High-crack-resistance fiber-reinforced ceramsite concrete wallboard and preparation method thereof

Abstract

The invention discloses a high-crack-resistance fiber-reinforced ceramsite concrete wallboard and a preparation method thereof. The high-crack-resistance fiber-reinforced ceramsite concrete wallboard is prepared from the following components per square: 151 to 155 kg of water, 6.8 to 11.6 kg of a water reducing agent, 252 to 465 kg of cement, 43 to 75 kg of fly ash, 43 to 75 kg of mineral powder, 185 to 615 kg of river sand, 617 to 665 kg of ceramsite with a large particle size (6 to 15 mm), 92 to 418 kg of ceramsite sand with a small particle size (1 to 5 mm) and 4.0 to 8.0 kg of polyvinyl alcohol fiber. The self-generated shrinkage rate of the prepared high-crack-resistance fiber-reinforced ceramsite concrete wallboard is lower than 40 * 10 <-6 >, the drying shrinkage rate is reduced by about 15% compared with that of concrete with the same strength grade, the crack resistance grade can reach grade I, the self-generated shrinkage of the concrete wallboard is effectively reduced, the cracking risk is reduced, and the high-crack-resistance fiber-reinforced ceramsite concrete wallboard is light in weight and high in strength, can be applied to prefabricated buildings, and has good application prospects. The building load and the hoisting cost are reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete and relates to a high-crack-resistant fiber-reinforced ceramsite concrete wallboard with low shrinkage and crack resistance reaching level I, and a preparation method thereof. Background Art

[0002] In actual concrete construction, autogenous shrinkage and drying shrinkage of concrete are the main causes of volume changes and cracks in concrete. Autogenous shrinkage is the volume change caused by the consumption of water during cement hydration, which creates negative pressure in the capillaries. Drying shrinkage is the phenomenon of volume shrinkage caused by the evaporation of water after the concrete has hardened, resulting in a decrease in internal humidity. Autogenous shrinkage and drying shrinkage are both volume changes caused by water loss. Due to the properties of concrete itself and construction conditions, cracks caused by autogenous shrinkage and drying shrinkage are difficult to avoid. After the concrete hardens, these cracks become stress concentration areas, adversely affecting the strength and durability of the concrete. Therefore, a method that can effectively and comprehensively suppress the occurrence of cracks is needed to overcome the above problems.

[0003] Ceramsite has a certain degree of water absorption and releases the water it absorbed during the mixing process when the internal humidity of concrete decreases. This can slow the drying process of concrete, thereby reducing both its natural and drying shrinkage. Fibers have a dispersing and reinforcing effect, reducing the occurrence of cracks. The crack-blocking effect of fibers can also hinder crack propagation. The combination of ceramsite and fibers can significantly reduce the occurrence of cracks in concrete and improve crack resistance. The lightweight nature of ceramsite also reduces the deadweight of concrete, thus saving construction costs. This has both economic and social benefits and aligns with national policies on the development of prefabricated buildings. Summary of the Invention

[0004] The present invention aims to provide a highly crack-resistant fiber-reinforced ceramsite concrete wallboard and a preparation method thereof. The highly crack-resistant fiber-reinforced ceramsite concrete wallboard is made of raw materials such as water, a water reducer, cement, fly ash, mineral powder, river sand, coarse-grained ceramsite (6-15 mm), fine-grained ceramsite sand (1-5 mm), and polyvinyl alcohol fiber. LC30, LC40, LC50, and LC60 ceramsite concrete wallboards can be produced. The ceramsite concrete wallboards have the characteristics of being lightweight, high-strength, good durability, low shrinkage, and not prone to cracking.

[0005] To achieve the above-mentioned purpose, the present invention adopts the following technical solution: a high crack-resistant fiber-reinforced ceramsite concrete wallboard, the formulation of which is shown in Table 1.

[0006] Table 1 Mix ratio of a high crack resistance fiber reinforced ceramsite concrete wallboard (kg / m 3 )

[0007]

[0008] According to the above scheme, the bulk density of the ceramsite is 1170kg / m 3 , particle size 6 to 15 mm, cylinder pressure strength greater than 14 MPa, 1h water absorption rate less than 5%.

[0009] According to the above scheme, the bulk density of the ceramic sand is 1170kg / m 3 , particle size 1 to 5 mm, water absorption rate less than 7% in 1 hour.

[0010] According to the above solution, the cement is P·O 42.5 ordinary Portland cement and P·O 52.5 ordinary Portland cement.

