Concrete suitable for centrifugally forming hollow enclosing wall stand column

Abstract

The invention discloses concrete suitable for centrifugally forming a hollow enclosing wall stand column, and relates to the technical field of energy-saving building materials. The invention discloses concrete suitable for centrifugally forming a hollow enclosure column. The concrete is prepared from the following raw materials in parts by mass: 300-350 parts of Portland cement, 50-80 parts of fly ash, 40-60 parts of superfine slag powder, 700-750 parts of fine aggregate, 250-300 parts of coarse aggregate, 5-8 parts of a water reducing agent, 130-150 parts of water, 0.5-1 part of a thickening agent, 1-2 parts of polypropylene fiber and 20-50 parts of an ultraviolet stabilizer. The ultraviolet stabilizer with a triazine ring conjugated system is introduced, and the light aging of the polypropylene fiber is effectively delayed by efficiently absorbing ultraviolet light and inhibiting free radical reaction, so that the concrete shows better degradation resistance in an ultraviolet irradiation environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy-saving building materials, and particularly relates to a concrete suitable for a centrifugal forming inner-void type enclosing wall column. BACKGROUND

[0002] In the field of construction engineering, the enclosing wall column as a key component of the enclosure structure is of great importance in performance and quality. The traditional enclosing wall column adopts a solid concrete structure, which has certain strength but also has many drawbacks. On the one hand, the solid concrete column is heavy, and a large amount of physical and mechanical power is consumed in the transportation and installation process, increasing the construction cost and time cost. On the other hand, the solid structure leads to a large amount of material consumption and serious resource waste, which is contrary to the current concept of energy-saving and environment-friendly buildings.

[0003] With the continuous development of building technology, the requirements for enclosing wall columns are also continuously improving. People begin to seek a new type of column that can guarantee strength, reduce weight and save materials, and the inner-void type enclosing wall column emerges as the times require. However, the concrete used for the inner-void type enclosing wall column still has some problems. The strength and durability are often difficult to achieve the ideal state, especially when facing complex natural environment and long-term use, cracking, weathering and other phenomena easily occur, affecting the service life and safety of the column.

[0004] In addition, when the advanced manufacturing process of centrifugal forming is applied to the production process of the inner-void type enclosing wall column, the existing concrete proportioning and performance are not well adapted to this process. It is difficult to be uniformly distributed and tightly formed under the action of centrifugal force, resulting in an insufficiently dense internal structure of the formed column, which further affects the overall quality and performance of the column. This makes it a technical problem to be solved in the building industry to develop a high-performance concrete specifically suitable for centrifugal forming of inner-void type enclosing wall columns. SUMMARY

[0005] The purpose of the present application is to solve the problems of insufficient strength, poor durability and poor adaptability to the centrifugal forming process of the existing inner-void type enclosing wall column concrete, and to provide a concrete suitable for centrifugal forming of inner-void type enclosing wall columns, which has high strength, durability and excellent forming effect.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present application is a concrete suitable for centrifugal forming of inner-void type enclosing wall columns, which is composed of the following mass parts of raw materials: Portland cement 300-350 parts, fly ash 50-80 parts, slag powder 40-60 parts, fine aggregate 700-750 parts, coarse aggregate 250-300 parts, water reducing agent 5-8 parts, water 130-150 parts, thickening agent 0.5-1 parts, polypropylene fiber 1-2 parts, and ultraviolet stabilizer 20-50 parts.

[0007] The ultraviolet stabilizer is a compound shown in the following structure:

[0008]

[0009] The R1 is selected from any one of the following: methyl, ethyl, tert-butyl, methoxy, ethoxy. Further, the fly ash is a grade II fly ash.

[0010] Further, the slag powder is a S95 grade slag powder.

[0011] Further, the coarse aggregate is a gravel with a particle size of 10-15 mm.

[0012] Further, the fine aggregate is fine sand with a particle size of 0.5-1.5 mm.

[0013] Further, the thickening agent is a low-viscosity cellulose ether with a relative molecular mass of 400-10000. Further, the water-reducing agent is an early-strength polycarboxylic acid water-reducing agent.

