A kind of concrete suitable for centrifugal forming inner hollow type wall column

Abstract

The application discloses concrete suitable for centrifugal forming of inner-void type surrounding wall columns and relates to the technical field of energy-saving building materials.The concrete suitable for centrifugal forming of inner-void type surrounding wall columns is composed of the following raw materials in parts by mass: 300-350 parts of Portland cement, 50-80 parts of fly ash, 40-60 parts of micro-fine slag, 700-750 parts of fine aggregate, 250-300 parts of coarse aggregate, 5-8 parts of water reducing agent, 130-150 parts of water, 0.5-1 part of thickening agent, 1-2 parts of polypropylene fiber and 20-50 parts of ultraviolet stabilizer. The ultraviolet stabilizer with a triazine ring conjugated system is introduced, high-efficiency ultraviolet light absorption and free radical reaction inhibition are realized, and the light aging of the polypropylene fiber is effectively delayed, so that the concrete exhibits better anti-deterioration capacity under the ultraviolet irradiation environment.

Description

Technical Field

[0001] This invention relates to the field of energy-saving building materials technology, specifically to a type of concrete suitable for centrifugally molded hollow wall columns. Background Technology

[0002] In the field of construction engineering, perimeter wall posts are key components of the enclosure structure, and their performance and quality are of paramount importance. Traditional perimeter wall posts mostly use solid concrete structures. While this structure possesses a certain degree of strength, it also has many drawbacks. On the one hand, solid concrete posts are heavy, requiring significant physical and mechanical effort during transportation and installation, increasing construction and time costs. On the other hand, their solid structure leads to large material consumption and substantial resource waste, contradicting the current advocacy of energy-saving and environmentally friendly building concepts.

[0003] With the continuous development of construction technology, the requirements for perimeter wall posts are also constantly increasing. People have begun to seek a new type of post that can ensure strength while reducing weight and saving materials, leading to the emergence of hollow perimeter wall posts. However, the concrete currently used for hollow perimeter wall posts still has some problems. Its strength and durability often fall short of ideal levels, especially when facing complex natural environments and long-term use, making it prone to cracking, weathering, and other phenomena, affecting the service life and safety of the posts.

[0004] Furthermore, when the advanced centrifugal molding manufacturing process is applied to the production of hollow wall columns, the existing concrete mix proportions and properties are poorly compatible with this process. It is difficult to achieve uniform distribution and compact molding under centrifugal force, resulting in an insufficiently dense internal structure of the molded columns, further affecting the overall quality and performance of the columns. This makes the development of a high-performance concrete specifically suitable for centrifugally molded hollow wall columns a pressing technical challenge for the construction industry. Summary of the Invention

[0005] The purpose of this invention is to address the problems of insufficient strength, poor durability, and poor compatibility with centrifugal molding process in existing hollow wall column concrete, and to provide a high-strength, durable concrete with excellent molding effect suitable for centrifugally molded hollow wall columns.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is a concrete suitable for centrifugally molded hollow wall columns, which is composed of the following raw materials in parts by weight: 300-350 parts of silicate 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-reducing agent, 130-150 parts of water, 0.5-1 part of thickener, 1-2 parts of polypropylene fiber, and 20-50 parts of ultraviolet stabilizer.

[0007] The ultraviolet stabilizer has the structure shown in Formula 1:

[0008]

[0009] R1 is selected from any one of methyl, ethyl, tert-butyl, methoxy, and ethoxy. Further, the fly ash is Grade II fly ash.

[0010] Furthermore, the slag powder is S95 grade mineral powder.

[0011] Furthermore, the coarse aggregate is crushed stone with a particle size of 10-15mm.

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

[0013] Furthermore, the thickener is a low-viscosity cellulose ether with a relative molecular mass of 400-10000. Furthermore, the water-reducing agent is an early-strength polycarboxylate water-reducing agent.

