Large-flow-state lightweight ultrahigh-strength concrete and preparation method thereof

Abstract

The invention relates to a large-flow-state lightweight ultrahigh-strength concrete, which is prepared from the following components in parts by weight: 1050 to 1200 parts of modified cement paste, 110 to 130 parts of silica fume, 100 to 110 parts of sand, 165 to 175 parts of glass beads, 20 to 30 parts of ceramsite, 205 to 215 parts of fiber, 22 to 26 parts of graphene oxide / polycarboxylic acid composite admixture and 230 to 250 parts of water. According to the invention, aluminate cement, tungsten tailing powder, zircon powder, low-grade silica fume and the like are used as main raw materials, various material modification and composite chemical activation means are combined, and a graphene oxide / warkovin / polycarboxylic acid composite multifunctional additive and light modified materials such as glass beads, fibers, ceramsite and the like are combined; the excellent properties such as high flowability, light weight, ultrahigh strength and durability of the obtained concrete can be effectively considered, and the method is suitable for popularization and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to a high-fluidity lightweight ultra-high-strength concrete and a preparation method thereof. Background Art

[0002] With the advancement of the modernization and urbanization construction processes, the requirements for the performance of concrete are also continuously increasing. The preparation and application of high-fluidity high-strength concrete have become the key research directions at present. The high-fluidity and high-strength properties of high-fluidity high-strength concrete can meet the construction and engineering requirements of concrete under various conditions. At present, some scholars have conducted research on the application of high-fluidity high-strength concrete with a fixed grade in engineering entity structures, the analysis of the influence of different lithology coarse aggregates on the performance of high-fluidity concrete, and the influence of some admixture systems on the performance of high-fluidity concrete. However, there are usually problems such as poor stability of the working performance of concrete, easy bleeding phenomenon, and large fluctuations in the appearance and later durability performance of the hardened concrete engineering entity.

[0003] In addition, in the current fields such as connection posts along railways, the laying of carriageways of long-span bridges, and super-high-rise buildings, etc., the structural concrete materials are required to have characteristics such as lightweight and high strength. However, due to the large self-weight of ordinary concrete, it brings certain limitations to the application of special parts of building structures. Lightweight aggregate concrete has advantages such as light weight, good heat preservation and sound insulation, and is increasingly favored. However, the strength of existing lightweight aggregate concrete is generally below 50 MPa, the durability is relatively poor, and the prepared concrete mixture is prone to problems such as floating of aggregates and poor workability due to the light weight of the aggregates. Summary of the Invention

[0004] The main purpose of the present invention is to provide a high-fluidity lightweight ultra-high-strength concrete aiming at the problems and deficiencies existing in the prior art. Using aluminate cement, tungsten tailings powder, zircon powder, low-grade microsilica powder, etc. as the main raw materials, combined with a variety of special material modification and composite chemical activation means, and then combined with graphene oxide / huaqiansu / polycarboxylic acid composite multifunctional admixtures and lightweight modification materials such as glass microspheres, fibers, and ceramsite, etc., it can effectively take into account the excellent properties of the obtained concrete such as high fluidity, light weight, ultra-high strength, and durability, and is suitable for popularization and application.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A large-flow lightweight ultra-high-strength concrete, the components and their respective weight parts include: 1050-1200 parts of modified cement paste, 110-130 parts of silica fume, 100-110 parts of sand, 165-175 parts of glass microspheres, 20-30 parts of ceramsite, 205-215 parts of fiber, 22-26 parts of graphene oxide / polycarboxylic acid composite admixture, and 230-250 parts of water; wherein, the modified cement paste is obtained by first subjecting a composite cementitious material formed by aluminate cement, tungsten tailings powder, zircon powder, and silica powder to modification treatment with citric acid and calcium hydroxide solution, and then incorporating a composite chemical activator and mixing.

[0007] In the above solution, the mass ratio of the aluminate cement, tungsten tailings powder, zircon powder, and silica powder is 1:0.6-0.8:0.04-0.06:0-0.10.

[0008] In the above solution, the mass ratio of the aluminate cement, citric acid, and calcium hydroxide solution is 1:0.002-0.004:0.70-0.80.

[0009] In the above solution, the concentration of the calcium hydroxide solution is 0.15-0.20 wt%.

[0010] In the above solution, the specific surface area of the aluminate cement ≥ 400 m 2 / kg, the initial setting time is 120-140 min, the final setting time is 230-250 min, the 1-day compressive strength ≥ 70 MPa, the 3-day compressive strength ≥ 80 MPa, the SiO 2 content ≥ 5%, the Al 2 O 3 content is 45-55%; the tungsten tailings powder is high-silica tungsten tailings powder, its SiO 2 content ≥ 70%, the Al 2 O 3 content is 10-15%, the proportion of +200 mesh is 92-96%, and the proportion of -200 mesh is 4-8%; the density of the zircon powder is 4.10-4.50 g / cm 3 , the Mohs hardness is 7.5-8.0, the ZrO 2 content ≥ 65%, the SiO 2 content ≥ 30%, the specific surface area is 280-350 m 2 / kg; the silica powder is low-grade microsilica powder, the specific surface area is 15000-18000 m 2 / kg, the activity index is 80-90% at 3 days, 85-95% at 7 days, 95-105% at 28 days, the silica dioxide content is 85-90%, and the water demand ratio is 115-120%.

