Modified micro-nano bubble water, a preparation method thereof, and low-density concrete mixed with the modified micro-nano bubble water and a preparation method thereof

Abstract

The present application relates to the technical field of building materials, and particularly relates to modified micro-nano bubble water, a preparation method thereof, low-density concrete mixed with the modified micro-nano bubble water and a preparation method of the low-density concrete. The components of the modified micro-nano bubble water include micro-nano bubble water, a modifier dispersed in the micro-nano bubble water and a graphene dispersion liquid; the modifier comprises an anionic air entraining agent, a foam stabilizer and a retarder. The present application provides the modified micro-nano bubble water, and the concrete is prepared by mixing the modified micro-nano bubble water. The concrete replaces the traditional light aggregate by introducing the modified micro-nano bubble water, so that the concrete density can be effectively reduced at a lower manufacturing cost, the performance of the low-density concrete is equivalent to that of the ordinary high-performance concrete, the concrete has good pumping performance, mechanical properties and durability, and the appearance of the concrete is good without obvious bubbles.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a modified micro-nano bubble water and its preparation method, and a low-density concrete with modified micro-nano bubble water and its preparation method. Background Technology

[0002] Low-density concrete is a special type of concrete material. Compared to ordinary ready-mixed concrete, its density (i.e., apparent density) is reduced, by approximately 200 kg / m³. 3 It is around that size, but it doesn't quite reach the category of lightweight concrete.

[0003] Since the inherent high weight of concrete is an unavoidable drawback, its further development is limited, and it is necessary to reduce its density.

[0004] The conventional method of replacing traditional aggregates with high-strength lightweight aggregates can achieve lightweight concrete and obtain low-density concrete. However, this method of obtaining low-density concrete has the following drawbacks:

[0005] High-strength lightweight aggregates are expensive, resulting in high production costs. Even if replacing concrete with high-strength lightweight aggregates can reduce its density, it will negatively impact properties such as compressive strength. For example, compared to benchmark concrete (using conventional aggregates), concrete prepared with high-strength lightweight aggregates may have a 7-9% lower density, but its compressive strength may decrease by about 10% or even more. Therefore, this method for preparing low-density concrete is still rarely used.

[0006] To solve the above problems, how to develop low-cost low-density concrete that can make the overall concrete structure lightweight while ensuring that the concrete has good compressive strength and fluidity is a technical problem that those skilled in the art are committed to solving. Summary of the Invention

[0007] To address the problems mentioned in the background section, this invention provides a modified micro / nano bubble water and its preparation method, and uses the modified micro / nano bubble water to prepare low-density concrete. The technical solution is as follows:

[0008] The modified micro / nano bubble water comprises micro / nano bubble water, a modifier dispersed within the micro / nano bubble water, and a graphene dispersion; the micro / nano bubble water contains dispersed micro / nano bubbles; the modifier includes anionic air-entraining agents, foam stabilizers, and retarders; the mass ratio of the micro / nano bubble water, the modifier, and the graphene dispersion is (18-21):(0.05-0.1):(3-4).

[0009] In some embodiments, the micro-nano bubble water is prepared by passing water through a micro-nano bubble water generating device, so that micro-nano bubbles are dispersed in the micro-nano bubble water.

[0010] Micro-nano bubble water was prepared using a micro-nano bubble water generating device. The large bubbles visible to the naked eye gradually dissipated over time, leaving only micro-nano-sized bubbles.

[0011] In some embodiments, the modifier comprises anionic air-entraining agent, foam stabilizer, and retarder.

[0012] In some embodiments, the mass ratio of the anionic air-entraining agent, foam stabilizer, and retarder is (3-10):(0.02-0.08):(1-4); the anionic air-entraining agent is one or more combinations of sodium α-alkenyl alkyl sulfonate and sodium alkyl polyoxyethylene ether sulfonate, wherein the alkyl group in the sodium alkyl polyoxyethylene ether sulfonate has 8-12 carbon atoms; the foam stabilizer is one or more combinations of dodecyl dimethylamine oxide, alkyl polyoxyethylene ether, and polyvinyl alcohol; the retarder is one or more combinations of white sugar, sodium gluconate, and sodium citrate; the graphene dispersion is a dispersion formed by dispersing graphene in water, and its solid content is 0.05%-0.2%; the graphene includes one or more combinations of graphene oxide and reduced graphene oxide, and is entirely black. The graphene sheets contain a large number of oxygen-containing functional groups, such as hydroxyl, carboxyl, and epoxy groups, which are easily dispersed in water due to the presence of these polar hydrophilic groups.

[0013] This invention also provides a method for preparing modified micro / nano bubble water, which includes the following preparation steps:

[0014] Add the modifier and graphene dispersion to the first part of water and disperse evenly to obtain solution C;

[0015] The second portion of water is introduced into solution C through a micro-nano bubble water generating device and left to stand to obtain the modified micro-nano bubble water.

[0016] The modifier includes anionic air-entraining agents, foam stabilizers, and retarders. The second portion of water is introduced into solution C through a micro-nano bubble water generating device to mix the second portion of water with the first portion of water and disperse micro-nano bubbles within it, forming the micro-nano bubble water. The mass ratio of the micro-nano bubble water, modifier, and graphene dispersion is (18-21):(0.05-0.1):(3-4), wherein the mass ratio is calculated as follows: in the process of calculating the mass ratio of the micro-nano bubble water, modifier, and graphene dispersion, the mass of the micro-nano bubble water is the sum of the first portion of water and the second portion of water.

[0017] In some embodiments, the mass ratio of the anionic air-entraining agent, foam stabilizer, and retarder is (3-10):(0.02-0.08):(1-4); and the mass ratio of the first portion of water to the second portion of water is (0.5-1):(1-1.5).