[0011] According to the above solution, the fly ash is Class F Grade II fly ash, and the fly ash fineness (residue on a 45 μm square sieve) is less than 30.0%.

[0012] According to the above solution, the mineral powder has an activity index greater than 95%.

[0013] According to the above scheme, the apparent density of the river sand is 2740kg / m 3 , river sand fineness modulus is 2.2~2.8.

[0014] According to the above solution, the water reducer is a polycarboxylic acid water reducer with a water reduction rate of 26.0%.

[0015] According to the above solution, the polyvinyl alcohol fiber has a length of 10 to 15 mm, a diameter of 20 to 35 μm, a breaking strength greater than 1500 MPa, an elongation at break of 11% to 25%, and an elastic modulus greater than 30 GPa.

[0016] According to the above solution, the method for preparing a highly crack-resistant fiber-reinforced ceramsite concrete wallboard is characterized by comprising the following steps:

[0017] A. Weigh the raw materials according to the proportions. The content of each component is: water 151-155 kg / m 3 , water reducing agent 6.8~11.6kg / m 3 、Cement 252~465kg / m 3 , fly ash 43~75kg / m 3 、Mineral powder 43~75kg / m 3 , River sand 185~615kg / m 3 , coarse particle size (6-15mm) ceramsite 617-665kg / m 3 , fine particle size (1-5mm) ceramic sand 92-418kg / m 3 , polyvinyl alcohol fiber 4.0~8.0kg / m 3 .

[0018] B. Place cement, fly ash, mineral powder, and polyvinyl alcohol fiber in a concrete mixer and dry mix for 30 seconds. Then, add one-third of the mixing water and mix for 30 seconds. Then, add sand, ceramsite, and ceramic sand, along with one-third of the mixing water and mix for 30 seconds. Then, add the remaining water and water reducer and continue mixing for 2 minutes to obtain a concrete mixture.

[0019] C. The concrete mixture is poured into the mold, vibrated into shape, and cured to obtain a highly crack-resistant fiber-reinforced ceramsite concrete wall panel.

[0020] According to the above solution, the vibration molding in step C adopts mechanical vibration molding, and the vibration time is 10 to 20 seconds.

[0021] According to the above scheme, the curing conditions in step C are a temperature of 20±2° C. and a relative humidity of 95% or more.

[0022] According to the above scheme, four different strength grades of LC30, LC40, LC50 and LC60 can be produced, with high crack resistance fiber reinforced ceramsite concrete wall panels and autogenous shrinkage rates less than 40×10 -6 The drying shrinkage rate is reduced by about 15% compared with concrete of the same strength grade, and the crack resistance grade can reach Level I, which effectively reduces the spontaneous shrinkage of concrete and reduces the risk of cracking. The frost resistance grade reaches F150, the sulfate resistance grade reaches KS100, and the water resistance grade reaches W11.

[0023] The principle of the present invention is:

[0024] Ceramsite has a certain degree of water absorption and can absorb a certain amount of water during the concrete mixing process. When the internal humidity of the concrete decreases due to evaporation, the ceramsite will release the water absorbed during mixing. This process can delay the self-drying process of concrete to a certain extent, thereby reducing concrete shrinkage. The crack-resistant effect of the fiber can synergize with the water absorption of the ceramsite to reduce the occurrence of cracks and delay the further expansion of existing cracks.

[0025] The high crack resistance fiber reinforced ceramsite concrete wallboard provided by the present invention has the following advantages compared with the prior art:

[0026] (1) The high crack resistance fiber reinforced ceramsite concrete wallboard is a composite of ceramsite, ceramic sand and polyvinyl alcohol fiber. The water absorption of ceramsite and ceramic sand is used to store mixing water and release water when the humidity inside the concrete decreases to reduce shrinkage. At the same time, the bridging crack-blocking effect of the fiber can also prevent the further expansion of cracks. The autogenous shrinkage rate of the high crack resistance fiber reinforced ceramsite concrete wallboard is less than 40×10 -6 The drying shrinkage rate is reduced by about 15% compared with concrete of the same strength grade, and the crack resistance grade reaches Grade I. It improves the crack resistance of concrete wall panels while also having good durability.

[0027] (2) The highly crack-resistant fiber-reinforced ceramsite concrete wallboard and its preparation method improve the poor fluidity of common fiber concrete by using ceramsite and ceramic sand and utilizing their spherical morphology effect, so that the slump of the concrete mixture reaches 170 to 240 mm, thereby improving the fluidity of the fiber-reinforced concrete and facilitating construction.