[0011] In the above solution, the composite chemical activator is obtained by compounding sodium sulfide, nano-magnesium oxide, and polystyrene amino magnetic beads.

[0012] Further, the particle size of the nano-magnesium oxide is 20 - 30 nm; the diameter of the polystyrene amino magnetic beads is 0.8 - 1.8 μm, and the percentage of magnetic iron is 36 - 45%.

[0013] Further, the mass ratio of sodium sulfide, nano-magnesium oxide, and polystyrene amino magnetic beads is 1:0.1 - 0.2:0.01 - 0.02.

[0014] In the above solution, the composite chemical activator is introduced by an external admixture method, and the dosage is 0.1 - 0.2% of the mass of the modified cement paste.

[0015] In the above solution, the solid content of the modified cement paste is 88.0 - 92.0%.

[0016] In the above solution, the graphene oxide / polycarboxylic acid composite admixture is obtained by polymerizing F-108 macromonomer, Huaqiansu, graphene oxide dispersion liquid, and unsaturated carboxylic acid monomer; the specific preparation steps include: stirring the F-108 macromonomer, Huaqiansu, and graphene oxide dispersion liquid at a low speed (rotation speed 50 - 70 r / min) for 3 - 4 h at 60 - 65 °C to mix evenly to obtain a base liquid; mixing ascorbic acid (VC), mercaptoacetic acid (TGA), and water evenly to prepare solution A, and mixing the unsaturated carboxylic acid monomer and water evenly to prepare solution B; simultaneously dropping solution A and solution B (the dropping time is 2.5 - 3.5 h) into the base liquid, and adding a certain amount of hydrogen peroxide and stabilizer during the dropping, and carrying out stirring treatment (50 - 60 min) during the dropping to obtain the graphene oxide / Huaqiansu / polycarboxylic acid composite admixture.

[0017] In the above solution, the unsaturated carboxylic acid monomer can be selected from acrylic acid, methacrylic acid, etc.

[0018] In the above solution, the solid content of the graphene oxide / Huaqiansu / polycarboxylic acid composite admixture is 32 - 38%.

[0019] In the above solution, the mass ratio of F-108 macromonomer, graphene oxide, Huaqiansu, and water (the water in the graphene oxide dispersion liquid) in the raw materials used for the base liquid is 1:0.02 - 0.04:0.2 - 0.4:1.8 - 2.2; the mass ratio of ascorbic acid (VC), mercaptoacetic acid (TGA), and water in the raw materials used for solution A is 1:0.48 - 0.52:35 - 38, and the mass ratio of the unsaturated carboxylic acid monomer and water in the raw materials used for solution B is 1:1.4 - 1.6.

[0020] Further, the molar ratio of the F-108 macromonomer, ascorbic acid, and unsaturated carboxylic acid monomer is 1:0.004 - 0.005:0.08 - 0.12.

[0021] In the above solution, the concentration of the graphene oxide dispersion is 0.5 - 1.0 wt%; the Huaqian element is the HQS-R series.

[0022] In the above solution, the length of the fiber is 35 - 40 mm, and the diameter is 0.70 - 0.80 mm; preferably steel fiber, specifically straight steel fiber or corrugated steel fiber; the ceramsite is gravel-type ceramsite or spherical ceramsite, and its particle size is 5 - 10 mm.

[0023] In the above solution, the sand is preferably river sand, and its apparent density is 2650 - 5750 kg / m 3 , and the fineness modulus is 3.1 - 3.3.

[0024] In the above solution, the apparent density of the glass microspheres is 480 - 520 kg / m 3 , and the floating rate is ≥95%.

[0025] The preparation method of the above large-flow lightweight ultra-high-strength concrete includes the following steps:

[0026] 1) Weigh each raw material according to the ratio. Each raw material and its weight parts include: 1050 - 1200 parts of modified cement paste, 110 - 130 parts of silica fume, 100 - 110 parts of sand, 165 - 175 parts of glass microspheres, 20 - 30 parts of ceramsite, 205 - 215 parts of fiber, 22 - 26 parts of graphene oxide / polycarboxylic acid composite admixture, and 230 - 250 parts of water;

[0027] 2) Add the weighed raw materials in the order of ceramsite, sand, glass microspheres, modified cement paste, silica fume, fiber, water, and graphene oxide / polycarboxylic acid composite admixture, stir and mix evenly (15 - 20 min), and then obtain the large-flow lightweight ultra-high-strength concrete through high-temperature steam curing and standard curing.

[0028] In the above solution, the high-temperature steam curing step includes: curing at 60 - 65°C for 22 - 24 h, curing at 80 - 85°C for 36 - 40 h, curing at 60 - 65°C for 22 - 24 h, and curing at 45 - 50°C for 36 - 40 h.

