Nanometer hydrated calcium silicate crystal nucleus early strength agent, and preparation method and application thereof

Abstract

The application belongs to the technical field of building materials, and particularly relates to a nano-hydrated calcium silicate crystal nucleus early strength agent, a preparation method and application thereof. The preparation method comprises the following steps: mixing a crystal nucleus growth inhibitor, an emulsifier and water to obtain an emulsion; under stirring, adding a soluble calcium source aqueous solution and a soluble silicon source aqueous solution into the emulsion; then adding alkali to adjust the pH value to above 12; and continuing to stir for a period of time, and the nano-hydrated calcium silicate crystal nucleus early strength agent is obtained. The crystal nucleus particle size of the nano-hydrated calcium silicate crystal nucleus early strength agent prepared by the preparation method is mainly distributed in 100-150 nm, which can significantly improve the early strength of concrete, and does not reduce the late strength of concrete.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a nano-hydrated calcium silicate crystal nucleation early strength agent, its preparation method, and its application. Background Technology

[0002] With the continuous advancement of my country's construction industrialization, precast concrete components and commercial concrete have achieved significant development. In the traditional production of precast concrete components, steam curing is required to improve the early strength of concrete, shorten demolding time, and increase formwork turnover efficiency. However, steam curing consumes a large amount of heat energy, increasing production costs, and simultaneously emits greenhouse gases and pollutants such as CO2, SO3, and nitrogen oxides, causing environmental pollution. Furthermore, it easily causes "thermal damage" to concrete, reducing its durability. Commercial concrete, due to the large amount of auxiliary cementitious materials incorporated, also has relatively low early strength. In engineering, early-strength agents are often used to accelerate the early hydration rate of cement to promote the development of early concrete strength. However, the addition of traditional early-strength agents often sacrifices the later strength of concrete to improve its early strength and easily causes many negative effects. For example, the dosage of triethanolamine-based early-strength agents is difficult to control, and excessive dosage can easily lead to super-retarded setting; chloride-containing early-strength agents can easily cause steel corrosion; sulfate-based early-strength agents can easily reduce the impermeability and corrosion resistance of concrete, leading to poor concrete durability.

[0003] In recent years, nanomaterials have been considered an effective way to improve the performance of cement-based materials. Studies have found that adding inorganic nanoparticles, especially nano-hydrated calcium silicate, to concrete can provide additional nucleation sites for the hydration product CSH gel, shortening the cement induction period and effectively improving the early mechanical properties of concrete. Simultaneously, nano-hydrated calcium silicate (CSH) can not only accelerate cement hydration but also compensate for the reduction in early strength caused by the incorporation of low-activity auxiliary cementitious materials, even achieving a no-steam-curing effect and increasing the durability of concrete. It is generally believed that the smaller the particle size of the CSH seed crystals, the better the early strength effect. However, according to the classical nucleation-growth theory, nano-CSH nuclei will gradually grow, reducing their early strength effect.

[0004] Existing technologies often introduce polymers as dispersants (usually polycarboxylate superplasticizers) to synthesize nanocomposites to inhibit crystal growth. However, this method has drawbacks such as long preparation time, ranging from several hours to several days, or poor crystal growth inhibition effect.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a novel nano-hydrated calcium silicate crystal nucleation early strength agent, its preparation method, and its application.

[0007] Specifically, the present invention provides the following technical solutions:

[0008] This invention first provides a method for preparing a nano-hydrated calcium silicate crystal nucleation early strength agent, comprising the following steps:

[0009] (1) Mix the crystal nucleus growth inhibitor, emulsifier and water to obtain an emulsion;

[0010] The crystal nucleus growth inhibitor is a silane inhibitor and / or an alcoholic acid inhibitor;

[0011] The silane inhibitors are selected from one or more of polymethylhydrosiloxane, polydimethylsiloxane, hexadecyltrimethoxysilane, ethoxytrimethylsilane, hexamethyldisiloxane, n-butylsilane, isobutylsilane, and isooctylsilane.

