A water-reducing shrinkage-reducing agent specially used for UHPC and its preparation method and application

Abstract

The invention discloses a special water-reducing shrinkage-reducing agent for UHPC and a preparation method and application thereof. The special water-reducing shrinkage-reducing agent for UHPC is mainly made of raw materials in the following molar ratios: 1.0 vinyl polyoxyethylene ether macromonomer, 3.0-8.0 unsaturated acid small monomers, 0.5-2.0 hydrophobic unsaturated small monomers, 0.05-0.30 initiators, and 0.05-0.20 chain transfer agents; wherein the hydrophobic unsaturated small monomers are mainly made of raw materials in the following molar ratios: 1.0 2-methyl-1,3-butadiene, and 1.0-1.05 unsaturated small monomers containing hydrophobic groups. The special water-reducing shrinkage-reducing agent for UHPC is used to prepare concrete. The present invention adopts the process of synthesizing the special water-reducing shrinkage-reducing agent for UHPC by Diels-Alder reaction and in-situ polymerization reaction, and the process is simple, which improves the shortcomings of the existing shrinkage-reducing agent in UHPC, such as slow dispersion speed, high viscosity, poor retention, and poor shrinkage crack resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of polycarboxylic acid-based water reducers, and in particular, relates to a UHPC-specific water-reducing shrinkage-reducing agent, a preparation method thereof, and an application thereof. Background Art

[0002] UHPC is an ultra-high strength cement-based material with high strength, high toughness and low porosity. Its basic formulation principle is to minimize the defects (pores and microcracks) inside the material by increasing the fineness and activity of the components and not using coarse aggregates, so as to obtain ultra-high strength and high durability.

[0003] UHPC has high durability, good workability and volume stability. With the development of modern concrete technology, it has been applied in engineering. Concrete made of mineral admixtures, high-performance water-reducing agents and ultra-low water-cement ratio improves the microstructure and has many excellent properties. However, the probability of shrinkage cracks increases, which may affect the appearance of the building more seriously than ordinary concrete, and pose a serious threat to the durability and service life of the structure. According to statistics, cracking of concrete structure is caused by deformation, and the volume deformation of concrete is mainly manifested as shrinkage. The problem of early cracking must be solved before it can be widely promoted and applied.

[0004] The most common solution to the shrinkage cracking problem of concrete is to use chemical admixtures for control, which are called shrinkage reducers. Concrete shrinkage reducers can effectively reduce the autogenous shrinkage and drying shrinkage of concrete. Polycarboxylate water reducer is a concrete admixture with good comprehensive performance on the market. It can significantly improve the flowability and mechanical properties of concrete, and has the advantages of low dosage, high water reduction rate, good collapse retention performance and environmental protection. It is a hot spot in the research and application of concrete admixtures. However, the addition of water reducer will increase the risk of concrete cracking. When water reducer and shrinkage reducer are used together, there is a compatibility problem with cement. Single-function shrinkage reducer can no longer meet the requirements of the market, and multifunctional shrinkage reducer is the development trend of concrete shrinkage reduction products in the future. As a functional water reducer, shrinkage-reducing polycarboxylate water reducer has a high water reduction rate and can effectively reduce the drying shrinkage of concrete and improve the durability of concrete. Compared with single shrinkage reducers, water-reducing shrinkage reducers have both water-reducing and shrinkage-reducing functions, which can overcome the negative problems of strength and shrinkage in the compound use of water-reducing and shrinkage-reducing agents, and are simple and convenient to use. Therefore, the molecular structure of water-reducing agents is designed to prepare water-reducing agents with shrinkage-reducing functions. While achieving the water-reducing effect, it can also reduce the shrinkage of concrete, which has good application prospects.

