Water-soluble polyurea early strength agent, preparation method and application thereof

Abstract

The application discloses a water-soluble polyurea early strength agent, a preparation method and application thereof. The method comprises the following steps: reacting diaminopolyether, diisocyanate and a catalyst to obtain a polyurea prepolymer; adding a chain extender into the polyurea prepolymer and continuously reacting to obtain polyurea; and finally, dropping the polyurea into water, continuously stirring in the dropping process, and obtaining a transparent water-soluble polyurea early strength agent. The water-soluble polyurea early strength agent is applied to cement paste, mortar and concrete mixing. The polyurea has abundant carboxyl sites, can be adsorbed on the surface of cement particles, prevents cement from condensing, improves the cohesiveness and water retention of the paste, and has better workability, can be uniformly dispersed and fully reacted in the concrete, so that the cement hydration is accelerated, and the early strength of the cement, mortar and concrete is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of concrete admixtures, and particularly relates to a water-soluble polyurea early strength agent as well as a preparation method and application thereof. BACKGROUND

[0002] With the rapid advancement of large-scale infrastructure construction in China, the demand for concrete is rising, and higher requirements for the early strength of concrete are put forward in order to speed up the construction progress and reduce the construction cost of projects. For example, in the production process of bridge and prefabricated building components, in order to speed up the formwork turnover efficiency, the strength of the prefabricated components when leaving the factory is required to be not less than 75% of the design value. Therefore, in order to improve the early strength of ready-mixed concrete, engineering and technical personnel add various types of inorganic, organic and composite early strength agents such as chlorides, sulfates, carbonates and triethanolamine to accelerate the hardening rate of concrete, which is convenient for winter, emergency rescue or rapid construction applications.

[0003] Document with application number 202410057762.9 discloses a high-viscosity polyurethane cement mortar and a preparation method thereof. The water-based polyurethane is added to the mortar containing polypropylene and carbon fiber, and a high-viscosity polyurethane cement mortar is prepared without a curing agent, which improves the bonding strength and mechanical strength of the mortar.

[0004] At present, there are still various problems in the application process of the concrete early strength agent. For example, although the organic early strength agent of triethanolamine can improve the early strength of concrete, it has a certain retarding effect. The early strength agent of polyurethane or polyurea has a large molecular weight and fewer hydrophilic groups, and can only be dispersed into an emulsion (particle size greater than 100 nm) in water, exists in micelles in water, cannot fully react with concrete, has poor stability in the complex environment of strong alkaline concrete, is easy to aggregate and precipitate, and can only increase the later toughness, but cannot improve the early strength. Therefore, it is necessary to develop a new type of water-soluble early strength agent to improve the early strength of concrete. SUMMARY

[0005] In view of the deficiencies of the prior art, the technical problem to be solved by the present application is to provide a water-soluble polyurea early strength agent, a preparation method and application thereof.

[0006] The technical scheme for solving the technical problem of the method of the present application is to provide a preparation method of a water-soluble polyurea early strength agent, characterized in that the method comprises the following steps:

[0007] (1) continuously stirring diamino polyether, diisocyanate and a catalyst in a water-free environment at 60-80 DEG C until the viscosity of the solution reaches 2 Pa s or more, stopping the reaction, and obtaining a polyurea prepolymer;

[0008] (2) add chain extender into polyurea prepolymer, stir and react at 60-80℃ in water-free environment until the solution viscosity reaches 5Pa·s or above, stop the reaction, and obtain polyurea;

[0009] (3) drop polyurea into water, continuously stir during the dropping process, and obtain transparent water-soluble polyurea early strength agent.

[0010] The technical scheme for solving the technical problem of the early strength agent is to provide a water-soluble polyurea early strength agent prepared by the preparation method, characterized in that the polyurea is a small-size micelle of 50nm or below in water, and the visible light transmittance of the water-soluble polyurea early strength agent is ≥90%.

