Polycarboxylate superplasticizer for uhpc and method for preparing the same

Abstract

This invention provides a polycarboxylate superplasticizer for UHPC and its preparation method. The polycarboxylate superplasticizer for UHPC, by weight fraction, comprises the following components: 60-80 parts polycarboxylate superplasticizer, 50-60 parts viscosity-reducing masterbatch, 0.05-0.12 parts defoamer, 2-5 parts hydration temperature rise inhibitor, 5-8 parts polymer emulsion, 0.01-0.05 parts air-entraining agent, and 100-120 parts water. This polycarboxylate superplasticizer for UHPC is obtained through specific proportions of polycarboxylate superplasticizer, viscosity-reducing masterbatch, defoamer, hydration temperature rise inhibitor, polymer emulsion, and air-entraining agent. It combines water-reducing, viscosity-reducing, and shrinkage-reducing effects, exhibiting an ultra-high water-reduction rate. It can reduce the viscosity between concrete components and decrease shrinkage without affecting concrete strength, effectively adjusting the overall performance of UHPC. It is suitable for large-scale promotion and industrial production, demonstrating significant environmental benefits and economic value, and has a positive significance for promoting the sustainable development of the construction industry.

Description

Technical Field

[0001] This invention relates to the field of concrete water-reducing agent technology, and in particular to a polycarboxylate water-reducing agent for UHPC and its preparation method. Background Technology

[0002] Since its introduction into the domestic concrete industry around 2000, polycarboxylate superplasticizers have been considered the most promising type of superplasticizer due to their advantages such as good molecular structure design, high water reduction, low dosage, good slump retention, good reinforcement, low alkali content, minimal impact on setting time, good compatibility with most cements, and no pollution. However, despite these advantages, polycarboxylate superplasticizers also face some technical challenges in practical applications. For example, the water-reducing effect of polycarboxylate superplasticizers is highly dependent on concrete raw materials, mix proportions, and superplasticizer dosage; the performance of fresh concrete is very sensitive to water content; segregation and stratification are common when preparing highly fluid concrete; and compatibility with other superplasticizers and modifying components is poor, resulting in poor product stability. These problems significantly limit the widespread application and development of polycarboxylate superplasticizers. This is especially true in ultra-high-performance concrete (UHPC), where the performance requirements for superplasticizers are even higher.

[0003] UHPC (Ultra-High-Strength Polymer) possesses high strength, high toughness, high durability, and high workability, making it widely used in bridge, tunnel, and high-rise building projects. However, due to its low water-cement ratio and lack of coarse aggregate, UHPC exhibits significant viscosity and shrinkage, affecting its construction and mechanical properties. To improve the performance requirements of UHPC, it is necessary to develop specialized water-reducing agents tailored to its characteristics, thereby enhancing its adaptability, stability, and overall performance.

[0004] Chinese patent CN117843882A, "A Polycarboxylate Superplasticizer for UHPC and its Preparation Method," discloses a superplasticizer synthesized by introducing modified polyols and vinyl aromatics. This superplasticizer possesses both strong hydrophilic and strong hydrophobic groups, significantly improving its adsorption capacity and reducing the interaction forces between the adhesive and water, as well as between adhesives themselves, thus reducing the viscosity of the system. However, its water reduction rate is relatively low, its viscosity is relatively high, and its ability to enhance the strength of UHPC still needs further improvement.

[0005] Therefore, it is of great significance to provide a polycarboxylate superplasticizer for UHPC with high water reduction rate, low viscosity, and the ability to significantly improve the working performance of UHPC, as well as its preparation method. Summary of the Invention

[0006] Given that existing polycarboxylate superplasticizers for UHPC have problems such as low water reduction rate, high viscosity, and the need for further improvement in enhancing the strength of UHPC, this invention provides a polycarboxylate superplasticizer for UHPC and its preparation method. It has compound water reduction, viscosity reduction and shrinkage reduction effects, and has an ultra-high water reduction rate. It can reduce the viscosity between concrete components and reduce shrinkage without affecting the strength of concrete, and effectively adjust the overall performance of UHPC.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A polycarboxylate superplasticizer for UHPC, comprising the following components by weight fraction: 60-80 parts polycarboxylate superplasticizer, 50-60 parts viscosity-reducing masterbatch, 0.05-0.12 parts defoamer, 2-5 parts hydration temperature rise inhibitor, 5-8 parts polymer emulsion, 0.01-0.05 parts air-entraining agent, and 100-120 parts water.

