High-stability ultra-high performance concrete and preparation method thereof

Abstract

The invention relates to high-stability ultra-high performance concrete and a preparation method thereof. The concrete comprises the following components in kg / m < 3 >: 800-1000 of cement; 40-60 parts of fly ash; 100 to 120 parts of granulated blast furnace slag powder; 40-60 parts of silica fume; 800 to 1000 parts of yellow sand; 40-50 parts of a high-efficiency water reducing agent; and the packaging needle tube is 0.5%-2%. The method comprises the following steps: 1, adding cement, medium sand, granulated blast furnace slag powder, fly ash and silica fume into a stirrer, and stirring for 30-60 seconds; 2, adding a high-efficiency water reducing agent and water, and stirring for 120-240 seconds; and 3, adding into a packaging needle tube, and stirring for 30 seconds. According to the ultra-high-performance concrete, the chopped hollow waste needle tubes replace microfilament steel fibers to serve as a toughening material, and the epoxy resin material is used for packaging treatment, so that engineering risks such as sudden component breakage caused by fiber sedimentation are effectively avoided, waste resources are recycled, and the application cost of the ultra-high-performance concrete is greatly reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of concrete, and particularly relates to a high-stability ultra-high performance concrete and a preparation method thereof. BACKGROUND

[0002] Ultra-high performance concrete (UHPC) is a new type of concrete with excellent performance and excellent durability. The tensile and shear performance of the ultra-high performance concrete is excellent, and when the ultra-high performance concrete is applied to a concrete component, the stress performance of the component can be greatly improved. Based on these excellent performances, the ultra-high performance concrete is usually applied to high-demand occasions such as bridges, military, water conservancy, and fabricated component nodes.

[0003] The toughening material in the ultra-high performance concrete is mainly high-strength short-cut fiber. At present, the most commonly used fiber in engineering is copper-plated micro-silicon steel fiber, and the length thereof is different from 3mm to 12mm. The copper-plated micro-silicon steel fiber can effectively improve the bending and tensile performance of the UHPC, but has many defects. The steel fiber itself has a high cost (10000 yuan / ton to 12000 yuan / ton), which greatly increases the use cost of the UHPC. In addition, the micro-silicon steel fiber with a large density is easy to cause gravity settlement after being poured and molded into concrete, so that the upper fiber of the concrete is rare, and local stress concentration is easy to occur when the concrete bears a load, which causes sudden fracture and causes engineering risks. At the same time, attention must be paid to the durability risk of the concrete caused by the corrosion of the steel fiber.

[0004] At present, researchers attempt to use organic synthetic fiber to replace the steel fiber to be mixed into the UHPC to improve the overall performance thereof. However, the experimental results show that the organic synthetic fiber has a very thin diameter, a large length-diameter ratio, and is a flexible fiber. After being applied to the UHPC, the organic synthetic fiber is difficult to move cooperatively with the fresh concrete slurry, and is easy to cause aggregation, entanglement and other phenomena, which seriously reduces the fluidity of the concrete and limits the application occasions of the UHPC. The ultra-high performance concrete prepared by using the organic synthetic fiber has generally poor fluidity.

[0005] Therefore, how to provide a high-stability ultra-high performance concrete and a preparation method thereof is a technical problem to be solved by those skilled in the art. SUMMARY

[0006] The application provides high-stability ultra-high-performance concrete and a preparation method thereof, wherein hollow waste needle tubes are cut into short pieces to replace micro-silicon steel fibers as toughening materials, and the short hollow waste needle tubes are encapsulated by epoxy resin materials.

[0007] To solve the above technical problems, the application comprises the following technical solutions.

[0008] A kind of high-stability ultra-high-performance concrete, the components of the concrete are kg / m 3 The mass ratio is:

[0009] Cement 800-1000, fly ash 40-60, granulated blast furnace slag powder 100-120, silica fume 40-60, yellow sand 800-1000, high-efficiency water reducing agent 40-50, and encapsulated needle tube 0.5%-2%.