[0029] The large-flow lightweight ultra-high-strength concrete prepared according to the above solution has a slump of more than 240 mm and a spread of more than 650 mm for the mixture, and the hardened concrete bulk density is 1800 kg / m 3Hereinafter, the 3d compressive strength ≥ 70 MPa, the 28d compressive strength ≥ 115 MPa, the strength grade can reach above C100, the 28d electric flux ≤ 450 C, the 28d chloride ion migration coefficient ≤ 2.5 (× 10 -12 m 2 / s), the frost resistance grade can reach above F200, and the sulfate resistance grade KS150 or above.

[0030] The principle of the present invention is as follows:

[0031] 1) It is proposed for the first time to introduce the 925 aluminate cement system into lightweight ultra-high-strength concrete, and combine various special material modifications and composite chemical activation methods, which can effectively overcome problems such as the decline of the later strength and poor stability of the 925 aluminate cement. Among them, tungsten tailings powder belongs to high-silica materials, which can effectively improve the problem of the decline of the later strength. Zircon powder belongs to high-hardness materials. While providing physical property support, it has a certain improvement effect on the workability of concrete, that is, the large-flow property. Silica fume belongs to high-specific surface area materials, which can improve the later strength stability of concrete and ensure that there is no bleeding problem under the large-flow characteristics of concrete. At the same time, silica fume has a lower density than other admixtures, which can improve the lightweight characteristics of concrete to a certain extent; then, it is modified by citric acid and calcium hydroxide solution, which can promote the combination stability of various materials and provide a favorable alkaline environment for the reaction, ensuring the high efficiency of the later concrete hydration process. Then, it is further combined with a composite activator enhanced activation technology. On the basis of traditional activators, nano-magnesium oxide and polystyrene amino magnetic bead materials are innovatively used. Among them, nano-magnesium oxide not only provides reaction activity but also plays a role in catalysis, adsorption and performance improvement. It can catalyze the reaction process, strengthen the overall binding property of the activated substances and improve the long-term durability performance of concrete. The introduced polystyrene amino magnetic beads utilize the functional characteristics of amino groups and the structural characteristics of the material itself, with excellent dispersion characteristics, reaction efficiency and stability. While enhancing the reaction activation efficiency, it can ensure the stability of the overall reaction, and play a role in promoting each other with nano-magnesium oxide, effectively improving the large-flow characteristics of the obtained concrete; through comprehensive modification and activation, the workability, mechanical properties and durability performance of the modified cement can be effectively improved.

[0032] 2) The composite multi-functional admixture combines the comprehensive properties of graphene oxide, water reducer and Huaqiansu. Through compound preparation, its application effect in concrete can be significantly improved: due to its templating effect, graphene oxide can provide a growth environment for hydration products and promote their dense growth. The incorporation of graphene oxide also increases the number of gel pores and capillary pores in the hardened cement paste, playing a role in refining the pore structure. At the same time, considering the graphite material nature and layered structure characteristics of graphene oxide, it can comprehensively improve the mechanical properties and durability of concrete and improve the fluidity of the concrete mixture. Huaqiansu has good cement adaptability and dispersibility, and has certain water-reducing and strengthening properties. In addition, when used together with graphene oxide, it can improve the dispersibility of graphene oxide, enhance the water-reducing efficiency of the composite functional admixture, and comprehensively improve the mechanical properties of concrete, especially in terms of the long-term strength growth.

[0033] 3) By virtue of the viscosity of the modified cement paste, it adheres to the surface of lightweight aggregates during the concrete mixing process, making the whole more integral and not easily floating to the upper surface of the concrete due to its lightweight characteristics under vibration or buoyancy. At the same time, combined with fiber materials, a network structure is formed during the concrete mixing process, which can prevent the problem of lightweight aggregates floating.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] 1) The present invention can effectively balance the properties of concrete such as high fluidity, lightweight, and ultra-high strength, and can effectively improve problems such as the easy floating of traditional lightweight aggregates and poor workability, providing a new idea for the preparation of lightweight and high-strength (especially ultra-high strength) concrete.

[0036] 2) The preparation cost involved in the present invention is relatively low, and it can realize the resource utilization of various mineral powders, which is suitable for popularization and application. Specific embodiments

[0037] The following further detailed description of the present invention is made in conjunction with embodiments, which is convenient for a clearer understanding of the present invention, but they do not constitute a limitation to the present invention.

[0038] In the following embodiments, the cement used is the CA50-(G9)-925 cement of Zhengzhou Yurui Refractory Materials Co., Ltd., with a specific surface area of 450 m 2 / kg, 1d compressive strength of 75.2 MPa, and 3d compressive strength of 82.5 MPa; the silica fume is provided by Xinjiang Dongfang Hope Group Co., Ltd. (Wucaiwan), with a specific surface area of 16000 m 2 / kg, 3d activity index of 83%, 7d activity index of 86%, 28d activity index of 98%, silica dioxide content of 88.6%, and water demand ratio of 118%.

[0039] The sand is river sand and concrete source sand, with a fineness modulus of 3.2, a water content of 2.5%, and a mud content of 1.1%; the glass microspheres are provided by Shanxi Hainuo Technology Co., Ltd., with an apparent density of 500 kg / m 3 , a floating rate of 98%; the ceramsite is Xinjiang Wucaiwan shale ceramsite, grade 800, with a continuous gradation of 5 - 10 mm, an apparent density of 1250 kg / m 3 , a cylinder compressive strength of 7.2 MPa, a 1-hour water absorption rate of 4.7%, and a 24-hour water absorption rate of 6.5%; the steel fiber is copper-plated steel fiber produced by Laiwu Xingtai Engineering Materials Co., Ltd., with a tensile strength of 2015 MPa, an average diameter of 0.75 mm, a length of 35 - 40 mm, and an apparent density of 8000 kg / m 3 .