[0011] The technical scheme for solving the technical problem of the application is to provide an application of the water-soluble polyurea early strength agent in cement paste, mortar and concrete mixing, characterized in that the water-soluble polyurea early strength agent is added together with cementitious materials, aggregates, admixtures and water.

[0012] Compared with the prior art, the water-soluble polyurea early strength agent has the following beneficial effects:

[0013] (1) The polyurea has low molecular weight, and is rich in carboxyl, amino and urea bond groups in the molecular structure, has excellent dispersion performance in water, high solubility, stable product, and is not easy to aggregate in the high-alkalinity cement paste environment, and is convenient for application in cement paste, mortar and concrete mixing.

[0014] (2) The polyurea has rich carboxyl sites, can be adsorbed on the surface of cement particles, prevent cement from agglomeration, improve the cohesiveness and water retention of the paste, and has better workability, can be uniformly dispersed and fully reacted in concrete, thereby accelerating the hydration of cement, and improving the early strength of cement, mortar and concrete. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a comparison chart of 1d, 3d and 7d concrete compressive strength of the embodiment 1, the comparative example 1, the comparative example 2 and the comparative example 3 of the present application;

[0016] Figure 2 It is a dynamic light scattering test result chart of the embodiment 1-4 of the present application;

[0017] Figure 3 It is a transmission electron microscope chart of the solute polyurea in the water-soluble polyurea early strength agent of the embodiment 1 of the present application. DETAILED DESCRIPTION

[0018] The specific embodiments of the present application are given below. The specific embodiments are only used to further illustrate the present application, and do not limit the protection scope of the present application.

[0019] The application provides a preparation method of water-soluble polyurea early strength agent (referred to as method), characterized by comprising the following steps:

[0020] (1) continuously stirring and reacting diamino polyether, diisocyanate and catalyst in anhydrous environment at 60-80 DEG C (preferably 70 DEG C) until the solution viscosity reaches 2 Pa s or more, stopping the reaction, and obtaining a polyurea prepolymer;

[0021] Preferably, in step (1), the water content of diamino polyether, diisocyanate and catalyst is less than 0.05 wt%; the water content requirement is achieved by using a drying process, and the drying is performed by vacuum drying, barium oxide drying or 4A molecular sieve drying.

[0022] Preferably, in step (1), the reactor is a glass, enamel or stainless steel reactor.

[0023] Preferably, in step (1), the diamino polyether is at least one of polytetrahydrofuran diamine, polyoxyethylene ether diamine and polyoxypropylene ether diamine, and the number average molecular weight is 250-2000 g / mol.

[0024] Preferably, in step (1), in order to ensure good solubility of the polyurea in water, the number average molecular weight of the polytetrahydrofuran diamine is 250-1000 g / mol, and the number average molecular weight of the polyoxyethylene ether diamine and the polyoxypropylene ether diamine is 500-1500 g / mol.

[0025] Preferably, in step (1), the diisocyanate is at least one of toluene diisocyanate, diphenyl methane diisocyanate, 1,6-hexane diisocyanate and isophorone diisocyanate.

[0026] Preferably, in step (1), the catalyst is dibutyltin dilaurate, stannous isooctoate or triethylenediamine, preferably dibutyltin dilaurate.

[0027] (2) adding a chain extender to the polyurea prepolymer, stirring and reacting in anhydrous environment at 60-80 DEG C (preferably 70 DEG C) until the solution viscosity reaches 5 Pa s or more, stopping the reaction, and obtaining a polyurea;

[0028] Preferably, in step (2), the chain extender contains two amino groups and at least one carboxyl group, which can improve the solubility of the polyurea in water, and specifically is any one of lysine, diaminopimelic acid or 2,3-diamino propionic acid.

[0029] Preferably, in step (2), the mass ratio of diisocyanate:diamino polyether:chain extender is 100:50-90:10-20, preferably 100:55-80:12-19, more preferably 100:60-70:15-18, and further preferably 100:65-68:16-17.

