Method and device for preparing aerated concrete by using recycled concrete aggregate

Abstract

The invention relates to the technical field of building materials, in particular to a method and device for preparing aerated concrete from recycled concrete aggregate. Comprising the following steps: carrying out modification treatment on recycled concrete aggregate to obtain modified recycled aggregate; blending, stirring and mixing the modified recycled aggregate, a cementing material, a supplementary siliceous material, water and an additive to obtain uniform mixed slurry; the mixed slurry is subjected to pouring and standing gas forming, and a hardened aerated concrete blank is obtained; cutting and autoclaved curing are performed on the hardened aerated concrete blank to obtain an aerated concrete finished product, so that the problems of high porosity, strong water absorption, high crushing index and low activity caused by the fact that old cement mortar is attached to the surface of the recycled aggregate are solved; the mechanical property, the drying shrinkage value and the durability of the aerated concrete can be seriously deteriorated when the concrete is directly used for preparing the aerated concrete.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a method and apparatus for preparing aerated concrete using recycled concrete aggregate. Background Technology

[0002] Autoclaved aerated concrete (AAC) is a lightweight, porous, and environmentally friendly building material with excellent thermal insulation properties. Its main raw materials are siliceous materials (such as quartz sand and fly ash) and calcareous materials (such as cement and lime), which form a porous structure through a gasification reaction.

[0003] Traditional aerated concrete mainly uses natural sand as siliceous aggregate, consuming a large amount of natural resources.

[0004] With urbanization, a large amount of construction waste is generated. Among them, recycled concrete aggregate (RCA), obtained by crushing and screening waste concrete, has become a potential alternative material. However, the surface of recycled aggregate is covered with old cement mortar, resulting in high porosity, strong water absorption, high crushing index, and low activity. Direct use in the preparation of aerated concrete will seriously deteriorate its mechanical properties, drying shrinkage value, and durability. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for preparing aerated concrete using recycled concrete aggregates. This invention aims to solve the technical problem in the prior art where recycled aggregates have old cement mortar adhering to their surface, resulting in high porosity, strong water absorption, high crushing index, and low activity. Direct use of these recycled aggregates in the preparation of aerated concrete would severely deteriorate their mechanical properties, drying shrinkage value, and durability.

[0006] To achieve the above objectives, the present invention employs a method for preparing aerated concrete using recycled concrete aggregate, comprising the following steps: modifying the recycled concrete aggregate to obtain modified recycled aggregate; mixing the modified recycled aggregate with cementitious materials, supplementary silica materials, water, and admixtures to obtain a uniform slurry; pouring and statically releasing the slurry to obtain a hardened aerated concrete blank; and cutting and autoclaving the hardened aerated concrete blank to obtain the finished aerated concrete product.

[0007] This includes providing a mixture of coarse and fine aggregates; The mixture was soaked in a composite modified liquid. The soaked aggregate is dried to obtain the modified recycled aggregate.

[0008] The fine aggregate is 0-5mm recycled concrete aggregate, and the mass ratio of the two is (3:7) to (4:6). The composite modification liquid is a mixture of 5-10% sodium silicate solution and 1-3% polyvinyl alcohol solution in a volume ratio of 1:(0.5-1). The soaking time is 10-30 minutes. The drying temperature is 80-120℃.

[0009] The following ingredients are weighed: 40-60 parts of the modified recycled aggregate, 15-25 parts of ordinary silicate cement, 8-15 parts of quicklime, 2-4 parts of gypsum, 10-20 parts of the supplementary silica material, 0.05-0.10 parts of aluminum powder paste, 0.02-0.05 parts of foam stabilizer, and 0.1-0.3 parts of water-reducing agent, with the water-to-material ratio controlled at 0.50-0.65. The modified recycled aggregate, the cementitious material, the supplementary silica material, and the water-reducing agent are dry-mixed for 60-90 seconds. Add 60-70% of the total water volume and perform the first wet stirring for 120-180 seconds; The aluminum powder paste and the foam stabilizer are dissolved in the remaining water to prepare a foam-generating agent suspension; The gas-generating agent suspension is added to the slurry being stirred and subjected to a second wet stirring for 30-60 seconds to obtain a uniform mixed slurry.

[0010] The mixture slurry is poured into a mold; Then let it stand still for 2-4 hours at 45-55℃; The hardened aerated concrete blank is obtained.

[0011] The hardened aerated concrete blank is subjected to vacuum treatment for 0.5 hours. The temperature is raised to 180-195℃ and 1.2-1.5MPa within 2-3 hours; Perform constant temperature and pressure curing treatment for 6-10 hours; Cool the room to room temperature within 2-3 hours; Finally, the aerated concrete product is obtained.