[0005] The development of a special water-reducing shrinkage reducer for UHPC is a breakthrough in the traditional shrinkage reducer technology. The polycarboxylic acid shrinkage reducers for ultra-high performance concrete described in most patents mainly achieve excellent performance by changing the reaction raw materials or process conditions. For example, Gu Benqing et al. disclosed in patent CN 111533856A an organic shrinkage reducer and its preparation method, which is synthesized using raw materials such as allyl polyoxyethylene ether, polyethylene glycol monooleate, maleic anhydride, N-hydroxymethyl acrylamide, benzoyl peroxide and chain transfer agent. The organic shrinkage reducer has the function of reducing shrinkage. When used in concrete, it can reduce shrinkage cracking of concrete, improve the durability and service life of concrete, and have a higher surface cleanliness. Wang Wenrong et al., in patent CN 115432953A, used polycarboxylate water reducer for micro-expansive ultra-high performance concrete and its preparation method and application, using 60-100 parts of isopentanol polyoxyethylene ether, 10-20 parts of fulvic acid, 0.01-0.03 parts of ferrous sulfate, 0.5-1.5 parts of reducing agent D-isoascorbic acid, 0.1-0.5 parts of 3-mercaptopropionic acid, 5-15 parts of acrylic acid, 3-6 parts of dimethylaminoethyl methacrylate, and 0.01-0.05 parts of persulfate to prepare polycarboxylate water reducer for micro-expansive ultra-high performance concrete. The water reducer with super high water reduction, high slump retention, viscosity reduction, crack control and other functions was obtained. Common synthetic raw materials are still selected to be directly polymerized onto the water-reducing agent molecules, and from the perspective of the main functional group structure of the raw materials and the cement hydration mechanism, there should be a specific applicable environment for the micro-expansion of UHPC; at the same time, this type of ordinary comb-type water-reducing agent is not designable at the molecular structure level in the preparation scheme, and most of them are comb-type structures containing adsorption groups and long side chains with steric hindrance, and it is difficult to form side chains of other structures through the polymerization of ordinary raw materials. Summary of the invention

[0006] Purpose of the invention: In order to solve the above technical problems, the present invention provides a special water-reducing shrinkage-reducing agent for UHPC and its preparation method and application. The present invention performs a Diels-Alder reaction on 2-methyl-1,3-butadiene and an unsaturated small monomer containing a hydrophobic group to generate an unsaturated small monomer of a six-membered cyclic compound containing a hydrophobic group, and then generates a special water-reducing shrinkage-reducing agent for UHPC through an in-situ polymerization reaction. The reaction production raw materials and process are simple, and the special water-reducing shrinkage-reducing agent for UHPC has ultra-high adsorption performance on the surface of cement particles. The embedded hydrophobic group and the six-membered cyclic alkyl have a lower HLB value and surface tension, and can be buried in the surface of cement particles in a direction, thereby improving the adaptability of the polycarboxylic acid water-reducing agent and cement and improving the dispersibility of cement; the ester group in the hydrophobic group can be hydrolyzed in the alkaline environment of concrete to release the carboxyl group, thereby improving the slump retention capacity of the water-reducing agent. The plasticity retention capacity of concrete is improved under the premise of high water reduction.

[0007] Technical solution: In order to achieve the above-mentioned invention object, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a water-reducing shrinkage-reducing agent for UHPC, which is mainly made of raw materials in the following molar ratios:

[0009] Vinyl polyoxyethylene ether macromonomer 1.0

[0010] Unsaturated acid small monomer 3.0~8.0

[0011] Hydrophobic unsaturated small monomer 0.5~2.0

[0012] Initiator 0.05~0.30

[0013] Chain transfer agent 0.05~0.20;

[0014] Wherein, the hydrophobic unsaturated small monomer is mainly made of raw materials with the following molar ratio:

[0015] 2-Methyl-1,3-butadiene 1.0

[0016] Contains 1.0 to 1.05 of unsaturated small monomer with hydrophobic group.

[0017] Preferably, the UHPC-specific water-reducing shrinkage-reducing agent is mainly made of raw materials in the following molar ratios:

[0018] Vinyl polyoxyethylene ether macromonomer 1.0

[0019] Unsaturated acid small monomer 4.0~8.0

[0020] Hydrophobic unsaturated small monomer 0.5~2.0

[0021] Initiator 0.05~0.30

[0022] Chain transfer agent 0.08~0.20;

[0023] Wherein, the hydrophobic unsaturated small monomer is mainly made of raw materials with the following molar ratio:

[0024] 2-Methyl-1,3-butadiene 1

[0025] Contains 1.0 to 1.01 of unsaturated small monomers with hydrophobic groups.