[0040] The water reducing agent used is a polycarboxylate superplasticizer from Kehuida Chemical Building Materials Co., Ltd., with a solid content of 12.15% and a water reduction rate of 27%.

[0041] In the following examples, the tungsten tailings powder used is the black and white tungsten gravity separation tailings from a certain place in Fujian, with a SiO 2 content of 73.85%, a proportion of +200 mesh of 93.87%, and a proportion of -200 mesh of 6.02%; the zircon powder used is made from zircon milled by Jiangxi Keyuan Environmental Protection Co., Ltd., with a density of 4.20 g / cm 3 , a Mohs hardness of 7.6, a ZrO 2 content of 67%, a SiO 2 content of 35%, and a specific surface area of 320 m 2 / kg; the nano-magnesium oxide is provided by Heze Chemical Industry, with a particle size of 20 - 30 nm, a purity of 98%, and a specific surface area of 42.05 m 2 / g; the polystyrene amino magnetic beads are provided by Beijing Anbiqi Biotechnology Co., Ltd., are of medium amino type, with a diameter of 1.0 μm, and a magnetic iron percentage of 40%.

[0042] The graphene oxide dispersion used is provided by Nanjing Jicang Nano Technology Co., Ltd., with analytical purity and a concentration of 0.6 wt%; Huaciansu is provided by Beijing Huaqian New Technology Co., Ltd., with a product model of HQS-R.

[0043] Example 1

[0044] A large-flow lightweight ultra-high-strength concrete, and its preparation method includes the following steps:

[0045] 1) First, add 100 parts of 925 aluminate cement, 60 parts of tungsten tailings powder, 4 parts of zircon powder, and 10 parts of silicon powder (parameters are as described above) that have been metered into a mixer, stir evenly for 10 min, and then add 0.2 part of citric acid modifier and 70 parts of calcium hydroxide solution (concentration of 0.20 wt%), and stir for 15 min to make a uniform primary modified cement paste;

[0046] 2) Weigh 100 parts of sodium sulfide, 10 parts of nano-magnesium oxide, and 1 part of polystyrene amino magnetic beads and mix them evenly to form a composite chemical activator. Incorporate the composite chemical activator into the modified cement paste at a mass ratio of 0.1% for one-time modification, and stir evenly for 20 min to obtain the modified cement paste;

[0047] 3) Weigh 100 parts of F-108 macromonomer, 20 parts of Huaqian element, 2 parts of graphene oxide, and 180 parts of deionized water, and stir them at a low speed (60 r / min) for 3 h at 60 °C to mix evenly, thus preparing the base liquid; Take 100 parts of ascorbic acid (VC), 48 parts of mercaptoacetic acid (TGA), and 3500 parts of water and mix them evenly to prepare solution A. Then take 100 parts of acrylic acid (AA) and 140 parts of deionized water and mix them evenly to prepare solution B; Use a peristaltic pump to control the flow rate, control the reaction temperature at 60 °C, and slowly drip solution A and solution B into the base liquid simultaneously (the dripping is completed in 3 h), and add a certain amount of hydrogen peroxide and stabilizer during the dripping. After the dripping is completed, stir at 60 °C for 50 min, and then cool down to room temperature of 25 °C to obtain a stable graphene oxide / Huaqian element / polycarboxylate composite admixture.

[0048] 4) Weigh 1050 parts of the modified cement paste, 110 parts of silica fume, 105 parts of river sand, 170 parts of glass microspheres, 25 parts of ceramsite (5 - 10 mm), 210 parts of steel fibers, 24 parts of graphene oxide / Huaqian element / polycarboxylate composite admixture, and 240 parts of water. Add them in sequence according to the order of ceramsite, sand, glass microspheres, modified cement paste, silica fume, fibers, water, and graphene oxide / Huaqian element / polycarboxylate composite admixture and stir evenly. The stirring time is 15 - 20 min. After curing at 60 °C for 24 h, 80 °C for 36 h, 60 °C for 24 h, and 45 °C for 36 h in sequence, then carry out standard curing at 20 °C until the total age of the specimen reaches 28 d to obtain high-flowability lightweight ultra-high-strength concrete.

[0049] After testing, for the prepared high-flowability lightweight ultra-high-strength concrete, the slump of the concrete mixture is 245 mm, the spread is 670 mm, the unit weight of the hardened concrete is 1750 kg / m 3 , the 3-day strength is 78.4 MPa, the 28-day strength is 125 MPa, the strength grade can reach above C100, the 28-day electric flux is 420 C, the 28-day chloride ion migration coefficient is 2.2 (×10 -12 m 2 / s), the frost resistance grade is F200, and the sulfate resistance grade is KS150, which can achieve the properties of high-flowability, lightweight, and ultra-high-strength of the concrete.

