A concrete nano-reinforcing agent, a preparation method and application thereof

Abstract

The application provides a concrete nano-reinforcing agent and a preparation method and application thereof, raw materials of the concrete nano-reinforcing agent include: silicon dioxide, graphene and calcium silicate; the particle size of the silicon dioxide is 1-20 nm; the particle size of the graphene is 20-200 nm; and the particle size of the calcium silicate is 200-700 nm. The concrete nano-reinforcing agent adopts three kinds of nano materials with different particle sizes, and the compactness of the concrete can be significantly increased by using the synergistic effect among the three kinds of nano materials; the voids of the concrete are filled by the nano materials with a particle size ladder distribution, so that the compactness of the concrete is increased, and the strength and durability of the concrete are improved.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, and in particular relates to a concrete nano-reinforcing agent, its preparation method and application. Background Technology

[0002] With the vigorous development of modern industry, reinforced concrete structures have become the most important construction method. Even with the great progress in technology and the continuous improvement of standards, it still faces huge tests and challenges in terms of energy, renewable resources, and materials.

[0003] Currently, people are dedicated to research and development in new materials, new energy sources, energy conservation, and environmental protection, with new technologies and materials for building construction gradually becoming a research focus. Therefore, the application and promotion of reinforcing agents in high-performance concrete has significant practical implications for energy conservation and emission reduction.

[0004] Concrete strengthening agents are a new type of concrete admixture developed to address issues such as cement particle agglomeration and the diversity of concrete raw materials. Currently, most concrete strengthening agents on the market primarily improve the 3-day early strength of concrete while reducing economic losses, but they cannot improve the 28-day and later strength, thus failing to achieve the goal of reducing cement usage.

[0005] CN105130242A discloses a novel concrete reinforcing agent for use in concrete. By weight, the concrete reinforcing agent comprises the following raw materials: 10-25 parts ethylene glycol, 6-10 parts isopropanol, 1-7 parts sodium metabisulfite, 2-7 parts sodium hexametaphosphate, 5-12 parts caustic soda, 2-5 parts triethanolamine, and 3-8 parts hydrophilic fumed silica. The concrete reinforcing agent is mixed with cement, mineral powder, fly ash, sand, water, gravel, and a water-reducing agent in a large mixer. The amount of concrete reinforcing agent used accounts for 3%-5% of the total weight of cement, mineral powder, and fly ash. The concrete reinforcing agent can comprehensively improve the mechanical properties of concrete and significantly increase the strength of concrete at all ages, thereby achieving the goal of reducing the amount of cement used in concrete. However, the amount of concrete reinforcing agent used is relatively large, resulting in high cost.

[0006] In addition, sand and stone materials account for more than 80% of the volume in existing concrete, which are called aggregates and play the role of load-bearing skeleton. Cement and water form cement paste, which coats the aggregates and fills their voids. However, the particle size of cement is 3-30μm, which cannot fill nanoscale voids and its density cannot be increased.

[0007] Therefore, to address the above problems, a novel concrete nano-reinforcing agent with low addition amount is provided, which can fill the voids in concrete, increase the density of concrete, and improve the strength and durability of concrete at all stages. Summary of the Invention

[0008] The purpose of this invention is to provide a concrete nano-reinforcing agent, its preparation method, and its application. The concrete nano-reinforcing agent uses nanomaterials of different particle sizes to fill the voids in concrete, increasing the density of concrete and thus improving its strength. At the same time, it can also increase the content and hydration of cement mineral components, thereby improving the strength and durability of concrete.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] This invention provides a concrete nano-reinforcing agent, the raw materials of which include: silicon dioxide, graphene and calcium silicate;

[0011] The particle size of the silicon dioxide is 1-20nm, for example, it can be 2nm, 3nm, 4nm, 5nm, 7nm, 9nm, 10nm, 12nm, 14nm, 15nm, 16nm, 18nm or 19nm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0012] The graphene has a particle size of 20-200nm, such as 30nm, 40nm, 50nm, 70nm, 90nm, 100nm, 120nm, 140nm, 150nm, 160nm, 180nm or 190nm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0013] The particle size of the calcium silicate is 200-700nm, for example, it can be 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm or 680nm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0014] The concrete nano-reinforcing agent of this invention uses three nanomaterials with different particle sizes as raw materials. The synergistic effect among these three materials significantly increases the density of concrete. The voids in the concrete are filled by the nanomaterials with a stepped particle size distribution, increasing the density and thus improving the strength of the concrete. Furthermore, the layered structure of graphene increases the dispersibility of the concrete, improving its workability; calcium silicate promotes cement hydration; and silica enhances strength during later cement hydration. The nanomaterials themselves participate in the cement hydration reaction and form a strong interwoven network structure with cement particles, further increasing the compressive and flexural strength of the concrete.