[0026] More preferably, the UHPC-specific water-reducing shrinkage-reducing agent is mainly made of the following raw materials in the following molar ratio:

[0027] Vinyl polyoxyethylene ether macromonomer 1.0

[0028] Unsaturated acid small monomer 5.0~6.0

[0029] Hydrophobic unsaturated small monomer 0.5~0.8

[0030] Initiator 0.25~0.30

[0031] Chain transfer agent 0.20;

[0032] Wherein, the hydrophobic unsaturated small monomer is mainly made of raw materials with the following molar ratio:

[0033] 2-Methyl-1,3-butadiene 1.0

[0034] Contains 1.0 small unsaturated monomer with hydrophobic group.

[0035] Preferably, the vinyl polyoxyethylene ether macromonomer is one or a combination of two or more of allyl polyoxyethylene ether, methyl allyl polyoxyethylene ether, and isopentenyl polyoxyethylene ether; its weight average molecular weight (Mw) is 1000 g / mol to 5000 g / mol, and more preferably 1000 g / mol to 4000 g / mol.

[0036] Preferably, the unsaturated acid small monomer is one or more combinations of acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, and sodium p-styrene sulfonate.

[0037] Preferably, the initiator is one of azobisisoheptanonitrile, azobisisobutyronitrile or dibenzoyl peroxide; the chain transfer agent is one or a combination of two or more of thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, sodium hypophosphite and mercaptoethanol.

[0038] Preferably, the unsaturated small monomer containing a hydrophobic group is one or a combination of two or more of dimethyl maleate, dimethyl fumarate, methyl acrylate, and ethyl acrylate.

[0039] In a second aspect, the present invention provides a method for preparing the water-reducing shrinkage-reducing agent for UHPC, comprising the following steps:

[0040] (1) Preparation of hydrophobic unsaturated small monomers: 2-methyl-1,3-butadiene and an unsaturated small monomer containing a hydrophobic group are subjected to a Diels-Alder reaction under catalyst conditions to generate a cyclic unsaturated compound with a hydrophobic group, and the hydrophobic unsaturated small monomer is obtained after dialysis;

[0041] (2) Preparation of a water-reducing shrinkage-reducing agent for UHPC: A vinyl polyoxyethylene ether macromonomer, an unsaturated acid small monomer and a hydrophobic unsaturated small monomer are polymerized in situ under the joint action of an initiator and a chain transfer agent to obtain a copolymer product, which is then post-treated to obtain the water-reducing shrinkage-reducing agent for UHPC.

[0042] Preferably, the catalyst is selected from Lewis acid; the Diels-Alder reaction is carried out in an ethanol solution; the reaction temperature of the Diels-Alder reaction is 5°C to 28°C, and the reaction time is 150min to 240min. Further preferably, the reaction temperature is 10°C to 20°C, and the reaction time is 210min.

[0043] Preferably, the reaction temperature of the in-situ polymerization is 60°C to 80°C, and the reaction time is 3h to 5h; further preferably, the reaction temperature is 65°C to 75°C, and the reaction time is 4.5h; water is added to the copolymerization product to a mass concentration of 20% to 50% (preferably 25% to 35%), and a base is added to adjust the pH value to 5 to 7 (preferably 6) to obtain the UHPC special water-reducing shrinkage-reducing agent; further preferably, the base is potassium hydroxide, sodium hydroxide, sodium gluconate or sodium thiosulfate, or a combination of two or more thereof.

[0044] In a third aspect, the present invention provides the use of the UHPC-specific water-reducing shrinkage-reducing agent in the preparation of concrete.

[0045] In a fourth aspect, the present invention provides a concrete comprising the above-mentioned UHPC-specific water-reducing shrinkage-reducing agent.

[0046] As an embodiment, the UHPC-specific water-reducing shrinkage-reducing agent provided by the present invention has a weight average molecular weight (Mw) of 15,000 to 80,000, and the preparation method of the UHPC-specific water-reducing shrinkage-reducing agent has the following structure:

[0047]

[0048] Among them, R1 and R5 are hydrogen atoms or methyl groups, R2 is a methoxy group or an ethoxy group, R3 and R4 are hydrogen atoms, methyl groups or carboxyl groups, and R6 and R7 are ester groups, hydrogen atoms or alkyl groups.

