is as follows:

[0044] Phase Four: Neutralization and Post-processing This stage does not involve polymerization; it primarily involves neutralization reactions, as shown in the following equation:

[0045] Reaction conditions: Temperature: Cool to below 40°C before neutralization. This prevents exothermic neutralization and polymer hydrolysis or degradation at high pH and high temperatures.

[0046] Neutralizing agent: Usually a 30% NaOH aqueous solution is used; Neutralization: Control the pH value to 6.0-7.5; Dilution: Add deionized water according to the solid content requirements to adjust to the target concentration.

[0047] II. Preparation of sustained-release slump-preserving components.

[0048] The slow-release slump-retaining component is a smart polymer with a dual-response slow-release function of "pH-calcium ion". It can achieve dual-triggered release of "time-hydration process", and the slump-retaining effect is dynamically matched with the actual hydration state of cement. It can better cope with the workability loss caused by cement type and temperature changes. Its synthesis process is as follows: 1) Constituent materials Backbone monomer: TPEG (isoprenol polyoxyethylene ether) - provides steric hindrance to the backbone; Anchoring monomer: Acrylic acid (AA) - provides initial adsorption groups; Stabilizing monomer: 2-Acrylamide-2-methylpropanesulfonic acid (AMPS) - provides sulfonic acid groups, enhancing salt resistance; Smart responsive monomer: Ethylene glycol acetoacetate methacrylate (AAEM) - provides both ester and β-diketone groups.

[0049] 2) Control of preparation process and reaction conditions Raw material ratio (molar ratio): TPEG:AA:AMPS:AAEM=1:(0.5-3.5):(0.03-0.3):(0.05-0.5); Chain transfer agent (mercaptopropionic acid): 0.8%~1.5% of the total monomer mass; Oxidizing agent (H2O2, 30%): accounting for 0.8%~1.2% of the total monomer mass; Reducing agent (vitamin C): accounting for 0.3%~0.6% of the total mass of monomers; Solvent: Deionized water, with a solid content controlled at 40%~50%.

[0050] Synthesis steps: Bottom water preparation and preheating: Add some bottom water to a four-hole shovel equipped with a stirrer, thermometer, constant pressure dropping funnel and nitrogen inlet tube, remove oxygen by nitrogen, and slowly raise the temperature to 60±2℃. Dropwise addition reaction: Dissolve TPEG, AA, AMPS, AAEM and chain transfer agent in the remaining water, adjust the pH to 5-6 with alkali, and prepare monomer mixed aqueous solution A; dissolve oxidant (H2O2) in a small amount of water to prepare solution B, and dissolve reducing agent (vitamin C) in water to prepare solution C; simultaneously and uniformly add solutions A and B to the reaction flask over 3-3.5 hours through two titration funnels, and solution C through another titration funnel, while maintaining the reaction temperature at 60±2℃; Incubation and ripening: After the addition is complete, keep the reaction at 60±2℃ for 1.5h; Cooling and neutralization: Cool the reaction system to below 40°C and neutralize it with 30% sodium hydroxide solution to pH 6.5-7.5 to obtain a slightly yellow or colorless transparent viscous liquid, which is the slow-release slump-preserving component.

[0051] 3. The viscosity-adjusting component is one or both of polyethylene glycol and hydroxypropyl methylcellulose.

[0052] IV. The defoaming component is one of the following: silicone defoamer or polyether defoamer.

[0053] V. Preparation of UHPC based on polycarboxylate superplasticizer.

[0054] Weigh the raw materials for the concrete according to the design mix proportions. The raw materials and their weight proportions are shown below:

[0055] Add the weighed raw materials into the mixer as sand-cementing materials and mix for 1 minute; Add the weighed water and water-reducing agent, and stir for 3 minutes; Add the weighed steel fibers and stir for 4 minutes; Ultra-high performance concrete paste was obtained.

[0056] The aforementioned cement includes at least one of P.II, P·IIR, and P·O cements with a strength grade ≥52.5; the fly ash microspheres are cenospheres; the silica fume contains ≥95% silica by mass; the metakaolin contains ≥50% silica by mass and has a mesh size ≥400 mesh; the quartz sand includes quartz sand with a fineness modulus of 2.6~3.0; and the steel fiber is copper-plated steel fiber.