[0012] The alcohol and acid inhibitors are selected from one or more of stearic acid, lauric acid, decanoic acid, oleic acid, citric acid, tartaric acid, triethanolamine, diethanolamine, monoethanolamine, triisopropanolamine, formic acid, and ethylene glycol.

[0013] (2) Under stirring conditions, add dropwise a soluble calcium source aqueous solution and a soluble silicon source aqueous solution to the emulsion; then add alkali to adjust the pH value to above 12;

[0014] (3) Continue stirring for a period of time to obtain the final product.

[0015] This invention discovers that by employing the aforementioned silane inhibitors, a robust isolation layer with a Si-O-Si framework can be formed through dehydration condensation with the hydroxyl groups on the surface of hydrated calcium silicate crystal nuclei, thus inhibiting crystal nucleus growth. Similarly, by employing the aforementioned alkyd inhibitors, the carboxyl and hydroxyl groups and other organic functional groups on the alkyd inhibitors bind to the calcium groups on the surface of nano-hydrated calcium silicate, reducing the growth rate of hydrated calcium silicate crystal nuclei and effectively inhibiting crystal growth. Compared to traditional polycarboxylic acid macromolecular crystal nucleus growth inhibitors, the silane inhibitors of this invention bind to the crystal nuclei faster and more firmly in a covalent bond manner; the alkyd inhibitors have more effective functional groups and a faster molecular diffusion rate, thus being more conducive to inhibiting the growth of nano-hydrated calcium silicate crystal nuclei. Therefore, applying the prepared nano-hydrated calcium silicate crystal nucleus emulsion to concrete can promote cement hydration, significantly improve the early strength of concrete, and without reducing the later strength of concrete.

[0016] To further enhance the early strength effect of the nano-hydrated calcium silicate nucleation agent, the preparation method of this invention has been optimized, as follows:

[0017] Preferably, in step (1), the silane inhibitor is selected from one or more of polymethylhydrosiloxane, polydimethylsiloxane, hexadecyltrimethoxysilane, hexamethyldisiloxane, isobutylsilane, and isooctylsilane.

[0018] Preferably, in step (1), the alcoholic acid inhibitor is selected from one or more of stearic acid, lauric acid, oleic acid, citric acid, tartaric acid, formic acid, triethanolamine, and triisopropanolamine.

[0019] By using the above-mentioned preferred crystal nucleus growth inhibitor, the resulting nano-hydrated calcium silicate crystal nucleus early strength agent has a smaller particle size and a better early strength effect.

[0020] Preferably, the number-average molecular weight of the polymethylhydrosiloxane and polydimethylsiloxane is 300-3500. This invention has found that the molecular weight of polymethylhydrosiloxane and polydimethylsiloxane affects the crystal nucleus size; using polymethylhydrosiloxane and polydimethylsiloxane within the above-mentioned molecular weight range is most beneficial for suppressing crystal nucleus growth.

[0021] Preferably, in step (1), the emulsifier is selected from one or more of the following: Pinto-Pinga O-25, AEO-9, OP-7, OP-10, Tween-20, Tween-80, Span-20, and Span-80; more preferably, it is selected from one or more of the following: Pinto-Pinga O-25, AEO-9, Tween-20, Tween-80, Span-20, and Span-80. In this invention, the purpose of adding the emulsifier is to emulsify and disperse the silane inhibitor to form an oil-in-water emulsion, adjust the solubility of the alkyd inhibitor, and thus uniformly disperse the crystal nucleation growth inhibitor in the aqueous solution. This invention has found that using the above-mentioned preferred emulsifier can better form nano-sized colloidal particles, adsorb nano-hydrated calcium silicate particles, provide nucleation sites, promote the nucleation of nano-calcium silicate, and simultaneously inhibit crystal nucleus growth, which is beneficial to the early effect of the early-strength crystal nucleation agent and also beneficial to the long-term stability of the early-strength agent suspension.