[0010] Further, the cement is P.II 52.5 Portland cement, the particle size is 20-30 microns, the fly ash is grade II fly ash, the granulated blast furnace slag powder includes S95, S105 and S115, the fine aggregate is medium sand, the fineness modulus is 2.3-3.0, the high-efficiency water reducing agent is a polycarboxylic acid type high-efficiency water reducing agent, the water-reducing rate is greater than or equal to 30%, and the water is ordinary tap water.

[0011] Further, the waste needle tube is a waste needle tube with a diameter of 0.2-1 mm, the waste needle tube is sterilized by chemical reagents, the waste needle tube after treatment is cut by a cutting machine, and the cutting length is 3-12 mm.

[0012] The application further provides a preparation method of the high-stability ultra-high-performance concrete.

[0013] Step S1, cement, medium sand, granulated blast furnace slag powder, fly ash and silica fume are added into a mixer, and stirred for 30-60 seconds;

[0014] Step S2, high-efficiency water reducing agent and water are added, and stirred for 120-240 seconds;

[0015] Step S3, encapsulated needle tubes are added, and stirred for 30 seconds.

[0016] Further, the preparation and treatment of the encapsulated needle tubes comprise the following steps:

[0017] Step S1: Weigh the two materials, E-44 epoxy resin and ethylenediamine curing agent, at a mass ratio of 100:8-12. Pour the weighed E-44 epoxy resin into a container and slowly add the ethylenediamine curing agent while stirring with a stirrer. The stirring time is generally 2-5 minutes.

[0018] Step S2: Slowly add 10-15% of the total mass of epoxy resin in acetone to the mixture while stirring with a stirrer to reduce the viscosity of the mixture.

[0019] Step S3: Weigh out a short needle tube with a mass of m1, add it to the mixture, stir gently to ensure that the epoxy resin adhesive is evenly coated on the surface of the needle tube.

[0020] Step S4: The total length l of the inserted short-cutting needle tube is calculated using the following formula:

[0021]

[0022] In the formula, R1 is the outer diameter of the stubbed needle tube, in meters (m), r is the inner diameter of the stubbed needle tube, in meters (m), and ρ... 钢 This is the density of steel, expressed in kg / m³. 3 ;

[0023] Step S5, the formula for calculating the total mass m of the chopped needle tube after epoxy resin coating is as follows:

[0024]

[0025] In the formula, R2 is the outer diameter of the packaged needle tube, in meters (m); R1 is the outer diameter of the chopped needle tube, in meters (m); ρ 环氧树脂 This refers to the density of epoxy resin, expressed in kg / m³. 3 .

[0026] Step S6: Place the epoxy resin-coated short-cut needle tube on a mechanical sieve and sieve away excess epoxy resin at a certain frequency until the total mass of the epoxy resin-coated short-cut needle tube is m. Stop the operation.

[0027] Step S7: After pouring out the treated syringe, spread it evenly on a smooth stainless steel tray. After 24 hours, the epoxy resin will be initially cured and can then be used to mix concrete.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] This invention provides a highly stable ultra-high performance concrete and its preparation method. It utilizes chopped hollow waste needles as a toughening material instead of microfiber steel fibers, and encapsulates them with epoxy resin. The chopped hollow waste needles, under the same volume conditions, weigh significantly less than ordinary microfiber steel fibers, are less prone to settling in concrete, and are more evenly distributed. The lightweight epoxy resin encapsulation further reduces the overall density, effectively avoiding engineering risks such as sudden component breakage caused by fiber settling. The application of chopped needles to ultra-high performance concrete represents the reuse of waste resources, responding to government environmental protection requirements and significantly reducing the application cost of ultra-high performance concrete. Attached Figure Description

[0030] Figure 1 In one embodiment of the present invention, a method for preparing high-stability, ultra-high-performance concrete is described.

[0031] ρ 封装针管 A schematic diagram of the functional relationship between a and α.

[0032] Figure 2 This is a schematic diagram of hollow needle encapsulation in a method for preparing high-stability ultra-high-performance concrete according to an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of a hollow needle tube in a method for preparing high-stability ultra-high-performance concrete according to an embodiment of the present invention.