[0015] As a preferred technical solution of the present invention, the weight of silica in the concrete nano-reinforcing agent is 6-8 parts, for example, it can be 6.2 parts, 6.4 parts, 6.5 parts, 6.6 parts, 6.8 parts, 7 parts, 7.2 parts, 7.4 parts, 7.5 parts, 7.6 parts, 7.8 parts or 7.9 parts, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0016] As a preferred embodiment of the present invention, the graphene comprises layered graphene.

[0017] Preferably, the graphene in the concrete nano-reinforcing agent is 4-6 parts by weight, for example, 4.2 parts, 4.4 parts, 4.5 parts, 4.6 parts, 4.8 parts, 5 parts, 5.2 parts, 5.4 parts, 5.5 parts, 5.6 parts, 5.8 parts, or 5.9 parts, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] As a preferred technical solution of the present invention, the weight percentage of calcium silicate in the concrete nano-reinforcing agent is 19.5-21 parts, for example, it can be 19.7 parts, 19.9 parts, 20 parts, 20.1 parts, 20.2 parts, 20.3 parts, 20.4 parts, 20.5 parts, 20.6 parts, 20.7 parts, 20.8 parts, or 20.9 parts, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] Preferably, the method for preparing calcium silicate includes: adding sodium metasilicate solution and calcium chloride solution dropwise to a solution containing silicon dioxide and graphene to obtain calcium silicate.

[0020] It is worth noting that commercially available calcium silicate has a relatively large particle size, which cannot meet the requirements for nanoscale production. Therefore, it is necessary to manufacture nano-sized calcium silicate in-house. This invention employs a one-step synthesis method for calcium silicate in a solution containing silicon dioxide and graphene, thereby controlling the particle size of calcium silicate within the range of 200-700 nm.

[0021] Preferably, the mass concentration of the sodium metasilicate solution is 42%-46%, for example, it can be 42.5%, 43%, 43.5%, 44%, 44.5%, 45% or 45.5%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] The sodium metasilicate solution of the present invention is prepared by dissolving sodium metasilicate and water, for example, 13.5 parts of sodium metasilicate pentahydrate and 17 parts of water are dissolved for later use.

[0023] Preferably, the mass concentration of the calcium chloride solution is 45%-47%, for example, it can be 45.1%, 45.2%, 45.4%, 45.5%, 45.7%, 45.9%, 46%, 46.2%, 46.4%, 46.5%, 46.7% or 46.9%, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0024] The calcium chloride solution of the present invention is prepared by dissolving calcium chloride in water, for example, 9 parts of calcium chloride and 10.4 parts of water.

[0025] Preferably, the mass ratio of the sodium metasilicate solution to the calcium chloride solution is (1.4-1.6):1, for example, it can be 1.42:1, 1.44:1, 1.46:1, 1.48:1, 1.5:1, 1.52:1, 1.54:1, 1.56:1, 1.58:1 or 1.59:1, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] Preferably, the dropping is carried out under stirring conditions.

[0027] Preferably, the dripping rate is 0.26-0.28 g / min, for example, it can be 0.262 g / min, 0.264 g / min, 0.265 g / min, 0.266 g / min, 0.268 g / min, 0.27 g / min, 0.272 g / min, 0.274 g / min, 0.276 g / min, 0.278 g / min or 0.279 g / min, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] Preferably, the stirring speed is 3400-3600 r / min, for example, it can be 3420 r / min, 3440 r / min, 3450 r / min, 3460 r / min, 3480 r / min, 3500 r / min, 3520 r / min, 3540 r / min, 3550 r / min, 3560 r / min or 3580 r / min, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0029] It is worth noting that the present invention achieves a particle size of 200-700 nm for the calcium silicate by controlling the stirring speed and material dropping speed range during the preparation of nano-calcium silicate.

[0030] As a preferred embodiment of the present invention, the concrete nano-reinforcing agent further includes a dispersant.

[0031] Preferably, the dispersant comprises triisopropanolamine.

[0032] Preferably, the dispersant in the concrete nano-reinforcing agent is 2-4 parts by weight, for example, 2.2 parts, 2.4 parts, 2.5 parts, 2.6 parts, 2.8 parts, 3 parts, 3.2 parts, 3.4 parts, 3.5 parts, 3.6 parts, 3.8 parts, or 3.9 parts, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0033] Preferably, the concrete nano-reinforcing agent further includes an antifoaming agent.

[0034] This invention does not limit the specific materials of the defoamer, as long as they can achieve the defoaming effect. Those skilled in the art can make specific selections according to the actual situation.