[0022] Preferably, in step (1), the mass ratio of the crystal nucleus growth inhibitor to the emulsifier is 8 to 10:1;

[0023] And / or, in step (1), the mass fraction of the emulsion is 8-12% (i.e., the ratio of the mass of the crystal nucleus growth inhibitor + emulsifier in the emulsion to the mass of the emulsion). In this invention, the amount of emulsifier and the mass fraction of the emulsion should not be too high or too low based on the above range, otherwise it will be detrimental to the effectiveness of the crystal nucleus growth inhibitor.

[0024] Preferably, in step (1), the crystal nucleus growth inhibitor, emulsifier, and water are mixed by stirring at a speed of 1000 r / min or higher for at least 20 minutes. This invention requires the crystal nucleus growth inhibitor and emulsifier to be stirred and mixed at high speed for a certain period of time; otherwise, the crystal nucleus growth inhibitor will not be effective.

[0025] Preferably, in step (2), the soluble calcium source is selected from one or more of calcium nitrate tetrahydrate, calcium formate, calcium acetate, calcium chloride, calcium gluconate, calcium hydrogen phosphate, and calcium lactate; more preferably, it is selected from one or more of calcium nitrate tetrahydrate, calcium formate, calcium acetate, calcium hydrogen phosphate, and calcium lactate.

[0026] And / or, the soluble silicon source is selected from one or more of tetraethyl orthosilicate, sodium metasilicate pentahydrate, potassium silicate, and sodium metasilicate nonahydrate; more preferably, it is one or more of tetraethyl orthosilicate, sodium metasilicate pentahydrate, and sodium metasilicate nonahydrate.

[0027] Preferably, in step (2), the mass fraction of the soluble calcium source aqueous solution is 8-12% (that is, the ratio of the mass of the soluble calcium source to the mass of the soluble silicon source aqueous solution);

[0028] And / or, in step (2), the mass fraction of the soluble silicon source aqueous solution is 8-12%;

[0029] And / or, in step (2), the time for adding the soluble calcium source aqueous solution and the soluble silicon source aqueous solution is 25 to 35 minutes;

[0030] And / or, in step (2), the stirring speed is 60-120 r / min. Controlling the above solution concentration, dropping time, and stirring speed can better achieve the formation of a solid isolation layer with Si-O-Si as the framework on the surface of hydrated calcium silicate crystal nuclei. Too high a concentration, too fast dropping, or too fast stirring will reduce the effect of inhibiting crystal nuclei growth.

[0031] Preferably, in step (2), the alkali is selected from one or more of sodium hydroxide aqueous solution, ammonium bicarbonate aqueous solution, and ammonia water; more preferably, the concentration of the sodium hydroxide aqueous solution, ammonium bicarbonate aqueous solution, and ammonia water is 10-20%.

[0032] Preferably, in step (2), the mass ratio of the nano-hydrated calcium silicate synthesized from the soluble calcium source and the soluble silicon source to the crystal nucleus growth inhibitor is 1:(0.01~0.1).

[0033] Preferably, in step (3), the stirring speed is 120–300 r / min and the stirring time is 25–35 min. The purpose of continuing to stir at the above stirring speed in step (3) for a period of time is to control the binding concentration of the crystal nucleation growth inhibitor on the surface of nano-hydrated calcium silicate, and to prevent the binding concentration of the crystal nucleation growth inhibitor from being too high, which would affect the function of the crystal nucleation of nano-hydrated calcium silicate.

[0034] Those skilled in the art can combine the above solutions based on common sense to obtain preferred embodiments of the preparation method of the present invention.

[0035] The present invention also provides a nano-hydrated calcium silicate crystal nucleation early strength agent, which is prepared by the above preparation method.

[0036] The present invention also provides the application of the above-mentioned nano-hydrated calcium silicate nucleus early strength agent or the nano-hydrated calcium silicate nucleus early strength agent prepared by the above preparation method in concrete preparation.

