Polycarboxylate superplasticizer for UHPC (Ultra High Performance Concrete) and preparation method thereof

Abstract

The invention provides a polycarboxylate superplasticizer for UHPC (Ultra High Performance Concrete) and a preparation method thereof, the polycarboxylate superplasticizer for UHPC is prepared from the following components in parts by weight: 60 to 80 parts of polycarboxylate superplasticizer, 50 to 60 parts of viscosity reduction mother liquor, 0.05 to 0.12 part of defoaming agent, 2 to 5 parts of hydration temperature rise inhibitor, 5 to 8 parts of polymer emulsion, 0.01 to 0.05 part of air entraining agent and 100 to 120 parts of water. The polycarboxylate superplasticizer for UHPC is prepared from the specific components including the polycarboxylate superplasticizer, the viscosity reduction mother liquor, the defoaming agent, the hydration temperature rise inhibitor, the polymer emulsion, the air entraining agent and the like according to a certain ratio, has the effects of water reduction, viscosity reduction and shrinkage reduction through compounding, has an ultrahigh water-reducing rate, and can reduce the viscosity among the components of concrete and reduce the shrinkage while the strength of the concrete is not influenced; the comprehensive performance of the UHPC is effectively adjusted, the method is suitable for large-scale popularization and industrial production, remarkable environmental benefits and economic values are shown, and the method has positive significance in promoting sustainable development of the building industry.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete water reducers, and particularly to a polycarboxylate water reducer for UHPC and a preparation method thereof. Background Art

[0002] Since the polycarboxylate water reducer began to be applied in the domestic concrete field around 2000, it has been regarded as the water reducer variety with the most development potential due to its good molecular structure design performance, high water reduction, low dosage, good slump retention, good strength enhancement, low alkali content, little influence on setting time, good compatibility with most cements and no pollution. However, despite the many advantages of the polycarboxylate water reducer, there are still some technical problems in actual applications. For example, the water reduction effect of the polycarboxylate water reducer depends greatly on the concrete raw materials, mix ratio, and water reducer dosage. The properties of fresh concrete are very sensitive to the water consumption. When preparing high-fluidity concrete, it is easy to segregate and delaminate. It has poor compatibility with other water reducers and modified components, and the product stability is not good. These problems greatly limit the wide application and development of the polycarboxylate water reducer. Especially in UHPC, higher performance requirements are imposed on the water reducer.

[0003] UHPC has the characteristics of high strength, high toughness, high durability, and high workability, and is widely used in projects such as bridges, tunnels, and high-rise buildings. However, due to the characteristics of low water-binder ratio and no coarse aggregate in UHPC, the viscosity and shrinkage of UHPC are relatively large, which affects its construction and mechanical properties. In order to improve the performance requirements of UHPC, it is necessary to develop a special water reducer for its characteristics to improve the adaptability, stability, and comprehensive performance of UHPC.

[0004] Chinese Patent CN117843882A, "A Special Polycarboxylate Water Reducer for UHPC and a Preparation Method Thereof", discloses a water reducer synthesized by introducing a modified polyol and vinyl aromatic hydrocarbon, which has both strong hydrophilic groups and strong hydrophobic groups, can greatly improve the adsorption capacity of the water reducer, and at the same time reduce the interaction between the binder and water as well as between the binder and the binder, playing a role in reducing the viscosity of the system. However, its water reduction rate is relatively low, the viscosity is relatively high, and the strength enhancement of UHPC still needs to be further improved.

[0005] Therefore, it is of great significance to provide a polycarboxylate water reducer for UHPC and a preparation method thereof with a high water reduction rate, low viscosity, and capable of greatly improving the work performance of UHPC. Summary of the Invention

[0006] In view of the problems existing in the existing special polycarboxylate superplasticizer for UHPC, such as low water reduction rate, high viscosity, and the need for further improvement in enhancing the strength of UHPC, the present invention provides a polycarboxylate superplasticizer for UHPC and its preparation method, which compound the functions of water reduction, viscosity reduction and shrinkage reduction, has an ultra-high water reduction rate, can reduce the viscosity between the components of concrete without affecting the strength of concrete, reduce shrinkage, and effectively adjust the comprehensive performance of UHPC.