[0050] Example 2

[0051] A high-flow lightweight ultra-high-strength concrete, and its preparation method includes the following steps:

[0052] 1) First, add 100 parts of 925 aluminate cement, 80 parts of tungsten tailings powder, 6 parts of zircon powder, and 10 parts of silicon powder (parameters are as described above) that have been measured into a mixer. After uniformly stirring for 10 minutes, then add 0.4 parts of citric acid modifier and 80 parts of calcium hydroxide solution (concentration is 0.20 wt%), and stir for 15 minutes to make a uniform primary modified cement paste;

[0053] 2) Weigh 100 parts of sodium sulfide, 15 parts of nano-magnesium oxide, and 2 parts of polystyrene amino magnetic beads and uniformly mix them into a composite chemical activator. Incorporate the composite chemical activator into the primary modified cement paste at a mass ratio of 0.1%, and stir uniformly for 20 minutes to obtain a modified cement paste;

[0054] 3) Weigh 100 parts of F-108 macromonomer, 30 parts of Huaqian element, 3 parts of graphene oxide, and 200 parts of deionized water, and stir at a low speed (60 r / min) at a temperature of 60 °C for 3 hours to mix evenly, thus preparing a base liquid; Take 100 parts of ascorbic acid (VC), 50 parts of mercaptoacetic acid (TGA), and 3600 parts of water and mix them evenly to prepare solution A. Then take 100 parts of acrylic acid (AA) and 160 parts of deionized water and mix them evenly to prepare solution B; Use a peristaltic pump to control the flow rate, control the reaction temperature at 60 °C, and slowly drip solution A and solution B into the base liquid simultaneously (the dripping is completed in 3 hours), and add a certain amount of hydrogen peroxide and stabilizer during the dripping. After the dripping is completed, stir at a temperature of 60 °C for 50 minutes, and then cool down to room temperature of 25 °C to obtain a stable graphene oxide / Huaqian element / polycarboxylate composite admixture.

[0055] 4) Weigh 1100 parts of modified cement paste, 120 parts of silica fume, 110 parts of river sand, 175 parts of glass microspheres, 30 parts of ceramsite (5 - 10 mm), 215 parts of steel fiber, 24 parts of graphene oxide / Huaqian element / polycarboxylate composite admixture, and 240 parts of water. Add them in sequence according to the order of ceramsite, sand, glass microspheres, modified cement paste, silica fume, fiber, water, graphene oxide / Huaqian element / polycarboxylate composite admixture and stir evenly. The stirring time is 15 - 20 minutes. After curing at 60 °C for 24 hours, 80 °C for 36 hours, 60 °C for 24 hours, and 45 °C for 36 hours in sequence, then carry out standard curing at 20 °C until the total age of the specimen reaches 28 days to obtain the high-flow lightweight ultra-high-strength concrete.

[0056] After testing, for the prepared high-flow lightweight ultra-high-strength concrete, the slump of the concrete mixture is 245 mm, the spread is 675 mm, and the bulk density of the hardened concrete is 1720 kg / m 3, the 3d strength is 80.1 MPa, the 28d strength is 127 MPa, and the strength grade can reach above C100. The 28d electric flux is 410 C, and the 28d chloride ion migration coefficient is 2.2 (×10 -12 m 2 / s). The frost resistance grade is F200, and the sulfate resistance grade is KS150. The properties of high fluidity, light weight, and ultra-high strength of concrete can be achieved.

[0057] Comparative Example 1

[0058] A kind of high fluidity, light weight, and ultra-high strength concrete, and its preparation method includes the following steps:

[0059] 1) First, add 100 parts of 925 aluminate cement, 60 parts of tungsten tailings powder, 4 parts of zircon powder, and 10 parts of silica fume (parameters are as described above) measured into a mixer. After stirring evenly for 10 min, then add 0.2 part of citric acid modifier and 70 parts of calcium hydroxide solution (concentration is 0.20 wt%), and stir for 15 min to make a uniform primary modified cement paste;

[0060] 2) Weigh 100 parts of sodium sulfide and 10 parts of nano magnesium oxide and mix them evenly to form a composite chemical activator. Incorporate the composite chemical activator into the primary modified cement paste according to the mass ratio of 0.1%, and stir evenly for 20 min to obtain a modified cement paste;

[0061] 3) Weigh 100 parts of F-108 macromonomer, 20 parts of Huaqian element, 2 parts of graphene oxide, and 180 parts of deionized water, and stir at a low speed (60 r / min) at 60°C for 3 h to mix evenly, thus preparing a base liquid; Take 100 parts of ascorbic acid (VC), 48 parts of mercaptoacetic acid (TGA), and 3500 parts of water and mix them evenly to prepare solution A. Then take 100 parts of acrylic acid (AA) and 140 parts of deionized water and mix them evenly to prepare solution B; Use a peristaltic pump to control the flow rate, control the reaction temperature at 60°C, and slowly drip solution A and solution B into the base liquid simultaneously (the dripping is completed in 3 h), and add a certain amount of hydrogen peroxide and stabilizer while dripping. After the dripping is completed, stir at 60°C for 50 min, and then cool down to room temperature of 25°C to obtain a stable graphene oxide / Huaqian element / polycarboxylate composite admixture.