[0030] Preferably, in step (2), the mass ratio of diisocyanate: diamino polyether: chain extender: catalyst is 100:50~90:10~20:0.01~1, more preferably 100:55~80:12~19:0.02~0.5, more preferably 100:60~70:15~18:0.05~0.1, and even more preferably 100:65~68:16~17:0.06~0.08.

[0031] Preferably, in step (2), the polyurea comprises two parts: a hard segment and a soft segment. The hard segment comprises diisocyanate and a chain extender, and the soft segment comprises diamino polyether. The hard segment and the soft segment are connected by urea bonds formed by the polycondensation of amino and isocyanate.

[0032] Preferably, in step (2), the polyurea is rich in hydrophilic groups such as amino, carboxyl and urea bonds. To ensure good solubility of polyurea in water, the number average molecular weight of polyurea is 4000~10000 g / mol, preferably 5000~8000 g / mol.

[0033] Preferably, in steps (1) and (2), the waterless environment is an oxygen-free environment, which is achieved by protection with nitrogen or an inert gas, with argon being the inert gas.

[0034] Preferably, in steps (1) and (2), the reaction time is 2 to 4 hours, preferably 3 hours.

[0035] (3) Add polyurea dropwise to water, stirring continuously during the dropwise process, so that the polyurea is completely dissolved or highly stable and uniformly dispersed in water, to obtain a transparent water-soluble polyurea early strength agent.

[0036] Preferably, step (3) is performed at room temperature.

[0037] Preferably, in step (3), the mass ratio of polyurea to water is 1:10~100, more preferably 1:20~90, and even more preferably 1:50~80.

[0038] Preferably, in step (3), the water-soluble polyurea early strength agent is an aqueous solution of polyurea with amino groups at both ends.

[0039] Preferably, in step (3), the polyurea is highly dispersed in water into small nano micelles of less than 50 nm, and the water-soluble polyurea early strength agent is highly transparent with a visible light transmittance of ≥90% (preferably ≥95%).

[0040] The present invention also provides a water-soluble polyurea early strength agent prepared by the above preparation method.

[0041] The application also provides application of the water-soluble polyurea early strength agent in cement paste, mortar and concrete mixing, characterized in that the water-soluble polyurea early strength agent is added together with cementitious materials, aggregates, admixtures and water.

[0042] Preferably, the cementitious materials are at least one of cement, fly ash or silica ash; the aggregates are gravel and / or sand; the admixtures are at least one of water reducing agent, retarder, pumping agent, waterproofing agent, thickening agent, air entraining agent and existing early strength agent. To further improve the early strength effect of the water-soluble polyurea early strength agent, the existing early strength agent is added in the system; the existing early strength agent is at least one of calcium chloride, triethanolamine and sodium sulfate, and the composite use of multiple early strength agents provides more abundant and effective multiple means for the adjustment of the early strength of cement paste, mortar and concrete. The water-soluble polyurea early strength agent can be used alone or mixed with one or more of at least one existing admixture, to improve the comprehensive performance of cement products and meet different application requirements.

[0043] Preferably, due to the different concentrations of the water-soluble polyurea early strength agent, the mass of the solute polyurea in the water-soluble polyurea early strength agent accounts for 0.001-0.1% (preferably 0.003-0.015%, more preferably 0.005-0.01%) of the mass of the cementitious materials, so as to improve the cohesiveness and water retention of the paste, promote cement hydration and increase the early strength.

[0044] Preferably, in cement paste mixing, the water-soluble polyurea early strength agent is added together with cement, fly ash, silica ash and admixtures; the mass of the polyurea accounts for 0.001-0.05% (preferably 0.002-0.01%) of the mass of the cementitious materials. In cement paste mixing, the water-soluble polyurea early strength agent has wide application prospects in neat paste experiments, material compatibility experiments, cement product manufacturing and crack repair engineering.