[0014] Further, the polypropylene fiber is a monofilament polypropylene fiber.

[0015] Further, the ultraviolet stabilizer is a compound shown in the following structure:

[0016]

[0017]

[0018] The present application provides a preparation method of a concrete suitable for centrifugal forming of an inner-void type fence column, comprising the following steps:

[0019] S1. The Portland cement, fly ash, slag powder, fine aggregate, and coarse aggregate are put into dry mixing for 2-3 minutes, and the water-reducing agent, thickening agent, and water are added and stirred for 5-8 minutes to obtain a mixture A;

[0020] S2. The polypropylene fiber and ultraviolet stabilizer are added to the mixture A, and stirring is continued for 3-5 minutes until uniform to obtain a mixture B;

[0021] S3. The mixture B is injected into a centrifugal mold, and centrifugal forming is performed at a rotation speed of 800-1200 r / min for 10-15 minutes; after demolding, steam curing is performed at a curing temperature of 60-80℃ and a humidity of ≥90% for 8-12 hours to obtain a concrete suitable for centrifugal forming of an inner-void type fence column.

[0022] Further, the polypropylene fiber is added in two times, 50% of the total amount is first added and stirred for 2 minutes, and the remaining amount is then added and stirred until uniform.

[0023] Further, the centrifugal process adopts a step speed-up, a low-speed stage of 100-300 r / min lasting for 2 minutes, a medium-speed stage of 300-800 r / min lasting for 5 minutes, and a high-speed stage of 800-1200 r / min lasting for 3-8 minutes.

[0024] The application of concrete suitable for centrifugal forming inner hollow type wall column in the energy-saving type oven, smelting furnace and electric furnace concrete shell.

[0025] The triazine ring in the ultraviolet stabilizer molecule is a strong ultraviolet absorption group, and the conjugated pi electron system can efficiently absorb ultraviolet light with a wavelength of 290-400 nm. The absorbed ultraviolet light can be converted into harmless heat energy, which is dissipated through molecular vibration, avoiding energy transmission to the polymer components in the concrete. The nitrogen atom on the triazine ring is electron-deficient and easy to capture free radicals, assisting in inhibiting photooxidation. The large conjugated structure in the ultraviolet stabilizer molecule enhances the absorption range and stability, and the fused ring structure expands the conjugated system, improving the ultraviolet absorption bandwidth and efficiency. The fused ring enhances the rigidity of the molecule, reduces the molecular structure damage caused by photodegradation, and prolongs the service life of the stabilizer. The cyano group in the ultraviolet stabilizer molecule reduces the electron density of the triazine ring through the inductive effect, enhances its ability to capture free radicals, and in the high alkalinity environment of concrete, the stability of the cyano group is better than that of the ester group or amino group, and it is not easy to hydrolyze and fail. The hydroxyl group provides a hydrogen bond site, binds with water or mineral surfaces in the concrete, improves the uniformity of dispersion, quenches free radicals, interrupts the oxidation chain reaction, and delays the aging of polypropylene fibers.

[0026] The portland cement can provide basic strength; the grade II fly ash can fill micropores, improve workability, and the later-stage pozzolanic effect can improve long-term strength; the active SiO2 and Al2O3 in the S95 slag powder react with Ca(OH)2 to generate C-S-H gel, enhancing the compactness; the three form a gradient hydration system, early strength of cement + medium-term strength of mineral powder + long-term strength of fly ash, avoiding defects of single material. The coarse aggregate forms the main skeleton, and the fine aggregate fills the gaps between the coarse aggregate, and the two cooperate to reduce the void ratio through intermittent grading, and improve the compactness; the single polypropylene fiber can reduce the risk of segregation in the centrifugal process.

[0027] Compared with the prior art, the present application has the following advantages:

[0028] 1. Mechanical property improvement: through optimization of the cement / fly ash / mineral powder gradient hydration system and the intermittent grading of coarse and fine aggregates, the concrete shows a more optimal strength development law from early to long-term age, and the overall compressive strength is improved.