[0009] Furthermore, the polycarboxylate superplasticizer is prepared by the following method:

[0010] S1. Mix the tetracarbon polyether macromonomer, 2-butenamide and water evenly to obtain a mixed solution for later use;

[0011] S2. Mix mercaptoethanol, reducing agent and water evenly to obtain material A; mix acrylic acid, isomeric ester and water evenly to obtain material B, and set aside for use;

[0012] S3. Add hydrogen peroxide to the mixed solution obtained in S1, mix for 5 min, and then add the A and B materials obtained in S2 dropwise. The addition time for material A is 170-210 min, and the addition time for material B is 160-200 min. Keep the mixture at 10-30℃ for 1 h to obtain the polycarboxylate superplasticizer.

[0013] Furthermore, the mass ratio of the tetracarbon polyether macromonomer, 2-butenamide, water and hydrogen peroxide in S1 to that in S3 is (160-190):(15-20):(130-150):(30-35).

[0014] Furthermore, in S2, the mass ratio of mercaptoethanol, reducing agent and water in component A is (6.5-7):(3-4):(280-300); and the mass ratio of acrylic acid, isomeric ester and water in component B is (240-250):(40-50):(60-80).

[0015] Furthermore, the viscosity-reducing mother liquor is prepared by the following method:

[0016] Step 1: Mix the hexacarbon polyether macromonomer, 32% liquid alkali, ferrous sulfate solution, maleic anhydride, and polyethylene glycol evenly and set aside.

[0017] Step 2: Mix mercaptoethanol, reducing agent and water evenly to obtain material A; mix acrylic acid, isomeric ester, polymerization inhibitor and water evenly to obtain material B, and set aside for use.

[0018] Step 3: Add hydrogen peroxide to the mixed solution obtained in S1, and add A and B materials obtained in S2 dropwise. The addition time for A material is 55-65 min, and the addition time for B material is 45-55 min. Keep the reaction at 15-25℃ for 1 h to obtain the viscosity-reducing mother liquor.

[0019] Furthermore, the maleic anhydride substance mentioned in step one is N-ethylmaleic anhydride and / or N-maleic anhydride; the concentration of the ferrous sulfate solution is 1%.

[0020] Furthermore, the mass ratio of the hexacarbon polyether macromonomer, 32% liquid alkali, ferrous sulfate solution, XX substance, polyethylene glycol and hydrogen peroxide mentioned in step one to that in step three is (340-360):(4-5):(1-3):(20-30):(15-40):(2-3).

[0021] Furthermore, in step two, the mass ratio of mercaptoethanol, reducing agent and water in component A is (0.8-1.2):(0.5-0.6):(80-120); and the mass ratio of acrylic acid, isomeric ester, polymerization inhibitor and water in component B is (25-35):(5-7):(0.01-0.03):(65-70).

[0022] Furthermore, the polymer emulsion is an acrylic emulsion and / or a styrene-butadiene emulsion.

[0023] Another object of the present invention is to provide a method for preparing a polycarboxylate superplasticizer for UHPC.