[0018] In some embodiments, the anionic air-entraining agent is one or more of sodium α-alkenyl alkyl sulfonate and sodium alkyl polyoxyethylene ether sulfonate, wherein the alkyl group in the sodium alkyl polyoxyethylene ether sulfonate has 8 to 12 carbon atoms; the foam stabilizer is one or more of dodecyl dimethylamine oxide, alkyl polyoxyethylene ether, and polyvinyl alcohol; the retarder is one or more of white sugar, sodium gluconate, and sodium citrate; the graphene dispersion is a dispersion formed by dispersing graphene in water, and its solid content is 0.05% to 0.2%; the graphene includes one or more of graphene oxide and reduced graphene oxide.

[0019] The present invention also provides a low-density concrete with modified micro-nano bubble water, wherein the raw material components, by weight, include: cement, modified micro-nano bubble water, fly ash, mineral powder, silica fume, coarse aggregate, fine aggregate, and high-performance water-reducing agent; wherein the modified micro-nano bubble water is the modified micro-nano bubble water as described above; or, the modified micro-nano bubble water is prepared by the preparation method described above.

[0020] In some embodiments, the raw material components, by weight, include: 221 to 294 parts cement, 147 to 167 parts modified micro-nano bubble water, 73 to 147 parts fly ash, 73 to 147 parts mineral powder, 15 to 39 parts silica fume, 1050 to 1100 parts coarse aggregate, 680 to 740 parts fine aggregate, and 3.9 to 5.9 parts high-performance water-reducing agent.

[0021] In some embodiments, the cement is one or more of P·O 42.5 cement, P·II 42.5 cement, and P·I 42.5 cement; the fly ash is one or more of Grade I fly ash and Grade II fly ash; and the mineral powder is S95 grade mineral powder with a specific surface area of ​​650 m² obtained by grinding. 2 / kg~750m 2 The mineral powder, at a density of / kg, has an activity index of 115%–122% after 28 days; the silica fume is one or more of SF94 grade silica fume and SF96 grade silica fume; the coarse aggregate is one or more of crushed stone with a particle size of 5mm–10mm, crushed stone with a particle size of 10mm–20mm, and crushed stone with a particle size of 5mm–20mm, with an apparent density of 2620 kg / m³. 3 ~2650kg / m 3The porosity is 38%–41%, and the crushing value is 2%–4%; the fine aggregate is manufactured sand with a fineness modulus of 2.6–2.8 and an apparent density of 2600 kg / m³. 3 ~2640kg / m 3 The porosity is 40%–44%, and the mud content is 0.1%–0.5%.

[0022] The high-performance water-reducing agent is composed of polycarboxylate superplasticizer mother liquor, slump retainer, defoamer, water retainer, regulator and water.

[0023] The high-performance water-reducing agent formulated as described above has a strong dispersing effect on cementitious materials, which shortens the concrete mixing time, quickly mixes various concrete raw materials, and optimizes the various properties of the concrete. Its water reduction rate reaches 28% to 33%, and its 28-day compressive strength ratio reaches 170% to 183%.

[0024] The present invention also provides a method for preparing low-density concrete with modified micro / nano bubble water as described above, which includes the following preparation steps:

[0025] Weigh each raw material component: Weigh cement, modified micro-nano bubble water, fly ash, mineral powder, silica fume, coarse aggregate, fine aggregate, and high-performance water-reducing agent according to a certain weight proportion;

[0026] The coarse aggregate and fine aggregate are mixed evenly to obtain mixture A;

[0027] Cement-modified micro-nano bubble water, fly ash, mineral powder, and silica fume are mixed evenly to obtain mixture B;

[0028] The high-performance water-reducing agent and the modified micro-nano bubble water were mixed evenly to obtain mixture C;

[0029] Mix mixture A and mixture B thoroughly, then add mixture C and mix thoroughly to obtain a mixture.

[0030] The resulting mixture is poured into a fixed mold and hardened to form the low-density concrete with modified micro-nano bubble water.

[0031] Compared with existing technologies, the present invention has the following advantages:

[0032] Compared to the approach of replacing traditional lightweight aggregates with high-strength lightweight aggregates, this invention provides a modified micro-nano bubble water. Concrete made by incorporating this modified micro-nano bubble water replaces traditional lightweight aggregates, effectively reducing concrete density at a lower manufacturing cost. Furthermore, while reducing density, it ensures that the properties of the low-density concrete are comparable to ordinary high-performance concrete. The concrete exhibits excellent pumpability, mechanical properties, and durability, with a superior appearance free of obvious bubbles. This low-density concrete facilitates component handling and installation, meets application requirements, and is both economical and practical. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] This invention provides an example of a method for preparing low-density concrete with modified micro / nano bubble water, which includes the following preparation steps:

[0035] 1. Apply template paint to the surface of a 150mm*150mm*150mm steel mold, let it stand for 24h to 36h, and then assemble it into a mold. It is essential to ensure that there are no gaps at the joints.

[0036] 2. Weigh the concrete raw material components: Weigh cement, modified micro-nano bubble water, fly ash, mineral powder, silica fume, coarse aggregate, fine aggregate, and high-performance water-reducing agent according to a certain weight ratio.

[0037] The raw material components, by weight, include: 221 to 294 parts cement, 147 to 167 parts modified micro-nano bubble water, 73 to 147 parts fly ash, 73 to 147 parts mineral powder, 15 to 39 parts silica fume, 1050 to 1100 parts coarse aggregate, 680 to 740 parts fine aggregate, and 3.9 to 5.9 parts high-performance water-reducing agent.

[0038] 3. Mix coarse aggregate and fine aggregate evenly to obtain mixture A; mix cement-modified micro-nano bubble water, fly ash, mineral powder and silica fume evenly to obtain mixture B; mix high-performance water-reducing agent and modified micro-nano bubble water evenly to obtain mixture C.

[0039] 4. Pour mixture A and mixture B into a mixer and stir for 10 to 30 seconds. Then add mixture C and stir for 210 to 300 seconds to obtain the mixture.