[0057] Experimental Example 1 The preparation method and raw materials of Example 1 were used.

[0058] Taking the production of 1000kg of 40% concentration dual-response intelligent slump-preserving UHPC-specific water-reducing agent as an example: 1. Preparation of the main component of the water-reducing agent: Add 320 kg of deionized water and 289.0 kg of isopentenyl alcohol polyoxyethylene ether TPEG (macromonomer) to a reactor, stir at medium to high speed, purge with nitrogen for protection, and slowly heat to 35°C. Mix 26.0 kg of acrylic acid AA (monomer), 5.0 kg of 2-acrylamide-2-methylpropanesulfonic acid AMPS (monomer), and 3.84 kg of mercaptopropionic acid MPA (chain transfer agent) with 35 kg of deionized water, stir and dissolve evenly to prepare solution A (monomer solution); Solution B (oxidizing agent solution) was prepared by dissolving 2.56 kg of ammonium persulfate (APS) (oxidizing agent) in 48.64 kg of deionized water. 0.64kg V C The reducing agent was dissolved in 12.16 kg of deionized water to prepare solution C (reducing agent solution).

[0059] Solutions A, B, and C are added dropwise to the reaction vessel separately, simultaneously, and slowly, maintaining a temperature of 35-60℃ and stirring at medium-high speed for 2.5-3 hours. After all materials have been added, the reaction system temperature is raised to 60-65℃ and the reaction is allowed to proceed for 1.5 hours. The reaction solution is then cooled to below 40℃, and 48.1 kg of a 30% sodium hydroxide solution (neutralizing agent) is slowly added to adjust the pH to 6.0-7.5. This yields a polycarboxylate polymer main agent solution.

[0060] In this embodiment, the mass ratio of oxidant, reducing agent, reactive monomer 1, reactive monomer 2, macromonomer, chain transfer agent, and neutralizing agent is 2.56:0.64:26:5:289:3.84:48.1.

[0061] 2. Synthesis of the slow-release slump-preserving component: Add 35.0 kg of deionized water to a reactor, purge with nitrogen, and heat to 60 ± 2℃; mix 70.8 kg of isopentenyl alcohol polyoxyethylene ether (TPEG) (skeletal monomer), 6.38 kg of acrylic acid (AA) (anchoring monomer), 1.22 kg of 2-acrylamide-2-methylpropanesulfonic acid (AMPS) (stabilizing monomer), 1.62 kg of acetoacetic acid methacrylate (AAEM) (smart responsive monomer), and 0.92 kg of mercaptopropionic acid (MPA) (chain transfer agent) with 23.3 kg of deionized water. Adjust the pH of the mixture to 5-6 with a small amount of 30% NaOH solution, stir evenly, and prepare solution A (monomer solution); 0.80 kg of 30% H2O2 solution (oxidant) is the oxidant solution B; add 0.36 kg of V... C (Reducing agent) is dissolved in 6.84 kg of deionized water to prepare solution C (reducing agent solution); Solutions A, B, and C were simultaneously and uniformly added to the reaction vessel through three dropping channels over 3-3.5 hours, with good stirring maintained. After the addition was complete, the reaction was continued at a constant temperature of 60±2℃ for 1.5 hours. The reaction solution was then cooled to below 40℃, and 11.8 kg of 30% sodium hydroxide solution (neutralizing agent) was added to adjust the pH to 6.5-7.5, yielding a slow-release, slump-preserving component solution.

[0062] In this embodiment, the molar ratio of the skeleton monomer, anchoring monomer, stabilizing monomer, and smart responsive monomer is 1:0.74:0.05:0.06. The chain transfer agent accounts for 1.15% of the mass of the reactants, the oxidant accounts for 1.00% of the mass of the reactants, and the reducing agent accounts for 0.45% of the mass of the reactants.