[0035] Preferably, the defoamer in the concrete nano-reinforcing agent is 0.05-0.15 parts by weight, for example, 0.06 parts, 0.07 parts, 0.08 parts, 0.09 parts, 0.1 parts, 0.11 parts, 0.12 parts, 0.13 parts or 0.14 parts, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] As a preferred embodiment of the present invention, the concrete nano-reinforcing agent further includes a suspending agent.

[0037] Preferably, the suspending agent comprises sodium polyacrylate.

[0038] Preferably, the relative molecular weight of the sodium polyacrylate is 2500-3500, for example, it can be 2600, 2700, 2800, 2900, 3000, 3100, 3200, 3300 or 3400, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0039] Preferably, the mass concentration of the sodium polyacrylate is 25%-32%, for example, it can be 25.5%, 26%, 26.5%, 27%, 27.5%, 28%, 28.5%, 29%, 29.5%, 30%, 30.5%, 31% or 31.5%, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0040] Preferably, the weight percentage of the suspending agent in the concrete nano-reinforcing agent is 4-6 parts, for example, 4.2 parts, 4.4 parts, 4.5 parts, 4.6 parts, 4.8 parts, 5 parts, 5.2 parts, 5.4 parts, 5.5 parts, 5.6 parts, 5.8 parts, or 5.9 parts, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] In a second aspect, the present invention provides a method for preparing a concrete nano-reinforcing agent as described in the first aspect, the method comprising:

[0042] The concrete nano-reinforcing agent was obtained by mixing silica, graphene and calcium silicate in a solvent using an emulsion suspension method.

[0043] It is worth noting that, since silica, graphene, and calcium silicate are insoluble in water, this invention employs an emulsion suspension method to uniformly mix the three materials with different particle sizes to obtain a concrete nano-reinforcing agent. The preparation method of the concrete nano-reinforcing agent provided by this invention is simple, and the concrete nano-reinforcing agent can be obtained using an emulsion suspension method at room temperature and pressure. This method has low production costs and is easy to promote and apply.

[0044] As a preferred technical solution of the present invention, the preparation method specifically includes:

[0045] (1) Add dispersant and defoamer to solvent, stir for the first time, then add silica, graphene and suspending agent in sequence, stir for the second time to obtain the first mixed emulsion;

[0046] (2) Add sodium metasilicate solution and calcium chloride solution to the first mixed emulsion in step (1) to obtain calcium silicate, and perform a third stirring to obtain the concrete nano-reinforcing agent.

[0047] In this invention, the solvent is water; the sum of the weight parts of the raw materials and the solvent is 100 parts.

[0048] The preparation method of the present invention first adds silica and graphene to a mixed solution of dispersant and defoamer to make them uniformly dispersed in water. Then, silica and graphene are first suspended by a suspending agent. Finally, nano-calcium silicate is synthesized in the above emulsion to obtain the concrete nano-reinforcing agent.

[0049] As a preferred technical solution of the present invention, the rotation speed of the first stirring in step (1) is 290-310 r / min, for example, it can be 292 r / min, 294 r / min, 295 r / min, 297 r / min, 299 r / min, 300 r / min, 302 r / min, 304 r / min, 305 r / min, 307 r / min or 309 r / min, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0050] Preferably, the stirring time in step (1) is 8-12 min, for example, it can be 8.5 min, 9 min, 9.5 min, 10 min, 10.5 min, 11 min or 11.5 min, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0051] Preferably, the stirring speed in step (1) is 2900-3100 r / min, for example, it can be 2920 r / min, 2940 r / min, 2950 r / min, 2970 r / min, 2990 r / min, 3000 r / min, 3020 r / min, 3040 r / min, 3050 r / min, 3070 r / min or 3090 r / min, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0052] Preferably, after adding silica in step (1), a second stirring is performed for 50-70 minutes, for example, 52 minutes, 54 minutes, 55 minutes, 56 minutes, 58 minutes, 60 minutes, 62 minutes, 64 minutes, 65 minutes, 66 minutes, 68 minutes or 69 minutes, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0053] Preferably, after adding graphene in step (1), a second stirring is performed for 50-70 minutes, such as 52 minutes, 54 minutes, 55 minutes, 56 minutes, 58 minutes, 60 minutes, 62 minutes, 64 minutes, 65 minutes, 66 minutes, 68 minutes or 69 minutes, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0054] Preferably, after adding the suspending agent in step (1), a second stirring is performed for 50-70 minutes, for example, 52 minutes, 54 minutes, 55 minutes, 56 minutes, 58 minutes, 60 minutes, 62 minutes, 64 minutes, 65 minutes, 66 minutes, 68 minutes or 69 minutes, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0055] Preferably, the dropwise addition in step (2) is carried out under stirring conditions.