[0049] The invention discloses a process for synthesizing a special water-reducing shrinkage reducer for UHPC by using Diels-Alder reaction and in-situ polymerization reaction. The process is simple and improves the shortcomings of the existing shrinkage reducer in UHPC, such as slow dispersion speed, high viscosity, poor retention and poor shrinkage crack resistance.

[0050] Beneficial effects:

[0051] 1. The special water-reducing shrinkage-reducing agent for UHPC of the present invention can effectively reduce the autogenous shrinkage and drying shrinkage of ultra-high performance concrete.

[0052] 2. The embedded hydrophobic groups and six-membered cyclic alkyl groups have lower HLB values ​​and surface tensions. Therefore, the main chain of the prepared shrinkage reducer itself has a certain anti-foaming effect. By attaching to the surface of cement particles, it can optimize the internal pore parameters and distribution uniformity of hardened concrete, thereby enhancing the density of concrete.

[0053] 3. The present invention adopts an in-situ polymerization method to solve the problem of low solubility of hydrophobic unsaturated small monomers in water. The hydrophobic unsaturated small monomers are fully dispersed into the polyether macromonomer through the in-situ polymerization method, thereby ensuring that they are polymerized to the main chain molecules of the shrinkage reducer.

[0054] 4. The presence of hydrophobic groups in the side chains of the shrinkage reducer of the present invention weakens the hydrogen bonding force between the water reducer and water, so the water reducer has greater freedom in the cement slurry and can be quickly adsorbed to the surface of cement particles. In the UHPC production process, this property is also possessed under extremely low water-cement ratio conditions, so the mixed UHPC can exhibit fast dispersion performance characteristics.

[0055] 5. The shrinkage reducer of the present invention has hydrophobic groups on the main chain. The strong hydrophobic property of the shrinkage reducer attached to the CSH of cement hydration hinders the agglomeration of CSH, increases the cavitation pressure of water in the pores, and releases part of the capillary-induced tensile stress, thereby reducing the drying shrinkage of concrete.

[0056] 6. The UHPC special water-reducing shrinkage-reducing agent product prepared by the method of the present invention has stable performance after being mixed with other water-reducing agents into an aqueous solution, does not stratify or precipitate during storage, and is convenient to transport. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is the unrestricted shrinkage rate / ppm of different samples. DETAILED DESCRIPTION

[0058] The present invention is further described below in conjunction with specific examples so that those skilled in the art can better understand the present invention and implement it. Using liquid chromatography tandem mass spectrometry technology, protein detection is used as an application example for scenario examples. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of this application.

[0059] Example 1

[0060] 1) Preparation of hydrophobic unsaturated small monomer: 1.0 mol of 2-methyl-1,3-butadiene and 1.0 mol of dimethyl maleate were subjected to DA reaction in the presence of 0.01 mol of Lewis acid and 5° C. ethanol solution. The stirring time was 150 min. After dialysis, a hydrophobic unsaturated small monomer was obtained.

[0061] 2) Preparation method of a special water-reducing shrinkage-reducing agent for UHPC: 1.0 mol of methyl allyl vinyl ether (weight average molecular weight Mw is 2400 g / mol), 4.0 mol of acrylic acid, 1 mol of sodium p-styrene sulfonate, 1.0 mol of the hydrophobic unsaturated small monomer obtained in step 1), 0.05 mol of azobisisoheptanenitrile and 0.08 mol of 3-mercaptopropionic acid are subjected to in-situ polymerization at 60° C. for 3 h, sodium hydroxide is added to adjust the pH value to 7, and water is added to obtain a special water-reducing shrinkage-reducing agent for UHPC with a mass concentration of 20% (weight average molecular weight Mw is 46000 g / mol).