[0040] 5. Pour the mixture evenly into the steel mold, vibrate it with a vibrating table for 4 to 7 seconds, tamp it several times with a trowel on the upper side walls, remove the excess concrete, and cover it with a film.

[0041] 6. After 48 to 72 hours, remove the steel formwork and place the low-density concrete specimens into the standard curing room. After they reach the required curing age, conduct relevant performance tests.

[0042] The present invention also provides a preferred embodiment of the preparation method of the modified micro / nano bubble water, the specific steps of which are as follows:

[0043] 1. Divide water (e.g., tap water) into two parts to obtain a first part A and a second part B; the mass ratio of the first part A to the second part B is (0.5-1):(1-1.5).

[0044] 2. Add the modifier and graphene dispersion to the first part of water A in proportion, and stir evenly with an electric mixer at a speed of 400 r / min to 600 r / min for 15 min to 30 min to obtain solution C;

[0045] 3. Then, use a micro-nano bubble water generator to introduce the second part of water B into solution C. The bubble outlet should be placed at 1 / 3 of the height from the bottom of the solution. Continue until all the second part of water B is used up. Let it stand for 5 to 8 minutes to obtain modified micro-nano bubble water.

[0046] The mass ratio of the anionic air-entraining agent, foam stabilizer, and retarder in the modifier is (3-10):(0.02-0.08):(1-4).

[0047] The mass ratio of the micro-nano bubble water, modifier, and graphene dispersion is (18-21):(0.05-0.1):(3-4). During the preparation process, a second portion of water is introduced into solution C through a micro-nano bubble water generating device, so that the second portion of water mixes with the first portion of water and contains micro-nano bubbles, forming micro-nano bubble water. Therefore, the mass ratio is calculated as follows: in the process of calculating the mass ratio of the micro-nano bubble water, modifier, and graphene dispersion, the weight of the micro-nano bubble water is the sum of the first and second portions of water.

[0048] The present invention also provides formulations (unit: parts by weight) for the embodiments and comparative examples shown in Table 1:

[0049] Table 1

[0050]

[0051]

[0052] Specifically, the embodiments and comparative examples and their preparation processes provided by this invention are as follows:

[0053] Example 1

[0054] In this embodiment, by weight, the raw materials of the concrete include: 221 parts cement, 147 parts modified micro-nano bubble water, 122 parts fly ash, 147 parts mineral powder, 24 parts silica fume, 1100 parts coarse aggregate, 680 parts fine aggregate, and 5.9 parts high-performance water-reducing agent.

[0055] The method for preparing the modified micro / nano bubble water is as follows:

[0056] (1) Divide the tap water into two equal parts to obtain tap water A and tap water B respectively;

[0057] (2) Add the modifier and graphene dispersion to tap water A in proportion, and stir evenly with an electric stirring machine at a speed of 400 r / min for 30 min to obtain solution C;

[0058] (3) Then, tap water B is introduced into solution C using a micro-nano bubble water generator. The bubble outlet should be placed at 1 / 3 of the height from the bottom of the solution until all tap water B is used up. Let it stand for 5 minutes to obtain modified micro-nano bubble water.

[0059] In the modified micro / nano bubble water, the mass ratio of micro / nano bubble water, anionic air-entraining agent, foam stabilizer, retarder, and graphene dispersion is 1840:5:0.05:1.8:360. The anionic air-entraining agent is sodium α-alkenylalkyl sulfonate, the foam stabilizer is alkyl polyoxyethylene ether, and the retarder is white sugar. A graphene dispersion is formed by dispersing graphene oxide in water, with a solid content of 0.06%.

[0060] The cement is P·II 42.5 cement; the fly ash is Grade I fly ash; the mineral powder is Grade S95 mineral powder, which is further ground to achieve a specific surface area of ​​654 m². 2 / kg, with a 28-day activity index of 115%; the silica fume is SF96 grade silica fume; the coarse aggregate is 5mm-20mm continuously graded crushed stone, with an apparent density of 2640kg / m³. 3 The porosity is 38%, and the crushing value is 2%; the fine aggregate is manufactured sand with a fineness modulus of 2.6 and an apparent density of 2600 kg / m³. 3 The porosity is 43% and the mud content is 0.5%; the high-performance water-reducing agent is Kezhijie's high-performance concrete-specific polycarboxylate water-reducing agent Point-60HGS, with a water reduction rate of up to 32%, which is compounded by special polycarboxylate water-reducing mother liquor, slump retainer, defoamer, water retainer, regulator and water.

[0061] In this embodiment, a low-density concrete incorporating modified micro / nano bubble water comprises the following preparation steps:

[0062] (1) Apply template paint to the surface of a steel mold with dimensions of 150mm*150mm*150mm, let it stand for 36 hours, and then assemble and splice it into a mold. It is necessary to ensure that there are no gaps at the joints.

[0063] (2) Weigh each raw material component: Weigh cement, modified micro-nano bubble water, fly ash, mineral powder, silica fume, coarse aggregate, fine aggregate and high-performance water-reducing agent according to a certain weight ratio.

[0064] (3) Mix coarse aggregate and fine aggregate evenly to obtain mixture A; mix cement-modified micro-nano bubble water, fly ash, mineral powder and silica fume evenly to obtain mixture B; mix high-performance water-reducing agent and modified micro-nano bubble water evenly to obtain mixture C.

[0065] (4) Pour mixture A and mixture B into a mixer and stir for 20 seconds. Then add mixture C and stir for 240 seconds to obtain a low-density concrete mixture with modified micro-nano bubble water.

[0066] (5) Pour the concrete mixture evenly into the steel mold, vibrate it for 6 seconds with a vibrating table, tamp it several times with a trowel on the upper side walls, wipe off the excess concrete on the top layer, and cover it with a film.

[0067] (6) After 72 hours, remove the steel formwork and place the low-density concrete specimens into the standard curing room. After they reach the required curing age, conduct relevant performance tests.

