Preparation method of reed concrete building block
By pretreating reed straws alkali and mixing them with cement, reed concrete building blocks with high compressive strength and tensile properties were prepared, which solved the problems of poor tensile properties and self-weight of cement-based materials, and achieved efficient use of materials and improved building performance.
Patent Information
- Application Number
- CN202411739135.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-29
- Publication Date
- 2025-02-28
AI Technical Summary
The existing cement-based materials have disadvantages such as poor tensile performance and large self-weight in construction projects, which limit their application.
By mixing reed straw with alkaline solution for alkali pretreatment, the lumpy and wax on the reed surface are removed, the specific surface area of the fiber is increased, and the molding and curing are mixed with cement to prepare reed concrete building blocks with high compressive strength and tensile properties.
The compressive strength and tensile performance of reed concrete building blocks are improved, while reducing self-weight, reducing production costs, and improving thermal insulation performance.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of manufacturing plant fiber cement-based composite materials, and particularly relates to a method for preparing a reed concrete building block. Background Art
[0002] Reed resources are abundant. If they are allowed to continue to reproduce, they will destroy the ecological balance of wetlands and lakes. If reeds are cut and collected, the reed straw that occupies space and cannot be used can only be burned like crop straw, which will cause environmental problems. Cement-based materials are the largest and most widely used man-made building materials in construction engineering structures. They have good compressive properties, but their poor tensile properties and heavy weight limit their application. Summary of the invention
[0003] In view of this, the object of the present invention is to provide a method for preparing a reed concrete building block, wherein the reed concrete building block prepared by the method has high compressive strength and high tensile performance and can reduce its own weight.
[0004] In order to achieve the above object, the present invention provides the following technical solutions:
[0005] The invention provides a method for preparing a reed concrete building block, comprising the following steps:
[0006] The reed straw raw material and the alkaline solution are mixed for alkali pretreatment, and the obtained alkali pretreated reed straw is dried, crushed and sieved in sequence to obtain reed crushed material;
[0007] The reed crushed material, cement and water are mixed, and the obtained mixture is molded and cured in sequence to obtain reed concrete building blocks.
[0008] Preferably, the alkaline solution is a sodium hydroxide solution; the mass concentration of the alkaline solution is 3-5%.
[0009] Preferably, the alkali pretreatment time is 20 to 24 hours; and the alkali pretreatment is carried out at room temperature.
[0010] Preferably, the sieve used for the screening has an aperture of 20 to 70 meshes.
[0011] Preferably, the mass of the reed crushed material is 4.5-8.5% of the mass of the cement.
[0012] Preferably, the mass ratio of water to cement is 0.30-0.50:1.
[0013] Preferably, the molding is as follows: placing the mixture in a mold, vibrating it and then smoothing it, and demoulding it after it is left to stand.
[0014] Preferably, the vibration rate is 1 to 2 s / time, and the vibration time is 1.5 to 2 min.
[0015] Preferably, the ambient temperature of the static state is 20±5° C., and the relative humidity of the static state is 60-65%; and the static state time is 24 hours.
[0016] Preferably, the curing time is 28 days; the curing temperature is 20±5° C.; and the curing relative humidity is 90-95%.
[0017] The invention provides a method for preparing a reed concrete building block, comprising the following steps: mixing a reed straw raw material and an alkaline solution for alkali pretreatment, sequentially drying, crushing and screening the alkali-pretreated reed straw to obtain reed crushed material; mixing the reed crushed material, cement and water, sequentially molding and curing the obtained mixture to obtain a reed concrete building block.