[0024] A method for preparing a polycarboxylate superplasticizer for UHPC according to any one of the preceding claims, characterized in that it includes the following steps:

[0025] Weigh out the polycarboxylate superplasticizer, viscosity reducer, defoamer, hydration temperature rise inhibitor, polymer emulsion, air-entraining agent, and water according to the required ratio, mix them, and stir evenly to obtain the polycarboxylate superplasticizer for UHPC.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] This invention provides a polycarboxylate superplasticizer for UHPC, which is obtained by specific components and proportions, including a polycarboxylate superplasticizer, a viscosity-reducing masterbatch, an antifoaming agent, a hydration temperature rise inhibitor, a polymer emulsion, and an air-entraining agent. Compared with traditional polycarboxylate superplasticizers, the specific polycarboxylate superplasticizer has better water-reducing effect and stability, and is less sensitive to changes in raw materials. The specific viscosity-reducing masterbatch can significantly improve the dispersion performance and fluidity of the superplasticizer, reduce the viscosity of concrete, and improve concrete performance. At the same time, with the addition of a small amount of hydration temperature rise inhibitor and polymer emulsion, it can effectively reduce the heat of hydration and shrinkage rate of UHPC during construction. The resulting polycarboxylate superplasticizer for UHPC has a compound effect of water reduction, viscosity reduction, and shrinkage reduction, with an ultra-high water reduction rate. It can reduce the viscosity between concrete components and reduce shrinkage without affecting the concrete strength, effectively adjusting the comprehensive performance of UHPC. It is suitable for large-scale promotion and industrial production, showing significant environmental benefits and economic value, and has a positive significance for promoting the sustainable development of the construction industry. Detailed Implementation

[0028] To better illustrate the objectives, technical solutions, and advantages of this invention, the following embodiments are provided. Obviously, the following embodiments are only a part of the embodiments of this invention, and not all of them; it should be understood that the embodiments of this invention are only used to illustrate the technical effects of this invention, and not to limit the scope of protection of this invention.

[0029] All raw materials used in the examples are commercially available; unless otherwise specified, the reagents, methods and equipment used in this invention are conventional reagents, methods and equipment in this technical field.

[0030] The hydration temperature rise inhibitor was purchased from Jiangsu Subote New Material Co., Ltd. and Wuhan Sanyuan Special Building Materials Co., Ltd.

[0031] The following examples are all cement paste.

[0032] Example 1

[0033] A method for preparing a polycarboxylate superplasticizer for UHPC includes the following steps:

[0034] Preparation of polycarboxylate superplasticizer:

[0035] S1. Mix 180 parts of tetracarbon polyether macromonomer, 20 parts of 2-butenamide and 150 parts of water evenly to obtain a mixed solution for later use;

[0036] S2. Mix 7 parts mercaptoethanol, 4 parts reducing agent and 300 parts water evenly to prepare material A; mix 250 parts acrylic acid, 50 parts isomeric ester and 80 parts water evenly to prepare material B, and set aside for use.

[0037] S3. Add 35 parts of hydrogen peroxide to the mixed solution obtained in S1, mix for 5 min, and then add the A and B materials obtained in S2 dropwise. The dropwise addition time for material A is 190 min and the dropwise addition time for material B is 180 min. Keep the reaction at 20℃ for 1 h to obtain the polycarboxylate superplasticizer, which is ready for use.

[0038] Preparation of viscosity-reducing mother liquor:

[0039] Step 1: Mix 360 parts of hexacarbon polyether macromonomer, 5 parts of 32% liquid alkali, 3 parts of 1% ferrous sulfate solution, 30 parts of N-ethylcis-butene diimide, and 40 parts of polyethylene glycol evenly and set aside.

[0040] Step 2: Mix 1.2 parts mercaptoethanol, 0.6 parts reducing agent, and 100 parts water evenly to obtain material A; mix 35 parts acrylic acid, 7 parts isomeric ester, 0.03 parts polymerization inhibitor, and 70 parts water evenly to obtain material B, which is ready for use.

[0041] Step 3: Add 3 parts of hydrogen peroxide to the mixed solution obtained in S1, and add A and B materials obtained in S2 dropwise respectively. The addition time of A material is 60 min and the addition time of B material is 50 min. Keep the reaction at 20℃ for 1 h to obtain the viscosity-reducing mother liquor, which is ready for use.

[0042] Weigh out 70 parts of polycarboxylate superplasticizer, 50 parts of viscosity reducer mother liquor, 0.06 parts of defoamer, 3 parts of hydration temperature rise inhibitor, 6 parts of acrylic emulsion, 0.03 parts of air entrainer, and 110 parts of water according to the required ratio, mix them, and stir evenly to obtain the polycarboxylate superplasticizer for UHPC.