[0062] Example 2

[0063] 1) Preparation of hydrophobic unsaturated small monomer: 1.0 mol of 2-methyl-1,3-butadiene and 1.01 mol of dimethyl fumarate were subjected to DA reaction in the presence of 0.01 mol of Lewis acid and 15° C. ethanol solution, with stirring time of 200 min. After dialysis, a hydrophobic unsaturated small monomer was obtained;

[0064] 2) Preparation method of a special water-reducing shrinkage-reducing agent for UHPC: 1.0 mol of allyl polyoxyethylene ether (weight average molecular weight Mw is 2900 g / mol), 3.0 mol of methacrylic acid, 1 mol of sodium p-styrene sulfonate, 0.5 mol of the hydrophobic unsaturated small monomer obtained in step 1), 0.1 mol of azobisisoheptanenitrile and 0.15 mol of 3-mercaptopropionic acid are subjected to in-situ polymerization at 75° C. for 3.5 h, sodium hydroxide is added to adjust the pH value to 5, and water is added to obtain a special water-reducing shrinkage-reducing agent for UHPC with a mass concentration of 45% (weight average molecular weight Mw is 33250 g / mol).

[0065] Example 3

[0066] 1) Preparation of hydrophobic unsaturated small monomer: 1.0 mol of 2-methyl-1,3-butadiene, 0.6 mol of dimethyl fumarate and 0.4 mol of methyl acrylate were subjected to DA reaction in the presence of 0.01 mol of Lewis acid and 28° C. ethanol solution. The stirring time was 180 min. After dialysis, a hydrophobic unsaturated small monomer was obtained.

[0067] 2) Preparation method of a special water-reducing shrinkage-reducing agent for UHPC: 1.0 mol of isopentyl polyoxyethylene ether (weight average molecular weight Mw is 3000 g / mol), 2.0 mol of acrylic acid, 3.0 mol of maleic anhydride, 1 mol of sodium p-styrene sulfonate, 1.5 mol of the hydrophobic unsaturated small monomer obtained in step 1), 0.1 mol of azobisisobutyronitrile, 0.1 mol of 2-mercaptopropionic acid and 0.1 mol of sodium hypophosphite are subjected to in-situ polymerization at 80° C. for 5 h, sodium gluconate is added to adjust the pH value to 6, and water is added to obtain a special water-reducing shrinkage-reducing agent for UHPC with a mass concentration of 50% (weight average molecular weight Mw is 50500 g / mol).

[0068] Example 4

[0069] 1) Preparation of hydrophobic unsaturated small monomer: 1.0 mol of 2-methyl-1,3-butadiene, 0.4 mol of dimethyl maleate and 0.6 mol of ethyl acrylate were subjected to DA reaction in the presence of 0.01 mol of Lewis acid and 25° C. ethanol solution. The stirring time was 240 min. After dialysis, a hydrophobic unsaturated small monomer was obtained.

[0070] 2) Preparation method of a special water-reducing shrinkage-reducing agent for UHPC: 0.2 mol of allyl polyoxyethylene ether (weight average molecular weight Mw is 5000 g / mol), 0.8 mol of isopentenyl polyoxyethylene ether (weight average molecular weight Mw is 3000 g / mol), 3.0 mol of methacrylic acid, 3.0 mol of fumaric acid, 2 mol of sodium p-styrene sulfonate, 2.0 mol of the hydrophobic unsaturated small monomer obtained in step 1), 0.1 mol of azobisisobutyronitrile, 0.2 mol of dibenzoyl peroxide, 0.05 mol of mercaptoethanol and 0.05 mol of sodium hypophosphite are subjected to in-situ polymerization at 65° C. for 4.5 h, sodium gluconate and sodium thiosulfate are added to adjust the pH value to 6, and water is added to obtain a special water-reducing shrinkage-reducing agent for UHPC with a mass concentration of 35% (weight average molecular weight Mw is 78000 g / mol).

[0071] Example 5

[0072] 1) Preparation of hydrophobic unsaturated small monomer: 1.0 mol of 2-methyl-1,3-butadiene, 0.5 mol of dimethyl maleate and 0.5 mol of methyl acrylate were subjected to DA reaction in the presence of 0.01 mol of Lewis acid and 20° C. ethanol solution. The stirring time was 210 min, and the hydrophobic unsaturated small monomer was obtained after dialysis.