[0045] Preferably, in mortar mixing, the water-soluble polyurea early strength agent is added together with cement, fly ash, silica ash, sand and admixtures; the mass of the polyurea accounts for 0.002-0.08% (preferably 0.005-0.06%) of the mass of the cementitious materials. In mortar mixing, the water-soluble polyurea early strength agent has wide application prospects in existing building reinforcement, winter construction of wall surfaces and rapid repair of roads.

[0046] Preferably, in concrete mixing, the water-soluble polyurea early strength agent is added together with cement, fly ash, silica ash, sand, gravel and admixtures; the mass of the polyurea accounts for 0.005-0.1% (preferably 0.006-0.01%) of the mass of the cementitious materials. In concrete mixing, the water-soluble polyurea early strength agent has wide application prospects in the production of high-iron, bridge, tunnel, subway and prefabricated building prefabricated components.

[0047] The application method of the water-soluble polyurea early strength agent is the same as the application method of the existing early strength agent, and the optimal amount can be determined by the skilled person in the art through small-batch laboratory experiments according to the actual engineering needs. When the early strength is not obviously improved, the amount can be increased. When the early strength is obviously increased and meets the requirements, the amount can be reduced to reduce the cost. However, during use, the amount of the water-soluble polyurea early strength agent should be gradually increased to avoid rapid hardening and difficult construction caused by a large increase in the amount.

[0048] Example 1

[0049] Preparation of the water-soluble polyurea early strength agent:

[0050] (1) 100 g of 1,6-hexane diisocyanate, 50 g of polyoxyethylene ether diamine (number average molecular weight: 500 g / mol), and 0.05 g of dibutyltin dilaurate that were previously dried were added to a 1 L glass reaction kettle equipped with magnetic stirring, and stirred at 70°C for 3 h under nitrogen protection to obtain a polyurea prepolymer;

[0051] (2) 10 g of diaminopimelic acid was added to the polyurea prepolymer as a chain extender, and stirred at 70°C for 3 h under nitrogen protection to obtain a polyurea (number average molecular weight: 6500 g / mol);

[0052] (3) The polyurea was added dropwise to 0.74 kg of water at room temperature, and stirring was continuously performed during the dropwise addition to obtain a transparent water-soluble polyurea early strength agent (visible light transmittance: 98%).

[0053] To evaluate the early strength effect of the water-soluble polyurea early strength agent in concrete mixing, 1500 g of cement, 1000 g of coal ash, 1000 g of silica ash, 8000 g of sand, 11000 g of gravel, 200 g of water reducing agent, 218.8 g of the water-soluble polyurea early strength agent of Example 1, and 500 g of water were added to a concrete mixer, and uniformly mixed according to the related method of GB / T 8076-2008 “Concrete Admixture”. The appearance and setting time of the concrete were as shown in Table 1. After steam curing for 1 d, 3 d, and 7 d, the compressive strength of the concrete test block was measured as shown in Table 1 and Table 2. Figure 1

[0054] Example 2

[0055] Preparation of the water-soluble polyurea early strength agent:

[0056] (1) 100 g of isophorone diisocyanate, 80 g of polyoxypropylene ether diamine (number average molecular weight: 1500 g / mol), and 0.1 g of isooctanoic acid stannous were added to a 1 L stainless steel reaction kettle equipped with mechanical stirring, and stirred at 60°C for 3.5 h under nitrogen protection to obtain a polyurea prepolymer; ​

[0057] (2) 19 g lysine was added as chain extender to the polyurea prepolymer, and the reaction was stirred at 60 °C for 4 h under nitrogen protection to obtain the polyurea (number average molecular weight 10000 g / mol);

[0058] (3) The polyurea was added dropwise into 18 kg water at room temperature, and the stirring was continued during the dropping to obtain the transparent water-soluble polyurea early strength agent (visible light transmittance 95%).