[0063] 3. Preparation of polycarboxylate superplasticizer: In a sufficiently large mixing vessel, add 791.0 kg of polycarboxylate polymer main agent solution and 159.0 kg of slow-release slump-retaining component solution sequentially. Start stirring, and add 2.0 kg of PEG-400 (viscosity adjusting component) and 0.8 kg of polyether defoamer (defoaming component) sequentially at room temperature. Add 47.2 kg of deionized water to make up the difference, and continue stirring for at least 30 minutes to ensure uniform mixing. A polycarboxylate superplasticizer with a concentration of 40.0 ± 5% is obtained. In this embodiment, the weight ratio of polycarboxylate polymer auxiliary agent, slow-release slump-retaining component, viscosity adjusting component, and defoaming component is 791:159:2:0.8.

[0064] 4. Preparation of UHPC: Weigh out water according to mass: 165 kg / m³ 3 Cement: 682 kg / m³ 3 Fly ash microspheres: 165 kg / m³ 3 Silica fume: 198 kg / m³ 3 Soil of relatively high age: 55 kg / m³ 3 Quartz sand: 1214 kg / m³ 3 Steel fiber: 156kg / m 3 Polycarboxylate superplasticizer: 13kg / m 3 In this embodiment, the weight ratio of water, cement, fly ash microspheres, silica fume, metakaolin, quartz sand, steel fiber, and polycarboxylate superplasticizer is 165:682:165:198:55:1214:156:13.

[0065] First, add quartz sand to the mixing pot, then add all the cementitious materials and stir for 1 minute. Dissolve the water-reducing agent in water and add it to the mixing pot, stir for 4 minutes. Then, use a sieve to slowly disperse the steel fibers in the mixing pot and stir for 2 minutes to obtain UHPC. Test its expansion and loss over time, and then mold concrete specimens.

[0066] Experimental Example 2 The preparation method and raw materials of Example 1 were used.

[0067] Taking the production of 1000kg of 35% concentration dual-response intelligent slump-preserving UHPC-specific water-reducing agent as an example: 1. Preparation of the main water-reducing agent: Add 280 kg of deionized water and 252.9 kg of TPEG (macromonomer) to a reactor, stir at medium to high speed, purge with nitrogen for protection, and slowly heat to 35°C. Mix 22.8 kg of acrylic acid AA (monomer), 4.4 kg of 2-acrylamide-2-methylpropanesulfonic acid AMPS (monomer), and 3.36 kg of mercaptopropionic acid MPA (chain transfer agent) with 30.6 kg of deionized water, stir and dissolve evenly to prepare solution A (monomer solution); 2.24 kg of ammonium persulfate (APS) (oxidant) was dissolved in 42.6 kg of deionized water to prepare solution B (oxidant solution); 0.56kgV C The reducing agent was dissolved in 10.6 kg of deionized water to prepare solution C (reducing agent solution).

[0068] Solutions A, B, and C are added dropwise to the reaction vessel separately, simultaneously, and slowly, maintaining a temperature of 35-60℃ and stirring at medium-high speed for 2.5-3 hours. After all materials have been added, the reaction system temperature is raised to 60-65℃ and the reaction is allowed to proceed for 1.5 hours. The reaction solution is then cooled to below 40℃, and 42.1 kg of a 30% sodium hydroxide solution (neutralizing agent) is slowly added to adjust the pH to 6.0-7.5. This yields a polycarboxylate polymer main agent solution.

[0069] In this embodiment, the mass ratio of oxidant, reducing agent, reactive monomer 1, reactive monomer 2, macromonomer, chain transfer agent, and neutralizing agent is 2.24:0.56:22.8:4.4:252.9:3.36:42.1.

[0070] 2. Synthesis of the slow-release slump-preserving component: Add 35.0 kg of deionized water to a reactor, purge with nitrogen, and heat to 60 ± 2℃; mix 62.0 kg of isopentenyl alcohol polyoxyethylene ether (TPEG) (skeletal monomer), 5.58 kg of acrylic acid (AA) (anchoring monomer), 1.07 kg of 2-acrylamide-2-methylpropanesulfonic acid (AMPS) (stabilizing monomer), 1.42 kg of acetoacetic acid methacrylate (AAEM) (smart responsive monomer), and 0.805 kg of mercaptopropionic acid (MPA) (chain transfer agent) with 20.4 kg of deionized water. Adjust the pH of the mixture to 5-6 with a small amount of 30% NaOH solution, stir evenly, and prepare solution A (monomer solution); 0.70 kg of 30% H2O2 solution (oxidant) is the oxidant solution B; add 0.315 kg of V... C(Reducing agent) is dissolved in 6.0 kg of deionized water to prepare solution C (reducing agent solution); Solutions A, B, and C were simultaneously and uniformly added to the reaction vessel through three dropping channels over 3-3.5 hours, with good stirring maintained. After the addition was complete, the reaction was continued at a constant temperature of 60±2℃ for 1.5 hours. The reaction solution was then cooled to below 40℃, and 10.3 kg of 30% sodium hydroxide solution (neutralizing agent) was added to adjust the pH to 6.5-7.5, yielding a slow-release, slump-preserving component solution.