[0068] Example 2

[0069] In this embodiment, by weight, the raw materials consist of: 294 parts cement, 157 parts modified micro-nano bubble water, 73 parts fly ash, 123 parts mineral powder, 24 parts silica fume, 1050 parts coarse aggregate, 740 parts fine aggregate, and 4.8 parts high-performance water-reducing agent.

[0070] The method for preparing the modified micro / nano bubble water is as follows:

[0071] (1) Divide the tap water into two equal parts to obtain tap water A and tap water B respectively;

[0072] (2) Add the modifier and graphene dispersion to tap water A in proportion, and stir evenly with an electric stirring machine at a speed of 400 r / min for 30 min to obtain solution C;

[0073] (3) Then, tap water B is introduced into solution C using a micro-nano bubble water generator. The bubble outlet should be placed at 1 / 3 of the height from the bottom of the solution until all tap water B is used up. Let it stand for 5 minutes to obtain modified micro-nano bubble water.

[0074] In the modified micro / nano bubble water, the mass ratio of micro / nano bubble water, anionic air-entraining agent, foam stabilizer, retarder, and graphene dispersion is 1840:5:0.05:1.8:360. The anionic air-entraining agent is sodium α-alkenylalkyl sulfonate, the foam stabilizer is alkyl polyoxyethylene ether, and the retarder is white sugar. A graphene dispersion is formed by dispersing graphene oxide in water, with a solid content of 0.06%.

[0075] The cement is P·II 42.5 cement; the fly ash is Grade I fly ash; the mineral powder is Grade S95 mineral powder, which is further ground to achieve a specific surface area of ​​654 m². 2 / kg, with a 28-day activity index of 115%; the silica fume is SF96 grade silica fume; the coarse aggregate is 5mm-20mm continuously graded crushed stone, with an apparent density of 2640kg / m³. 3 The porosity is 38%, and the crushing value is 2%; the fine aggregate is manufactured sand with a fineness modulus of 2.6 and an apparent density of 2600 kg / m³. 3 The porosity is 43% and the mud content is 0.5%; the high-performance water-reducing agent is Kezhijie's high-performance concrete-specific polycarboxylate water-reducing agent Point-60HGS, with a water reduction rate of up to 32%, which is compounded by special polycarboxylate water-reducing mother liquor, slump retainer, defoamer, water retainer, regulator and water.

[0076] In this embodiment, a low-density concrete incorporating modified micro / nano bubble water comprises the following preparation steps:

[0077] (1) Apply template paint to the surface of a steel mold with dimensions of 150mm*150mm*150mm, let it stand for 36 hours, and then assemble and splice it into a mold. It is necessary to ensure that there are no gaps at the joints.

[0078] (2) Weigh each raw material component: Weigh cement, modified micro-nano bubble water, fly ash, mineral powder, silica fume, coarse aggregate, fine aggregate and high-performance water-reducing agent according to a certain weight ratio.

[0079] (3) Mix coarse aggregate and fine aggregate evenly to obtain mixture A; mix cement-modified micro-nano bubble water, fly ash, mineral powder and silica fume evenly to obtain mixture B; mix high-performance water-reducing agent and modified micro-nano bubble water evenly to obtain mixture C.

[0080] (4) Pour mixture A and mixture B into a mixer and stir for 20 seconds. Then add mixture C and stir for 240 seconds to obtain a low-density concrete mixture with modified micro-nano bubble water.

[0081] (5) Pour the concrete mixture evenly into the steel mold, vibrate it for 6 seconds with a vibrating table, tamp it several times with a trowel on the upper side walls, wipe off the excess concrete on the top layer, and cover it with a film.

[0082] (6) After 72 hours, remove the steel formwork and place the low-density concrete specimens into the standard curing room. After they reach the required curing age, conduct relevant performance tests.

[0083] Example 3

[0084] In this embodiment, by weight, the raw materials consist of: 221 parts cement, 167 parts modified micro-nano bubble water, 147 parts fly ash, 122 parts mineral powder, 24 parts silica fume, 1100 parts coarse aggregate, 680 parts fine aggregate, and 3.9 parts high-performance water-reducing agent.

[0085] The method for preparing the modified micro / nano bubble water is as follows:

[0086] (1) Divide the tap water into two equal parts to obtain tap water A and tap water B respectively;

[0087] (2) Add the modifier and graphene dispersion to tap water A in proportion, and stir evenly with an electric stirring machine at a speed of 400 r / min for 30 min to obtain solution C;

[0088] (3) Then, tap water B is introduced into solution C using a micro-nano bubble water generator. The bubble outlet should be placed at 1 / 3 of the height from the bottom of the solution until all tap water B is used up. Let it stand for 5 minutes to obtain modified micro-nano bubble water.

[0089] In the modified micro / nano bubble water, the mass ratio of micro / nano bubble water, anionic air-entraining agent, foam stabilizer, retarder, and graphene dispersion is 1840:5:0.05:1.8:360. The anionic air-entraining agent is sodium α-alkenylalkyl sulfonate, the foam stabilizer is alkyl polyoxyethylene ether, and the retarder is white sugar. A graphene dispersion is formed by dispersing graphene oxide in water, with a solid content of 0.06%.

[0090] The cement is P·II 42.5 cement; the fly ash is Grade I fly ash; the mineral powder is Grade S95 mineral powder, which is further ground to achieve a specific surface area of ​​654 m². 2 / kg, with a 28-day activity index of 115%; the silica fume is SF96 grade silica fume; the coarse aggregate is 5mm-20mm continuously graded crushed stone, with an apparent density of 2640kg / m³. 3 The porosity is 38%, and the crushing value is 2%; the fine aggregate is manufactured sand with a fineness modulus of 2.6 and an apparent density of 2600 kg / m³. 3 The porosity is 43% and the mud content is 0.5%; the high-performance water-reducing agent is Kezhijie's high-performance concrete-specific polycarboxylate water-reducing agent Point-60HGS, with a water reduction rate of up to 32%, which is compounded by special polycarboxylate water-reducing mother liquor, slump retainer, defoamer, water retainer, regulator and water.