[0062] 4) Weigh 1050 parts of modified cement paste, 110 parts of silica fume, 105 parts of river sand, 170 parts of glass microspheres, 25 parts of ceramsite (5 - 10 mm), 210 parts of steel fiber, 24 parts of graphene oxide / Huaqian element / polycarboxylic acid composite admixture, and 240 parts of water. Add them in the order of ceramsite, sand, glass microspheres, modified cement paste, silica fume, fiber, water, and graphene oxide / Huaqian element / polycarboxylic acid composite admixture, and stir evenly. The stirring time is 15 - 20 min. Cure at 60 °C for 24 h, 80 °C for 36 h, 60 °C for 24 h, and 45 °C for 36 h in sequence, and then carry out standard curing at 20 °C until the total age of the specimen reaches 28 d to obtain high-flow lightweight ultra-high-strength concrete.

[0063] After testing, for the prepared high-flow lightweight ultra-high-strength concrete, the slump of the concrete mixture is 220 mm, the spread is 590 mm, and the unit weight of the hardened concrete is 1750 kg / m 3 , the 3-day strength is 67.4 MPa (14% lower than that of Example 1), the 28-day strength is 92.1 MPa (27% lower than that of Example 1), the strength grade does not reach C100, the 28-day electric flux is 600 C (43% higher than that of Example 1), and the 28-day chloride ion migration coefficient is 2.8 (×10 -12 m 2 / s), which is 27% higher than that of Example 1. The frost resistance grade is F150, and the sulfate resistance grade is KS120; compared with Example 1, the workability, mechanical properties, and durability performance all decline, especially in terms of the later durability performance.

[0064] Comparative Example 2

[0065] A high-flow lightweight ultra-high-strength concrete, and its preparation method includes the following steps:

[0066] 1) First, add the measured 100 parts of 925 aluminate cement, 60 parts of tungsten tailings powder, 4 parts of zircon powder, and 10 parts of silicon powder (parameters are all as described above) into the mixer, stir evenly for 10 min, and then add 0.2 parts of citric acid modifier and 70 parts of calcium hydroxide solution (concentration is 0.20 wt%), and stir for 15 min to make a uniform primary modified cement paste;

[0067] 2) Weigh 100 parts of sodium sulfide, 10 parts of nano-magnesium oxide, and 1 part of polystyrene amino magnetic beads and mix them evenly as a composite chemical activator. Incorporate the composite chemical activator into the primary modified cement paste at a mass ratio of 0.1%, and stir evenly for 20 min to obtain a modified cement paste;

[0068] 3) Weigh 100 parts of F-108 macromonomer, 2 parts of graphene oxide, and 180 parts of deionized water, and stir them at a low speed (60 r / min) for 3 h at 60 °C to mix them evenly, thus preparing a base liquid; weigh 100 parts of ascorbic acid (VC), 48 parts of thioglycolic acid (TGA), and 3500 parts of water and mix them evenly to prepare solution A, and then weigh 100 parts of acrylic acid (AA) and 200 parts of deionized water and mix them evenly to prepare solution B; use a peristaltic pump to control the flow rate, control the reaction temperature at 60 °C, and slowly drip solution A and solution B into the base liquid simultaneously (the dripping is completed in 3 h), and add a certain amount of hydrogen peroxide and stabilizer while dripping. After the dripping is completed, stir at 60 °C for 50 min, and then cool down to room temperature of 25 °C to obtain a stable graphene oxide / polycarboxylic acid composite admixture, and then mix in 20 parts of Huaqian element to obtain a mixed admixture;

[0069] 4) Weigh 1050 parts of modified cement paste B, 110 parts of silica fume, 105 parts of river sand, 170 parts of glass microspheres, 25 parts of ceramsite (5 - 10 mm), 210 parts of steel fiber, 24 parts of mixed admixture, and 240 parts of water, and add them in the order of ceramsite, sand, glass microspheres, modified cement paste, silica fume, fiber, water, and mixed admixture and stir evenly. The stirring time is 15 - 20 min. After curing at 60 °C for 24 h, 80 °C for 36 h, 60 °C for 24 h, and 45 °C for 36 h in sequence, then carry out standard curing at 20 °C until the total age of the specimen reaches 28 d to obtain high-flowability lightweight ultra-high-strength concrete.

[0070] After testing, for the prepared high-flowability lightweight ultra-high-strength concrete, the slump of the concrete mixture is 210 mm, the spread is 600 mm, the bulk density of the hardened concrete is 1755 kg / m 3 , the 3-day strength is 63.2 MPa, which is 19% lower than that of Example 1, the 28-day strength is 85.6 MPa, which is 32% lower than that of Example 1, the strength grade does not reach C100, the 28-day electric flux is 560 C, which is 33% higher than that of Example 1, the 28-day chloride ion migration coefficient is 2.6 (×10 -12 m 2 / s), which is 18% higher than that of Example 1, the frost resistance grade is F150, the sulfate resistance grade is KS150, and its workability, mechanical properties, and durability are all lower than those of Example 1, especially in terms of mechanical properties.