[0059] To evaluate the early strength effect of the water-soluble polyurea early strength agent in the mixing of cement paste, 300 g cement, 50 g silica ash, 50 g coal ash, 6.5 g of the water-soluble polyurea early strength agent of Example 2, 1.5 g of water reducing agent and 87 g of water were added into a cement paste stirring pot, and then uniformly mixed according to the cement paste test method of GB / T 8077-2012 "Concrete Admixture Homogeneity Test Method", and then steam curing was performed to obtain the early strength type cement product.

[0060] Example 3

[0061] Preparation of the water-soluble polyurea early strength agent:

[0062] (1) 100 g of toluene diisocyanate, 60 g of polytetrahydrofuran diamine (number average molecular weight 250 g / mol) and 0.5 g of triethylene diamine were added into a 1 L mechanical stirring porcelain reaction kettle, and the reaction was stirred at 80 °C for 4 h under nitrogen protection to obtain the polyurea prepolymer;

[0063] (2) 18 g of 2,3-diamino propionic acid was added as chain extender to the polyurea prepolymer, and the reaction was stirred at 80 °C for 2 h under nitrogen protection to obtain the polyurea (number average molecular weight 4000 g / mol);

[0064] (3) The polyurea was added dropwise into 8 kg water at room temperature, and the stirring was continued during the dropping to obtain the transparent water-soluble polyurea early strength agent (visible light transmittance 90%).

[0065] To evaluate the early strength effect of the water-soluble polyurea early strength agent in the mixing of cement paste, 300 g cement, 50 g silica ash, 50 g coal ash, 6.5 g of the water-soluble polyurea early strength agent of Example 2, 1.5 g of water reducing agent and 87 g of water were added into a cement paste stirring pot, and then uniformly mixed according to the cement paste test method of GB / T 8077-2012 "Concrete Admixture Homogeneity Test Method", and then steam curing was performed to obtain the early strength type cement product.

[0066] Example 4

[0067] Preparation of the water-soluble polyurea early strength agent:

[0068] (1) 100 g of diphenylmethane diisocyanate, 68 g of polyoxyethylene ether diamine (number average molecular weight 500 g / mol) and 0.5 g of triethylene diamine, which were dried in advance, were added to a 1 L glass reaction kettle equipped with magnetic stirring, and stirred at 80°C for 2 h under nitrogen to obtain a polyurea prepolymer;

[0069] (2) 16 g of 2,3-diaminopropionic acid was added to the polyurea prepolymer as a chain extender, and stirred at 80°C for 3.5 h under nitrogen to obtain a polyurea (number average molecular weight 8000 g / mol);

[0070] (3) The polyurea was added dropwise to 14.7 kg of water at room temperature, and stirring was continued during the dropwise addition to obtain a transparent water-soluble polyurea early strength agent (visible light transmittance 96%).

[0071] To evaluate the early strength effect of the water-soluble polyurea early strength agent in mortar mixing, 450 g of cement, 150 g of silica fume, 10.0 g of the water-soluble polyurea early strength agent of Example 4, 6.0 g of water reducing agent, 150 g of water and 2500 g of standard sand were added to a mortar instrument stirring pot, and mixed uniformly according to the cement mortar test method of GB / T 8077-2012 "Concrete Admixture Homogeneity Test Method", and then steam-cured to obtain an early strength mortar product.

[0072] Comparative Example 1

[0073] Preparation of polyurea emulsion:

[0074] (1) 100 g of 1,6-hexane diisocyanate, 50 g of polycaprolactone diamine (number average molecular weight 500 g / mol) and 0.05 g of dibutyl tin dilaurate, which were dried in advance, were added to a 1 L glass reaction kettle equipped with magnetic stirring, and stirred at 70°C for 3 h under nitrogen to obtain a polyurea prepolymer;

[0075] (2) 10 g of 1,4-butanediamine was added to the polyurea prepolymer as a chain extender, and stirred at 70°C for 3 h under nitrogen to obtain a polyurea (number average molecular weight 17000 g / mol);

[0076] (3) The polyurea was added dropwise to 0.75 kg of water at room temperature, and stirring was continued during the dropwise addition to obtain a milky white polyurea solution, which was a polyurea emulsion (visible light transmittance 12%).