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

[0015] Furthermore, the UV stabilizer is a compound with the following structure:

[0016]

[0017]

[0018] This invention provides a method for preparing concrete suitable for centrifugally molded hollow wall columns, comprising the following steps:

[0019] S1. Add the silicate cement, fly ash, slag powder, fine aggregate, and coarse aggregate to the dry mix for 2-3 minutes, add the water-reducing agent, thickener, and water, and stir for 5-8 minutes to obtain mixture A;

[0020] S2. Add the polypropylene fiber and UV stabilizer to the mixture A, and continue stirring for 3-5 minutes until uniform to obtain mixture B;

[0021] S3. Inject the mixture B into a centrifugal mold and centrifuge at 800-1200 r / min for 10-15 minutes; after demolding, steam cure at 60-80℃ and ≥90% humidity for 8-12 hours to obtain a concrete suitable for centrifugally formed hollow wall columns.

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

[0023] Furthermore, the centrifugation process employs a stepped speed increase: 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] Application of a type of concrete suitable for centrifugally molded hollow wall columns in the concrete shells of energy-saving ovens, furnaces, and electric furnaces.

[0025] The triazine ring in the UV stabilizer molecule described in this invention is a potent UV absorber, and its conjugated π-electron system can efficiently absorb UV light with wavelengths of 290-400 nm. The absorbed UV light energy is converted into harmless heat energy, which is dissipated through molecular vibration, preventing energy transfer to the polymer components in the concrete. The nitrogen atom on the triazine ring is electron-deficient, readily capturing free radicals and aiding in the inhibition of photo-oxidation reactions. The large conjugated structure in the UV stabilizer molecule enhances the absorption range and stability, while the fused ring structure expands the conjugated system, improving the UV absorption bandwidth and efficiency. The fused ring enhances molecular rigidity, reducing molecular structural damage caused by photodegradation and extending the stabilizer's lifespan. The cyano group in the UV stabilizer molecule reduces the electron density of the triazine ring through an inductive effect, enhancing its ability to capture free radicals. In the highly alkaline environment of concrete, the cyano group exhibits better stability than ester or amino groups, and is less prone to hydrolysis and failure. The hydroxyl group provides hydrogen bonding sites, binding with moisture or mineral surfaces in the concrete, improving dispersion uniformity, quenching free radicals, interrupting the oxidation chain reaction, and delaying the aging of polypropylene fibers.

[0026] The silicate cement described in this invention provides basic strength; Grade II fly ash fills micropores, improving workability, and the pozzolanic effect enhances long-term strength; active SiO2 and Al2O3 in S95 slag powder react with Ca(OH)2 to form CSH gel, increasing density; these three components form a gradient hydration system, combining the early strength of cement, the mid-term strength of mineral powder, and the late-term strength of fly ash, avoiding the defects of a single material. Coarse aggregate forms the main skeleton, while fine aggregate fills the gaps between coarse aggregate; their synergistic effect and discontinuous gradation reduce porosity and increase density; monofilament polypropylene fibers reduce the risk of segregation during centrifugation.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1. Improved mechanical properties: By optimizing the gradient hydration system of cement / fly ash / mineral powder and the discontinuous gradation of coarse and fine aggregates, concrete exhibits a better strength development pattern from early to long age, and the overall compressive strength is improved.

[0029] 2. Enhanced process adaptability: The specific polypropylene fiber incorporation method works synergistically with the stepped centrifugation process to significantly improve the material segregation problem during centrifugal molding, and enhance the internal structural density and molding uniformity.

[0030] 3. Significantly improved durability: The introduction of a UV stabilizer with a triazine ring conjugated system effectively delays the photoaging of polypropylene fibers by efficiently absorbing UV light and inhibiting free radical reactions, enabling concrete to exhibit better resistance to degradation under UV irradiation. Attached Figure Description

[0031] Figure 1 The UV stabilizer 1 described in this invention 1 HNMR image. Detailed Implementation

[0032] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and 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.

[0033] Synthesis example 1

[0034] Synthesis of UV stabilizer 1:

[0035]

[0036] Step 1: Under a 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 were added to the reaction system. The mixture was heated at 85 °C for 16 hours. After cooling, the reaction mixture was extracted with ammonia solution and methyl tert-butyl ether. The organic phase was washed five times with water and then twice with saturated NaCl solution. Finally, the combined organic phase was dried over anhydrous magnesium sulfate, filtered, evaporated to dryness, and subjected to silica gel column chromatography with a mixture of petroleum ether and ethyl acetate as eluent. The mixture was evaporated to dryness to obtain 18.82 g of intermediate 1.