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

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

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

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

[0011] S2. Mix mercaptoethanol, a reducing agent and water evenly to prepare Material A; mix acrylic acid, isomeric ester and water evenly to prepare Material B for use;

[0012] S3. Add hydrogen peroxide to the mixed solution obtained in S1, mix for 5 min, and dropwise add Material A and Material B obtained in S2 respectively. The dropping time of Material A is 170 - 210 min, the dropping time of Material B is 160 - 200 min, and keep the temperature at 10 - 30 °C for reaction for 1 h to obtain the polycarboxylate superplasticizer.

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

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

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

[0016] Step 1. Mix a six-carbon polyether macromonomer, 32% liquid caustic soda, ferrous sulfate solution, maleimide substances, and polyethylene glycol evenly for use;

[0017] Step 2: Mix mercaptoethanol, reducing agent and water evenly to obtain Material A; mix acrylic acid, isomeric ester, inhibitor and water evenly to obtain Material B for standby.

[0018] Step 3: Add hydrogen peroxide to the mixed solution obtained in S1, and dropwise add Material A and Material B obtained in S2 respectively. The dropping time of Material A is 55 - 65 min, the dropping time of Material B is 45 - 55 min, and keep the temperature at 15 - 25 °C for reaction for 1 h to obtain the viscosity-reducing mother liquor.

[0019] Furthermore, the maleimide substance in Step 1 is N-ethyl maleimide and / or N-maleimide; the concentration of the ferrous sulfate solution is 1%.

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

[0021] Furthermore, the mass ratio of mercaptoethanol, reducing agent and water in Material A in Step 2 is (0.8 - 1.2):(0.5 - 0.6):(80 - 120); the mass ratio of acrylic acid, isomeric ester, inhibitor and water in Material B is (25 - 35):(5 - 7):(0.01 - 0.03):(65 - 70).

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

[0023] Another object of the present invention is to provide a preparation method of a polycarboxylate water reducer for UHPC.

[0024] A preparation method of a polycarboxylate water reducer for UHPC according to any one of the foregoing, characterized by including the following steps:

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

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

[0027] The present invention provides a polycarboxylate water reducer for UHPC, which is obtained through specific components and ratios of polycarboxylate water reducer, viscosity-reducing mother liquor, defoamer, hydration temperature rise inhibitor, polymer emulsion, air-entraining agent, etc. The specific polycarboxylate water reducer has better water-reducing effect and stability compared with traditional polycarboxylate water reducers, is not sensitive to raw material changes. The specific viscosity-reducing mother liquor can significantly improve the dispersion performance and fluidity of the water reducer, reduce the viscosity of concrete, and improve the performance of concrete. At the same time, with a small amount of hydration temperature rise inhibitor and polymer emulsion, it can well reduce the hydration heat and shrinkage rate of UHPC during construction. The obtained polycarboxylate water reducer for UHPC has the compound functions of water reduction, viscosity reduction and shrinkage reduction, has an ultra-high water reduction rate, can reduce the viscosity between components of concrete without affecting the strength of concrete, reduce shrinkage, effectively adjust the comprehensive performance of UHPC, is suitable for large-scale promotion and industrial production, shows significant environmental benefits and economic value, and has positive significance for promoting the sustainable development of the construction industry. Detailed implementation manners

[0028] To better illustrate the purpose, technical solution and advantages of the present invention, the present invention is further illustrated by the following embodiments. Obviously, the following embodiments are only a part of the embodiments of the present invention, rather than all embodiments; it should be understood that the embodiments of the present invention are only used to illustrate the technical effects of the present invention, rather than to limit the protection scope of the present invention.

[0029] The raw materials in the embodiments can all be obtained through commercial channels; unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the technical field.

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

[0031] The following embodiments are all cement pastes.