[0077] To compare the early strength effect of the water-soluble polyurea early strength agent and the polyurea emulsion of Comparative Example 1 in the mixing of concrete, 1500 g of cement, 1000 g of fly ash, 1000 g of silica fume, 8000 g of sand, 11000 g of gravel, 200 g of water reducing agent, 218.8 g of the polyurea emulsion of Comparative Example 1 and 500 g of water were added into a concrete mixer, and after mixing uniformly according to the relevant method of GB / T 8076-2008 “Concrete Admixture”, the appearance and setting time of the concrete were as shown in Table 1, and the compressive strength of the concrete test block measured after steam curing for 1 d, 3 d and 7 d was as shown in Table 1 and Figure 1

[0078] Comparative Example 2

[0079] Comparative Example 2 used a commercially available early strength agent triethanolamine.

[0080] To compare the early strength effect of the water-soluble polyurea early strength agent and the commercially available early strength agent triethanolamine in the mixing of concrete, 1500 g of cement, 1000 g of fly ash, 1000 g of silica fume, 8000 g of sand, 11000 g of gravel, 200 g of water reducing agent, 35 g of the commercially available triethanolamine of Comparative Example 2 and 683.8 g of water were added into a concrete mixer, and after mixing uniformly according to the relevant method of GB / T 8076-2008 “Concrete Admixture”, the appearance and setting time of the concrete were as shown in Table 1, and the compressive strength of the concrete test block measured after steam curing for 1 d, 3 d and 7 d was as shown in Table 1 and Figure 1

[0081] Comparative Example 3

[0082] To compare the early strength of concrete without adding an early strength agent, 1500 g of cement, 1000 g of fly ash, 1000 g of silica fume, 8000 g of sand, 11000 g of gravel, 200 g of water reducing agent and 718.8 g of water were added into a concrete mixer, and after mixing uniformly according to the relevant method of GB / T 8076-2008 “Concrete Admixture”, the appearance and setting time of the concrete were as shown in Table 1, and the compressive strength of the concrete test block measured after steam curing for 1 d, 3 d and 7 d was as shown in Table 1 and Figure 1

[0083]

[0084] From Table 1 and Figure 1 ​​​It can be seen from the data that, compared with the freshly mixed concrete, the concrete without early strength agent (comparative example 3) has better fluidity, but poor paste wrapping, serious stone exposure, poor cohesiveness and water retention performance; the concrete added with the commercially available early strength agent triethanolamine (comparative example 2) also has poor wrapping, serious stone exposure, slightly improved cohesiveness, but delayed concrete setting time; the concrete added with the polyurea emulsion (comparative example 1) has slightly decreased fluidity, but improved paste cohesiveness; the concrete added with the water-soluble polyurea early strength agent (example 1) also has slightly decreased fluidity, but greatly improved paste cohesiveness and water retention performance, excellent paste wrapping and slightly improved setting time, indicating that the water-soluble polyurea early strength agent has obvious effect on improving the workability of the concrete without obviously affecting the setting time of the concrete.

[0085] Compared with the concrete cured for 1d, 3d and 7d, the strength of the test block without early strength agent grows slowly, and the addition of triethanolamine can obviously improve the early strength of the test block. The polyurea emulsion also has certain early strength performance, but is obviously weaker than triethanolamine, and the water-soluble polyurea early strength agent obviously improves the compressive strength of the test block and is superior to triethanolamine, indicating that the water-soluble polyurea early strength agent of the application has obvious improvement effect on improving the early strength of the concrete.