[0012] The present invention also provides an apparatus for preparing aerated concrete using recycled concrete aggregate, comprising a pretreatment module, a batching and mixing module, a molding and static curing module, and a cutting and curing module. The batching and mixing module is connected to the pretreatment module, the molding and static curing module is connected to the batching and mixing module, and the cutting and curing module is connected to the molding and static curing module.

[0013] This invention discloses a method and apparatus for preparing aerated concrete using recycled concrete aggregate. The method involves modifying the recycled concrete aggregate to obtain modified recycled aggregate; mixing the modified recycled aggregate with cementitious materials, supplementary silica materials, water, and admixtures to obtain a uniform slurry; pouring and statically releasing the slurry to obtain a hardened aerated concrete blank; and cutting and autoclaving the hardened aerated concrete blank to obtain the finished aerated concrete product. This invention solves the technical problem that recycled aggregate with adhered old cement mortar has high porosity, high water absorption, high crushing index, and low activity, which would severely deteriorate the mechanical properties, drying shrinkage value, and durability of aerated concrete if used directly. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a flowchart of the steps of the method for preparing aerated concrete using recycled concrete aggregate according to the present invention.

[0016] Figure 2 This is a flowchart of steps S100 of the present invention.

[0017] Figure 3 This is a flowchart of steps S200 of the present invention.

[0018] Figure 4 This is a flowchart of steps S300 of the present invention.

[0019] Figure 5 This is a flowchart of steps S400 of the present invention.

[0020] Figure 6 This is a schematic diagram of the device for preparing aerated concrete using recycled concrete aggregate according to the present invention.

[0021] Pretreatment module, 502-Ingredient mixing module, 503-Forming and static stopping module, 504-Cutting and curing module. Detailed Implementation

[0022] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application.

[0023] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0024] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0025] Please see Figures 1-5 , Figure 1 This is a flowchart illustrating the steps of the method for preparing aerated concrete using recycled concrete aggregate according to the present invention. Figure 2 This is a flowchart of steps S100 of the present invention. Figure 3 This is a flowchart of steps S200 of the present invention. Figure 4 This is a flowchart of steps S300 of the present invention. Figure 5 This is a flowchart of steps S400 of the present invention.

[0026] This invention provides a method for preparing aerated concrete using recycled concrete aggregate, comprising the following steps: S100 modifies recycled concrete aggregate to obtain modified recycled aggregate; S200 involves mixing the modified recycled aggregate with cementitious materials, supplementary silica materials, water, and additives to obtain a uniform slurry. S300 involves pouring and statically stopping the gas generation of the mixed slurry to obtain a hardened aerated concrete blank; S400 cuts and autoclaves the hardened aerated concrete blank to obtain the finished aerated concrete product.

[0027] In this embodiment, the recycled concrete aggregate is modified to obtain modified recycled aggregate; the modified recycled aggregate is mixed with cementitious materials, supplementary silica materials, water and admixtures to obtain a uniform slurry; the slurry is poured and allowed to stand for aeration to obtain a hardened aerated concrete blank; the hardened aerated concrete blank is cut and autoclaved to obtain the finished aerated concrete product; this method solves the technical problem that recycled aggregate with old cement mortar adhering to its surface has high porosity, strong water absorption, high crushing index and low activity, which would seriously deteriorate the mechanical properties, drying shrinkage value and durability of aerated concrete if used directly.

[0028] Furthermore, in the step of modifying recycled concrete aggregate to obtain modified recycled aggregate: Provides a mixture of coarse and fine aggregates; The mixture was soaked in a composite modified liquid. The soaked aggregate is dried to obtain the modified recycled aggregate.

[0029] In this embodiment, firstly, the coarse and fine aggregates of recycled concrete are weighed and uniformly mixed to obtain an aggregate mixture with reasonable gradation; then, a composite modifying liquid is prepared and applied, and the aggregate mixture is completely immersed in the modifying liquid for thorough soaking treatment; finally, the treated aggregates are separated and dried, and the soaked aggregates are taken out and dried at a constant temperature to finally obtain the modified recycled aggregates with optimized performance.

[0030] Furthermore, the fine aggregate is 0-5mm recycled concrete aggregate, and the mass ratio of the two is (3:7) to (4:6). The composite modification liquid is a mixture of 5-10% sodium silicate solution and 1-3% polyvinyl alcohol solution in a volume ratio of 1:(0.5-1). The soaking time is 10-30 minutes. The drying temperature is 80-120℃.