[0043] Example 2

[0044] A method for preparing a polycarboxylate superplasticizer for UHPC includes the following steps:

[0045] Preparation of polycarboxylate superplasticizer:

[0046] S1. Mix 180 parts of tetracarbon polyether macromonomer, 20 parts of 2-butenamide and 150 parts of water evenly to obtain a mixed solution for later use;

[0047] S2. Mix 7 parts mercaptoethanol, 4 parts reducing agent and 300 parts water evenly to prepare material A; mix 250 parts acrylic acid, 50 parts isomeric ester and 80 parts water evenly to prepare material B, and set aside for use.

[0048] S3. Add 35 parts of hydrogen peroxide to the mixed solution obtained in S1, mix for 5 min, and then add the A and B materials obtained in S2 dropwise. The dropwise addition time for material A is 198 min and the dropwise addition time for material B is 175 min. Keep the reaction at 22℃ for 1 h to obtain the polycarboxylate superplasticizer, which is ready for use.

[0049] Preparation of viscosity-reducing mother liquor:

[0050] Step 1: Mix 360 parts of hexacarbon polyether macromonomer, 5 parts of 32% liquid alkali, 3 parts of 1% ferrous sulfate solution, 30 parts of N-ethylcis-butene diimide, and 40 parts of polyethylene glycol evenly and set aside.

[0051] Step 2: Mix 1.2 parts mercaptoethanol, 0.6 parts reducing agent, and 100 parts water evenly to obtain material A; mix 35 parts acrylic acid, 7 parts isomeric ester, 0.03 parts polymerization inhibitor, and 70 parts water evenly to obtain material B, which is ready for use.

[0052] Step 3: Add 3 parts of hydrogen peroxide to the mixed solution obtained in S1, and add A and B materials obtained in S2 dropwise respectively. The addition time of A material is 61 min and the addition time of B material is 54 min. Keep the reaction at 20℃ for 1 h to obtain the viscosity-reducing mother liquor, which is ready for use.

[0053] Weigh out 60 parts of polycarboxylate superplasticizer, 50 parts of viscosity reducer mother liquor, 0.08 parts of defoamer, 2 parts of hydration temperature rise inhibitor, 5 parts of styrene-butadiene emulsion, 0.01 parts of air entrainer, and 100 parts of water according to the required ratio, mix them, and stir evenly to obtain the polycarboxylate superplasticizer for UHPC.

[0054] Example 3

[0055] A method for preparing a polycarboxylate superplasticizer for UHPC includes the following steps:

[0056] Preparation of polycarboxylate superplasticizer:

[0057] S1. Mix 180 parts of tetracarbon polyether macromonomer, 20 parts of 2-butenamide and 150 parts of water evenly to obtain a mixed solution for later use;

[0058] S2. Mix 7 parts mercaptoethanol, 4 parts reducing agent and 300 parts water evenly to prepare material A; mix 250 parts acrylic acid, 50 parts isomeric ester and 80 parts water evenly to prepare material B, and set aside for use.

[0059] S3. Add 33 parts of hydrogen peroxide to the mixed solution obtained in S1, mix for 5 min, and then add the A and B materials obtained in S2 dropwise. The dropwise addition time for material A is 187 min and the dropwise addition time for material B is 188 min. Keep the reaction at 20℃ for 1 h to obtain the polycarboxylate superplasticizer, which is ready for use.

[0060] Preparation of viscosity-reducing mother liquor:

[0061] Step 1: Mix 350 parts of hexacarbon polyether macromonomer, 5 parts of 32% liquid alkali, 3 parts of 1% ferrous sulfate solution, 30 parts of N-ethylcis-butene diimide, and 40 parts of polyethylene glycol evenly and set aside.

[0062] Step 2: Mix 1.2 parts mercaptoethanol, 0.6 parts reducing agent, and 100 parts water evenly to obtain material A; mix 35 parts acrylic acid, 7 parts isomeric ester, 0.03 parts polymerization inhibitor, and 70 parts water evenly to obtain material B, which is ready for use.