[0018] The present invention utilizes an alkaline solution to perform alkali pretreatment on the reed straw raw material, removes the suberin, siliceous protrusions and wax on the outer surface of the reed straw, exposes the tissue under the thin-walled cells, and precipitates the slow-setting and anti-setting sugar substances while ensuring the orderliness of the fiber structure, leaving narrow and long gaps, thereby increasing the specific surface area, improving the mechanical bite force of the interface combined with cement, and enhancing the bonding force, thereby improving the compressive strength and tensile properties of the reed concrete building blocks. When the reed concrete building blocks prepared by the present invention are used as non-load-bearing wall blocks, they can reduce production costs, reduce deadweight, and improve thermal insulation properties while ensuring strength. DETAILED DESCRIPTION
[0019] The invention provides a method for preparing a reed concrete building block, comprising the following steps:
[0020] The reed straw raw material and the alkaline solution are mixed for alkali pretreatment, and the obtained alkali pretreated reed straw is dried, crushed and sieved in sequence to obtain reed crushed material;
[0021] The reed crushed material, cement and water are mixed, and the obtained mixture is molded and cured in sequence to obtain reed concrete building blocks.
[0022] Unless otherwise specified, the present invention has no special requirements on the sources of the raw materials used, and commercially available products known to those skilled in the art may be used.
[0023] The invention mixes reed straw raw materials with alkaline solution to perform alkali pretreatment to obtain alkali-pretreated reed straw.
[0024] As an implementation mode, the length of the reed straw raw material is 5 to 15 cm, and in a specific embodiment, it is 5 to 10 cm.
[0025] As an embodiment, the preparation method of the reed straw raw material is: after harvesting and removing the leaves of the reed straw, drying it, cooling the obtained dry defoliated reed straw and crushing it to obtain the reed straw raw material; the drying temperature is 80-110°C, and in a specific embodiment, it is 95-100°C; the drying is performed until the obtained dry defoliated reed straw is in an absolutely dry state; the cooling is performed to 40°C; the equipment used for the crushing is a crusher.
[0026] As an implementation mode, the alkaline solution is a sodium hydroxide solution; the mass concentration of the alkaline solution is 3-5%, and in a specific embodiment, it is 3%.
[0027] As an embodiment, the mixing is performed by soaking the reed straw in an alkaline solution.
[0028] As an embodiment, the alkali pretreatment time is 20 to 24 hours, and in a specific embodiment, it is 24 hours; the alkali pretreatment is carried out at room temperature.
[0029] The present invention utilizes an alkaline solution to perform alkali pretreatment on a reed straw raw material, removes the suberin, siliceous protrusions and wax on the outer surface of the reed straw, exposes the tissue under the thin-walled cells, and precipitates slow-setting and anti-setting sugar substances while ensuring the orderliness of the fiber structure, leaving narrow gaps, thereby increasing the specific surface area, improving the mechanical bite force of the interface combined with cement, and enhancing the bonding force, thereby improving the compressive strength and tensile performance of the reed concrete building block.
[0030] After obtaining the alkali-pretreated reed straw, the present invention sequentially dries, crushes and sieves the alkali-pretreated reed straw to obtain reed fragments.
[0031] As an implementation mode, the drying temperature is 80-100° C., and in a specific embodiment, 90-95° C.; the drying is performed until the reed straw is in an absolutely dry state after the alkali pretreatment.
[0032] The present invention has no particular limitation on the pulverizing process, and any pulverizing process known in the art may be used.
[0033] As an implementation mode, the aperture of the screen used for screening is 20-70 meshes, and in specific embodiments, it is 40-50 meshes, 50-60 meshes or 60-70 meshes; the equipment used for screening is a vibrating standard vibrating screen machine.
[0034] After obtaining the reed fragments, the present invention mixes the reed fragments, cement and water, and the obtained mixture is molded and cured in sequence to obtain reed concrete building blocks.
[0035] As an implementation mode, the mass ratio of water to cement is 0.30-0.50:1, and in a specific embodiment, it is 0.35:1.
[0036] The present invention has no particular limitation on the specific type of cement, and any P.C42.5 composite silicate cement well known in the art may be used.
[0037] As an implementation mode, the mass of the reed crushed material is 4.5-8.5% of the mass of the cement, and in a specific embodiment, it is 6.5-7.5%.
[0038] As an implementation mode, the reed crushed material, cement and water are mixed as follows: after the reed crushed material and cement are fully stirred for a first time, the obtained mixture is added to water for a second stirring.
[0039] As an implementation manner, the rates of the first stirring and the second stirring are independently 62±5 r / min, and 62 r / min in a specific embodiment; the time of the second stirring is 2 min.