[0073] 2) Preparation method of a special water-reducing shrinkage-reducing agent for UHPC: 1.0 mol of isopentyl polyoxyethylene ether (weight average molecular weight Mw is 1000 g / mol), 5.0 mol of methacrylic acid, 1 mol of sodium p-styrene sulfonate, 0.5 mol of the hydrophobic unsaturated small monomer obtained in step 1), 0.25 mol of dibenzoyl peroxide and 0.2 mol of mercaptoethanol, in-situ polymerization reaction is carried out at 75° C. for 4.5 h, sodium hydroxide and sodium thiosulfate are added to adjust the pH value to 6, and water is added to obtain a special water-reducing shrinkage-reducing agent for UHPC with a mass concentration of 35% (weight average molecular weight Mw is 15200 g / mol).

[0074] Example 6

[0075] 1) Preparation of hydrophobic unsaturated small monomer: 1.0 mol of 2-methyl-1,3-butadiene, 0.5 mol of dimethyl maleate and 0.5 mol of dimethyl fumarate were subjected to DA reaction in the presence of 0.01 mol of Lewis acid and 10° C. ethanol solution. The stirring time was 210 min, and the hydrophobic unsaturated small monomer was obtained after dialysis.

[0076] 2) Preparation method of a special water-reducing shrinkage-reducing agent for UHPC: 1.0 mol of methyl allyl polyoxyethylene ether (weight average molecular weight Mw is 4000 g / mol), 4.0 mol of acrylic acid, 1 mol of sodium p-styrene sulfonate, 0.8 mol of the hydrophobic unsaturated small monomer obtained in step 1), 0.30 mol of azobisisoheptanenitrile and 0.2 mol of mercaptoacetic acid are subjected to in-situ polymerization at 65° C. for 4.5 h, potassium hydroxide and sodium thiosulfate are added to adjust the pH value to 6, and water is added to obtain a special water-reducing shrinkage-reducing agent for UHPC with a mass concentration of 25% (weight average molecular weight Mw is 43000 g / mol).

[0077] Comparative Example 1

[0078] The preparation method of a common shrinkage reducing agent is as follows: 1.0 mol of isopentenyl polyoxyethylene ether (weight average molecular weight Mw is 3000 g / mol), 2.0 mol of acrylic acid, 3.0 mol of maleic anhydride, 1 mol of sodium p-styrene sulfonate, 0.1 mol of azobisisobutyronitrile, 0.1 mol of 2-mercaptopropionic acid and 0.1 mol of sodium hypophosphite are subjected to in-situ polymerization reaction at 80°C for 5 hours, sodium gluconate is added to adjust the pH value to 6, and water is added to obtain a UHPC-specific water-reducing shrinkage reducing agent (weight average molecular weight Mw is 35500 g / mol) with a mass concentration of 50%.

[0079] The expansion is tested in accordance with GB / T 50080-2016 "Standard for Test Methods for Performance of Ordinary Concrete Mixtures", the compressive strength at different ages is tested in accordance with GB / T 50081-2002 "Standard for Test Methods for Mechanical Properties of Ordinary Concrete", and the elastic modulus and shrinkage rate at different ages are tested in accordance with GB50010-2010 "Code for Design of Concrete Structures" and JTG / T178-2009 "Technical Code for Application of Shrinkage Compensating Concrete".

[0080] The water-reducing shrinkage-reducing agents obtained in Examples 1 to 6, the sample obtained in Control Example 1, and a commercially available high-quality shrinkage-reducing agent KKR-JSJ were taken respectively, all of which were converted into 20% solid content and compounded with 20% solid content BST-902 water reducer in a ratio of 6:4, and concrete samples were prepared according to the following concrete raw material ratio, wherein the amount of each compounded water reducer group was 3.5% of the adhesive.

[0081] The mix proportion of ultra-high performance concrete used in the test is shown in Table 1.

[0082] Table 1 Mix ratio of ultra-high performance concrete Unit: kg / m 3

[0083]

[0084] The test results of the expansion, compressive strength and elastic modulus of each sample of ultra-high performance concrete are shown in Table 2.

[0085] Table 2 Ultra-high performance concrete testing indicators

[0086]

[0087] The test results of the non-restricted shrinkage rate of ultra-high performance concrete of each sample are shown in Table 3.

[0088] Table 3 Unrestricted shrinkage of ultra-high performance concrete

[0089]

[0090] The non-restricted shrinkage comparison data of commercially available shrinkage reducer KKR-JSJ, control example 1, example 1 and example 5 are as follows: Figure 1 .