[0063] Step 3: Add 3 parts of hydrogen peroxide to the mixed solution obtained in S1, and add A and B materials obtained in S2 dropwise respectively. The addition time of A material is 60 min and the addition time of B material is 50 min. Keep the reaction at 20℃ for 1 h to obtain the viscosity-reducing mother liquor, which is ready for use.

[0064] Weigh out 80 parts of polycarboxylate superplasticizer, 60 parts of viscosity reducer, 0.12 parts of defoamer, 4 parts of hydration temperature rise inhibitor, 3 parts of acrylic emulsion, 3 parts of styrene-butadiene emulsion, 0.03 parts of air entrainer, and 120 parts of water according to the required ratio, mix them, and stir evenly to obtain the polycarboxylate superplasticizer for UHPC.

[0065] Example 4

[0066] A method for preparing a polycarboxylate superplasticizer for UHPC includes the following steps:

[0067] Preparation of polycarboxylate superplasticizer:

[0068] S1. Mix 170 parts of tetracarbon polyether macromonomer, 20 parts of 2-butenamide and 140 parts of water evenly to obtain a mixed solution for later use;

[0069] S2. Mix 7 parts mercaptoethanol, 4 parts reducing agent and 300 parts water evenly to prepare material A; mix 250 parts acrylic acid, 50 parts isomeric ester and 80 parts water evenly to prepare material B, and set aside for use.

[0070] S3. Add 35 parts of hydrogen peroxide to the mixed solution obtained in S1, mix for 5 min, and then add the A and B materials obtained in S2 dropwise. The dropwise addition time for material A is 190 min and the dropwise addition time for material B is 180 min. Keep the reaction at 20℃ for 1 h to obtain the polycarboxylate superplasticizer, which is ready for use.

[0071] Preparation of viscosity-reducing mother liquor:

[0072] Step 1: Mix 360 parts of hexacarbon polyether macromonomer, 5 parts of 32% liquid alkali, 3 parts of 1% ferrous sulfate solution, 30 parts of N-cis-butene diimide, and 40 parts of polyethylene glycol evenly and set aside.

[0073] Step 2: Mix 1.2 parts mercaptoethanol, 0.6 parts reducing agent, and 100 parts water evenly to obtain material A; mix 35 parts acrylic acid, 7 parts isomeric ester, 0.03 parts polymerization inhibitor, and 70 parts water evenly to obtain material B, which is ready for use.

[0074] Step 3: Add 3 parts of hydrogen peroxide to the mixed solution obtained in S1, and add A and B materials obtained in S2 dropwise respectively. The addition time of A material is 60 min and the addition time of B material is 50 min. Keep the reaction at 20℃ for 1 h to obtain the viscosity-reducing mother liquor, which is ready for use.

[0075] Weigh out 70 parts of polycarboxylate superplasticizer, 50 parts of viscosity reducer mother liquor, 0.06 parts of defoamer, 3 parts of hydration temperature rise inhibitor, 6 parts of acrylic emulsion, 0.03 parts of air entrainer, and 110 parts of water according to the required ratio, mix them, and stir evenly to obtain the polycarboxylate superplasticizer for UHPC.

[0076] Comparative Example 1

[0077] A method for preparing a polycarboxylate superplasticizer for UHPC includes the following steps:

[0078] Preparation of polycarboxylate superplasticizer:

[0079] S1. Mix 180 parts of tetracarbon polyether macromonomer, 20 parts of 2-butenamide and 150 parts of water evenly to obtain a mixed solution for later use;

[0080] S2. Mix 7 parts mercaptoethanol, 4 parts reducing agent and 300 parts water evenly to prepare material A; mix 250 parts acrylic acid, 50 parts isomeric ester and 80 parts water evenly to prepare material B, and set aside for use.