[0091] In this embodiment, a low-density concrete incorporating modified micro / nano bubble water comprises the following preparation steps:

[0092] (1) Apply template paint to the surface of a steel mold with dimensions of 150mm*150mm*150mm, let it stand for 36 hours, and then assemble and splice it into a mold. It is necessary to ensure that there are no gaps at the joints.

[0093] (2) Weigh each raw material component: Weigh cement, modified micro-nano bubble water, fly ash, mineral powder, silica fume, coarse aggregate, fine aggregate and high-performance water-reducing agent according to a certain weight ratio.

[0094] (3) Mix coarse aggregate and fine aggregate evenly to obtain mixture A; mix cement-modified micro-nano bubble water, fly ash, mineral powder and silica fume evenly to obtain mixture B; mix high-performance water-reducing agent and modified micro-nano bubble water evenly to obtain mixture C.

[0095] (4) Pour mixture A and mixture B into a mixer and stir for 20 seconds. Then add mixture C and stir for 240 seconds to obtain a low-density concrete mixture with modified micro-nano bubble water.

[0096] (5) Pour the concrete mixture evenly into the steel mold, vibrate it for 6 seconds with a vibrating table, tamp it several times with a trowel on the upper side walls, remove the excess concrete on the top layer, and cover it with a film.

[0097] (6) After 72 hours, remove the steel formwork and place the low-density concrete specimens into the standard curing room. After they reach the required curing age, conduct relevant performance tests.

[0098] Comparative Example 1

[0099] The only difference between Comparative Example 1 and Example 3 is that in Comparative Example 1, the modified micro-nano bubble water of Example 3 was replaced with tap water in equal amounts. All other conditions remained unchanged.

[0100] Comparative Example 2

[0101] The only difference between Comparative Example 2 and Example 3 is that the micro-nano bubble water of Example 3 in Comparative Example 2 was not modified (no modifier or graphene dispersion was added), while other conditions remained unchanged.

[0102] Comparative Example 3

[0103] The only difference between Comparative Example 3 and Example 3 is that Comparative Example 3 modifies the micro-nano bubble water of Example 3 by adding a modifier but does not add graphene dispersion, while keeping other conditions unchanged.

[0104] Comparative Example 4

[0105] The only difference between Comparative Example 4 and Example 3 is that Comparative Example 4 replaces the silica fume of Example 3 with cement in an equal amount, while keeping other conditions unchanged. The cement used is P·II 42.5 cement.

[0106] Comparative Example 5

[0107] The only difference between Comparative Example 5 and Example 3 is that Comparative Example 5 modifies the micro-nano bubble water of Example 3 by adding only a modifier and graphene dispersion, without adding a retarder, while keeping other conditions unchanged.

[0108] In the examples and comparative examples, the prepared bubble water was left to stand for 1 day before being added to concrete raw materials to prepare a mixture.

[0109] Performance testing of products obtained in the examples and comparative examples:

[0110] The concrete prepared in the above embodiments and comparative examples was subjected to performance tests according to standards GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", and GB / T 50082-2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete". The results are shown in Table 2.

[0111] Table 2

[0112]

[0113] In Table 2, the slump, spread, and plastic viscosity are the properties of fresh concrete mixtures; dry apparent density refers to the mass per unit volume of concrete after molding, hardening, and demolding; 56-day compressive strength represents the compressive strength of concrete after 56 days; and 56-day chloride ion diffusion coefficient represents the chloride ion diffusion resistance of concrete after 56 days.

[0114] Among them, the unit weight of concrete is reflected by the dry apparent density; the pumpability of concrete is reflected by the slump, spread, viscosity and other characteristics; the mechanical properties of concrete are reflected by the compressive strength; and the durability of concrete is reflected by the chloride ion diffusion coefficient.

[0115] The test results in Table 2 show that:

[0116] (1) Examples 1-3

[0117] The test results from Examples 1-3 show that adding modified micro-nano bubble water can effectively reduce the dry apparent density of concrete by 7% to 9%, achieving a lightweight effect while maintaining good pumpability, mechanical properties, and durability. Compared to conventional concrete with pure tap water added in Comparative Example 1, its dry apparent density is effectively reduced by 7% to 9%, while the compressive strength remains at 95.72%-99.23%. Furthermore, using existing high-strength lightweight aggregates to replace traditional aggregates, while reducing the dry apparent density of the concrete prepared by high-strength lightweight aggregate replacement by 7-9%, the compressive strength decreases by approximately 10%. The concrete prepared in the embodiments of this invention meets the requirements of the C50 high-performance concrete standard, which requires a compressive strength ≥ 59.87 MPa and a chloride ion diffusion coefficient < 0.5%.

[0118] 3.0*10 -12 m 2 The density is reduced by 1 / s, and the concrete surface does not develop obvious bubbles due to the introduction of a large amount of gas, resulting in a better appearance. Therefore, the present invention reduces the dry apparent density of concrete while maintaining good pumpability, compressive strength, and durability.

[0119] Comparing the test results of Examples 1-3, it can be seen that increasing the amount of modified micro-nano bubble water in the present invention can effectively reduce the dry apparent density of concrete. Due to the introduction of a large number of micro-nano bubbles, the concrete strength will be slightly reduced, and the concrete viscosity will be significantly reduced.

[0120] (2) Comparison of Examples 1-3 and Comparative Example 1

[0121] Tap water was used in Comparative Example 1. Compared with Example 3, the concrete slump and spread of Comparative Example 1 increased, the dry apparent density and plastic viscosity increased significantly, and the chloride ion diffusion coefficient also increased slightly.