[0091] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A water-reducing shrinkage-reducing agent for UHPC, characterized in that: Mainly made of raw materials in the following molar ratio: Vinyl polyoxyethylene ether macromonomer 1.0 Unsaturated acid small monomer 3.0~8.0 Hydrophobic unsaturated small monomer 0.5~2.0 Initiator 0.05~0.30 Chain transfer agent 0.05~0.20; Wherein, the hydrophobic unsaturated small monomer is mainly made of raw materials with the following molar ratio: 2-Methyl-1,3-butadiene 1.0 Contains 1.0 to 1.05 of unsaturated small monomers with hydrophobic groups; The unsaturated small monomer containing a hydrophobic group is one or a combination of two or more of dimethyl maleate, dimethyl fumarate, methyl acrylate, and ethyl acrylate; The preparation method of the hydrophobic unsaturated small monomer comprises the following steps: subjecting 2-methyl-1,3-butadiene and an unsaturated small monomer containing a hydrophobic group to a Diels-Alder reaction under a catalyst condition to generate a cyclic unsaturated compound with a hydrophobic group, and obtaining the hydrophobic unsaturated small monomer after dialysis.

2. The UHPC-specific water-reducing shrinkage-reducing agent according to claim 1, characterized in that: The vinyl polyoxyethylene ether macromonomer is one or a combination of two or more of allyl polyoxyethylene ether, methyl allyl polyoxyethylene ether and isopentenyl polyoxyethylene ether; and its weight average molecular weight (Mw) is 1000 g / mol to 5000 g / mol.

3. The UHPC-specific water-reducing shrinkage-reducing agent according to claim 1, characterized in that: The unsaturated acid small monomer is one or more combinations of acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, and sodium p-styrene sulfonate.

4. The UHPC-specific water-reducing shrinkage-reducing agent according to claim 1, characterized in that: The initiator is one of azobisisoheptanenitrile, azobisisobutyronitrile or dibenzoyl peroxide; the chain transfer agent is one or a combination of two or more of thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, sodium hypophosphite and mercaptoethanol.

5. The method for preparing the water-reducing shrinkage-reducing agent for UHPC according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Preparation of hydrophobic unsaturated small monomers: 2-methyl-1,3-butadiene and unsaturated small monomers containing hydrophobic groups are subjected to Diels-Alder reaction under catalyst conditions to generate cyclic unsaturated compounds with hydrophobic groups, and the hydrophobic unsaturated small monomers are obtained after dialysis; (2) Preparation of a special water-reducing shrinkage-reducing agent for UHPC: The vinyl polyoxyethylene ether macromonomer, the unsaturated acid small monomer and the hydrophobic unsaturated small monomer are polymerized in situ under the joint action of an initiator and a chain transfer agent to obtain a copolymer product, which is then post-treated to obtain the special water-reducing shrinkage-reducing agent for UHPC.

6. The method for preparing the water-reducing shrinkage-reducing agent for UHPC according to claim 5, characterized in that: In step (1), the catalyst is selected from Lewis acid; the Diels-Alder reaction is carried out in an ethanol solution; the reaction temperature of the Diels-Alder reaction is 5°C to 28°C, and the reaction time is 150min to 240min.

7. The method for preparing a water-reducing shrinkage-reducing agent for UHPC according to claim 5, characterized in that: In step (2), the reaction temperature of the in-situ polymerization is 60° C. to 80° C., and the reaction time is 3 h to 5 h; water is added to the copolymer product to a mass concentration of 20% to 50%, and alkali is added to adjust the pH value to 5 to 7, thereby obtaining the UHPC special water-reducing shrinkage-reducing agent.

8. The method for preparing a water-reducing shrinkage-reducing agent for UHPC according to claim 7, characterized in that: The alkali is one or a combination of two or more of potassium hydroxide, sodium hydroxide, sodium gluconate or sodium thiosulfate.

9. Use of the special water-reducing shrinkage-reducing agent for UHPC according to any one of claims 1 to 4 in preparing concrete.

10. A concrete comprising the UHPC-specific water-reducing shrinkage-reducing agent according to any one of claims 1 to 4.

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