[0081] S3. Add 35 parts of hydrogen peroxide to the mixed solution obtained in S1, mix for 5 min, and then add the A and B materials obtained in S2 dropwise. The dropwise addition time for material A is 190 min and the dropwise addition time for material B is 180 min. Keep the reaction at 20℃ for 1 h to obtain the polycarboxylate superplasticizer, which is ready for use.

[0082] Preparation of viscosity-reducing mother liquor:

[0083] Step 1: Mix 360 parts of hexacarbon polyether macromonomer, 5 parts of 32% liquid alkali, 3 parts of 1% ferrous sulfate solution, 30 parts of N-ethylcis-butene diimide, and 40 parts of polyethylene glycol evenly and set aside.

[0084] Step 2: Mix 1.2 parts mercaptoethanol, 0.6 parts reducing agent, and 100 parts water evenly to obtain material A; mix 35 parts acrylic acid, 7 parts isomeric ester, 0.03 parts polymerization inhibitor, and 70 parts water evenly to obtain material B, which is ready for use.

[0085] Step 3: Add 3 parts of hydrogen peroxide to the mixed solution obtained in S1, and add A and B materials obtained in S2 dropwise respectively. The addition time of A material is 60 min and the addition time of B material is 50 min. Keep the reaction at 20℃ for 1 h to obtain the viscosity-reducing mother liquor, which is ready for use.

[0086] Weigh out 70 parts of polycarboxylate superplasticizer, 50 parts of viscosity reducer mother liquor, 0.06 parts of defoamer, 3 parts of hydration temperature rise inhibitor, 0.03 parts of air entrainer, and 110 parts of water according to the required ratio, mix them, and stir evenly to obtain the polycarboxylate superplasticizer for UHPC.

[0087] Compared with Example 1, the main difference in this comparative example is that no polymer emulsion was added.

[0088] Comparative Example 2

[0089] A method for preparing a polycarboxylate superplasticizer for UHPC includes the following steps:

[0090] Preparation of viscosity-reducing mother liquor:

[0091] Step 1: Mix 360 parts of hexacarbon polyether macromonomer, 5 parts of 32% liquid alkali, 3 parts of 1% ferrous sulfate solution, 30 parts of N-ethylcis-butene diimide, and 40 parts of polyethylene glycol evenly and set aside.

[0092] Step 2: Mix 1.2 parts mercaptoethanol, 0.6 parts reducing agent, and 100 parts water evenly to obtain material A; mix 35 parts acrylic acid, 7 parts isomeric ester, 0.03 parts polymerization inhibitor, and 70 parts water evenly to obtain material B, which is ready for use.

[0093] Step 3: Add 33 parts of hydrogen peroxide to the mixed solution obtained in S1, and add A and B materials obtained in S2 dropwise respectively. The addition time of A material is 60 min and the addition time of B material is 50 min. Keep the reaction at 20℃ for 1 h to obtain the viscosity-reducing mother liquor, which is ready for use.

[0094] Weigh out 70 parts of commercially available water-reducing agent, 50 parts of viscosity-reducing mother liquor, 0.06 parts of defoamer, 3 parts of hydration temperature rise inhibitor, 6 parts of acrylic emulsion, 0.03 parts of air-entraining agent, and 110 parts of water according to the required ratio, mix them, and stir evenly to obtain the polycarboxylate water-reducing agent for UHPC.

[0095] Compared with Example 1, the main difference in this comparative example is that a commercially available water-reducing agent is used instead of a polycarboxylate water-reducing agent.

[0096] Comparative Example 3

[0097] A method for preparing a polycarboxylate superplasticizer for UHPC includes the following steps:

[0098] Preparation of polycarboxylate superplasticizer:

[0099] S1. Mix 180 parts of tetracarbon polyether macromonomer, 20 parts of 2-butenamide and 150 parts of water evenly to obtain a mixed solution for later use;

[0100] S2. Mix 7 parts mercaptoethanol, 4 parts reducing agent and 300 parts water evenly to prepare material A; mix 250 parts acrylic acid, 50 parts isomeric ester and 80 parts water evenly to prepare material B, and set aside for use.