[0032] Example 1

[0033] A preparation method of a polycarboxylate water reducer for UHPC includes the following steps:

[0034] Prepare the polycarboxylate water reducer:

[0035] S1. Mix 180 parts of four-carbon 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 of mercaptoethanol, 4 parts of reducing agent and 300 parts of water evenly to prepare Material A; mix 250 parts of acrylic acid, 50 parts of isomeric ester and 80 parts of water evenly to prepare Material B for later use;

[0037] S3. Add 35 parts of hydrogen peroxide to the mixed solution obtained in S1, mix for 5 min, and separately dropwise add the A and B materials obtained in S2. The dropping time of the A material is 190 min, and the dropping time of the B material is 180 min. Keep the temperature at 20 °C and react for 1 h to obtain the polycarboxylate water reducer for standby;

[0038] Prepare the viscosity-reducing mother liquor:

[0039] Step 1: Mix 360 parts of hexacarbon polyether macromonomer, 5 parts of 32% liquid caustic soda, 3 parts of 1% ferrous sulfate solution, 30 parts of N-ethyl maleimide, and 40 parts of polyethylene glycol evenly for standby;

[0040] Step 2: Mix 1.2 parts of mercaptoethanol, 0.6 parts of reducing agent with 100 parts of water evenly to obtain the A material; mix 35 parts of acrylic acid, 7 parts of isomeric ester, 0.03 parts of inhibitor and 70 parts of water evenly to obtain the B material for standby;

[0041] Step 3: Add 3 parts of hydrogen peroxide to the mixed solution obtained in S1, separately dropwise add the A and B materials obtained in S2. The dropping time of the A material is 60 min, and the dropping time of the B material is 50 min. Keep the temperature at 20 °C and react for 1 h to obtain the viscosity-reducing mother liquor for standby;

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

[0043] Example 2

[0044] A preparation method of a polycarboxylate water reducer for UHPC, comprising the following steps:

[0045] Prepare the polycarboxylate water reducer:

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

[0047] S2. Mix 7 parts of mercaptoethanol, 4 parts of reducing agent with 300 parts of water evenly to obtain the A material; mix 250 parts of acrylic acid, 50 parts of isomeric ester with 80 parts of water evenly to obtain the B material for standby;

[0048] S3. Add 35 parts of hydrogen peroxide to the mixed solution obtained in S1, mix for 5 min, and separately dropwise add the A and B materials obtained in S2. The dropping time of the A material is 198 min, and the dropping time of the B material is 175 min. Keep the temperature at 22 °C and react for 1 h to obtain the polycarboxylate water reducer for standby;

[0049] Prepare the viscosity-reducing mother liquor:

[0050] Step 1: Mix 360 parts of hexacarbon polyether macromonomer, 5 parts of 32% liquid caustic soda, 3 parts of 1% ferrous sulfate solution, 30 parts of N-ethylmaleimide, and 40 parts of polyethylene glycol evenly for later use;

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

[0052] Step 3: Add 3 parts of hydrogen peroxide to the mixed solution obtained in S1, and dropwise add Material A and Material B obtained in S2 respectively. The dropping time of Material A is 61 min, and the dropping time of Material B is 54 min. Keep the temperature at 20°C and react for 1 h to obtain the viscosity-reducing mother liquor for later use;

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

[0054] Example 3

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

[0056] Prepare 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 of mercaptoethanol, 4 parts of reducing agent and 300 parts of water evenly to obtain Material A; mix 250 parts of acrylic acid, 50 parts of isomeric ester and 80 parts of water evenly to obtain Material B for later use;

[0059] S3. Add 33 parts of hydrogen peroxide to the mixed solution obtained in S1, mix for 5 min, and dropwise add Material A and Material B obtained in S2 respectively. The dropping time of Material A is 187 min, and the dropping time of Material B is 188 min. Keep the temperature at 20°C and react for 1 h to obtain the polycarboxylate superplasticizer for later use;

[0060] Prepare viscosity-reducing mother liquor:

[0061] Step 1: Mix 350 parts of hexacarbon polyether macromonomer, 5 parts of 32% liquid caustic soda, 3 parts of 1% ferrous sulfate solution, 30 parts of N-ethylmaleimide, and 40 parts of polyethylene glycol evenly for later use;

[0062] Step 2: Mix 1.2 parts of mercaptoethanol, 0.6 part of reducing agent and 100 parts of water evenly to obtain Material A; mix 35 parts of acrylic acid, 7 parts of isomeric ester, 0.03 part of inhibitor and 70 parts of water evenly to obtain Material B for standby;