[0086] From the results of dynamic light scattering Figure 2 It can be seen that the particle size of example 1 is 36.5±5.0nm, the particle size of example 2 is 44.6±3.5nm, the particle size of example 3 is 33.2±10.2nm, and the particle size of example 4 is 38.8±7.6nm.

[0087] From the results of dynamic light scattering Figure 3 It can be seen that the transmission electron microscope particle size of example 1 is 35.0±5.0nm, which is consistent with the dynamic light scattering result.

[0088] The unmentioned part of the application is applicable to the prior art.

Claims

1. A method for preparing a water-soluble polyurea early strength agent, characterized by, The method comprises the following steps: (1) continuously stirring diamino polyether, diisocyanate and catalyst in anhydrous environment at 60-80℃ for 2-4h until the solution viscosity reaches 2Pa·s or above, stopping the reaction to obtain polyurea pre-polymer; (2) adding chain extender to the polyurea pre-polymer, stirring and reacting in anhydrous environment at 60-80℃ for 2-4h until the solution viscosity reaches 5Pa·s or above, stopping the reaction to obtain polyurea; The chain extender contains two amino groups and at least one carboxyl group, specifically any one of lysine, diaminopimelic acid or 2,3-diaminopropionic acid; (3) adding the polyurea into water continuously stirring during the process to obtain transparent water-soluble polyurea early strength agent.

2. The method for preparing the water-soluble polyurea early-strength agent according to claim 1, characterized in that, In step (1), the diamino polyether is at least one of polytetrahydrofuran diamine, polyoxyethylene ether diamine and polyoxypropylene ether diamine, with a number average molecular weight of 250-2000g / mol; The diisocyanate is at least one of toluene diisocyanate, diphenylmethane diisocyanate, 1,6-hexane diisocyanate and isophorone diisocyanate; The catalyst is dibutyltin dilaurate, stannous isooctoate or triethylenediamine.

3. The method for preparing the water-soluble polyurea early-strength agent according to claim 2, characterized in that, In step (1), the number average molecular weight of the polytetrahydrofuran diamine is 250-1000g / mol, and the number average molecular weight of the polyoxyethylene ether diamine and polyoxypropylene ether diamine is 500-1500g / mol.

4. The method for preparing the water-soluble polyurea early-strength agent according to claim 1, characterized in that, In step (2), the mass ratio of diisocyanate:diamino polyether:chain extender is 100:50-90:10-20; The mass ratio of diisocyanate:diamino polyether:chain extender: catalyst is 100:50-90:10-20:0.01-1; The number average molecular weight of the polyurea is 4000-10000g / mol.

5. The method for preparing the water-soluble polyurea early-strength agent according to claim 1, characterized in that, In steps (1) and (2), the anhydrous environment is an anhydrous and anaerobic environment, which is achieved by nitrogen or inert gas protection, and the inert gas is argon.

6. The method for preparing the water-soluble polyurea early-strength agent according to claim 1, characterized in that, In step (3), the mass ratio of polyurea to water is 1:10-100.

7. The water-soluble polyurea early strength agent prepared by the method of any one of claims 1-6, characterized in that, The polyurea in water is a small-size micelle of 50nm or below, and the visible light transmittance of the water-soluble polyurea early strength agent is ≥90%.

8. Use of the water-soluble polyurea early strength agent according to claim 7 in cement paste, mortar and concrete mixing, characterized in that, The water-soluble polyurea early strength agent is added together with cementitious material, aggregate, admixture and water.

9. Use according to claim 8, characterized in that, The cementitious material is at least one of cement, fly ash or silica ash; the aggregate is crushed stone and / or sand; the admixture is at least one of water reducing agent, retarder, pumping agent, waterproofing agent, thickening agent, air entraining agent and existing early strength agent; The mass of the solute polyurea in the water-soluble polyurea early strength agent accounts for 0.001-0.1% of the mass of the cementitious material.

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