[0122] In this embodiment of the invention, the incorporation of modified micro-nano bubble water can form closed micro-nano-sized spaces inside the concrete, thereby reducing the apparent density of the concrete. The bubbles in the slurry can form a "ball effect," which greatly reduces the plastic viscosity of the concrete. The bubbles are evenly distributed, and the bubble spaces form a barrier to chloride ion penetration, increasing the chloride ion migration distance and thus reducing the chloride ion diffusion coefficient of the concrete (reducing the chloride ion diffusion coefficient of the concrete is beneficial to protecting the internal steel bars of the concrete, preventing the surface of the steel bars from being corroded by free chloride ions, and causing material performance deterioration), and has little impact on the strength of the concrete.

[0123] (3) Comparison of Examples 1-3 and Comparative Example 2

[0124] Comparative Example 2 uses the micro-nano bubble water from Example 3 without modification (no modifier or graphene dispersion added). Compared with Comparative Example 1, the micro-nano bubble water in Comparative Example 2 is unmodified, and its slump result is similar to that of Comparative Example 1. However, the addition of unmodified micro-nano bubble water can slightly reduce the dry apparent density of concrete, enhance the strength of concrete, and slightly improve the resistance to chloride ions. This indicates that unmodified micro-nano bubble water also has the effect of reducing bulk density and improving mechanical properties and durability.

[0125] However, compared with the modified micro-nano bubble water of the present invention, the dry apparent density of Comparative Example 2 decreased by a very small amount, and obviously the effect did not meet the bulk density requirements.

[0126] (4) Comparison of Examples 1-3 and Comparative Example 3

[0127] In the modification process of the bubble water in Comparative Example 3, only a modifier was added, without the addition of graphene dispersion. Compared with Example 3, the modified micro-nano bubble water in Comparative Example 3, which did not contain graphene dispersion, showed a decrease in dry apparent density and a significant reduction in strength, indicating that graphene dispersion has a certain defoaming effect and can significantly improve the compressive strength of concrete.

[0128] Compared to Comparative Example 2, Comparative Example 3 showed a significant decrease in both dry apparent density and compressive strength. This indicates that adding a modifier can effectively reduce its dry apparent density and plastic viscosity, and improve its chloride ion resistance, but it has a significant impact on its strength. It is evident that while modifying micro-nano bubble water with a modifier can stabilize the micro-nano bubbles and avoid the risk of breakage, effectively reducing the density of concrete, it cannot maintain good compressive strength in the reduced-density concrete. The compressive strength of the concrete in Comparative Example 3 was significantly reduced.

[0129] (5) Comparison of Examples 1-3 and Comparative Example 4

[0130] Compared with Example 3, Comparative Example 4 replaced an equal amount of silica fume with cement. The dry apparent density and plastic viscosity of the concrete increased slightly, while the compressive strength and chloride ion penetration resistance decreased. This indicates that silica fume can slightly reduce the apparent density and plastic viscosity of concrete, and can effectively improve the compressive strength and chloride ion penetration resistance of concrete.

[0131] Silica fume, as a lightweight mineral admixture, has a large specific surface area and small particles, which can effectively fill the pores between cement particles and improve the various properties of concrete.

[0132] (6) Comparison of Examples 1-3 and Comparative Example 5

[0133] Compared with Example 3, no retarder was added to the modified micro-nano bubble water in Comparative Example 5, resulting in increased concrete fluidity, higher dry apparent density, and enhanced strength.

[0134] This indicates that retarders have the effect of extending the bubble retention time. As the number of micro-nano bubbles introduced decreases, bubbles are lost during the molding and hardening process of concrete, and the dry apparent density also increases. Although this has a certain effect on strength, it is a chain reaction caused by the increase in dry apparent density, and it does not meet the requirements of low density concrete.

[0135] In summary, the solution provided by this invention includes the novelty, mechanism of action, principle, and beneficial effects described below:

[0136] First

[0137] Compared to conventional methods that use high-strength lightweight aggregates to replace traditional aggregates to obtain low-density concrete, this invention not only effectively reduces preparation costs, but also maintains good pumpability, compressive strength, and durability of the concrete while reducing density. All properties of the concrete can meet the requirements of the C50 high-performance concrete standard, and the chloride ion diffusion coefficient of the concrete is reduced.

[0138] The mechanism and principle of this invention to achieve the desired effect are as follows: 1. This invention prepares micro-nano bubble water through a micro-nano bubble water generating device. Large bubbles visible to the naked eye gradually dissipate over time, leaving only micro-nano-sized bubbles.

[0139] 2. The micro-nano bubble water produced by the micro-nano bubble water generating device is treated with modifier and graphene dispersion. The incorporation of modified micro-nano bubble water can form closed micro-nano size spaces inside the concrete, thereby reducing the apparent density of the concrete. The bubbles can form a "ball effect" in the slurry, which greatly reduces the plastic viscosity of the concrete. The bubbles are evenly distributed, and the bubble space forms a barrier to chloride ion penetration, increasing the chloride ion migration distance, thereby reducing the chloride ion diffusion coefficient of the concrete, and having little impact on the concrete strength. (1) Modifier:

[0140] Modifiers include anionic air-entraining agents, foam stabilizers, and retarders; one of the functions of modifiers is to reduce the liquid surface tension of the generated micro-nano bubble water, making it easier for micro-nano bubbles to remain in the aqueous solution, and enabling the micro-nano bubble water to contain a large number of tiny and stable micro-nano bubbles.

[0141] Among them, the role of anionic gas-entraining agent is to arrange the gas-entraining molecules neatly at the gas-liquid interface to form a stable gas-liquid interface. During the solution stirring process, it makes the introduced bubbles more stable and does not generate bubbles itself. On the other hand, it can generate surface charge on micro- and nano-bubbles, promote electrostatic stability, and inhibit the fusion of micro- and nano-bubbles, reducing the risk of bubbles becoming larger and breaking.

[0142] Foam stabilizers can create a protective layer on the surface of micro and nano bubbles to enhance bubble stability;

[0143] Retarder can increase the viscosity of the bubble surface, reduce the risk of breakage, and prolong the bubble retention time in bubble water.