[0056] Preferably, the dripping rate in step (2) is 0.26-0.28 g / min, for example, it can be 0.262 g / min, 0.264 g / min, 0.265 g / min, 0.266 g / min, 0.268 g / min, 0.27 g / min, 0.272 g / min, 0.274 g / min, 0.276 g / min, 0.278 g / min or 0.279 g / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0057] Preferably, the stirring speed is 3400-3600 r / min, for example, it can be 3420 r / min, 3440 r / min, 3450 r / min, 3460 r / min, 3480 r / min, 3500 r / min, 3520 r / min, 3540 r / min, 3550 r / min, 3560 r / min or 3580 r / min, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0058] Preferably, the rotation speed of the third stirring in step (2) is 3400-3600 r / min, for example, it can be 3420 r / min, 3440 r / min, 3450 r / min, 3460 r / min, 3480 r / min, 3500 r / min, 3520 r / min, 3540 r / min, 3550 r / min, 3560 r / min or 3580 r / min, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0059] Preferably, the third stirring time in step (2) is 25-35 min, for example, it can be 26 min, 27 min, 28 min, 29 min, 30 min, 31 min, 32 min, 33 min or 34 min, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0060] Thirdly, the present invention provides a concrete comprising the concrete nano-reinforcing agent described in the first aspect or the concrete nano-reinforcing agent prepared by the preparation method described in the second aspect.

[0061] Preferably, the amount of concrete nano-reinforcing agent added to the concrete is 0.5%-0.8%, for example, it can be 0.52%, 0.54%, 0.55%, 0.56%, 0.58%, 0.6%, 0.62%, 0.64%, 0.65%, 0.66%, 0.68%, 0.7%, 0.72%, 0.74%, 0.75%, 0.76%, or 0.78%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0062] By adding the aforementioned concrete nano-reinforcing agent to the concrete of this invention, the amount of cement used in the concrete is reduced while the strength and durability of the concrete are improved.

[0063] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0064] Compared with the prior art, the present invention has the following beneficial effects:

[0065] (1) The concrete nano-reinforcing agent provided by the present invention uses three nanomaterials with different particle sizes as raw materials. The synergistic effect between the three can significantly increase the density of concrete. The voids in the concrete are filled by nanomaterials with a stepped particle size distribution, which increases the density of concrete and thus improves the strength and durability of concrete.

[0066] (2) The preparation method provided by the present invention prepares nano-calcium silicate in a solution containing silicon dioxide and graphene, and uniformly mixes three materials with different particle sizes using an emulsion suspension method to obtain a concrete nano-reinforcing agent. The preparation method is simple and can be obtained by using an emulsion suspension method at room temperature and pressure. It has low production cost and is easy to promote and apply. Detailed Implementation

[0067] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0068] In the following examples and comparative examples, the sodium metasilicate solutions were all prepared by dissolving sodium metasilicate pentahydrate in water; and the calcium chloride solutions were all prepared by dissolving calcium chloride in water.

[0069] Example 1

[0070] This embodiment provides a concrete nano-reinforcing agent and its preparation method. The raw materials of the concrete nano-reinforcing agent include: 7 parts of silica with a particle size of 10 nm, 5 parts of layered graphene with a particle size of 110 nm, calcium silicate with a particle size of 500 nm, 3 parts of triisopropanolamine, 0.1 parts of defoamer, 5 parts of sodium polyacrylate with a relative molecular weight of 3000 and a mass concentration of 30%, and 30 parts of water.

[0071] The raw materials for preparing the calcium silicate are: 30.5 parts of sodium metasilicate solution with a mass concentration of 44.3% and 19.4 parts of calcium chloride solution with a mass concentration of 46.4%;

[0072] The preparation method of the concrete nano-reinforcing agent includes the following steps:

[0073] (1) Add triisopropanolamine and defoamer to 30 parts of water, stir for 10 minutes at a speed of 300 r / min, then add silica and stir for 60 minutes, then add graphene and stir for 60 minutes, and finally add sodium polyacrylate and stir for 60 minutes to obtain the first mixed emulsion.

[0074] The second stirring speed is 3000 r / min;

[0075] (2) Add sodium metasilicate solution and calcium chloride solution dropwise to the first mixed emulsion in step (1) at a rate of 0.3 g / min to obtain calcium silicate. After the dropwise addition is completed, stir for a third time at a speed of 3500 r / min for 30 min to obtain the concrete nano-reinforcing agent.

[0076] The dropping was carried out under stirring conditions at a speed of 3500 r / min.