[0037] The present invention also provides an early-strength concrete, the raw materials of which include: cement, sand, stone and the above-mentioned nano-hydrated calcium silicate crystal nucleation early-strength agent or the nano-hydrated calcium silicate crystal nucleation early-strength agent prepared by the above preparation method.

[0038] Preferably, each cubic meter of the raw material includes 0.5–3 kg of the nano-hydrated calcium silicate nucleation early-strength agent. This invention has found that the amount of nano-hydrated calcium silicate nucleation early-strength agent added to concrete should not be excessive. Exceeding the above-mentioned dosage range, the organic components of the nano-hydrated calcium silicate nucleation early-strength agent bind to the surface of the concrete's cementitious material, affecting the setting time and hardening structure of the cementitious material, and consequently affecting the strength of the early-strength concrete.

[0039] The early-strength concrete provided by this invention can significantly improve early strength without reducing later strength, reduce external curing conditions, and save energy and reduce emissions.

[0040] The beneficial effects of this invention are as follows:

[0041] The method for preparing the nano-hydrated calcium silicate nucleus early-strength agent provided by this invention can be rapidly synthesized under simple synthetic conditions. The resulting nano-hydrated calcium silicate nucleus early-strength agent has a particle size mainly distributed between 100 and 150 nm, with stable nucleus size and long shelf life. When applied to concrete preparation, it can promote early hydration of cement, significantly improve the early strength of concrete, and does not affect later performance, providing strong technical support for energy conservation and emission reduction in concrete. Detailed Implementation

[0042] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention. Any modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and essence of the invention are within the scope of the invention.

[0043] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. All reagents or instruments without specified manufacturers are conventional products that can be purchased through legitimate channels.

[0044] Example 1

[0045] This embodiment provides a nano-hydrated calcium silicate crystal nucleation early strength agent (NS-S-25), and the preparation method of the nano-hydrated calcium silicate crystal nucleation early strength agent includes the following steps:

[0046] (1) Prepare 29.5 kg of a 10% emulsion by mixing polymethylhydrosiloxane (molecular weight 1700-3200), Pingpingjia O-25 and water in a ratio of 9:1:90. Stir at 2000 r / min for 30 min to prepare a 10% concentration emulsion and add it to the reaction vessel.

[0047] (2) Prepare 16.4 kg of calcium nitrate and 56.8 kg of sodium metasilicate nonahydrate into 10% solutions respectively, and add them dropwise to the reaction vessel while stirring. Adjust the dropping speed according to the mass of the two solutions. The addition is completed simultaneously in 30 min, and the stirring speed is 90 r / min.

[0048] (3) Add sodium hydroxide solution dropwise to adjust the pH of the solution in the reactor to 12.5;

[0049] (4) After the addition is complete, the stirring speed is adjusted to 200 r / min and stirred for 30 min to prepare a nano-hydrated calcium silicate crystal nucleus early strength agent emulsion.

[0050] Example 2

[0051] This embodiment provides a nano-hydrated calcium silicate crystal nucleation early strength agent (NS-S-09), and the preparation method of the nano-hydrated calcium silicate crystal nucleation early strength agent includes the following steps:

[0052] (1) Prepare 21.96 kg of a 10% emulsion by mixing hexadecyltrimethoxysilane, AEO-09 and water in a ratio of 9:1:90. Stir the mixture at 2000 r / min for 30 min to prepare a 10% concentration emulsion and add it to the reaction vessel.

[0053] (2) Prepare 16.4 kg of calcium nitrate and 42.6 kg of sodium metasilicate nonahydrate into 10% solutions respectively, and add them dropwise to the reaction vessel while stirring. Adjust the dropping speed according to the mass of the two solutions. The addition is completed simultaneously in 30 min, and the stirring speed is 90 r / min.

[0054] (3) Add sodium hydroxide solution dropwise to adjust the pH of the solution in the reactor to 12.5;

[0055] (4) After the addition is complete, the stirring speed is adjusted to 200 r / min and stirred for 30 min to prepare a nano-hydrated calcium silicate crystal nucleus early strength agent emulsion.