[0034] In the picture,

[0035] 1-Needle wall, 2-Epoxy resin layer. Detailed Implementation

[0036] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a high-stability, ultra-high-performance concrete and its preparation method based on the present invention. The advantages and features of the present invention will become clearer from the following description.

[0037] The high-stability ultra-high-performance concrete and its preparation method of the present invention are described in detail below with reference to the accompanying drawings.

[0038] A high-stability, ultra-high-performance concrete, wherein the components of the concrete are expressed in kg / m³. 3 The mass ratio is:

[0039] Cement 800-1000; Fly ash 40-60; Granulated blast furnace slag powder 100-120; Silica fume 40-60; Yellow sand 800-1000; High-efficiency water-reducing agent 40-50; Encapsulating needle 0.5%-2%.

[0040] In this embodiment, more preferably, the cement is P.II 52.5 silicate cement with a particle size of 20-30 micrometers; the fly ash is Grade II fly ash; the granulated blast furnace slag powder grades include S95, S105, and S115; the fine aggregate is medium sand with a fineness modulus of 2.3-3.0; the high-efficiency water-reducing agent is a polycarboxylate high-efficiency water-reducing agent with a water reduction rate of ≥30%; and the water is ordinary tap water.

[0041] In this embodiment, more preferably, the waste needle is a waste needle with a diameter of 0.2 to 1 mm. The waste needle is sterilized by chemical reagents and then cut into short lengths of 3 mm to 12 mm using a short-cutting machine.

[0042] This invention also provides a method for preparing high-stability ultra-high-performance concrete, which includes the following steps:

[0043] Step S1: Add cement, medium sand, granulated blast furnace slag powder, fly ash and silica fume into the mixer and mix for 30-60 seconds.

[0044] Step S2: Add high-efficiency water-reducing agent and water, and stir for 120-240 seconds;

[0045] Step S3: Add the encapsulation syringe and stir for 30 seconds.

[0046] In this embodiment, more preferably, the preparation process of the encapsulated needle includes the following steps:

[0047] Step S1: Weigh the two materials, E-44 epoxy resin and ethylenediamine curing agent, at a mass ratio of 100:8-12. Pour the weighed E-44 epoxy resin into a container and slowly add the ethylenediamine curing agent while stirring with a stirrer. The stirring time is generally 2-5 minutes.

[0048] Step S2: Slowly add 10-15% of the total mass of epoxy resin in acetone to the mixture while stirring with a stirrer to reduce the viscosity of the mixture.

[0049] Step S3: Weigh out a short needle tube with a mass of m1, add it to the mixture, stir gently to ensure that the epoxy resin adhesive is evenly coated on the surface of the needle tube.

[0050] Step S4: The total length l of the inserted short-cutting needle tube is calculated using the following formula:

[0051]

[0052] Please refer to the formula. Figure 2 R1 is the outer diameter of the stub needle tube in meters (m), r is the inner diameter of the stub needle tube in meters (m), and ρ... 钢This is the density of steel, expressed in kg / m³. 3 The area between the inner and outer diameters of the short-cut needle tube is the needle tube wall 1.

[0053] Step S5, the formula for calculating the total mass m of the chopped needle tube after epoxy resin coating is as follows:

[0054]

[0055] Please refer to the formula. Figure 3 R2 is the outer diameter of the packaged needle, in meters; R1 is the outer diameter of the chopped needle, in meters; ρ 环氧树脂 This refers to the density of epoxy resin, expressed in kg / m³. 3 .

[0056] Step S6: Place the epoxy resin-coated short-cut needle tube on a mechanical sieve and sieve away excess epoxy resin at a certain frequency until the total mass of the epoxy resin-coated short-cut needle tube is m. Stop the operation.

[0057] Step S7: After pouring out the treated syringe, spread it evenly on a smooth stainless steel tray. After 24 hours, the epoxy resin will be initially cured and can then be used to mix concrete.

[0058] The inner diameter of a hollow discarded syringe is typically about half its outer diameter; therefore, the volume of its hollow portion is approximately one-quarter of the total syringe volume. Thin-walled syringes have an even larger hollow portion volume ratio. For the same material density, chopped hollow syringes weigh only three-quarters or less of ordinary steel fiber. Chopped hollow syringes are usually made of high-quality medical-grade stainless steel, possessing excellent corrosion resistance without special treatment, making them suitable as a toughening material inside concrete.