[0029] 2. Process adaptability enhancement: the specific polypropylene fiber incorporation method cooperates with the step centrifugal process to significantly improve the material segregation problem in the centrifugal forming process, and improve the internal structure compactness and forming uniformity.

[0030] 3. Remarkable improvement in durability: The introduction of ultraviolet stabilizer with triazine ring conjugated system, by high-efficiency absorption of ultraviolet light and inhibition of free radical reaction, effectively delays the photoaging of polypropylene fibers, making the concrete exhibit better anti-deterioration ability in the ultraviolet irradiation environment. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 For the ultraviolet stabilizer 1 described in the present application 1 HNMR chart. DETAILED DESCRIPTION

[0032] The technical solutions of the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0033] Synthesis Example 1

[0034] Synthesis of ultraviolet stabilizer 1:

[0035]

[0036] First step: under nitrogen atmosphere, 20 g of raw material 1, 8.87 g of raw material 2, 22.74 g of potassium phosphate trihydrate, 0.05 g of pyridine-2-carboxylic acid, 0.4 g of CuI and 200 g of DMSO are added into the reaction system, heated to 85℃ for 16 hours; after cooling, the reaction mixture is extracted with ammonia solution and methyl tert-butyl ether, the organic phase is washed with water five times, and then with saturated NaCl solution twice; finally, the combined organic phase is dried with anhydrous magnesium sulfate, filtered, rotary evaporated, and subjected to silica gel column chromatography with a mixture of petroleum ether and ethyl acetate as eluent, rotary evaporated to obtain 18.82 g of intermediate 1.

[0037] Second step: under nitrogen atmosphere, 18.82 g of intermediate 1, 9.07 g of raw material 3, 9.28 g of anhydrous potassium carbonate, 1.16 g of tetrakis(triphenylphosphine)palladium and 200 g of a mixture of toluene, ethanol and water (volume ratio 2:1:1) are added into the reaction system, heated to 95℃ for 10 hours, the heating is turned off, cooled to room temperature, and left to stand for separation, the aqueous phase is extracted with ethyl acetate twice, the combined organic phase is dried with anhydrous magnesium sulfate, filtered, rotary evaporated, and subjected to silica gel column chromatography with a mixture of petroleum ether and ethyl acetate as eluent, rotary evaporated to obtain 17.78 g of intermediate 2.

[0038] Step 3: Under nitrogen atmosphere, 17.78 g of intermediate 2, 9.11 g of raw material 4, 0.3 g of tri-tert-butyl phosphine, 0.16 g of palladium on carbon, 7.44 g of anhydrous potassium carbonate and 200 g of toluene were added into the reaction system, and the reaction was refluxed at 120°C for 12 hours. After the reaction was completed, the temperature was slightly lowered, and diatomite was used for filtration. After the filtrate was cooled to room temperature, it was washed with water for three times, and the organic phase was reserved. Then, the aqueous phase was extracted with ethyl acetate, and the combined organic phase was dried with anhydrous magnesium sulfate, filtered and rotary evaporated. Silica gel column chromatography was performed with petroleum ether and ethyl acetate mixture as the eluent, and rotary evaporation was performed to obtain 18.76 g of ultraviolet stabilizer 1.

[0039] Product structure identification:

[0040] MS (m / z) of intermediate 1 - [M+H] + = 560;

[0041] MS (m / z) of intermediate 2 - [M+H] + = 661;

[0042] MS (m / z) of ultraviolet stabilizer 1 - [M+H] + = 862;

[0043] HNMR of ultraviolet stabilizer 1 1 HNMR-Chloroform D: δ 9.13 (s, 1H), 8.78 (dd, 1H), 8.32-8.23 (m, 1H), 8.23-8.09 (m, 1H), 8.12-8.00 (m, 3H), 7.98-7.82 (m, 4H), 7.74-7.29 (m, 9H), 7.26-7.17 (m, 2H), 7.17-7.03 (m, 2H), 6.98 (t, 1H), 6.01 (d, 1H), 4.81 (d, 2H), 3.08-2.91 (m, 2H), 2.74 (m, 2H), 2.49 (d, 3H), 1.85-1.67 (m, 4H).