[0056] Example 3

[0057] This embodiment provides a nano-hydrated calcium silicate crystal nucleation early strength agent (NS-T-20), and the preparation method of the nano-hydrated calcium silicate crystal nucleation early strength agent includes the following steps:

[0058] (1) Prepare 16.88 kg of a 10% emulsion by mixing isobutylsilane, Tween-20 and water in a ratio of 9:1:90. Stir the mixture at 2000 r / min for 30 min to prepare a 10% concentration emulsion and add it to the reaction vessel.

[0059] (2) Prepare 16.4 kg of calcium nitrate and 51.12 kg of sodium metasilicate nonahydrate into 10% solutions respectively, and add them dropwise to the reaction vessel while stirring. Adjust the dropping speed according to the mass of the two solutions. The addition is completed simultaneously in 30 min, and the stirring speed is 90 r / min.

[0060] (3) Add sodium hydroxide solution dropwise to adjust the pH of the solution in the reactor to 12.5;

[0061] (4) After the addition is complete, the stirring speed is adjusted to 200 r / min and stirred for 30 min to prepare a nano-hydrated calcium silicate crystal nucleus early strength agent emulsion.

[0062] Example 4

[0063] This embodiment provides a nano-hydrated calcium silicate crystal nucleation early strength agent (NS-TP-20), and the preparation method of the nano-hydrated calcium silicate crystal nucleation early strength agent includes the following steps:

[0064] (1) Prepare 16.88 kg of a 10% emulsion by mixing polydimethylsiloxane (molecular weight about 550), Tween-20 and water in a ratio of 9:1:90. Stir the mixture at 2000 r / min for 30 min to prepare a 10% concentration emulsion and add it to the reaction vessel.

[0065] (2) Prepare 16.4 kg of calcium nitrate and 51.12 kg of sodium metasilicate nonahydrate into 10% solutions respectively, and add them dropwise to the reaction vessel while stirring. Adjust the dropping speed according to the mass of the two solutions. The addition is completed simultaneously in 30 min, and the stirring speed is 90 r / min.

[0066] (3) Add sodium hydroxide solution dropwise to adjust the pH of the solution in the reactor to 12.5;

[0067] (4) Add 37.12 kg of 10% polycarboxylate superplasticizer (Chang'an Yucai polycarboxylate superplasticizer GK-3000, the same below) dropwise, and complete the addition simultaneously in 120 min, with a stirring speed of 90 r / min;

[0068] (5) After the addition is complete, the stirring speed is adjusted to 200 r / min and stirred for 30 min to prepare a nano-hydrated calcium silicate crystal nucleus early strength agent emulsion.

[0069] Example 5

[0070] This embodiment provides a nano-hydrated calcium silicate crystal nucleation early strength agent (NS-YZ-25), and the preparation method of the nano-hydrated calcium silicate crystal nucleation early strength agent includes the following steps:

[0071] (1) Prepare 29.5 kg of a 10% emulsion by mixing stearic acid, Pingpingjia O-25 and water in a ratio of 9:1:90. Stir at 2000 r / min for 30 min to prepare a 10% concentration emulsion and add it to the reaction vessel.

[0072] (2) Prepare 16.4 kg of calcium nitrate and 56.8 kg of sodium metasilicate nonahydrate into 10% solutions respectively, and add them dropwise to the reaction vessel while stirring. Adjust the dropping speed according to the mass of the two solutions. The addition is completed simultaneously in 30 min, and the stirring speed is 90 r / min.

[0073] (3) Add sodium hydroxide solution dropwise to adjust the pH of the solution in the reactor to 12.5;

[0074] (4) After the addition is complete, the stirring speed is adjusted to 200 r / min and stirred for 30 min to prepare a nano-hydrated calcium silicate crystal nucleus early strength agent emulsion.