[0040] As an embodiment, the molding is as follows: placing the mixture in a mold, vibrating it and then smoothing it, and demolding it after standing it.
[0041] As an implementation manner, the vibration rate of the vibration is 1 to 2 s / time, and in a specific embodiment, it is 1 s / time, and the vibration time is 1.5 to 2 min, and in a specific embodiment, it is 1.5 min.
[0042] As an implementation manner, the ambient temperature of the static state is 20±5° C., and in a specific embodiment, it is 20° C.; the relative humidity of the environment is 60-65%, and in a specific embodiment, it is 65%; and the static state time is 24 hours.
[0043] As an implementation mode, the curing time is 28 days; the relative temperature of the curing is 20±5°C, and in a specific embodiment, it is 20°C; the relative humidity of the curing is 90-95%, and in a specific embodiment, it is 95%.
[0044] The present invention has no special requirements on the size of the reed concrete building blocks, which can be set according to actual needs.
[0045] The main chemical components of reeds are similar to those of wood, mainly consisting of lignin, hemicellulose and cellulose. Adding reed straw to cement matrix can reduce the weight of cement matrix and inhibit or delay the generation and development of cracks while ensuring the basic mechanical properties of cement matrix. In addition, reed straw fibers can also improve the toughness of reed concrete building blocks and enhance their thermal insulation capabilities by absorbing energy, friction and even pulling.
[0046] When the reed concrete building blocks prepared by the invention are used as non-load-bearing wall blocks, the production cost can be reduced, the deadweight can be lightened, and the thermal insulation performance can be improved while ensuring the strength.
[0047] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, but they should not be construed as limiting the protection scope of the present invention.
[0048] Example 1
[0049] The leaves of the reed straw are removed, bundled and sent to a drying kiln, dried at 100°C to an absolute dry state, and then the dried leafless reed straw is taken out and cooled to 40°C to obtain dried leafless reed straw; the dried leafless reed straw is cut into 5-15 cm reed straw raw materials using a crusher;
[0050] The reed straw raw material is subjected to alkali pretreatment, and the reed straw raw material is soaked in a NaOH solution with a mass concentration of 3% at room temperature for 24 hours, dried to an absolute dry state at 100° C., crushed by a dry and wet straw crusher, and sieved by a vibrating standard vibrating sieve machine with a 50-60 mesh screen to obtain reed crushed material;
[0051] The reed crushed materials and cement (P.C42.5 composite silicate cement) are fully mixed, the mass of the reed crushed materials is 6.5% of the mass of the cement, and then the obtained mixture is added into water, the mass ratio of water to cement is 0.35:1, and stirred by a mixer at a stirring rate of 62r / min and a stirring time of 2min. The obtained mixture is poured into a mold, and vibrated by a vibration machine at a vibration rate of 1s / time and a vibration time of 1.5min. After vibration, it is smoothed, and demolded after standing for 24h in an environment with a temperature of 20°C and a humidity of 65%. Then, it is cured for 28 days in an environment with a temperature of 20°C and a humidity of 95% to obtain reed concrete building blocks.
[0052] Example 2
[0053] The difference from Example 1 is that the mass of the reed fragments is 7.5% of the mass of cement, and the rest is the same as Example 1.
[0054] Example 3
[0055] The difference from Example 1 is that a vibrating standard sieve vibrating machine is used to screen with a 40-50 mesh screen to obtain reed fragments, and the rest is the same as Example 1.
[0056] Example 4
[0057] The difference from Example 3 is that the mass of the reed fragments is 7.5% of the mass of cement, and the rest is the same as Example 3.
[0058] Example 5
[0059] The difference from Example 1 is that a vibrating standard sieve vibrating machine is used to screen with a 60-70 mesh screen to obtain reed fragments, and the rest is the same as Example 1.
[0060] Example 6
[0061] The difference from Example 5 is that the mass of the reed fragments is 7.5% of the mass of cement, and the rest is the same as Example 5.
[0062] Comparative Example 1
[0063] The difference from Example 1 is that no NaOH solution is used for alkali pretreatment, and the rest is the same as Example 1.