[0028] (3) The high crack resistance fiber reinforced ceramsite concrete wall panel does not use crushed stone but uses coarse particle size (6-15mm) ceramsite as the entire coarse aggregate, while using fine particle size (1-5mm) ceramsite sand to replace part of the river sand as the fine aggregate. This method makes the most of the lightweight characteristics of ceramsite so that the dry apparent density of the concrete is controlled at 1820-1940kg / m 3 , which greatly reduces the weight of concrete while ensuring the strength grade.

[0029] (4) The preparation method of the high crack-resistant fiber-reinforced ceramsite concrete wallboard can prepare concrete wallboards of multiple strength grades (LC30, LC40, LC50 and LC60) by adjusting the mix ratio parameters. The operation is simple and has good applicability. DETAILED DESCRIPTION

[0030] In order to better understand the technical solution of the present invention, the technical solution provided by the present invention is described in detail below with reference to embodiments.

[0031] In the following examples, the bulk density of the ceramsite is 1170 kg / m 3 , particle size 6 to 15 mm, cylinder pressure strength greater than 14 MPa, 1h water absorption rate 5%.

[0032] The bulk density of the ceramic sand is 1170 kg / m 3 , particle size 1~5mm, water absorption rate 7% in 1h.

[0033] The cement is P·O 42.5 ordinary Portland cement and P·O 52.5 ordinary Portland cement.

[0034] The fly ash is Class F II fly ash with an apparent density of 2350 kg / m 3 , activity index 78%.

[0035] The mineral powder is S95 grade mineral powder with an apparent density of 2910 kg / m 3 , activity index 103%.

[0036] The apparent density of the river sand is 2740 kg / m 3 , fineness modulus 2.2.

[0037] The water reducer is a polycarboxylic acid water reducer with a water reduction rate of 26.0% and a solid content of 12.0%.

[0038] The polyvinyl alcohol fiber has a length of 10 to 15 mm, a diameter of 20 to 35 μm, a breaking strength of 1500 MPa, a breaking elongation of 11% to 25%, and an elastic modulus of 30 GPa.

[0039] Example 1

[0040] A highly crack-resistant fiber-reinforced ceramsite concrete wall panel, the formulation of which is shown in Table 2.

[0041] Table 2 Raw material proportions of Example 1 (kg / m 3 )

[0042]

[0043] A high crack resistance fiber reinforced ceramsite concrete wallboard, the preparation process of which includes the following steps:

[0044] Step 1: Prepare the concrete mix

[0045] Weigh the raw materials according to the proportions in Table 2. Place 252 kg of cement, 54 kg of fly ash, 54 kg of mineral powder, and 4.0 kg of polyvinyl alcohol fiber in a concrete mixer and dry mix for 30 seconds. Then, add one-third of the mixing water (i.e., 52 kg) and stir for 30 seconds. Then, add 185 kg of river sand, 632 kg of ceramsite, 418 kg of ceramic sand, and one-third of the mixing water (i.e., 52 kg) and continue stirring for 30 seconds. Finally, add the remaining water and 6.5 kg of water reducer and continue stirring for 2 minutes to obtain a concrete mixture.

[0046] Step 2: Casting

[0047] Pour the concrete mixture into the mold, place it on a vibrating table and vibrate for 15 seconds, smooth the surface with a scraper, and remove the mold after it has stood for 24 hours.

[0048] Part 3: Component Maintenance

[0049] After curing for 28 days under standard conditions (temperature 20±2°C, relative humidity above 95%), a high crack-resistant fiber-reinforced ceramsite concrete wallboard is obtained.

[0050] Example 2

[0051] A highly crack-resistant fiber-reinforced ceramsite concrete wall panel, the formulation of which is shown in Table 8.

[0052] Table 3 Raw material proportions of Example 2 (kg / m 3 )

[0053]

[0054] A high crack resistance fiber reinforced ceramsite concrete wallboard, the preparation process of which includes the following steps:

[0055] A. Weigh the raw materials according to the proportions in Table 3. Place 350 kg of cement, 75 kg of fly ash, 75 kg of mineral powder, and 5.3 kg of polyvinyl alcohol fiber in a concrete mixer and dry mix for 30 seconds. Then, add one-third of the mixing water (i.e., 52 kg) and stir for 30 seconds. Then, add 475 kg of river sand, 635 kg of ceramsite, and 190 kg of ceramic sand, along with one-third of the mixing water (i.e., 52 kg), and continue stirring for 30 seconds. Finally, add the remaining water and 10 kg of water reducer, and continue stirring for 2 minutes to obtain a concrete mixture.