[0101] S3. Add 35 parts of hydrogen peroxide to the mixed solution obtained in S1, mix for 5 min, and then add the A and B materials obtained in S2 dropwise. The dropwise addition time for material A is 190 min and the dropwise addition time for material B is 180 min. Keep the reaction at 20℃ for 1 h to obtain the polycarboxylate superplasticizer, which is ready for use.

[0102] Weigh out 70 parts of polycarboxylate superplasticizer, 50 parts of commercially available viscosity-reducing mother liquor, 0.06 parts of defoamer, 3 parts of hydration temperature rise inhibitor, 6 parts of acrylic emulsion, 0.03 parts of air-entraining agent, and 110 parts of water according to the required ratio, mix them, and stir evenly to obtain the polycarboxylate superplasticizer for UHPC.

[0103] Compared with Example 1, the main difference in this comparative example is that a commercially available viscosity-reducing stock solution was used instead of a viscosity-reducing stock solution.

[0104] Performance tests were conducted on the above embodiments and comparative examples, and UHPC was prepared according to the concrete mix proportions shown in Table 1:

[0105] Table 1. Mixing proportions of UHPC (kg / m³) 3 )

[0106] cement silica ash Mineral powder limestone powder steel fiber sand water 650 110 60 300 90 900 220

[0107] The specific testing methods and standards are as follows:

[0108] The slump spread test was conducted according to the "Standard for Test Methods of Performance of Ordinary Concrete Mixtures (GB / T50080-2016)"; the water reduction rate test was conducted according to the method described in the "Specification for Concrete Admixtures (GB 8076-2008)"; the pouring time was conducted according to the "Standard for Test Methods of Performance of Ordinary Concrete Mixtures (GB / T50080-2016)"; the shrinkage rate test was conducted according to GB50204-2015 "Code for Acceptance of Quality of Concrete Structures" to test the 28-day shrinkage rate of concrete samples; the compressive strength test was conducted according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete (GB / T 50081-2019)" to test the 3-day and 28-day compressive strength of concrete samples.

[0109] The results are shown below:

[0110] Table 2. Performance test results of polycarboxylate superplasticizers for UHPC prepared in the examples and comparative examples.

[0111]

[0112] As shown in Table 2, the polycarboxylate superplasticizers for UHPC prepared in Examples 1-4 of this invention all have excellent working performance. The water reduction rate of the UHPCs used is all higher than 37%, with excellent water reduction effect, short pouring time, low viscosity, low shrinkage rate and high strength, showing obvious comprehensive performance advantages.

[0113] In Comparative Example 1, no polymer emulsion was added, resulting in a high shrinkage rate of the UHPC used, which made it more prone to problems such as shrinkage stress concentration and shrinkage cracks, leading to poor performance. Comparative Example 2 used a commercially available water-reducing agent instead of a polycarboxylate water-reducing agent, resulting in a significant decrease in the water reduction rate of the water-reducing agent, with a 3-day compressive strength of less than 65 MPa and a 28-day compressive strength of less than 110 MPa. Comparative Example 3 used a commercially available viscosity-reducing masterbatch instead of a viscosity-reducing masterbatch, resulting in a high pouring time of 26.58 seconds, high viscosity, which was not conducive to adjusting the overall performance of UHPC, leading to poor performance.