[0037] Step 2: Under a nitrogen atmosphere, add 18.82 g of intermediate 1, 9.07 g of raw material 3, 9.28 g of anhydrous potassium carbonate, 1.16 g of tetra(triphenylphosphine)palladium, and 200 g of a mixed solution of toluene, ethanol, and water (volume ratio 2:1:1) to the reaction system. Heat to 95°C and reflux for 10 hours. Turn off the heating, cool to room temperature, allow to stand and separate the phases. Extract the aqueous phase twice with ethyl acetate, combine the organic phases, dry the organic phase with anhydrous magnesium sulfate, filter, evaporate to dryness, and perform silica gel column chromatography using a mixture of petroleum ether and ethyl acetate as eluent. Evaporate to dryness to obtain 17.78 g of intermediate 2.

[0038] Step 3: Under a nitrogen atmosphere, add 17.78 g of intermediate 2, 9.11 g of raw material 4, 0.3 g of tri-tert-butylphosphine, 0.16 g of palladium on carbon, 7.44 g of anhydrous potassium carbonate, and 200 g of toluene to the reaction system. Heat to 120 °C and reflux for 12 hours. After the reaction is complete, lower the temperature slightly, filter with diatomaceous earth, cool the filtrate to room temperature, wash three times with water, retain the organic phase, extract the aqueous phase with ethyl acetate, combine the organic phases, dry the organic phase with anhydrous magnesium sulfate, filter, evaporate to dryness, and perform silica gel column chromatography with a mixture of petroleum ether and ethyl acetate as eluent. Evaporate to dryness to obtain 18.76 g of UV stabilizer 1.

[0039] Product structure identification:

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

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

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

[0043] UV stabilizer 1 1 HNMR-Chloroform D: δ9.13(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 Example 2-Synthesis Example 5

[0045] In Synthesis Examples 2-5, UV stabilizer 2-UV stabilizer 5 were synthesized sequentially, following the same synthesis method as in Synthesis Example 1, except that raw material 3 was replaced; the rest remained the same as in Synthesis Example 1. Specific structures of raw material 3, UV stabilizer 2-UV stabilizer 5, and MS (m / z)-[M+H] are described. + The data is shown in Table 1.

[0046] Table 1. Structures of raw material 3, UV stabilizer 2 to UV stabilizer 5, and MS (m / z)-[M+H] involved in Synthesis Examples 2-5 + data.

[0047]

[0048] Example 1

[0049] This embodiment provides a concrete suitable for centrifugally molded hollow wall columns. The raw material composition by weight is as follows: 330 parts of silicate cement (purchased from Hunan Xindingli New Material Technology Co., Ltd., ordinary silicate cement, Huaxin Cement PC425), 65 parts of fly ash: Grade II fly ash, 50 parts of slag powder: S95 grade slag powder, 720 parts of fine aggregate: fine sand with a particle size of 0.5-1.5mm, 280 parts of coarse aggregate: crushed stone with a particle size of 10-15mm, 6 parts of water-reducing agent: early-strength polycarboxylate water-reducing agent, 140 parts of water, 0.8 parts of thickener: low viscosity cellulose ether (average molecular weight 4000), 1.5 parts of polypropylene fiber: monofilament polypropylene fiber, and 35 parts of UV stabilizer: UV stabilizer 1 (UV stabilizer 1 synthesized in Synthesis Example 1).

[0050] Preparation method:

[0051] S1. Put silicate cement, grade II fly ash, grade S95 slag powder, fine sand and crushed stone into a forced mixer and dry mix at 60 r / min for 2.5 minutes. Add early-strength polycarboxylate superplasticizer, low viscosity cellulose ether and water, and speed up to 120 r / min and mix for 6 minutes to obtain homogeneous mixture A.

[0052] S2. Add monofilament polypropylene fiber (in two parts: first add 50% and stir for 2 minutes, then add the remaining amount) and UV stabilizer 1 to mixture A, and continue stirring for 4 minutes until the fiber is evenly dispersed to obtain mixture B;

[0053] S3. Inject the mixture B into a columnar centrifugal mold and centrifuge using a stepped centrifugation program: low speed stage: 200 r / min for 2 minutes; medium speed stage: 500 r / min for 5 minutes; high speed stage: 1000 r / min for 5 minutes; after demolding, place it in a constant temperature and humidity curing room and cure it at 70℃ and 95% humidity for 10 hours to obtain a concrete suitable for centrifugally formed hollow wall columns.