[0063] Step 3: Add 3 parts of hydrogen peroxide to the mixed solution obtained in S1, and dropwise add Materials A and B obtained in S2 respectively. The dropping time of Material A is 60 min, and the dropping time of Material B is 50 min. Keep the temperature at 20 °C and react for 1 h to obtain the viscosity-reducing mother liquor for standby;

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

[0065] Example 4

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

[0067] Prepare polycarboxylate superplasticizer:

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

[0069] S2. Mix 7 parts of mercaptoethanol, 4 parts of reducing agent and 300 parts of water evenly to obtain Material A; mix 250 parts of acrylic acid, 50 parts of isomeric ester and 80 parts of water evenly to obtain Material B for standby;

[0070] S3. Add 35 parts of hydrogen peroxide to the mixed solution obtained in S1, mix for 5 min, and dropwise add Materials A and B obtained in S2 respectively. The dropping time of Material A is 190 min, and the dropping time of Material B is 180 min. Keep the temperature at 20 °C and react for 1 h to obtain the polycarboxylate superplasticizer for standby;

[0071] Prepare viscosity-reducing mother liquor:

[0072] Step 1: Mix 360 parts of six-carbon polyether macromonomer, 5 parts of 32% liquid caustic soda, 3 parts of 1% ferrous sulfate solution, 30 parts of N-maleimide and 40 parts of polyethylene glycol evenly for standby;

[0073] Step 2: Mix 1.2 parts of mercaptoethanol, 0.6 part of reducing agent and 100 parts of water evenly to obtain Material A; mix 35 parts of acrylic acid, 7 parts of isomeric ester, 0.03 part of inhibitor and 70 parts of water evenly to obtain Material B for standby;

[0074] Step 3: Add 3 parts of hydrogen peroxide to the mixed solution obtained in S1, and dropwise add the A and B materials obtained in S2. The dropping time of the A material is 60 min, and the dropping time of the B material is 50 min. Keep the temperature at 20 °C and react for 1 h to obtain the viscosity-reducing mother liquor for standby use.

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

[0076] Comparative Example 1

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

[0078] Prepare polycarboxylate superplasticizer:

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

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

[0081] S3. Add 35 parts of hydrogen peroxide to the mixed solution obtained in S1, mix for 5 min, and dropwise add the A and B materials obtained in S2. The dropping time of the A material is 190 min, and the dropping time of the B material is 180 min. Keep the temperature at 20 °C and react for 1 h to obtain the polycarboxylate superplasticizer for standby use.

[0082] Prepare viscosity-reducing mother liquor:

[0083] Step 1: Mix 360 parts of six-carbon polyether macromonomer, 5 parts of 32% liquid caustic soda, 3 parts of 1% ferrous sulfate solution, 30 parts of N-ethylmaleimide, and 40 parts of polyethylene glycol evenly for standby use.

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

[0085] Step 3: Add 3 parts of hydrogen peroxide to the mixed solution obtained in S1, and dropwise add the A and B materials obtained in S2. The dropping time of the A material is 60 min, and the dropping time of the B material is 50 min. Keep the temperature at 20 °C and react for 1 h to obtain the viscosity-reducing mother liquor for standby use.

[0086] Weigh 70 parts of polycarboxylate superplasticizer, 50 parts of viscosity-reducing mother liquor, 0.06 part of defoamer, 3 parts of hydration temperature rise inhibitor, 0.03 part of air-entraining agent, and 110 parts of water according to the required ratio, mix them evenly, and the polycarboxylate superplasticizer for UHPC is obtained.

[0087] Compared with Example 1, the main difference in this comparative example is that the polymer emulsion is not added.

[0088] Comparative Example 2

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

[0090] Prepare the viscosity-reducing mother liquor:

[0091] Step 1: Mix 360 parts of hexacarbon polyether macromonomer, 5 parts of 32% liquid caustic soda, 3 parts of 1% ferrous sulfate solution, 30 parts of N-ethyl maleimide, and 40 parts of polyethylene glycol evenly for later use;

[0092] Step 2: Mix 1.2 parts of mercaptoethanol, 0.6 part of reducing agent with 100 parts of water evenly to obtain Material A; mix 35 parts of acrylic acid, 7 parts of isomeric ester, 0.03 part of inhibitor with 70 parts of water evenly to obtain Material B for later use;

[0093] Step 3: Add 33 parts of hydrogen peroxide to the mixed solution obtained in S1, and dropwise add Material A and Material B obtained in S2 respectively. The dropping time of Material A is 60 minutes, and the dropping time of Material B is 50 minutes. Keep the temperature at 20 °C and react for 1 hour to obtain the viscosity-reducing mother liquor for later use;

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

[0095] Compared with Example 1, the main difference in this comparative example is that commercially available superplasticizer is used to replace the polycarboxylate superplasticizer.