[0071] Comparative Example 3

[0072] A high-flowability lightweight ultra-high-strength concrete, and its preparation method includes the following steps:

[0073] 1) First, add 100 parts of 925 aluminate cement and 10 parts of silica fume (parameters as described above) into a blender. After stirring evenly for 10 min, then add 0.2 parts of citric acid modifier and 70 parts of calcium hydroxide solution (concentration 0.20 wt%), and stir for 15 min to make a uniform primary modified cement paste;

[0074] 2) Weigh 100 parts of sodium sulfide, 10 parts of nano-magnesium oxide, and 1 part of polystyrene amino magnetic beads and mix them evenly to form a composite chemical activator. Incorporate the composite chemical activator into the primary modified cement paste at a mass ratio of 0.1%, and stir evenly for 20 min to obtain a modified cement paste;

[0075] 3) Weigh 100 parts of F-108 macromonomer, 20 parts of Huaqian element, 2 parts of graphene oxide, and 180 parts of deionized water, and stir at a low speed (60 r / min) at 60 °C for 3 h to mix evenly, thereby preparing a base liquid; Take 100 parts of ascorbic acid (VC), 48 parts of mercaptoacetic acid (TGA), and 3500 parts of water and mix them evenly to prepare solution A. Then take 100 parts of acrylic acid (AA) and 140 parts of deionized water and mix them evenly to prepare solution B; Use a peristaltic pump to control the flow rate, control the reaction temperature at 60 °C, and slowly drip solution A and solution B into the base liquid simultaneously (finished dripping in 3 h), and add a certain amount of hydrogen peroxide and stabilizer while dripping. After dripping, stir at 60 °C for 50 min, and then cool down to room temperature 25 °C to obtain a stable graphene oxide / Huaqian element / polycarboxylic acid composite admixture.

[0076] 4) Weigh 1050 parts of modified cement paste B, 110 parts of silica fume, 105 parts of river sand, 170 parts of glass microspheres, 25 parts of ceramsite (5 - 10 mm), 210 parts of steel fibers, 24 parts of graphene oxide / Huaqian element / polycarboxylic acid composite admixture, and 240 parts of water. Add them in the order of ceramsite, sand, glass microspheres, modified cement paste, silica fume, fibers, water, graphene oxide / Huaqian element / polycarboxylic acid composite admixture and stir evenly. The stirring time is 15 - 20 min. After curing at 60 °C for 24 h, 80 °C for 36 h, 60 °C for 24 h, and 45 °C for 36 h in sequence, then carry out standard curing at 20 °C until the total age of the specimen reaches 28 d to obtain high-flowability lightweight ultra-high-strength concrete.

[0077] After testing, for the prepared high-flowability lightweight ultra-high-strength concrete, the slump of the concrete mixture is 230 mm, the spread is 650 mm, the bulk density of the hardened concrete is 1740 kg / m 3 ³, the 3-day strength is 70.1 MPa, which is 11% lower than that of Example 1, the 28-day strength is 106 MPa, which is 17% lower than that of Example 1, the 28-day electric flux is 505 C, which is 20% higher than that of Example 1, and the 28-day chloride ion migration coefficient is 2.4 (×10 -12 -¹²2 / s), which is 9% higher than that of Example 1. The frost resistance grade is F200, and the sulfate resistance grade is KS150. The workability, mechanical properties and durability are all lower than those of Example 1.

[0078] Comparative Example 4

[0079] A high-flow lightweight ultra-high-strength concrete, and its preparation method includes the following steps:

[0080] 1) First, add 100 parts of 925 aluminate cement, 60 parts of tungsten tailings powder, 4 parts of zircon powder and 10 parts of silica fume (parameters are as described above) that have been measured into a mixer, and stir evenly for 10 minutes. Then, add 0.2 parts of citric acid modifier and 70 parts of calcium hydroxide solution (concentration is 0.20 wt%) and stir for 15 minutes to make a uniform primary modified cement paste;

[0081] 2) Weigh 100 parts of sodium sulfide, 10 parts of nano-magnesium oxide, and 1 part of polystyrene amino magnetic beads and mix them evenly to form a composite chemical activator. Incorporate the composite chemical activator into the primary modified cement paste according to a mass ratio of 0.1%, and stir evenly for 20 minutes to obtain a modified cement paste;

[0082] 3) Weigh 100 parts of F-108 macromonomer, 20 parts of Huaqian element, 2 parts of graphene oxide, and 180 parts of deionized water, and stir at a low speed (60 r / min) at 60 °C for 3 hours to mix evenly, thereby preparing a base liquid; Take 100 parts of ascorbic acid (VC), 48 parts of mercaptoacetic acid (TGA) and 3500 parts of water and mix them evenly to prepare solution A, and then take 100 parts of acrylic acid (AA) and 140 parts of deionized water and mix them evenly to prepare solution B; Use a peristaltic pump to control the flow rate, control the reaction temperature at 60 °C, and slowly drip solution A and solution B into the base liquid at the same time (the dripping is completed in 3 hours), and add a certain amount of hydrogen peroxide and stabilizer while dripping. After the dripping is completed, stir at 60 °C for 50 minutes, and then cool down to room temperature of 25 °C to obtain a stable graphene oxide / Huaqian element / polycarboxylate composite admixture.