[0144] 1) If one of the components in the modifier is missing, the resulting concrete will be of poor quality:

[0145] For example, if no retarder is added to the modifier, the micro-nano bubble water prepared will not be able to maintain itself in the water for a long time. When it is mixed and used after standing for a certain period of time, a lot of bubbles will be lost, and the concrete produced will not meet the requirements of low density concrete.

[0146] Similarly, without adding foam stabilizers and anionic air-entraining agents to the modifier, the micro-nano bubble water prepared has poor stability of micro-nano bubbles.

[0147] 2) If the timing of the addition of the modifier varies, it will result in poor concrete quality:

[0148] If the retarder in the modifier is not added to the micro-nano bubble water beforehand to modify it, but is added when it is mixed with other raw materials of concrete, the retarder cannot stabilize the bubbles in the micro-nano bubble water and prolong the bubble retention time, resulting in the concrete density not reaching the required effect.

[0149] Similarly, modifiers containing foam stabilizers, anionic air-entraining agents, and retarders, if not added to the micro-nano bubble water beforehand for modification, but added during mixing with other concrete raw materials, will not be able to stabilize the bubbles in the micro-nano bubble water or prolong the bubble retention time.

[0150] 3) In addition, if the modifier ratio exceeds the limits specified in this application, the resulting concrete will be of poor quality.

[0151] This invention controls the modifier within a reasonable mass range, thereby controlling the content and stability of bubbles in the aerated concrete. If the amount of modifier added is below the limit specified in this application, the amount of microbubbles in the aerated concrete will be unstable and the content will be low, resulting in concrete that does not achieve the effects of lightweight and low density. Conversely, if the amount of modifier added is above the limit specified in this application, the amount of bubbles will be excessive, drastically reducing the compressive strength of the concrete.

[0152] (2) The addition and modification of graphene dispersion mainly have the following two effects:

[0153] The graphene dispersion was added to the micro-nano bubble water beforehand to provide more support sites for the micro-nano bubbles in the bubble water, so that the micro-nano bubbles could be evenly distributed throughout the interface.

[0154] In addition, graphene will leverage its unique two-dimensional structure, superior mechanical properties, and ultra-high specific surface area to not only effectively absorb the stress in concrete but also prevent the penetration of moisture and gas, thereby enhancing the strength and durability of concrete.

[0155] 1) The absence of graphene dispersion will result in poor concrete quality:

[0156] In this invention, the absence of graphene dispersion will significantly reduce the compressive strength of the concrete, failing to meet the required application requirements.

[0157] 2) If the timing of the addition of the graphene dispersion varies, it will result in poor concrete quality.

[0158] Graphene dispersion needs to be added to the micro-nano bubble water beforehand to provide bubble support and ensure uniform distribution of micro-nano bubbles; if it is added during mixing with other concrete materials, it will not achieve the desired effect.

[0159] 3) In addition, if the proportion of graphene dispersion exceeds the range specified in this application, the resulting concrete will be of poor quality.

[0160] The present invention controls the graphene dispersion within a reasonable mass range to achieve the desired effect; if the amount of graphene dispersion added is lower than the range specified in this application, the stability and uniform dispersion of the microbubbles in the bubble water will be poor, and the compressive strength and durability of the concrete will not meet the required performance.

[0161] However, if the amount of graphene dispersion added exceeds the limit specified in this application, the following defects will occur: (1) increased cost; (2) reduced reduction in concrete density; (3) may even affect the pumping performance.

[0162] second

[0163] Compared to methods that only add stabilizers and surfactants to prepare micro / nano bubble water (e.g., application number 202210304373.2), the innovative design and effects of this invention are significantly different:

[0164] The scheme in application number 202210304373.2 is fundamentally different from the present invention in the method of producing and modifying micro-nano bubble water, and the application and purpose are also different. The scheme uses a bubble initiator to generate modified micro-nano bubble water, and then uses a stabilizer to stabilize it, thus obtaining bubble-stable micro-nano bubble water. The present invention uses a modified micro-nano bubble water generating device to produce modified micro-nano bubble water, and then uses an air-entraining agent, a foam stabilizer, and a graphene dispersion for composite modification. Its purpose is to reduce the density of concrete while maintaining good pumpability, compressive strength, and other properties of concrete.

[0165] Although using water containing micro- and nano-sized bubbles can create a "ball effect" in the slurry, significantly reducing the plastic viscosity of concrete and improving its workability, theoretically increasing its compressive strength, introducing a large amount of water containing stable bubbles to reduce the concrete's density will inevitably lead to a substantial decrease in compressive strength. For example, in Comparative Example 3, the micro- and nano-sized bubble water modified with a modifier to ensure stable bubble formation has a lower specific gravity, but its compressive strength is significantly reduced.

[0166] While application number 202210304373.2 describes the use of stabilizers and surfactants to ensure the stable existence of micro- and nano-bubbles in bubble water, its description of using the ball-bearing effect to enhance compressive strength is clearly not applicable to situations requiring a significant reduction in concrete density. This solution discloses a simple bubble water solution with a large number of stable bubbles, but its direct application to concrete, even when achieving a certain degree of reduction in concrete density, cannot guarantee good compressive strength and durability.

[0167] Compared to the scheme disclosed in application number 202210304373.2, this invention aims to significantly reduce the density of concrete. In addition to modifying the concrete with a modifier to stabilize micro-nano bubbles, a graphene dispersant is added. This not only has the effect of stabilizing and unifying bubbles, but also enables the concrete to maintain good compressive strength and durability while reducing its density.

[0168] Third, the novelty and practicality of this invention:

[0169] In this invention, modified micro-nano bubble water is incorporated into concrete, effectively reducing its apparent density. More significantly, it maintains comparable performance to ordinary high-performance concrete while exhibiting superior appearance with no obvious air bubbles. The manufacturing cost of this low-density concrete increases only slightly, making it economical. The use of modified micro-nano bubble water to achieve lightweighting replaces traditional methods of reducing density with high-strength lightweight aggregates, demonstrating novelty and ingenuity. It also enhances the workability of concrete, reduces labor costs, and the entire preparation process is simple, using readily available materials, making it practical.