[0054] Examples 2-5

[0055] The preparation of concrete suitable for centrifugally molded hollow wall columns is carried out by referring to the preparation method of Example 1, except that the ultraviolet stabilizer is replaced in sequence with ultraviolet stabilizer 2-ultraviolet stabilizer 5 prepared in Synthesis Examples 2-5, and the rest is the same as in Example 1.

[0056] Comparative Example 1

[0057] The preparation of concrete suitable for centrifugally molded hollow wall columns is the same as in Example 1, except that the ultraviolet stabilizer is not added.

[0058] Comparative Example 2

[0059] A method for preparing concrete suitable for centrifugally molded hollow wall columns is described, referring to the preparation method of Example 1, except that the mass fraction of fly ash is replaced with 20 parts, while the rest remains the same as in Example 1.

[0060] Comparative Example 3

[0061] A method for preparing concrete suitable for centrifugally molded hollow wall columns is described, referring to the preparation method of Example 1, except that the mass fraction of the thickener is replaced with 5 parts, while the rest remains the same as in Example 1.

[0062] Performance testing:

[0063] 1. The compressive strength (MPa) of a type of concrete suitable for centrifugally molded hollow wall columns prepared according to the test examples and comparative examples in GB / T50081-2019 at 7, 14, 28 and 60 days is shown in Table 2.

[0064] Table 2. Compressive strength (MPa) at 7, 14, 28, and 60 days of a type of concrete suitable for centrifugally molded hollow wall columns prepared in the test examples and comparative examples.

[0065]

[0066] All examples showed a continuous increase in strength at different ages, with minimal performance fluctuations among examples. The strength development curve of Comparative Example 1 was lower than that of the examples, proving that the UV stabilizer affected the mechanical properties. The strength growth of Comparative Example 2 was delayed in the early stage but gradually recovered in the later stage, showing that the insufficient key components inhibited the hydration process in stages. Comparative Example 3 showed an abnormal trend of significant deterioration in strength at all ages, revealing the systematic damage of excessive thickener to the hydration reaction and microstructure.

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

Claims

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

2. The concrete suitable for centrifugally molded hollow wall columns as described in claim 1, characterized in that, The fly ash is Class II fly ash.

3. The concrete suitable for centrifugally molded hollow wall columns as described in claim 1, characterized in that, The slag powder is S95 grade mineral powder.

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

5. The concrete suitable for centrifugally molded 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-reducing agent is an early-strength polycarboxylate water-reducing agent; The polypropylene fiber is a monofilament polypropylene fiber.

6. A method for preparing concrete suitable for centrifugally molded hollow wall columns, as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Put the silicate cement, fly ash, slag powder, fine aggregate, and coarse aggregate into a forced mixer and dry mix for 2-3 minutes. Add the water-reducing agent, thickener, and water, and mix for 5-8 minutes to obtain 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 mixture B; S3. Inject the mixture B into a centrifugal mold and centrifuge at 800-1200 r / min for 10-15 minutes; after demolding, steam cure at 60-80℃ and ≥90% humidity for 8-12 hours to obtain a concrete suitable for centrifugally formed hollow wall columns.

7. A method for preparing concrete suitable for centrifugally molded hollow wall columns according to claim 6, characterized in that, The polypropylene fiber is added in two stages: first, 50% of the total amount is added and stirred for 2 minutes, then the remaining amount is added and stirred until uniform.

8. A method for preparing concrete suitable for centrifugally molded hollow wall columns according to claim 6, characterized in that, The centrifugation process employs a stepped speed increase: a low-speed stage of 100-300 r / min lasting 2 minutes, a medium-speed stage of 300-800 r / min lasting 5 minutes, and a high-speed stage of 800-1200 r / min lasting 3-8 minutes.

9. The application of a type of concrete suitable for centrifugally molded hollow wall columns as described in any one of claims 1-5 in the concrete shell of energy-saving ovens, furnaces, and electric furnaces.

Images