[0044] Synthesis Examples 2-5

[0045] Ultraviolet stabilizers 2-5 were synthesized in Synthesis Examples 2-5 in turn, and the synthesis method of Synthesis Example 1 was referred to, and raw material 3 therein was replaced. The structures of raw material 3, ultraviolet stabilizers 2-5 and MS (m / z) - [M+H] + The data are shown in Table 1.

[0046] Table 1. The structures of raw material 3, ultraviolet stabilizers 2-5 and MS (m / z) - [M+H] involved in Synthesis Examples 2-5 + data.

[0047]

[0048] Example 1

[0049] The present example provides a kind of concrete suitable for centrifugal forming inner empty type surrounding wall column, and the raw material composition is as follows by mass fraction: Portland cement (purchased from: Hunan Xindingli New Material Technology Co., Ltd., ordinary Portland cement, Huaxin cement PC425) 330 parts, fly ash: II grade fly ash 65 parts, slag powder: S95 grade slag powder 50 parts, fine aggregate: fine sand of particle size 0.5-1.5mm 720 parts, coarse aggregate: gravel of particle size 10-15mm 280 parts, water reducing agent: early strength polycarboxylic acid water reducing agent 6 parts, water 140 parts, thickening agent: low viscosity cellulose ether (average molecular weight 4000) 0.8 parts, polypropylene fiber: monofilament polypropylene fiber 1.5 parts, ultraviolet stabilizer: ultraviolet stabilizer 1 (ultraviolet stabilizer 1 synthesized in synthesis example 1) 35 parts.

[0050] Preparation method:

[0051] S1, Portland cement, II grade fly ash, S95 grade slag powder, fine sand, gravel are put into forced stirrer, dry mixing at 60r / min speed for 2.5 minutes, early strength polycarboxylic acid water reducing agent, low viscosity cellulose ether and water are added, and stirring speed is increased to 120r / min for 6 minutes, to obtain homogeneous mixture A;

[0052] S2, monofilament polypropylene fiber (added in two times: first add 50% amount and stir for 2 minutes, then add the remaining amount) and ultraviolet stabilizer 1 are added to mixture A, and continue to stir for 4 minutes until the fiber is uniformly dispersed, to obtain mixture B;

[0053] S3, mixture B is injected into columnar centrifugal mold, and ladder centrifugal program is adopted: low speed stage: 200r / min centrifugation for 2 minutes; Medium speed stage: 500r / min centrifugation for 5 minutes; High speed stage: 1000r / min centrifugation for 5 minutes; After demolding, it is placed in constant temperature and humidity curing room, and cured at 70 DEG C, 95% humidity for 10 hours, to obtain a kind of concrete suitable for centrifugal forming inner empty type surrounding wall column.

[0054] Example 2-Example 5

[0055] A kind of concrete suitable for centrifugal forming inner empty type surrounding wall column is prepared, referring to the preparation method of example 1, ultraviolet stabilizer therein is replaced by ultraviolet stabilizer 2-ultraviolet stabilizer 5 prepared in synthesis example 2-synthesis example 5 in turn, and the rest remains the same as example 1.

[0056] Comparative example 1

[0057] A preparation of a concrete suitable for centrifugal forming of an inner hollow type surrounding wall column, referring to the preparation method of Example 1, without adding the ultraviolet stabilizer therein, and the rest remains the same as Example 1.

[0058] Comparative Example 2

[0059] A preparation of a concrete suitable for centrifugal forming of an inner hollow type surrounding wall column, referring to the preparation method of Example 1, replacing the mass fraction of fly ash therein with 20 parts, and the rest remains the same as Example 1.

[0060] Comparative Example 3

[0061] A preparation of a concrete suitable for centrifugal forming of an inner hollow type surrounding wall column, referring to the preparation method of Example 1, replacing the mass fraction of thickening agent therein with 5 parts, and the rest remains the same as Example 1.