[0071] In this embodiment, the molar ratio of the skeleton monomer, anchoring monomer, stabilizing monomer, and smart responsive monomer is 1:0.74:0.05:0.06. The chain transfer agent accounts for 1.15% of the mass of the reactants, the oxidant accounts for 1% of the mass of the reactants, and the reducing agent accounts for 0.45% of the mass of the reactants.

[0072] 3. Preparation of polycarboxylate superplasticizer: In a sufficiently large mixing vessel, add the polycarboxylate polymer main agent solution (692.0 kg) and the slow-release slump-retaining component solution (139.0 kg) sequentially. Start stirring, and at room temperature, add 2.0 kg of PEG-400 (viscosity adjusting component) and 0.8 kg of polyether defoamer (defoaming component). Add 166.2 kg of deionized water to make up the difference, and continue stirring for at least 30 minutes to ensure uniform mixing. A polycarboxylate superplasticizer with a concentration of 35.0 ± 5% is obtained.

[0073] In this embodiment, the weight ratio of polycarboxylate polymer additive, slow-release slump-preserving component, viscosity-modifying component, and defoaming component is 692:139:2:0.8.

[0074] 4. Preparation of UHPC: Weigh out water according to mass: 165 kg / m³ 3 Cement: 682 kg / m³ 3 Fly ash microspheres: 165 kg / m³ 3 Silica fume: 198 kg / m³ 3 Soil of relatively high age: 55 kg / m³ 3 Quartz sand: 1214 kg / m³ 3 Steel fiber: 156kg / m 3 Polycarboxylate superplasticizer: 15kg / m 3 .

[0075] In this embodiment, the weight ratio of water, cement, fly ash microspheres, silica fume, metakaolin, quartz sand, steel fiber, and polycarboxylate superplasticizer is 165:682:165:198:55:1214:156:15.

[0076] First, add quartz sand to the mixing pot, then add all the cementitious materials and stir for 1 minute. Dissolve the water-reducing agent in water and add it to the mixing pot, stir for 4 minutes. Then, use a sieve to slowly disperse the steel fibers in the mixing pot and stir for 2 minutes to obtain UHPC. Test its expansion and loss over time, and then mold concrete specimens.

[0077] Experimental Example 3 The preparation method and raw materials of Example 1 were used.

[0078] Taking the production of 1000kg of 45% concentration dual-response intelligent slump-preserving UHPC-specific water-reducing agent as an example: 1. Preparation of the main component of the water-reducing agent: Add 100 kg of deionized water and 325.1 kg of isopentenyl alcohol polyoxyethylene ether TPEG (macromonomer) to a reactor, stir at medium to high speed, purge with nitrogen for protection, and slowly heat to 35°C. Mix 29.3 kg of acrylic acid AA (monomer), 6.4 kg of 2-acrylamide-2-methylpropanesulfonic acid AMPS (monomer), and 4.32 kg of mercaptopropionic acid MPA (chain transfer agent) with 35.0 kg of deionized water, stir and dissolve evenly to prepare solution A (monomer solution); 2.88 kg of ammonium persulfate (APS) (oxidant) was dissolved in 50.0 kg of deionized water to prepare solution B (oxidant solution). 0.72kg V C The reducing agent is dissolved in 12.0 kg of deionized water to prepare solution C (reducing agent solution).