[0075] Example 6

[0076] This embodiment provides a nano-hydrated calcium silicate crystal nucleation early strength agent (NS-YS-09), and the preparation method of the nano-hydrated calcium silicate crystal nucleation early strength agent includes the following steps:

[0077] (1) Prepare 21.96 kg of 10% emulsion by mixing oleic acid, AEO-09 and water in a ratio of 9:1:90. Stir at 2000 r / min for 30 min to prepare an emulsion with a concentration of 10%, and add it to the reaction vessel.

[0078] (2) Prepare 16.4 kg of calcium nitrate and 42.6 kg of sodium metasilicate nonahydrate into 10% solutions respectively, and add them dropwise to the reaction vessel while stirring. Adjust the dropping speed according to the mass of the two solutions. The addition is completed simultaneously in 30 min, and the stirring speed is 90 r / min.

[0079] (3) Add sodium hydroxide solution dropwise to adjust the pH of the solution in the reactor to 12.5;

[0080] (4) After the addition is complete, the stirring speed is adjusted to 200 r / min and stirred for 30 min to prepare a nano-hydrated calcium silicate crystal nucleus early strength agent emulsion.

[0081] Example 7

[0082] This embodiment provides a nano-hydrated calcium silicate crystal nucleation early strength agent (NS-SY-20), and the preparation method of the nano-hydrated calcium silicate crystal nucleation early strength agent includes the following steps:

[0083] (1) Prepare a 10% emulsion of triethanolamine, Tween-20 and water in a ratio of 9:1:90, weigh 13.5 kg, and stir at 2000 r / min for 30 min to prepare a 10% concentration emulsion, and add it to the reaction vessel;

[0084] (2) Prepare 16.4 kg of calcium nitrate and 51.12 kg of sodium metasilicate nonahydrate into 10% solutions respectively, and add them dropwise to the reaction vessel while stirring. Adjust the dropping speed according to the mass of the two solutions. The addition is completed simultaneously in 30 min, and the stirring speed is 90 r / min.

[0085] (3) Add sodium hydroxide solution dropwise to adjust the pH of the solution in the reactor to 12.5;

[0086] (4) After the addition is complete, the stirring speed is adjusted to 200 r / min and stirred for 30 min to prepare a nano-hydrated calcium silicate crystal nucleus early strength agent emulsion.

[0087] Example 8

[0088] This embodiment provides a nano-hydrated calcium silicate crystal nucleation early strength agent (NS-NM-20), and the preparation method of the nano-hydrated calcium silicate crystal nucleation early strength agent includes the following steps:

[0089] (1) Prepare 13.5 kg of 10% emulsion by mixing citric acid, Tween-20 and water in a ratio of 9:1:90. Stir at 2000 r / min for 30 min to prepare an emulsion with a concentration of 10%, and add it to the reaction vessel.

[0090] (2) Prepare 16.4 kg of calcium nitrate and 51.12 kg of sodium metasilicate nonahydrate into 10% solutions respectively, and add them dropwise to the reaction vessel while stirring. Adjust the dropping speed according to the mass of the two solutions. The addition is completed simultaneously in 30 min, and the stirring speed is 90 r / min.

[0091] (3) Add sodium hydroxide solution dropwise to adjust the pH of the solution in the reactor to 12.5;

[0092] (4) Add 37.12 kg of 10% polycarboxylate superplasticizer dropwise over 120 min, stirring at a speed of 90 r / min.

[0093] (5) After the addition is complete, the stirring speed is adjusted to 200 r / min and stirred for 30 min to prepare a nano-hydrated calcium silicate crystal nucleus early strength agent emulsion.

[0094] Comparative Example 1

[0095] This comparative example provides a nano-hydrated calcium silicate crystal nucleation early strength agent. The preparation method of the nano-hydrated calcium silicate crystal nucleation early strength agent (NS-P-3000) includes the following steps:

[0096] (1) Prepare 16.4 kg of calcium nitrate and 51.12 kg of sodium metasilicate nonahydrate into 10% solutions respectively, and add them dropwise to the reaction vessel while stirring. Adjust the dropping speed according to the mass of the two solutions. The addition is completed simultaneously in 120 min, with a stirring speed of 90 r / min.