[0031] In this embodiment, the fine aggregate is 0-5mm recycled concrete aggregate selected by screening, and is precisely mixed with coarse aggregate by an automatic batching system at a mass ratio of (3:7) to (4:6). The mixed aggregate is then transported to a soaking tank containing a composite modified liquid formed by a 1:(0.5-1) volume ratio of 5-10% sodium silicate solution and 1-3% polyvinyl alcohol solution, and soaked for 10-30 minutes. After soaking, the aggregate is sent to a rotary dryer via a drain conveyor and dried at a temperature of 80-120°C to finally obtain the modified recycled aggregate.

[0032] Furthermore, in the step of mixing and stirring the modified recycled aggregate with cementitious materials, supplementary silica materials, water, and additives to obtain a uniform slurry: Weigh out 40-60 parts of the modified recycled aggregate, 15-25 parts of ordinary Portland cement, 8-15 parts of quicklime, 2-4 parts of gypsum, 10-20 parts of the supplementary silica material, 0.05-0.10 parts of aluminum powder paste, 0.02-0.05 parts of foam stabilizer, and 0.1-0.3 parts of water-reducing agent, and control the water-material ratio to be 0.50-0.65; The modified recycled aggregate, the cementitious material, the supplementary silica material, and the water-reducing agent are dry-mixed for 60-90 seconds. Add 60-70% of the total water volume and perform the first wet stirring for 120-180 seconds; The aluminum powder paste and the foam stabilizer are dissolved in the remaining water to prepare a foam-generating agent suspension; The gas-generating agent suspension is added to the slurry being stirred and subjected to a second wet stirring for 30-60 seconds to obtain a uniform mixed slurry.

[0033] In this embodiment, firstly, 40-60 parts by weight of the modified recycled aggregate, 15-25 parts of the ordinary silicate cement, 8-15 parts of the quicklime, 2-4 parts of the gypsum, 10-20 parts of the supplementary silicate material, 0.05-0.10 parts of the aluminum powder paste, 0.02-0.05 parts of the foam stabilizer, 0.1-0.3 parts of the water-reducing agent, and the total amount of water (controlling the water-to-material ratio between 0.50 and 0.65) are accurately weighed or measured using an electronic scale and a liquid metering system. All dry materials except the mixing water are added to a forced mixer and dry-mixed for 60-90 seconds. Then, about 60%-70% of the total amount of mixing water is added to the mixer, and mixing is continued for 120-180 seconds to complete the first wet mixing. At the same time, aluminum powder paste and foam stabilizer are dissolved in the reserved remaining mixing water in a separate container and fully dispersed to prepare a gas-generating agent suspension. Finally, the suspension is quickly added to the running mixer and mixing is continued for 30-60 seconds to obtain a final mixed slurry with uniform gas generation and good stability.

[0034] Furthermore, in the step of pouring and statically releasing the mixed slurry to obtain a hardened aerated concrete blank: The mixture slurry is poured into the mold; Then let it stand still for 2-4 hours at 45-55℃; The hardened aerated concrete blank is obtained.

[0035] In this embodiment, the mixed slurry is continuously and uniformly poured into the forming molds pre-arranged on the mold conveyor line through the discharge port of the pouring mixer; then, the molds after pouring are smoothly transferred to the constant temperature static curing chamber via the conveying system, and are left to cure in a precisely controlled 45-55℃ humid and hot environment for 2-4 hours, so that the slurry can complete gas expansion, thickening and solidification and preliminary hardening; after the strength of the green body develops to meet the requirements for demolding and cutting, the hardened aerated concrete green body with complete structure is obtained.

[0036] Furthermore, in the step of cutting and autoclaving the hardened aerated concrete blank to obtain the finished aerated concrete product: The hardened aerated concrete blank was subjected to vacuum treatment for 0.5 hours; The temperature is raised to 180-195℃ and 1.2-1.5MPa within 2-3 hours; Perform constant temperature and pressure curing treatment for 6-10 hours; Cool the room to room temperature within 2-3 hours; Finally, the aerated concrete product is obtained.

[0037] In this embodiment, the cut and hardened aerated concrete billet, along with the curing trolley, is fed into a large autoclave. First, the autoclave door is closed and a vacuuming process is initiated, reducing the pressure inside the autoclave to negative within 0.5 hours. Then, an automatic temperature and pressure increase process is executed, uniformly raising the temperature and pressure inside the autoclave to the set values ​​of 180-195°C and 1.2-1.5 MPa within 2-3 hours. Afterward, the system automatically switches to and maintains this constant temperature and pressure state for 6-10 hours of core curing. After curing, a controllable cooling process is executed, allowing the temperature and pressure inside the autoclave to steadily decrease to room temperature and atmospheric pressure within 2-3 hours. Finally, the autoclave door is opened, and the cured product is removed and inspected, yielding the stable aerated concrete finished product.