[0079] Solutions A, B, and C are added dropwise to the reaction vessel separately, simultaneously, and slowly, maintaining a temperature of 35-60℃ and stirring at medium-high speed for 2.5-3 hours. After all materials have been added, the reaction system temperature is raised to 60-65℃ and the reaction is allowed to proceed for 1.5 hours. The reaction solution is then cooled to below 40℃, and 54.1 kg of 30% sodium hydroxide solution (neutralizing agent) is slowly added to adjust the pH to 6.0-7.5. This yields a polycarboxylate polymer main agent solution.

[0080] In this embodiment, the mass ratio of oxidant, reducing agent, reactive monomer 1, reactive monomer 2, macromonomer, chain transfer agent, and neutralizing agent is 2.88:0.72:29.3:6.4:325.1:4.32:54.1.

[0081] 2. Synthesis of the slow-release slump-preserving component: Add 30.0 kg of deionized water to a reactor, purge with nitrogen, and heat to 60 ± 2℃; mix 79.7 kg of isopentenyl alcohol polyoxyethylene ether (TPEG) (skeletal monomer), 7.18 kg of acrylic acid AA (anchoring monomer), 1.37 kg of 2-acrylamide-2-methylpropanesulfonic acid AMPS (stabilizing monomer), 1.82 kg of acetoacetic acid methacrylate ethylene glycol ester (AAEM) (smart responsive monomer), and 1.035 kg of mercaptopropionic acid MPA (chain transfer agent) with 18.0 kg of deionized water. Adjust the pH of the mixture to 5-6 with a small amount of 30% NaOH solution, stir evenly, and prepare solution A (monomer solution); 0.90 kg of 30% H2O2 (oxidant) solution is oxidant solution B; add 0.405 kg of V C (Reducing agent) is dissolved in 7.0 kg of deionized water to prepare solution C (reducing agent solution); Solutions A, B, and C were simultaneously and uniformly added to the reaction vessel through three dropping channels over 3-3.5 hours, with good stirring maintained. After the addition was complete, the reaction was continued at a constant temperature of 60±2℃ for 1.5 hours. The reaction solution was then cooled to below 40℃, and 13.3 kg of 30% sodium hydroxide solution (neutralizing agent) was added to adjust the pH to 6.5-7.5, yielding a slow-release, slump-preserving component solution.

[0082] In this embodiment, the molar ratio of the skeleton monomer, anchoring monomer, stabilizing monomer, and smart responsive monomer is 1:0.74:0.05:0.06. The chain transfer agent accounts for 1.15% of the mass of the reactants, the oxidant accounts for 1% of the mass of the reactants, and the reducing agent accounts for 0.45% of the mass of the reactants.

[0083] 3. Preparation of polycarboxylate superplasticizer: In a sufficiently large mixing vessel, add the polycarboxylate polymer main agent solution (720.0 kg) and the slow-release slump-retaining component solution (150.0 kg) sequentially. Start stirring, and at room temperature, add 2.0 kg of PEG-400 (viscosity adjusting component) and 0.8 kg of polyether defoamer (defoaming component). Add 267.0 kg of deionized water to make up the difference, and continue stirring for at least 30 minutes to ensure uniform mixing. A polycarboxylate superplasticizer with a concentration of 45.0 ± 5% is obtained.

[0084] In this embodiment, the weight ratio of the polycarboxylate polymer main agent, the slow-release slump-preserving component, the viscosity-adjusting component, and the defoaming component is 720:150:2:0.8.

[0085] 4. Preparation of UHPC: Weigh out water according to mass: 165 kg / m³ 3 Cement: 682 kg / m³ 3 Fly ash microspheres: 165 kg / m³ 3Silica fume: 198 kg / m³ 3 Soil of relatively high age: 55 kg / m³ 3 Quartz sand: 1214 kg / m³ 3 Steel fiber: 156kg / m 3 Polycarboxylate superplasticizer: 10kg / m 3 .

[0086] In this embodiment, the weight ratio of water, cement, fly ash microspheres, silica fume, metakaolin, quartz sand, steel fiber, and polycarboxylate superplasticizer is 165:682:165:198:55:1214:156:10.

[0087] First, add quartz sand to the mixing pot, then add all the cementitious materials and stir for 1 minute. Dissolve the water-reducing agent in water and add it to the mixing pot, stir for 4 minutes. Then, use a sieve to slowly disperse the steel fibers in the mixing pot and stir for 2 minutes to obtain UHPC. Test its expansion and loss over time, and then mold concrete specimens.