[0059] The overall density of a hollow syringe can be calculated using the following formula:

[0060]

[0061] When R1 = 2r, substituting into the formula, we can calculate ρ. 针管 =0.75ρ 钢 =5.89kg / m 3 The density of fiber-free ultra-high performance concrete is generally 2.4–3.0 kg / m³. 3 Therefore, it still cannot meet the requirements.

[0062] The hollow needle tube is encapsulated using epoxy resin. Due to the density of epoxy resin (1.25 kg / m³),... 3 Much lower than the density of steel, 7.85 kg / m³ 3Therefore, the overall density of the hollow needle can be further reduced. Additionally, uncured epoxy resin has a high viscosity, and under non-vacuum adsorption conditions, it is difficult for air to enter and escape from the hollow needle due to capillary action. After curing, the air is sealed inside the needle, ensuring a reduction in the overall density of the hollow needle after treatment. Cured epoxy resin has good alkali resistance and is not prone to aging over a long period. Its inert characteristics protect the hollow needle from the erosion of the internal environment of the concrete substrate, improving the durability of the concrete. The surface of the cured epoxy resin is rougher than that of the needle, which improves the bonding strength between the needle and the substrate, preventing the needle from slipping out of the concrete under load and ensuring the mechanical properties of the concrete. The density of the hollow needle after epoxy resin encapsulation can be calculated using the following formula:

[0063]

[0064] When R1 = 2r and R2 = ar, the above formula can be further simplified to the following:

[0065]

[0066] ρ 环氧树脂 and ρ 钢 All are known constants, therefore, ρ 封装针管 The functional relationship with a is as follows: Figure 1 Where the horizontal axis represents the value of 'a', and the vertical axis represents 'ρ'. 封装针管 value.

[0067] Since the density of fiber-free ultra-high performance concrete is generally 2.4–3.0 kg / m³, 3 To ensure the anti-settling performance of the syringe after packaging, the ρ should be required. 封装针管 This is equal to the density of fiber-free ultra-high performance concrete. Substituting into the above formula, the value of 'a' can be calculated to be in the range of 3.26 to 4.02. That is, the thickness of the epoxy resin layer 2 is approximately the same as the diameter of the needle tube, and the fiber aspect ratio does not change much, still playing a role in bridging cracks and toughening. Therefore, the application of epoxy resin encapsulation method is a feasible technical route and can fully meet the requirements for anti-settlement.

[0068] By using encapsulated chopped hollow needles instead of steel fibers in concrete, the density of the ultra-high performance concrete is basically the same as that of ordinary ultra-high performance concrete, and the gravity settlement rate is much lower than that of ordinary microfiber steel fibers. Therefore, the ultra-high performance concrete produced has a uniform fiber distribution and the stability of the concrete is effectively improved.

[0069] The following are specific examples. The fluidity of the mortar was tested according to standard GB / T2419-2005 "Method for Determination of Flowability of Cement Mortar"; the flexural strength and compressive strength were tested according to standard GB / T 17671-1999 "Test Method for Strength of Cement Mortar (ISO Method)". The flexural strength test was performed on the sample first, and the compressive strength test was performed on each section after it was broken.

[0070] The following are specific examples, and the mix proportions of ultra-high performance concrete are shown in Table 1. Example 1 is ultra-high performance concrete with microfiber steel fibers incorporated, and Example 2 is ultra-high performance concrete with short-cut hollow needles incorporated.

[0071] Example:

[0072] Table 1. Mix Proportion Table for High-Stability Ultra-High Performance Concrete (kg / m³) 3 )

[0073]

[0074] The mechanical properties of high-stability ultra-high performance concrete were tested in accordance with standard GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". The performance table (workability and mechanical properties) of high-stability ultra-high performance concrete is shown in Table 2.