[0083] 4) Weigh 1050 parts of modified cement paste, 110 parts of silica fume, 105 parts of river sand, 170 parts of glass microspheres, 25 parts of ceramsite (5 - 10 mm), 210 parts of steel fibers, 24 parts of graphene oxide / Huaqian element / polycarboxylate composite admixture, and 240 parts of water, and add them in sequence according to the order of ceramsite, sand, glass microspheres, modified cement paste, silica fume, fibers, water, graphene oxide / Huaqian element / polycarboxylate composite admixture and stir evenly. The stirring time is 15 - 20 minutes. After high-temperature curing at 80 °C for 24 hours, then carry out standard curing at 20 °C until the total age of the specimen reaches 28 days to obtain high-flow lightweight ultra-high-strength concrete.

[0084] After testing, for the prepared high-fluidity lightweight ultra-high-strength concrete, the slump of the concrete mixture is 240 mm, the spread is 665 mm, and the unit weight of the hardened concrete is 1755 kg / m 3 , the 3-day strength is 68.1 MPa, which is 13% lower than that of Example 1, the 28-day strength is 105 MPa, which is 16% lower than that of Example 1, the 28-day electric flux is 510 C, which is 21% higher than that of Example 1, and the 28-day chloride ion migration coefficient is 2.4 (×10 -12 m 2 / s), which is 9% higher than that of Example 1. The frost resistance grade is F200, and the sulfate resistance grade is KS150. Compared with Example 1, mainly the mechanical properties and durability properties have decreased.

[0085] The present invention is not limited to the above embodiments. For those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and retouches can be made, and these improvements and retouches are also regarded as within the protection scope of the present invention. The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

Claims

1. A high-flow lightweight ultra-high-strength concrete, characterized in that, each component and its weight parts include: 1050 - 1200 parts of modified cement paste, 110 - 130 parts of silica fume, 100 - 110 parts of sand, 165 - 175 parts of glass microspheres, 20 - 30 parts of ceramsite, 205 - 215 parts of fiber, 22 - 26 parts of graphene oxide / polycarboxylic acid composite admixture, and 230 - 250 parts of water; wherein, the modified cement paste is obtained by first subjecting a composite cementitious material formed by aluminate cement, tungsten tailings powder, zircon powder, and silica powder to modification treatment with citric acid and calcium hydroxide solution, and then mixing in a composite chemical activator.

2. The high-flow lightweight ultra-high-strength concrete according to claim 1, characterized in that, the mass ratio of the aluminate cement, tungsten tailings powder, zircon powder, and silica powder is 1:0.6 - 0.8:0.04 - 0.06:0 - 0.

10.

3. The high-flow lightweight ultra-high-strength concrete according to claim 1, characterized in that, the mass ratio of the aluminate cement, citric acid, and calcium hydroxide solution is 1:0.002 - 0.004:0.70 - 0.

80.

4. The high-flow lightweight ultra-high-strength concrete according to claim 1, characterized in that, the composite chemical activator is obtained by compounding sodium sulfide, nano-magnesium oxide, and polystyrene amino magnetic beads.

5. The high-flow lightweight ultra-high-strength concrete according to claim 4, characterized in that, the mass ratio of the sodium sulfide, nano-magnesium oxide, and polystyrene amino magnetic beads is 1:0.1 - 0.2:0.01 - 0.

02.

6. The high-flow lightweight ultra-high-strength concrete according to claim 1, characterized in that, the dosage of the composite chemical activator is 0.1 - 0.2% of the mass of the modified cement paste.

7. The high-flow lightweight ultra-high-strength concrete according to claim 1, characterized in that, the graphene oxide / polycarboxylic acid composite admixture is obtained by polymerization reaction using F-108 macromonomer, Huaqiansu, graphene oxide dispersion liquid, and unsaturated carboxylic acid monomer as main raw materials.

8. The high-flow lightweight ultra-high-strength concrete according to claim 7, characterized in that, the mass ratio of the F-108 macromonomer, graphene oxide, Huaqiansu, and unsaturated carboxylic acid monomer is 1:0.02 - 0.04:0.2 - 0.4:0.08 - 0.

12.

9. The preparation method of the high-flow lightweight ultra-high-strength concrete according to any one of claims 1 - 8, characterized in that, it includes the following steps: 1) Weigh each raw material according to the ratio. Each raw material and its weight parts include: 1050 - 1200 parts of modified cement paste, 110 - 130 parts of silica fume, 100 - 110 parts of sand, 165 - 175 parts of glass microspheres, 20 - 30 parts of ceramsite, 205 - 215 parts of fiber, 22 - 26 parts of graphene oxide / polycarboxylic acid composite admixture, and 230 - 250 parts of water; 2) Add the weighed raw materials in the feeding order of aggregate, powder, water, and admixture, stir and mix evenly, and then perform high-temperature steam curing and standard curing to obtain the high-flow lightweight ultra-high-strength concrete.

10. The preparation method according to claim 9, characterized in that, the high-temperature steam curing step includes: curing at 60-65°C for 22-24 h, curing at 80-85°C for 36-40 h, curing at 60-65°C for 22-24 h, and curing at 45-50°C for 36-40 h.