[0077] The concrete nano-reinforcing agent prepared in this embodiment was subjected to mortar strength testing. The flexural strength and compressive strength were determined in accordance with GB / T17671-1999 Cement Mortar Strength Test Method (ISO Method). PO42.5 cement was used. The results were compared with commercially available reinforcing agents. The performance test results are shown in Table 1.

[0078] Table 1

[0079]

[0080] Among them: the blank product is prepared using a standard mortar formula without any reinforcing agent; commercially available product 1 is a commercially available nano concrete reinforcing agent; commercially available product 2 is a commercially available high-efficiency concrete reinforcing agent.

[0081] As shown in Table 1, compared with commercially available reinforcing agents, the concrete nano-reinforcing agent prepared in Example 1 of this invention has a better effect when incorporated into mortar, and can effectively improve the flexural strength and compressive strength of mortar.

[0082] The concrete nano-reinforcing agent prepared in this embodiment was used for concrete strength testing. Compressive strength tests were conducted according to GB / T50081-2002, Test Methods for Mechanical Properties of Ordinary Concrete, using C30 concrete. The mix proportions of the C30 concrete are shown in Table 2. The compressive strength test results with constant and reduced cement content are shown in Tables 3 and 4, respectively.

[0083] Table 2

[0084] cement fly ash Mineral powder water Manufactured sand pebbles Water reducing agent Dosage / kg 220 80 60 170 895 970 11

[0085] The cement used is PO42.5, the fly ash is Grade II fly ash, the mineral powder is S95 mineral powder, and the fineness modulus of the manufactured sand is 2.9.

[0086] Table 3

[0087]

[0088] Table 4

[0089]

[0090] As shown in Tables 3 and 4, compared with commercially available reinforcing agents, the concrete nano-reinforcing agent prepared in Example 1 of this invention has superior compressive strength when incorporated into concrete, and still has good compressive strength and durability when the amount of cement is reduced.

[0091] Example 2

[0092] This embodiment provides a concrete nano-reinforcing agent and its preparation method. The raw materials of the concrete nano-reinforcing agent include: 6 parts of silica with a particle size of 2 μm, 6 parts of layered graphene with a particle size of 20 nm, calcium silicate with a particle size of 200 nm, 2 parts of triisopropanolamine, 0.05 parts of defoamer, 6 parts of sodium polyacrylate with a relative molecular weight of 2500 and a mass concentration of 25%, and 30.55 parts of water.

[0093] The raw materials for preparing the calcium silicate are: 30 parts of sodium metasilicate solution with a mass concentration of 43% and 19.4 parts of calcium chloride solution with a mass concentration of 47%.

[0094] The preparation method of the concrete nano-reinforcing agent includes the following steps:

[0095] (1) Add triisopropanolamine and defoamer to 30.55 parts of water, stir for 12 minutes at a speed of 290 r / min, then add silica and stir for 70 minutes, then add graphene and stir for 70 minutes, and finally add sodium polyacrylate and stir for 70 minutes to obtain the first mixed emulsion.

[0096] The second stirring speed is 2900 r / min;

[0097] (2) Add sodium metasilicate solution and calcium chloride solution to the first mixed emulsion in step (1) at a rate of 0.26 g / min to obtain calcium silicate. After the addition is completed, stir for a third time at a speed of 3600 r / min for 35 min to obtain the concrete nano-reinforcing agent.

[0098] The dropping was carried out under stirring conditions at a speed of 3600 r / min.

[0099] Example 3

[0100] This embodiment provides a concrete nano-reinforcing agent and its preparation method. The raw materials of the concrete nano-reinforcing agent include: 8 parts of silica with a particle size of 20 nm, 4 parts of layered graphene with a particle size of 200 nm, calcium silicate with a particle size of 700 nm, 4 parts of triisopropanolamine, 0.15 parts of defoamer, 4 parts of sodium polyacrylate with a relative molecular weight of 3500 and a mass concentration of 32%, and 30.85 parts of water.

[0101] The raw materials for preparing the calcium silicate are: 29 parts of sodium metasilicate solution with a mass concentration of 46% and 20 parts of calcium chloride solution with a mass concentration of 45%.

[0102] The preparation method of the concrete nano-reinforcing agent includes the following steps:

[0103] (1) Add triisopropanolamine and defoamer to 30.85 parts of water, stir for 8 minutes at a speed of 310 r / min, then add silica and stir for 50 minutes, then add graphene and stir for 50 minutes, and finally add sodium polyacrylate and stir for 50 minutes to obtain the first mixed emulsion.

[0104] The second stirring speed is 3100 r / min;

[0105] (2) Sodium metasilicate solution and calcium chloride solution are added dropwise to the first mixed emulsion in step (1) at a rate of 0.28 g / min to obtain calcium silicate. After the dropwise addition is completed, the mixture is stirred for a third time at a speed of 3400 r / min for 27 min to obtain the concrete nano-reinforcing agent.