[0096] Comparative Example 3

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

[0098] Prepare the polycarboxylate superplasticizer:

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

[0100] S2. Mix 7 parts of mercaptoethanol, 4 parts of reducing agent and 300 parts of water evenly to obtain Material A; mix 250 parts of acrylic acid, 50 parts of isomeric ester and 80 parts of water evenly to obtain Material B for later use.

[0101] S3. Add 35 parts of hydrogen peroxide to the mixed solution obtained in S1, mix for 5 min, and dropwise add Material A and Material B obtained in S2 respectively. The dropping time of Material A is 190 min, and the dropping time of Material B is 180 min. Keep the temperature at 20 °C and react for 1 h to obtain the polycarboxylate superplasticizer for later use.

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

[0103] Compared with Example 1, the main difference of this comparative example is that commercially available viscosity-reducing mother liquor is used to replace the viscosity-reducing mother liquor.

[0104] Perform performance tests on the above examples and comparative examples, and prepare UHPC according to the concrete mix ratio shown in Table 1:

[0105] Table 1 UHPC mix ratio (kg / m 3 )

[0106] Cement Silica fume Ground granulated blast-furnace slag Limestone powder Steel fiber Sand Water 650 110 60 300 90 900 220

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

[0108] The slump flow test is carried out in accordance with the Standard Test Method for Properties of Ordinary Concrete Mixtures (GB / T 50080-2016); the water reduction rate test is carried out according to the method described in the Specification for Concrete Admixtures (GB 8076-2008); the bucket inversion time is referred to the Standard Test Method for Properties of Ordinary Concrete Mixtures (GB / T 50080-2016); the shrinkage rate test is carried out on the 28-day shrinkage rate of the concrete specimen according to the Code for Acceptance of Concrete Structure Engineering Quality (GB50204-2015); the compressive strength test is carried out on the 3-day and 28-day compressive strengths of the concrete specimen according to the Standard Test Method for Physical and Mechanical Properties of Concrete (GB / T 50081-2019).

[0109] The results are as follows:

[0110] Table 2 Test results of application performance of polycarboxylate superplasticizer for UHPC prepared in examples and comparative examples

[0111]

[0112] As can be seen from Table 2, the polycarboxylate water reducers prepared in Examples 1-4 of the present invention all have excellent working properties. The water reduction rates of the UHPCs applied are all higher than 37%, with excellent water reduction effects, short barrel tipping times, low viscosities, low shrinkage rates and high strengths, showing obvious comprehensive performance advantages.

[0113] In Comparative Example 1, no polymer emulsion was added, and the UHPC used had a high shrinkage rate, and was more prone to problems such as shrinkage stress concentration and shrinkage cracks, with poor performance; in Comparative Example 2, a commercially available water reducer was used to replace the polycarboxylate water reducer, and the water reduction rate of the obtained water reducer decreased significantly, the 3-day compressive strength was less than 65 MPa, and the 28-day compressive strength was lower than 110 MPa; in Comparative Example 3, a commercially available viscosity-reducing masterbatch was used to replace the viscosity-reducing masterbatch, the barrel tipping time was as high as 26.58 s, and the viscosity was high, which was not conducive to adjusting the comprehensive performance of UHPC, with poor performance.