[0170] In summary, the present invention has the following effects.

[0171] Compared to the approach of replacing traditional lightweight aggregates with high-strength lightweight aggregates, this invention provides a modified micro-nano bubble water. Concrete made by incorporating this modified micro-nano bubble water replaces traditional lightweight aggregates, effectively reducing concrete density at a lower manufacturing cost. While reducing density, it also ensures that the properties of the low-density concrete are comparable to ordinary high-performance concrete. The concrete exhibits good pumpability, mechanical properties, and durability, and has a superior appearance with no obvious bubbles. The low-density concrete facilitates component handling and installation, and its performance meets application requirements, making it both economical and practical.

[0172] In summary, this invention provides modified micro-nano bubble water and low-density concrete with modified micro-nano bubble water. The low-density concrete, with modified micro-nano bubble water and high-performance admixtures, can effectively solve the problem of high apparent density of concrete. More significantly, it can ensure that the strength meets the preparation requirements while maintaining cost-effectiveness. Furthermore, by optimizing the concrete mix proportion, the density of the concrete is increased, thereby improving its durability.

[0173] It should be noted that:

[0174] In this article, “~” is used to represent a numerical range, and the range of this expression includes two endpoint values;

[0175] The specific parameters or some commonly used reagents or raw materials in the above embodiments are specific or preferred embodiments under the concept of the present invention, and are not intended to limit it; those skilled in the art can make adaptive adjustments within the concept and protection scope of the present invention.

[0176] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A modified micro / nano bubble water, characterized in that: Its components include micro-nano bubble water, modifiers dispersed in the micro-nano bubble water, and graphene dispersion; The micro-nano bubble water contains dispersed micro-nano bubbles; the modifier includes anionic air-entraining agents, foam stabilizers, and retarders; the mass ratio of the anionic air-entraining agent, foam stabilizer, and retarder is (3-10):(0.02-0.08):(1-4); The mass ratio of the micro-nano bubble water, modifier, and graphene dispersion is (18-21):(0.05-0.1):(3-4); The micro-nano bubble water is prepared by passing water through a micro-nano bubble water generating device, so that micro-nano bubbles are dispersed in the micro-nano bubble water. The anionic air-entraining agent is one or more combinations of sodium α-alkenyl alkyl sulfonate and sodium alkyl polyoxyethylene ether sulfonate; the alkyl group in the sodium alkyl polyoxyethylene ether sulfonate has 8 to 12 carbon atoms. The foam stabilizer is one or more combinations of dodecyl dimethylamine oxide, alkyl polyoxyethylene ether, and polyvinyl alcohol. The retarder is one or more of the following: white sugar, sodium gluconate, and sodium citrate. The graphene dispersion is a dispersion formed by dispersing graphene in water as a solvent, and its solid content is 0.05% to 0.2%; the graphene includes one or more combinations of graphene oxide and reduced graphene oxide.

2. A method for preparing modified micro / nano bubble water as described in claim 1, characterized in that, The preparation steps include the following: The modifier and graphene dispersion were added to the first part of water and dispersed evenly to obtain solution C; The second portion of water is introduced into solution C through a micro-nano bubble water generating device and left to stand to obtain the modified micro-nano bubble water. The second portion of water is introduced into solution C through a micro-nano bubble water generating device, so that the second portion of water is mixed with the first portion of water and micro-nano bubbles are dispersed in it to form the micro-nano bubble water.

3. The method for preparing modified micro / nano bubble water according to claim 2, characterized in that: The mass ratio of the first part of water to the second part of water is (0.5~1):(1~1.5).

4. A low-density concrete incorporating modified micro-nano bubble water, characterized in that: By weight, its raw material components include: cement, modified micro-nano bubble water, fly ash, mineral powder, silica fume, coarse aggregate, fine aggregate, and high-performance water-reducing agent. The modified micro / nano bubble water is the modified micro / nano bubble water as described in claim 1; or, the modified micro / nano bubble water prepared by the preparation method described in any one of claims 2-3.

5. The low-density concrete with modified micro / nano bubble water as described in claim 4, characterized in that: By weight, its raw material components include: 221-294 parts cement, 147-167 parts modified micro-nano bubble water, 73-147 parts fly ash, 73-147 parts mineral powder, 15-39 parts silica fume, 1050-1100 parts coarse aggregate, 680-740 parts fine aggregate, and 3.9-5.9 parts high-performance water-reducing agent.

6. The low-density concrete with modified micro / nano bubble water as described in claim 5, characterized in that: The cement is one or more of P·O 42.5 cement, P·II 42.5 cement, and P·I 42.5 cement; The fly ash is one or more combinations of Grade I fly ash and Grade II fly ash; The mineral powder is S95 grade mineral powder that has been ground to obtain a specific surface area of ​​650m². 2 / kg~750m 2 The activity index of mineral powder at 28 days is 115%–122%; The silica fume is one or more of SF94 grade silica fume and SF96 grade silica fume; The coarse aggregate is one or more combinations of crushed stone with a particle size of 5mm to 10mm, crushed stone with a particle size of 10mm to 20mm, and crushed stone with a particle size of 5mm to 20mm, and its apparent density is 2620 kg / m³. 3 ~2650kg / m 3 The porosity is 38%–41%, and the crushing value is 2%–4%. The fine aggregate is manufactured sand with a fineness modulus of 2.6–2.8 and an apparent density of 2600 kg / m³. 3 ~2640kg / m 3 The porosity is 40%–44%, and the mud content is 0.1%–0.5%. The high-performance water-reducing agent is composed of polycarboxylate superplasticizer mother liquor, slump retainer, defoamer, water-retaining agent, regulator and water.

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