[0064] Comparative Example 2
[0065] The difference from Example 1 is that the mass of the reed fragments is 2% of the mass of cement, and the rest is the same as Example 1.
[0066] Comparative Example 3
[0067] The difference from Example 1 is that the mass of the reed crushed material is 10% of the mass of cement, and the rest is the same as Example 1.
[0068] Performance Testing
[0069] With reference to the standard "GB / T 4111-2013 Test methods for concrete blocks and bricks", the performance tests were carried out on the reed concrete building blocks of Examples 1 to 6 and Comparative Examples 1 to 3. The results are shown in Table 1.
[0070] Table 1 Compressive strength and tensile strength of concrete building blocks of Examples 1 to 6 and Comparative Examples 1 to 3
[0071]
[0072]
[0073] From the results of Examples 1 to 6 and Comparative Example 1 in Table 1, it can be seen that before preparing the reed concrete building blocks, the present invention uses 3wt% NaOH solution to perform alkali pretreatment on the reed straw raw material to remove the corky, siliceous protrusions and wax on the outer surface of the reed straw. Compared with the method without alkali pretreatment, it achieves a significant modification effect, the mechanical bite force of the interface between the reed and cement is significantly improved, and the compressive strength of the reed concrete building blocks is significantly increased. By comparing the results of Examples 1 to 6 and Comparative Examples 2 and 3, it can be found that too much or too little addition of reed crushed material will reduce the compressive strength and tensile strength of the concrete building blocks.
[0074] By comparing the results of Example 1, Example 3 and Example 5, it can be found that when the mesh number of reed crushed materials is between 40 and 70, the reeds have a mechanical reinforcement effect. When the mesh number of reed crushed materials is 50 to 60, the mechanical bite force between reed crushed materials and cement-based materials is optimal, and the mechanical reinforcement effect is obvious, so that the compressive strength of the building blocks of Example 1 is better than that of Example 3 and Example 5. From the results of Example 1 and Example 2, it can be seen that when the amount of reed crushed materials added is 6.5%, the influence of the moisture absorbed by the reeds on the cement hydration reaction is the smallest. The preparation process of the reed concrete building blocks obtained by the scheme of selecting 50 to 60 mesh reed crushed materials, adding 6.5%, and the mass ratio of water to cement is 0.35:1 is optimal, and the compressive strength of the blocks is the highest.
[0075] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention rather than all the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.
Claims
1. A method for preparing a reed concrete building block, characterized in that: The following steps are involved: The reed straw raw material and the alkaline solution are mixed for alkali pretreatment, and the obtained alkali pretreated reed straw is dried, crushed and sieved in sequence to obtain reed crushed material; The reed crushed material, cement and water are mixed, and the obtained mixture is molded and cured in sequence to obtain reed concrete building blocks.
2. The preparation method according to claim 1, characterized in that: The alkaline solution is a sodium hydroxide solution; the mass concentration of the alkaline solution is 3-5%.
3. The preparation method according to claim 1 or 2, characterized in that: The alkali pretreatment time is 20 to 24 hours; the alkali pretreatment is carried out at room temperature.
4. The preparation method according to claim 1, characterized in that: The aperture of the sieve used for the screening is 20 to 70 meshes.
5. The preparation method according to claim 1, characterized in that: The mass of the reed fragments is 4.5-8.5% of the mass of the cement.
6. The preparation method according to claim 1 or 5, characterized in that: The mass ratio of water to cement is 0.30-0.50:
1.
7. The preparation method according to claim 1, characterized in that: The molding process comprises placing the mixed material in a mold, vibrating the mixed material, smoothing the mixed material, and demoulding the mixed material after standing.
8. The preparation method according to claim 7, characterized in that: The vibration rate of the vibration is 1 to 2 seconds per time, and the vibration time is 1.5 to 2 minutes.
9. The preparation method according to claim 7, characterized in that: The ambient temperature of the static state is 20±5° C., and the relative humidity of the static state is 60-65%. The static state time is 24 hours.
10. The preparation method according to claim 1, characterized in that: The curing time is 28 days; the curing temperature is 20±5° C.; and the curing relative humidity is 90-95%.