[0075] Table 2 Performance of High-Stability Ultra-High-Performance Concrete

[0076] Slurry fluidity (mm) 1 d flexural strength (MPa) 1 day compressive strength (MPa) Example 1 230*230 6.5 32.7 Example 2 205*210 12.6 46.3

[0077] Observing the cross-sectional morphology of concrete specimens after 28 days of static curing, it was found that the microfiber steel fibers were all concentrated in the lower 1 / 4 section height area of ​​the specimen, and the fiber distribution was very uneven; while the encapsulated needle tubes showed a uniform distribution in the concrete. It can be seen that the ultra-high performance concrete using encapsulated needle tubes as toughening material has a much higher long-term internal stability than ordinary steel fiber ultra-high performance concrete.

[0078] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. The above embodiments only illustrate several implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A high-stability, ultra-high-performance concrete, characterized in that, The components of the concrete are specified in kg / m³. 3 The mass ratio is: Cement 800-1000; Fly ash 40-60; Granulated blast furnace slag powder 100-120; Silica fume 40-60; Yellow sand 800-1000; High-efficiency water-reducing agent 40-50; Encapsulating needle 0.5%-2%.

2. The high-stability ultra-high-performance concrete according to claim 1, characterized in that, The cement is P.II 52.5 silicate cement with a particle size of 20-30 micrometers; the fly ash is Grade II fly ash; the granulated blast furnace slag powder grades include S95, S105, and S115; the fine aggregate is medium sand with a fineness modulus of 2.3-3.0; the high-efficiency water-reducing agent is a polycarboxylate high-efficiency water-reducing agent with a water reduction rate of ≥30%; and the water is ordinary tap water.

3. The high-stability ultra-high-performance concrete according to claim 1, characterized in that, The discarded syringes are those with a diameter of 0.2 to 1 mm. The discarded syringes are disinfected and sterilized with chemical reagents. After treatment, the discarded syringes are cut into short sections with a cutting length of 3 mm to 12 mm.

4. A method for preparing highly stable ultra-high performance concrete, characterized in that, The method for preparing the high-stability, ultra-high-performance concrete according to any one of claims 1 to 3 comprises the following steps: Step S1: Add cement, medium sand, granulated blast furnace slag powder, fly ash and silica fume into the mixer and mix for 30-60 seconds. Step S2: Add high-efficiency water-reducing agent and water, and stir for 120-240 seconds; Step S3: Add the encapsulation syringe and stir for 30 seconds.

5. The preparation method according to claim 4, characterized in that, The preparation process of the packaged needle includes the following steps: Step S1: Weigh the two materials, E-44 epoxy resin and ethylenediamine curing agent, at a mass ratio of 100:8-12. Pour the weighed E-44 epoxy resin into a container and slowly add the ethylenediamine curing agent while stirring with a stirrer. The stirring time is generally 2-5 minutes. Step S2: Slowly add 10-15% of the total mass of epoxy resin in acetone to the mixture while stirring with a stirrer to reduce the viscosity of the mixture. Step S3: Weigh out a short needle tube with a mass of m1, add it to the mixture, stir gently to ensure that the epoxy resin adhesive is evenly coated on the surface of the needle tube. Step S4: The total length l of the inserted short-cutting needle tube is calculated using the following formula: In the formula, R1 is the outer diameter of the stubbed needle tube, in meters (m), r is the inner diameter of the stubbed needle tube, in meters (m), and ρ... 钢 This is the density of steel, expressed in kg / m³. 3 ; Step S5, the formula for calculating the total mass m of the chopped needle tube after epoxy resin coating is as follows: In the formula, R2 is the outer diameter of the packaged needle tube, in meters (m); R1 is the outer diameter of the chopped needle tube, in meters (m); ρ 环氧树脂 This refers to the density of epoxy resin, expressed in kg / m³. 3 . Step S6: Place the epoxy resin-coated short-cut needle tube on a mechanical sieve and sieve away excess epoxy resin at a certain frequency until the total mass of the epoxy resin-coated short-cut needle tube is m. Stop the operation. Step S7: After pouring out the treated syringe, spread it evenly on a smooth stainless steel tray. After 24 hours, the epoxy resin will be initially cured and can then be used to mix concrete.

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