[0062] Performance test:

[0063] 1. Refer to GB / T50081-2019 to test the 7, 14, 28, 60-day compressive strength (MPa) of a concrete suitable for centrifugal forming of an inner hollow type surrounding wall column prepared in the examples and comparative examples, and the data is shown in Table 2.

[0064] Table 2. 7, 14, 28, 60-day compressive strength (MPa) of a concrete suitable for centrifugal forming of an inner hollow type surrounding wall column prepared in the examples and comparative examples.

[0065]

[0066] All examples show a continuous strength development law at different ages, and the performance fluctuation between examples is small; the strength development curve of Comparative Example 1 is lower than that of the examples, proving that the ultraviolet stabilizer affects the mechanical properties; Comparative Example 2 shows a lag in early strength growth but gradually recovers later, indicating that the lack of key components inhibits the hydration process in stages; while Comparative Example 3 shows an abnormal trend of significant deterioration of strength at each age, revealing that excessive thickening agent systematically destroys the hydration reaction and microstructure.

[0067] Although embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made thereto without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A concrete suitable for centrifugally forming hollow wall columns, characterized in that: The invention is composed of the following raw materials in parts by weight: 300-350 parts of Portland cement, 50-80 parts of fly ash, 40-60 parts of slag powder, 700-750 parts of fine aggregate, 250-300 parts of coarse aggregate, 5-8 parts of water reducer, 130-150 parts of water, 0.5-1 part of thickener, 1-2 parts of polypropylene fiber, and 20-50 parts of UV stabilizer. The UV stabilizer has a structure shown in Formula 1: The R1 is selected from any one of methyl, ethyl, tert-butyl, methoxy and ethoxy.

2. The concrete suitable for centrifugally forming hollow wall columns according to claim 1, characterized in that: The fly ash is Class II fly ash.

3. The concrete suitable for centrifugally forming hollow wall columns according to claim 1, characterized in that: The slag powder is S95 grade slag powder.

4. The concrete suitable for centrifugally forming hollow wall columns according to claim 1, characterized in that: The coarse aggregate is crushed stone with a particle size of 10-15 mm; The fine aggregate is fine sand with a particle size of 0.5-1.5 mm.

5. The concrete suitable for centrifugally forming hollow wall columns according to claim 1, characterized in that: The thickener is a low-viscosity cellulose ether with a relative molecular mass of 400-10000; The water reducer is an early strength polycarboxylate water reducer; The polypropylene fiber is a monofilament polypropylene fiber.

6. The concrete suitable for centrifugally forming hollow wall columns according to claim 1, characterized in that: The UV stabilizer is a compound shown in the following structure:

7. A method for preparing concrete suitable for centrifugally forming hollow wall columns according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. The Portland cement, fly ash, slag powder, fine aggregate, coarse aggregate were added and dry-mixed for 2-3 minutes, the water reducer, thickener and water were added, and stirred for 5-8 minutes to obtain a mixture A; S2. Add the polypropylene fiber and UV stabilizer to the mixture A and continue stirring for 3-5 minutes until uniform to obtain a mixture B; S3. The mixture B is injected into a centrifugal mold and centrifuged at a speed of 800-1200r / min for 10-15 minutes; steam curing after demolding, curing temperature 60-80 ℃, humidity ≥90%, for 8-12 hours, to obtain a concrete suitable for centrifugal molding of hollow wall columns.

8. A method for preparing concrete suitable for centrifugally forming hollow wall columns according to claim 7, characterized in that: The polypropylene fiber is added in two portions. First, 50% of the total amount is added and stirred for 2 minutes. Then, the remaining amount is added and stirred until uniform.

9. A method for preparing concrete suitable for centrifugally forming hollow wall columns according to claim 7, characterized in that: The centrifugation process adopts a step-by-step speed increase, wherein the low-speed stage of 100-300 r / min lasts for 2 minutes, the medium-speed stage of 300-800 r / min lasts for 5 minutes, and the high-speed stage of 800-1200 r / min lasts for 3-8 minutes.

10. Use of the concrete suitable for centrifugally forming hollow wall columns according to any one of claims 1 to 6 in the concrete shell of energy-saving ovens, melting furnaces, and electric furnaces.

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