[0088] Experiment Example 4 Water was weighed and collected separately: 165 kg / m³ 3 Cement: 682 kg / m³ 3 Fly ash microspheres: 165 kg / m³ 3 Silica fume: 198 kg / m³ 3 Soil of relatively high age: 55 kg / m³ 3 Quartz sand: 1214 kg / m³ 3 Steel fiber: 156kg / m 3 Water-reducing agent: 25kg / m³ 3 The water-reducing agent is a common polycarboxylate water-reducing agent with a solid content of 40%.

[0089] First, add quartz sand to the mixing pot, then add all the cementitious materials and stir for 1 minute. Dissolve the water-reducing agent in water and add it to the mixing pot, stir for 4 minutes. Then, use a sieve to slowly disperse the steel fibers in the mixing pot and stir for 2 minutes to obtain UHPC. Test its expansion and loss over time, and then mold concrete specimens.

[0090] Verification Example The performance of the UHPCs prepared for each experimental example was verified.

[0091] Test the fresh mixing performance and hardening properties of UHPC.

[0092] I. Verification method: Test according to the "Standard for Test Methods of Performance of Ordinary Concrete Mixtures" (GB / T 50080).

[0093] II. The performance test results are shown in the table below.

[0094] Table 1 Performance of Freshly Mixed Materials

[0095] Table 2 Hardening properties

[0096] As shown in Table 1, under the same spread, comparing Experiments 1, 2, and 3, it can be seen that as the solid content of the water-reducing agent increases, the 2-hour spread loss is basically the same, while the 4-hour spread loss decreases with increasing solid content. The main reason is that with the increase of solid content, the corresponding slow-release slump-preserving component increases. This situation also appears when comparing the initial and final setting times, indicating that the water-reducing agent can maintain the workability of UHPC well, and the effect increases with increasing solid content.

[0097] Comparing Experiments 1, 2, 3, and 4 in Table 1, it can be seen that although ordinary polycarboxylate superplasticizers can also make the UHPC expansion reach about 600mm, their workability is not stable, especially after 2 hours, the workability is reduced by half, and it is basically impossible to construct.

[0098] Comparing experimental examples 1, 2, and 3 in Table 2, it can be seen that as the solid content increases, the strength of UHPC first increases and then decreases. The maximum strength occurs when the solid content is 40% water-reducing agent. It can also be found that when the solid content is between 35% and 45%, the 28-day compressive strength of UHPC can exceed 170 MPa.

[0099] Comparing experimental examples 1, 2, 3, and 4 in Table 2, it can be seen that using a UHPC-specific water-reducing agent can maintain high workability and robustness while having little impact on the later-stage strength of UHPC, highlighting the advanced nature of the water-reducing agent proposed in this patent and the rationality of the mix design.

[0100] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0101] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A robust ultra-high performance concrete, characterized in that, The raw materials include the following parts by weight: The raw materials for preparing the polycarboxylate superplasticizer include: polycarboxylate polymer main agent, slow-release slump-retaining component, viscosity-adjusting component, and defoaming component; the weight ratio of the polycarboxylate polymer main agent, slow-release slump-retaining component, viscosity-adjusting component, and defoaming component is (650-850):(120-165):(1.5-2.5):(0.5-1.2).

2. The ultra-high performance concrete according to claim 1, characterized in that, The raw materials for preparing the polycarboxylic acid polymer master agent include: oxidizing agent, reducing agent, reactive monomer, chain transfer agent, and neutralizing agent; The mass ratio of the oxidant, reducing agent, reactant 1, reactant 2, macromonomer, chain transfer agent, and neutralizing agent is (2-3):(0.4-1):(20-30):(4-7):(200-350):(3-5):(40-60). The oxidant includes ammonium persulfate, the reducing agent includes vitamin C, the reactive monomer 1 includes acrylic acid, the reactive monomer 2 includes 2-acrylamide-2-methylpropanesulfonic acid, the macromonomer includes isopentenyl polyoxyethylene ether, the chain transfer agent includes mercaptopropionic acid, and the neutralizing agent includes sodium hydroxide.