[0106] The dropping was carried out under stirring conditions at a speed of 3400 r / min.

[0107] Example 4

[0108] This embodiment provides a concrete nano-reinforcing agent and its preparation method. Except that the weight of silica in the concrete nano-reinforcing agent is 4 parts and the water content is increased accordingly, all other conditions are the same as in Example 1.

[0109] Example 5

[0110] This embodiment provides a concrete nano-reinforcing agent and its preparation method. Except that the weight of silica in the concrete nano-reinforcing agent is 10 parts and the water content is reduced accordingly, all other conditions are the same as in Example 1.

[0111] Example 6

[0112] This embodiment provides a concrete nano-reinforcing agent and its preparation method. Except that the weight of layered graphene in the concrete nano-reinforcing agent is 2 parts and the water content is increased accordingly, all other conditions are the same as in Example 1.

[0113] Example 7

[0114] This embodiment provides a concrete nano-reinforcing agent and its preparation method. Except that the weight of layered graphene in the concrete nano-reinforcing agent is 8 parts and the water content is reduced accordingly, all other conditions are the same as in Example 1.

[0115] Example 8

[0116] This embodiment provides a concrete nano-reinforcing agent and its preparation method. Except for the sodium metasilicate solution having a mass concentration of 40%, all other conditions are the same as in Example 1.

[0117] Example 9

[0118] This embodiment provides a concrete nano-reinforcing agent and its preparation method. Except for the sodium metasilicate solution having a mass concentration of 50%, all other conditions are the same as in Example 1.

[0119] Example 10

[0120] This embodiment provides a concrete nano-reinforcing agent and its preparation method. Except for the dripping rate of 0.24 g / min in step (2), all other conditions are the same as in Example 1.

[0121] Example 11

[0122] This embodiment provides a concrete nano-reinforcing agent and its preparation method. Except for the dripping rate of 0.30 g / min in step (2), all other conditions are the same as in Example 1.

[0123] Example 12

[0124] This embodiment provides a concrete nano-reinforcing agent and its preparation method. Except for the addition in step (2) which is carried out under stirring conditions at a speed of 3300 r / min, all other conditions are the same as in Example 1.

[0125] Example 13

[0126] This embodiment provides a concrete nano-reinforcing agent and its preparation method. Except for step (2), which is carried out under stirring conditions at a speed of 3700 r / min, all other conditions are the same as in Example 1.

[0127] Comparative Example 1

[0128] This comparative example provides a concrete nano-reinforcing agent and its preparation method. Except for the particle size of silica being 30 nm, all other conditions are the same as in Example 1.

[0129] Comparative Example 2

[0130] This comparative example provides a concrete nano-reinforcing agent and its preparation method. Except that silica is not added to the raw materials and the water content is increased accordingly, all other conditions are the same as in Example 1.

[0131] Comparative Example 3

[0132] This comparative example provides a concrete nano-reinforcing agent and its preparation method. Except for the particle size of the layered graphene being 10 nm, all other conditions are the same as in Example 1.

[0133] Comparative Example 4

[0134] This comparative example provides a concrete nano-reinforcing agent and its preparation method. Except for the particle size of the layered graphene being 300 nm, all other conditions are the same as in Example 1.

[0135] Comparative Example 5

[0136] This comparative example provides a concrete nano-reinforcing agent and its preparation method. Except that layered graphene is not added to the raw materials and the water content is increased accordingly, all other conditions are the same as in Example 1.

[0137] Comparative Example 6

[0138] This comparative example provides a concrete reinforcing agent and its preparation method. Except that the calcium silicate used is commercially available calcium silicate (particle size of 37 μm), all other conditions are the same as in Example 1.

[0139] Comparative Example 7

[0140] This comparative example provides a concrete nano-reinforcing agent and its preparation method, wherein the raw materials of the concrete nano-reinforcing agent are the same as those in Example 1;

[0141] The preparation method of the concrete nano-reinforcing agent includes the following steps:

[0142] (1) Add triisopropanolamine and defoamer to 30 parts of water, stir for 10 minutes at a speed of 300 r / min, then add silica and stir for 60 minutes, then add graphene and stir for 60 minutes, and finally add sodium polyacrylate and stir for 60 minutes to obtain the first mixed emulsion.

[0143] The second stirring speed is 3000 r / min;

[0144] (2) Sodium metasilicate solution and calcium chloride solution are added dropwise to a container at a rate of 0.3 g / min to prepare calcium silicate; the dropwise addition is carried out under stirring conditions at a speed of 3500 r / min;

[0145] (3) Mix the first mixed emulsion from step (1) and the calcium silicate prepared in step (2), and then stir for 30 minutes at a speed of 3500 r / min to obtain the concrete nano-reinforcing agent.