[0097] (2) Add sodium hydroxide solution dropwise to adjust the pH of the solution in the reactor to 12.5;

[0098] (3) Add 54 kg of 10% polycarboxylate superplasticizer dropwise over 120 min, stirring at a speed of 90 r / min.

[0099] (4) After the addition is complete, the stirring speed is adjusted to 200 r / min and stirred for 30 min to prepare a nano-hydrated calcium silicate crystal nucleus early strength agent emulsion.

[0100] Comparative Example 2

[0101] This comparative example provides a nano-hydrated calcium silicate crystal nucleation early strength agent (NS-S-550), the preparation method of which includes the following steps:

[0102] (1) Prepare 29.5 kg of 10% emulsion by mixing KH550, Pingpingjia O-25 and water in a ratio of 9:1:90, and stir at 2000 r / min for 30 min to prepare an emulsion with a concentration of 10%, and add it to the reaction vessel;

[0103] (2) Prepare 16.4 kg of calcium nitrate and 56.8 kg of sodium metasilicate nonahydrate into 10% solutions respectively, and add them dropwise to the reaction vessel while stirring. Adjust the dropping speed according to the mass of the two solutions. The addition is completed simultaneously in 30 min, and the stirring speed is 90 r / min.

[0104] (3) Add sodium hydroxide solution dropwise to adjust the pH of the solution in the reactor to 12.5;

[0105] (4) After the addition is complete, the stirring speed is adjusted to 200 r / min and stirred for 30 min to prepare a nano-hydrated calcium silicate crystal nucleus early strength agent emulsion.

[0106] Comparative Example 3

[0107] This comparative example provides a nano-hydrated calcium silicate crystal nucleation early strength agent (NS-BS-25), the preparation method of which includes the following steps:

[0108] (1) Prepare 29.5 kg of a 10% emulsion by mixing glycerol, phenacetin O-25 and water in a ratio of 9:1:90. Stir the mixture at 2000 r / min for 30 min to prepare a 10% concentration emulsion and add it to the reaction vessel.

[0109] (2) Prepare 16.4 kg of calcium nitrate and 56.8 kg of sodium metasilicate nonahydrate into 10% solutions respectively, and add them dropwise to the reaction vessel while stirring. Adjust the dropping speed according to the mass of the two solutions. The addition is completed simultaneously in 30 min, and the stirring speed is 90 r / min.

[0110] (3) Add sodium hydroxide solution dropwise to adjust the pH of the solution in the reactor to 12.5;

[0111] (4) After the addition is complete, the stirring speed is adjusted to 200 r / min and stirred for 30 min to prepare a nano-hydrated calcium silicate crystal nucleus early strength agent emulsion.

[0112] Experimental Example 1: Particle size of nano-hydrated calcium silicate crystal nucleation early strength agent

[0113] The particle size of the nucleation early strength agents prepared in the examples and comparative examples was tested using a nanoparticle size and ZETA potential meter, and the results are shown in Table 1.

[0114] Table 1 Particle size of crystal nucleation early strength agent

[0115]

[0116]

[0117] As can be seen from the data in Table 1, the particle size of the nucleation accelerator synthesized using the embodiments of the present invention is mainly distributed in the range of 100–150 nm, which is smaller than that of Comparative Examples 1–3, indicating that this method can effectively control the particle size of the nucleation accelerator. Meanwhile, the technical effects of Comparative Examples 2 and 3 show that not all silane or alkyd small molecules can achieve the effect of inhibiting nucleus growth.

[0118] Experimental Example 2: Early Strength Test of Nano-Hydrated Calcium Silicate Nucleation Agent

[0119] The raw materials for concrete are as follows:

[0120] PI 42.5 cement, S95 mineral powder, grade II fly ash, limestone aggregate (5-20mm), medium sand from zone II, polycarboxylate superplasticizer, and crystal nucleation early strength agent.

[0121] The raw material formula for concrete is shown in Table 2.