3. The ultra-high performance concrete according to claim 1, characterized in that, The raw materials for preparing the sustained-release slump-preserving component include: reactive monomers, chain transfer agents, oxidants, and reducing agents; the reactive monomers include: framework monomers, anchoring monomers, stabilizing monomers, and smart responsive monomers. The molar ratio of the skeleton unit, anchoring unit, stabilizing unit, and smart response unit is 1:(0.5-3.5):(0.03-0.3):(0.05-0.5); The chain transfer agent accounts for 0.8% to 1.5% of the mass of the reactant monomer, the oxidant accounts for 0.8% to 1.2% of the mass of the reactant monomer, and the reducing agent accounts for 0.3% to 0.6% of the mass of the reactant monomer.

4. The ultra-high performance concrete according to claim 3, characterized in that, The skeleton monomer includes isopentenyl polyoxyethylene ether, the anchoring monomer includes acrylic acid, the stabilizing monomer includes 2-acrylamide-2-methylpropanesulfonic acid, and the smart response monomer includes ethylene glycol acetoacetate methacrylate. The chain transfer agent includes mercaptopropionic acid, the oxidizing agent includes hydrogen peroxide, and the reducing agent includes vitamin C.

5. The ultra-high performance concrete according to claim 1, characterized in that, The viscosity-adjusting component includes at least one of polyethylene glycol and hydroxypropyl methylcellulose; the defoaming component includes at least one of silicone defoamer and polyether defoamer.

6. The ultra-high performance concrete according to claim 1, characterized in that, The cement includes at least one of P.II, P·IIR, and P·O cements with a strength grade ≥52.5; the fly ash microspheres are cenospheres; the silica fume contains ≥95% silica by mass; the metakaolin contains ≥50% silica by mass and has a mesh size ≥400 mesh; The quartz sand includes quartz sand with a fineness modulus of 2.6 to 3.0; The steel fiber is copper-plated steel fiber.

7. The method for preparing ultra-high performance concrete according to any one of claims 1-6, characterized in that, The process includes the following steps: mixing cement, fly ash microspheres, silica fume, metakaolin, and quartz sand, stirring, adding water and polycarboxylate superplasticizer, stirring, adding steel fibers, and stirring to obtain ultra-high performance concrete.

8. The preparation method according to claim 7, characterized in that, The preparation method of the polycarboxylate superplasticizer includes the following steps: preparing a polycarboxylate polymer main agent, preparing a slow-release slump-retaining component, mixing the polycarboxylate polymer main agent and the slow-release slump-retaining component, stirring, adding a viscosity adjusting component, stirring until dissolved, adding an antifoaming component, stirring, adding water, stirring, and obtaining the polycarboxylate superplasticizer. The preparation of the polycarboxylic acid polymer main agent includes: dissolving an oxidant to obtain an oxidant solution, dissolving a reducing agent to obtain a reducing agent solution, dissolving a macromonomer, heating under a protective atmosphere, adding reactant 1 and reactant 2 to obtain a monomer solution; adding and mixing the monomer solution, oxidant solution, and reducing agent solution dropwise to react and obtain a reaction solution, cooling, adding a neutralizing agent, adjusting the pH value, and obtaining the polycarboxylic acid polymer main agent; The preparation of the sustained-release slump-retaining component includes: dissolving the reactant and chain transfer agent in water, adjusting the pH to 5-6 to obtain solution A, dissolving the oxidant in water to obtain solution B, dissolving the reducing agent in water to obtain solution C, adding solutions A, B, and C dropwise to water, reacting under a protective atmosphere, cooling, and neutralizing to a pH of 6.5-7.5 to obtain the sustained-release slump-retaining component.

9. The preparation method according to claim 8, characterized in that, In the step of preparing the polycarboxylic acid polymer main agent, the temperature of the dropwise mixing is 35-60℃ and the time is 2.5-3h; the reaction temperature is 60-65℃ and the time is 1-2h; and the pH value is adjusted to 6.0-7.

5. In the step of preparing the sustained-release slump-preserving component, the dropwise addition time is 3-3.5 h, and the reaction conditions include: temperature 60±2℃, reaction time 1-2 h; the cooling temperature is ≤40℃.

10. A building material, characterized in that, Including the ultra-high performance concrete according to any one of claims 1-6.

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