[0146] The concrete reinforcing agents prepared in the above examples and comparative examples were incorporated into concrete for concrete density and compressive strength testing. C30 concrete was used for the tests, with the concrete reinforcing agent dosage being 0.6%. The mix proportions of the C30 concrete are shown in Table 2. The test results are shown in Table 5.

[0147] The density of concrete is expressed as porosity. The smaller the porosity, the higher the density of the concrete. The porosity is tested by the water absorption method, which involves immersing the concrete specimen in water for 48 hours, measuring the water absorption volume, and then calculating the porosity by dividing the water absorption volume by the specimen volume. The compressive strength of concrete is tested in accordance with GB / T50081-2002 Test Method for Mechanical Properties of Ordinary Concrete.

[0148] Table 5. Test results of concrete porosity and compressive strength

[0149]

[0150]

[0151] As shown in Table 5:

[0152] (1) The concrete nano-reinforcing agent prepared in Examples 1-3 of the present invention uses three nanomaterials with different particle sizes. By utilizing the synergistic effect between the three, the density of concrete can be significantly increased, thereby improving the early and late compressive strength of concrete. After 90 days, the compressive strength is ≥43 MPa, thus improving the workability of concrete.

[0153] (2) Comparing Example 1 and Example 4-5, it can be seen that when the amount of silica added is too small, the concrete strength and density will decrease due to the small amount of silica participating in the reaction; when the amount of silica added is too large, the concrete workability will deteriorate due to the large amount of silica reacting with cement. Although the strength will be improved in the early stage, the strength will decrease in the later stage.

[0154] (3) Comparing Example 1 and Example 6-7, it can be seen that when the amount of layered graphene added is too small, the layered structure of graphene has little effect on improving the dispersibility of concrete, resulting in less flow and less density of concrete; when the amount of layered graphene added is too large, the dispersibility of concrete is too large, resulting in poor concrete encapsulation and lower concrete strength.

[0155] (4) Comparing Examples 1 and 8-9, it can be seen that when the concentration of sodium metasilicate decreases, the amount of calcium silicate generated decreases, resulting in lower concrete strength; when the concentration of sodium metasilicate increases, the amount of calcium silicate generated remains unchanged, so the concrete strength does not change much, but the raw material cost increases.

[0156] (5) A comparison of Examples 1 and 10-11 shows that when the dripping speed during the synthesis of calcium silicate is too slow, the particle size becomes smaller due to the slow reaction speed, resulting in high initial strength of the concrete but low later strength; when the dripping speed during the synthesis of calcium silicate is too fast, the particle size becomes larger due to the fast reaction speed, resulting in lower concrete density and lower strength; a comparison of Examples 1 and 12-13 shows that when the stirring speed during the synthesis of calcium silicate is too slow, the particle size of calcium silicate becomes larger, resulting in lower concrete density and lower strength; when the stirring speed during the synthesis of calcium silicate is too fast, the particle size of calcium silicate becomes smaller, resulting in higher concrete density, higher initial strength, but lower later strength.

[0157] (6) A comparison of Example 1 and Comparative Example 1 shows that when the silica particle size used is too large, the concrete density decreases, resulting in lower concrete strength in the later stages. A comparison of Example 1 and Comparative Examples 3-4 shows that when the layered graphene particle size used is too small, it is similar to the silica particle size, resulting in increased concrete porosity and lower concrete strength. When the layered graphene particle size used is too large, the large difference in diameter between it and the silica particles results in increased porosity and lower concrete strength. A comparison of Example 1 and Comparative Example 6 shows that when commercially available calcium silicate is used, its large particle size results in increased concrete porosity and lower concrete strength in the later stages.

[0158] (7) Comparison of Example 1 and Comparative Example 7 shows that when calcium silicate is not synthesized in a one-step process in a solution containing silica and graphene, the particle size of calcium silicate is uncontrollable, which leads to a single particle size in the concrete nano-reinforcing agent, which cannot be distributed in a stepped manner, resulting in a decrease in the density of the concrete and a decrease in the strength of the concrete.

[0159] The applicant declares that the detailed structural features of the present invention are illustrated through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components selected in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0160] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A concrete nano-reinforcing agent, characterized in that, The raw materials of the concrete nano-reinforcing agent include: silicon dioxide, graphene, and calcium silicate; The silicon dioxide has a particle size of 1-20 nm; the graphene has a particle size of 20-200 nm; and the calcium silicate has a particle size of 200-700 nm. The concrete nano-reinforcing agent contains 6-8 parts by weight of silica; The graphene in the concrete nano-reinforcing agent is 4-6 parts by weight; The weight percentage of calcium silicate in the concrete nano-reinforcing agent is 19.5-21 parts; The method for preparing calcium silicate includes: adding sodium metasilicate solution and calcium chloride solution dropwise to a solution containing silicon dioxide and graphene to obtain calcium silicate; The addition is carried out under stirring conditions; The dropping rate is 0.26-0.28 g / min; The stirring speed is 3400-3600 r / min.