[0114] In summary, the present invention obtains a polycarboxylate water reducer for UHPC through specific components and ratios such as polycarboxylate water reducer, viscosity-reducing masterbatch, defoamer, hydration temperature rise inhibitor, polymer emulsion, air-entraining agent, etc. It has good water reduction effect and stability, can significantly improve the dispersion performance and fluidity of the water reducer, reduce the viscosity of concrete, improve the performance of concrete, and at the same time can well reduce the hydration heat and shrinkage rate of UHPC during construction, with combined water reduction, viscosity reduction and shrinkage reduction effects, and has an ultra-high water reduction rate. It can reduce the viscosity between the components of concrete and reduce shrinkage without affecting the strength of concrete, effectively adjusting the comprehensive performance of UHPC, suitable for large-scale promotion and industrial production, showing significant environmental benefits and economic value, and having positive significance for promoting 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, rather than limiting the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polycarboxylate water reducer for UHPC, characterized in that: The composition comprises the following components by weight: 60-80 parts of polycarboxylic acid water-reducing agent, 50-60 parts of viscosity-reducing mother solution, 0.05-0.12 parts of defoaming agent, 2-5 parts of hydration temperature rise inhibitor, 5-8 parts of polymer emulsion, 0.01-0.05 parts of air entraining agent and 100-120 parts of water.

2. A polycarboxylate water-reducing agent for UHPC according to claim 1, characterized in that: The polycarboxylate water reducer is prepared by the following method: S1. The four-carbon polyether macromonomer, 2-butene amide and water are mixed uniformly to obtain a mixed solution for standby use; S2. The mercaptoethanol, reducing agent and water are mixed to obtain material A; acrylic acid, isomeric esters and water are mixed to obtain material B for standby use; S3. Add hydrogen peroxide to the mixed solution obtained in S1, mix for 5 minutes, and dropwise add materials A and B obtained in S2, the dropping time of material A is 170-210 minutes, and the dropping time of material B is 160-200 minutes. Keep the reaction at 10-30°C for 1 hour to obtain the polycarboxylic acid water reducer.

3. A polycarboxylate water-reducing agent for UHPC according to claim 2, characterized in that: The mass ratio of the four-carbon polyether macromonomer, 2-buteneamide, water in S1 to the hydrogen peroxide in S3 is (160-190):(15-20):(130-150):(30-35).

4. A polycarboxylate water-reducing agent for UHPC according to claim 2, characterized in that: The mass ratio of mercaptoethanol, reducing agent and water in material S2 A is (6.5-7):(3-4):(280-300); the mass ratio of acrylic acid, isomeric ester and water in material B is (240-250):(40-50):(60-80).

5. A polycarboxylate water-reducing agent for UHPC according to claim 1, characterized in that: The viscosity reducing mother solution is prepared by the following method: Step 1: Evenly mix the hexacarbon polyether macromonomer, 32% liquid alkali, ferrous sulfate solution, maleimide substances, and polyethylene glycol for standby use; Step 2: Evenly mix mercaptoethanol, reducing agent and water to obtain material A; evenly mix acrylic acid, isomeric ester, polymerization inhibitor and water to obtain material B for standby use; Step 3: Add hydrogen peroxide to the mixed solution obtained in S1, and dropwise add materials A and B obtained in S2 respectively. The dropping time of material A is 55-65 min, and the dropping time of material B is 45-55 min. Keep the reaction at 15-25° C. for 1 h to obtain the viscosity-reducing mother solution.

6. A polycarboxylate water-reducing agent for UHPC according to claim 5, characterized in that: In step 1, the maleic imide substance is N-ethylmaleimide and / or N-maleimide; the concentration of the ferrous sulfate solution is 1%.

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

8. A polycarboxylate water-reducing agent for UHPC according to claim 5, characterized in that: In step 2, the mass ratio of mercaptoethanol, reducing agent and water in material A is (0.8-1.2):(0.5-0.6):(80-120); the mass ratio of acrylic acid, isomeric ester, inhibitor and water in material B is (25-35):(5-7):(0.01-0.03):(65-70).

9. A polycarboxylate water-reducing agent for UHPC according to claim 1, characterized in that: The polymer emulsion is acrylic emulsion and / or styrene-butadiene emulsion.

10. A method for preparing a polycarboxylate water-reducing agent for UHPC according to any one of the preceding claims, characterized in that: The following steps are involved: The polycarboxylate water reducer, viscosity reducing mother solution, defoamer, hydration temperature rise inhibitor, polymer emulsion, air entraining agent and water are weighed and mixed according to the required proportion, and stirred evenly to obtain the polycarboxylate water reducer for UHPC.

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