[0122] Table 2 Concrete material mix proportions (kg / m³) 3 )

[0123] cement fly ash Mineral powder silica ash Big rocks water Water reducing agent Crystal nucleation early strength agent 152 22 33 13 1655 57 4.8 1.0

[0124] The strength of each concrete was tested according to GB 50081-2019, and the results are shown in Table 3.

[0125] Table 3. Application effects of different early-strength agents in various concretes.

[0126]

[0127]

[0128] Table 3 shows that the concrete with the nucleation accelerators from Examples 1 to 8 all exhibited increased strength, especially early-age strength. The 1-day strength increased by 25.9%, 27.8%, 24.1%, 27.8%, 16.7%, 25.9%, 33.3%, and 14.8%, respectively, significantly improving upon the effects of traditional polycarboxylate nucleation growth inhibitors. Simultaneously, it was found that accelerators using KH550 or glycerol as nucleation growth inhibitors did not achieve the desired early-age effect; instead, the concrete strength decreased significantly, highlighting the importance of inhibitor selection.

[0129] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a nano-hydrated calcium silicate crystal nucleation early strength agent, characterized in that, Includes the following steps: (1) Mix the crystal nucleus growth inhibitor, emulsifier and water to obtain an emulsion; The crystal nucleus growth inhibitor is a silane inhibitor and / or an alcoholic acid inhibitor; The silane inhibitor is selected from one or more of polymethylhydrosiloxane, polydimethylsiloxane, hexadecyltrimethoxysilane, and isobutylsilane; The alcoholic acid inhibitors are selected from one or more of stearic acid, oleic acid, citric acid, and triethanolamine; (2) Under stirring conditions, add soluble calcium source aqueous solution and soluble silicon source aqueous solution dropwise to the emulsion; then add alkali to adjust the pH value to above 12; (3) Continue stirring for a period of time to obtain the final product; In step (1), the mass ratio of the crystal nucleus growth inhibitor to the emulsifier is 8~10:1; In step (1), the mass fraction of the emulsion is 8-12%; In step (1), the crystal growth inhibitor, emulsifier and water are mixed by stirring at a speed of more than 1000 r / min for more than 20 min.

2. The preparation method according to claim 1, characterized in that, In step (1), the emulsifier is selected from one or more of the following: Pinto-Ping-Gar O-25, AEO-9, OP-7, OP-10, Tween-20, Tween-80, Span-20, and Span-80.

3. The preparation method according to claim 1, characterized in that, In step (2), the soluble calcium source is selected from one or more of calcium nitrate tetrahydrate, calcium formate, calcium acetate, calcium chloride, calcium gluconate, calcium hydrogen phosphate, and calcium lactate. And / or, the soluble silicon source is selected from one or more of tetraethyl orthosilicate, sodium metasilicate pentahydrate, potassium silicate, and sodium metasilicate nonahydrate.

4. The preparation method according to claim 1, characterized in that, In step (2), the mass fraction of the soluble calcium source aqueous solution is 8-12%; And / or, in step (2), the mass fraction of the soluble silicon source aqueous solution is 8~12%; And / or, in step (2), the time for adding the soluble calcium source aqueous solution and the soluble silicon source aqueous solution is 25~35 min; And / or, in step (2), the stirring speed is 60~120 r / min.

5. The preparation method according to claim 1, characterized in that, In step (3), the stirring speed is 120~300 r / min and the stirring time is 25~35 min.

6. A nano-hydrated calcium silicate crystal nucleation early strength agent, characterized in that, It is prepared by the preparation method according to any one of claims 1-5.

7. A type of early-strength concrete, characterized in that, The raw materials include: cement, sand, stone, and the nano-hydrated calcium silicate crystal nucleation early strength agent as described in claim 6 or the nano-hydrated calcium silicate crystal nucleation early strength agent prepared by the preparation method described in any one of claims 1-5.

8. The early-strength concrete according to claim 7, characterized in that, Each cubic meter of the raw material includes 0.5~3 kg of the nano-hydrated calcium silicate crystal nucleation early strength agent.

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