2. The concrete nano-reinforcing agent according to claim 1, characterized in that, The graphene includes layered graphene.

3. The concrete nano-reinforcing agent according to claim 1, characterized in that, The mass concentration of the sodium metasilicate solution is 42%-46%.

4. The concrete nano-reinforcing agent according to claim 1, characterized in that, The calcium chloride solution has a mass concentration of 45%-47%.

5. The concrete nano-reinforcing agent according to claim 1, characterized in that, The mass ratio of the sodium metasilicate solution to the calcium chloride solution is (1.4-1.6):

1.

6. The concrete nano-reinforcing agent according to claim 1, characterized in that, The concrete nano-reinforcing agent also includes a dispersant.

7. The concrete nano-reinforcing agent according to claim 6, characterized in that, The dispersant includes triisopropanolamine.

8. The concrete nano-reinforcing agent according to claim 6, characterized in that, The dispersant in the concrete nano-reinforcing agent is 2-4 parts by weight.

9. The concrete nano-reinforcing agent according to claim 1, characterized in that, The concrete nano-reinforcing agent also includes an antifoaming agent.

10. The concrete nano-reinforcing agent according to claim 9, characterized in that, The defoamer in the concrete nano-reinforcing agent is 0.05-0.15 parts by weight.

11. The concrete nano-reinforcing agent according to claim 1, characterized in that, The concrete nano-reinforcing agent also includes a suspending agent.

12. The concrete nano-reinforcing agent according to claim 11, characterized in that, The suspending agent includes sodium polyacrylate.

13. The concrete nano-reinforcing agent according to claim 12, characterized in that, The sodium polyacrylate has a relative molecular weight of 2500-3500.

14. The concrete nano-reinforcing agent according to claim 12, characterized in that, The sodium polyacrylate has a mass concentration of 25%-32%.

15. The concrete nano-reinforcing agent according to claim 12, characterized in that, The weight percentage of the suspending agent in the concrete nano-reinforcing agent is 4-6 parts.

16. A method for preparing a concrete nano-reinforcing agent as described in any one of claims 1-15, characterized in that, The preparation method includes: The concrete nano-reinforcing agent was obtained by mixing silica, graphene and calcium silicate in a solvent using an emulsion suspension method.

17. The method for preparing the concrete nano-reinforcing agent according to claim 16, characterized in that, The preparation method specifically includes: (1) Add dispersant and defoamer to solvent, stir for the first time, then add silica, graphene and suspending agent in sequence, stir for the second time to obtain the first mixed emulsion; (2) Add sodium metasilicate solution and calcium chloride solution to the first mixed emulsion in step (1) to obtain calcium silicate, and perform a third stirring to obtain the concrete nano-reinforcing agent.

18. The method for preparing the concrete nano-reinforcing agent according to claim 17, characterized in that, Step (1) The first stirring speed is 290-310 r / min.

19. The method for preparing the concrete nano-reinforcing agent according to claim 17, characterized in that, Step (1) The first stirring time is 8-12 min.

20. The method for preparing the concrete nano-reinforcing agent according to claim 17, characterized in that, In step (1), the second stirring speed is 2900-3100 r / min.

21. The method for preparing the concrete nano-reinforcing agent according to claim 17, characterized in that, After adding silica in step (1), stir for 50-70 minutes.

22. The method for preparing the concrete nano-reinforcing agent according to claim 17, characterized in that, After adding graphene in step (1), stir for 50-70 minutes.

23. The method for preparing the concrete nano-reinforcing agent according to claim 17, characterized in that, After adding the suspending agent in step (1), stir for a second time for 50-70 minutes.

24. The method for preparing the concrete nano-reinforcing agent according to claim 17, characterized in that, The rotation speed of the third stirring in step (2) is 3400-3600 r / min.

25. The method for preparing the concrete nano-reinforcing agent according to claim 17, characterized in that, The third stirring time in step (2) is 25-35 minutes.

26. A type of concrete, characterized in that, The concrete includes the concrete nano-reinforcing agent according to any one of claims 1-15 or the concrete nano-reinforcing agent prepared by the preparation method according to any one of claims 16-25.

27. The concrete according to claim 26, characterized in that, The amount of concrete nano-reinforcing agent added to the concrete is 0.5%-0.8%.

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