[0056] B. Pour the concrete mixture into the mold, place it on a vibrating table and vibrate for 10 to 20 seconds, smooth the surface with a scraper, and remove the mold after it has stood for 24 hours.

[0057] C. Curing under standard conditions (temperature 20±2℃, relative humidity above 95%) for 28 days will produce high crack resistance fiber reinforced ceramsite concrete wall panels.

[0058] Example 3

[0059] A highly crack-resistant fiber-reinforced ceramsite concrete wall panel, the formulation of which is shown in Table 14.

[0060] Table 4 Raw material proportions of Example 3 (kg / m 3 )

[0061]

[0062]

[0063] A high crack resistance fiber reinforced ceramsite concrete wallboard, the preparation process of which includes the following steps:

[0064] A. Weigh the raw materials according to the proportions in Table 4. Place 345 kg of cement, 43 kg of fly ash, 43 kg of mineral powder, and 6.8 kg of polyvinyl alcohol fiber in a concrete mixer and dry mix for 30 seconds. Then, add one-third of the mixing water (i.e., 50 kg) and stir for 30 seconds. Then, add 497 kg of river sand, 665 kg of ceramsite, 198 kg of ceramic sand, and one-third of the mixing water (i.e., 50 kg) and continue stirring for 30 seconds. Finally, add the remaining water and 8.6 kg of water reducer and continue stirring for 2 minutes to obtain a concrete mixture.

[0065] B. Pour the concrete mixture into the mold, place it on a vibrating table and vibrate for 10 to 20 seconds, smooth the surface with a scraper, and remove the mold after it has stood for 24 hours.

[0066] C. Curing under standard conditions (temperature 20±2℃, relative humidity above 95%) for 28 days will produce high crack resistance fiber reinforced ceramsite concrete wall panels.

[0067] Example 4

[0068] A highly crack-resistant fiber-reinforced ceramsite concrete wall panel, the formulation of which is shown in Table 20.

[0069] Table 5 Raw material proportions of Example 4 (kg / m 3 )

[0070]

[0071] A high crack resistance fiber reinforced ceramsite concrete wallboard, the preparation process of which includes the following steps:

[0072] A. Weigh the raw materials according to the proportions in Table 5. Place 465 kg of cement, 58 kg of fly ash, 58 kg of mineral powder, and 8.0 kg of polyvinyl alcohol fiber in a concrete mixer and dry mix for 30 seconds. Then, add one-third of the mixing water (i.e., 50 kg) and stir for 30 seconds. Then, add 615 kg of river sand, 617 kg of ceramsite, 92 kg of ceramic sand, and one-third of the mixing water (i.e., 50 kg) and continue stirring for 30 seconds. Finally, add 151 kg of water and 11.7 kg of water reducer and continue stirring for 2 minutes to obtain a concrete mixture.

[0073] B. Pour the concrete mixture into the mold, place it on a vibrating table and vibrate for 10 to 20 seconds, smooth the surface with a scraper, and remove the mold after it has stood for 24 hours.

[0074] C. Curing under standard conditions (temperature 20±2℃, relative humidity above 95%) for 28 days will produce high crack resistance fiber reinforced ceramsite concrete wall panels.

[0075] The high-strength, low-shrinkage autoclaved fly ash ceramsite lightweight aggregate concretes prepared in the four examples above were tested for their mix properties, mechanical properties, volume stability, and durability. These tests were conducted in accordance with national standards: JGJ / T 12-2019 "Technical Standard for the Application of Lightweight Aggregate Concrete," GB / T50080-2016 "Standard for Test Methods for Ordinary Concrete Mixture Properties," GB / T50081-2017 "Standard for Test Methods for Mechanical Properties of Ordinary Concrete," CCES 01-2005 "Guidelines for Durability Design and Construction of Concrete Structures," and GB / T 50082-2009 "Standard for Test Methods for Long-Term Performance and Durability of Ordinary Concrete." The results are shown in Tables 6 to 11.