[0114] In summary, this invention provides a polycarboxylate superplasticizer for UHPC through specific components and proportions, including a polycarboxylate superplasticizer, a viscosity-reducing mother liquor, an antifoaming agent, a hydration temperature rise inhibitor, a polymer emulsion, and an air-entraining agent. This superplasticizer exhibits excellent water-reducing effect and stability, significantly improving the dispersion and flowability of the superplasticizer, reducing concrete viscosity, and enhancing concrete performance. Simultaneously, it effectively reduces the heat of hydration and shrinkage rate of UHPC during construction. The combined water-reducing, viscosity-reducing, and shrinkage-reducing effects result in an ultra-high water-reducing rate. It reduces the viscosity between concrete components and minimizes shrinkage without affecting concrete strength, effectively adjusting the overall performance of UHPC. This makes it suitable for large-scale promotion and industrial production, demonstrating significant environmental and economic benefits and contributing positively to the sustainable development of the construction industry.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polycarboxylate superplasticizer for UHPC, characterized in that, By weight, it includes the following components: 60-80 parts polycarboxylate superplasticizer, 50-60 parts viscosity reducer masterbatch, 0.05-0.12 parts defoamer, 2-5 parts hydration temperature rise inhibitor, 5-8 parts polymer emulsion, 0.01-0.05 parts air entrainer, and 100-120 parts water. The polycarboxylate superplasticizer is prepared by the following method: S1. Mix the tetracarbon polyether macromonomer, 2-butenamide and water evenly to obtain a mixed solution for later use; S2. Mix mercaptoethanol, reducing agent and water evenly to obtain material A; mix acrylic acid, isomeric ester and water evenly to obtain material B, and set aside for use; S3. Add hydrogen peroxide to the mixed solution obtained in S1, mix for 5 min, and then add the A and B materials obtained in S2 dropwise. The dropwise addition time for material A is 170-210 min, and the dropwise addition time for material B is 160-200 min. Keep the reaction at 10-30℃ for 1 h to obtain the polycarboxylate superplasticizer. The viscosity-reducing mother liquor was prepared by the following method: Step 1: Mix the hexacarbon polyether macromonomer, 32% liquid alkali, ferrous sulfate solution, maleic anhydride, and polyethylene glycol evenly and set aside. Step 2: Mix mercaptoethanol, reducing agent and water evenly to obtain material A; mix acrylic acid, isomeric ester, polymerization inhibitor and water evenly to obtain material B, and set aside for use. Step 3: Add hydrogen peroxide to the mixed solution obtained in S1, and add A and B materials obtained in S2 dropwise. The addition time for A material is 55-65 min, and the addition time for B material is 45-55 min. Keep the reaction at 15-25℃ for 1 h to obtain the viscosity-reducing mother liquor. The polymer emulsion is an acrylic emulsion and / or a styrene-butadiene emulsion.

2. A polycarboxylate superplasticizer for UHPC according to claim 1, characterized in that, The mass ratio of the tetracarbon polyether macromonomer, 2-butenamide, water, and hydrogen peroxide in S1 to that in S3 is (160-190):(15-20):(130-150):(30-35).

3. A polycarboxylate superplasticizer for UHPC according to claim 1, characterized in that, The mass ratio of mercaptoethanol, reducing agent and water in component A of S2 is (6.5-7):(3-4):(280-300); the mass ratio of acrylic acid, isomeric ester and water in component B is (240-250):(40-50):(60-80).

4. A polycarboxylate superplasticizer for UHPC according to claim 1, characterized in that, The maleic anhydride substance mentioned in step one is N-ethylmaleic anhydride and / or N-maleic anhydride; the concentration of the ferrous sulfate solution is 1%.

5. A polycarboxylate superplasticizer for UHPC according to claim 1, characterized in that, The mass ratio of the hexacarbon polyether macromonomer, 32% liquid alkali, ferrous sulfate solution, maleic anhydride, polyethylene glycol, and hydrogen peroxide in step one to that in step three is (340-360):(4-5):(1-3):(20-30):(15-40):(2-3).

6. A polycarboxylate superplasticizer for UHPC according to claim 1, characterized in that, In step two, the mass ratio of mercaptoethanol, reducing agent and water in component A is (0.8-1.2):(0.5-0.6):(80-120); and the mass ratio of acrylic acid, isomeric ester, polymerization inhibitor and water in component B is (25-35):(5-7):(0.01-0.03):(65-70).

7. A method for preparing a polycarboxylate superplasticizer for UHPC according to any one of claims 1-6, characterized in that, Includes the following steps: Weigh out the polycarboxylate superplasticizer, viscosity reducer, defoamer, hydration temperature rise inhibitor, polymer emulsion, air-entraining agent, and water according to the required ratio, mix them, and stir evenly to obtain the polycarboxylate superplasticizer for UHPC.

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