[0076] Table 6 Concrete mixture properties in each example

[0077]

[0078] Table 7 Mechanical properties of concrete in various examples

[0079]

[0080]

[0081] Table 8 Autogenous volume shrinkage of concrete in various examples

[0082]

[0083] Table 9 Concrete drying shrinkage in each embodiment

[0084]

[0085] Table 10 Early crack resistance of concrete slabs in various embodiments

[0086]

[0087] Table 11 Durability of concrete in various examples

[0088]

[0089] The above examples show that:

[0090] The high crack resistance fiber reinforced ceramsite concrete wallboard mixture prepared in each embodiment has good performance, mechanical properties, volume stability and durability. The dry apparent density is 1820-1940 kg / m 3 The dry apparent density of lightweight aggregate concrete shall not exceed 1950 kg / m 3 The compressive strength meets the design value. The 50d autogenous shrinkage rate is less than 37×10 -6 , 50d drying shrinkage is less than 540×10 -6 , lower than ordinary concrete of the same strength grade, and the crack resistance grade can reach Grade I, effectively reducing the autogenous shrinkage of concrete and lowering the risk of cracking. The frost resistance grade reaches F150, the sulfate resistance grade reaches KS100, and the anti-seepage grade reaches W11.

[0091] The high-cracking-resistant fiber-reinforced ceramsite concrete wallboard prepared by the present invention can have low shrinkage and good crack resistance while meeting the requirements of mechanical properties and durability.

[0092] The mixing ratio and process parameters involved in the present invention are not limited to the above embodiments, and the present invention can be implemented within the value range.

Claims

1. A high crack resistance fiber reinforced ceramsite concrete wallboard, characterized in that: The content of each component is: water 151~155kg / m 3 , water reducing agent 6.8~11.6kg / m 3 、Cement 252~465kg / m 3 , fly ash 43~75kg / m 3 、Mineral powder 43~75kg / m 3 , River sand 185~615kg / m 3 , coarse particle size (6-15mm) ceramsite 617-665kg / m 3 , fine particle size (1-5mm) ceramic sand 92-418kg / m 3 , polyvinyl alcohol fiber 4.0~8.0kg / m 3 .

2. According to claim 1, a high crack resistance fiber reinforced ceramsite concrete wallboard is characterized in that: The bulk density of the coarse particle size ceramsite is less than 1170 kg / m 3 , particle size 6 to 15 mm, cylinder pressure strength greater than 14 MPa, 1h water absorption rate less than 5%.

3. The high crack resistance fiber reinforced ceramsite concrete wallboard according to claim 1, characterized in that: The bulk density of the fine-grained ceramic sand is less than 1170 kg / m 3 , particle size 1 to 5 mm, water absorption rate less than 7% in 1 hour.

4. The high crack resistance fiber reinforced ceramsite concrete wallboard according to claim 1, characterized in that: The cement grades are P·O 42.5 ordinary Portland cement and P·O 52.5 ordinary Portland cement.

5. The high crack resistance fiber reinforced ceramsite concrete wallboard according to claim 1, characterized in that: The fly ash fineness (residue on a 45 μm square sieve) is less than 30.0%.

6. The high crack resistance fiber reinforced ceramsite concrete wallboard according to claim 1, characterized in that: The mineral powder has an activity index greater than 95%.

7. The high crack resistance fiber reinforced ceramsite concrete wallboard according to claim 1, characterized in that: The river sand fineness modulus is 2.2 to 2.

8.

8. The high crack resistance fiber reinforced ceramsite concrete wallboard according to claim 1, characterized in that: The polyvinyl alcohol fiber has a length of 10 to 15 mm, a diameter of 20 to 35 μm, a breaking strength greater than 1500 MPa, a breaking elongation of 11% to 25%, and an elastic modulus greater than 30 GPa.

9. The method for preparing a highly crack-resistant fiber-reinforced ceramsite concrete wallboard according to any one of claims 1 to 9, characterized in that: The following steps are involved: A. Weigh the raw materials according to the proportions. The content of each component is: water 151-155 kg / m 3 , water reducing agent 6.8~11.6kg / m 3 、Cement 252~465kg / m 3 , fly ash 43~75kg / m 3 、Mineral powder 43~75kg / m 3 , River sand 185~615kg / m 3 , coarse particle size (6-15mm) ceramsite 617-665kg / m 3 , fine particle size (1-5mm) ceramic sand 92-418kg / m 3 , polyvinyl alcohol fiber 4.0~8.0kg / m 3 B. Place cement, fly ash, mineral powder, and polyvinyl alcohol fiber in a concrete mixer and dry mix for 30 seconds. Then, add one-third of the mixing water and stir for 30 seconds. Then, add sand, ceramsite, and ceramic sand, along with one-third of the mixing water, and stir for 30 seconds. Then, add the remaining water and water reducer and continue stirring for 2 minutes to obtain a concrete mixture. C. The concrete mixture is poured into the mold, vibrated into shape, and cured to obtain a highly crack-resistant fiber-reinforced ceramsite concrete wall panel.

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