[0038] Corresponding to the aforementioned embodiments of the method for preparing aerated concrete using recycled concrete aggregate, this application also provides embodiments of an apparatus for preparing aerated concrete using recycled concrete aggregate.

[0039] Figure 6 This is a schematic diagram illustrating the structural principle of the apparatus for preparing aerated concrete using recycled concrete aggregate according to the present invention. (Refer to...) Figure 6 The device includes a pretreatment module 501, a batching and mixing mold 502, a molding and static stopping module 503, and a cutting and curing module 504. The batching and mixing mold 502 is connected to the pretreatment module 501, the molding and static stopping module 503 is connected to the batching and mixing mold 502, and the cutting and curing module 504 is connected to the molding and static stopping module 503.

[0040] In this embodiment, the pretreatment module 501 is used to modify the recycled concrete aggregate and output modified recycled aggregate; the batching and mixing mold 502 is connected to the pretreatment module 501 and is used to receive the modified recycled aggregate and meter and mix it with cementitious materials, supplementary silica materials, water and admixtures to output a uniform slurry; the molding and static curing module 503 is connected to the batching and mixing mold 502 and is used to receive the slurry and perform pouring, aeration and thickening hardening to output a hardened aerated concrete blank; the cutting and curing module 504 is connected to the molding and static curing module 503 and is used to receive the hardened aerated concrete blank and perform cutting and autoclaving curing to output the finished aerated concrete product. This solves the technical problem that the recycled aggregate has old cement mortar adhering to its surface, resulting in high porosity, strong water absorption, high crushing index and low activity, which would seriously deteriorate the mechanical properties, drying shrinkage value and durability of aerated concrete if used directly.

[0041] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this application according to actual needs. Those skilled in the art can understand and implement this without any inventive effort.

Claims

1. A method for preparing aerated concrete using recycled concrete aggregate, characterized in that, Includes the following steps: Modified recycled concrete aggregate is obtained by modifying recycled aggregate. The modified recycled aggregate is mixed with cementitious materials, supplementary silica materials, water and additives to obtain a uniform slurry. The mixed slurry is poured and allowed to stand still to generate gas, in order to obtain a hardened aerated concrete blank; The hardened aerated concrete blank is cut and autoclaved to obtain the finished aerated concrete product.

2. The method for preparing aerated concrete using recycled concrete aggregate as described in claim 1, characterized in that, In the step of modifying recycled concrete aggregate to obtain modified recycled aggregate: Provides a mixture of coarse and fine aggregates; The mixture was soaked in a composite modified liquid. The soaked aggregate is dried to obtain the modified recycled aggregate.

3. The method for preparing aerated concrete using recycled concrete aggregate as described in claim 2, characterized in that, The fine aggregate is 0-5mm recycled concrete aggregate, and the mass ratio of the two is (3:7) to (4:6). The composite modification liquid is a mixture of 5-10% sodium silicate solution and 1-3% polyvinyl alcohol solution in a volume ratio of 1:(0.5-1). The soaking time is 10-30 minutes. The drying temperature is 80-120℃.

4. The method for preparing aerated concrete using recycled concrete aggregate as described in claim 2, characterized in that, In the step of mixing and stirring the modified recycled aggregate with cementitious materials, supplementary silica materials, water, and additives to obtain a uniform slurry: Weigh out 40-60 parts of the modified recycled aggregate, 15-25 parts of ordinary Portland cement, 8-15 parts of quicklime, 2-4 parts of gypsum, 10-20 parts of the supplementary silica material, 0.05-0.10 parts of aluminum powder paste, 0.02-0.05 parts of foam stabilizer, and 0.1-0.3 parts of water-reducing agent, and control the water-material ratio to be 0.50-0.65; The modified recycled aggregate, the cementitious material, the supplementary silica material, and the water-reducing agent are dry-mixed for 60-90 seconds. Add 60-70% of the total water volume and perform the first wet stirring for 120-180 seconds; The aluminum powder paste and the foam stabilizer are dissolved in the remaining water to prepare a foaming agent suspension; The gas-generating agent suspension is added to the slurry being stirred and subjected to a second wet stirring for 30-60 seconds to obtain a uniform mixed slurry.

5. The method for preparing aerated concrete using recycled concrete aggregate as described in claim 4, characterized in that, In the step of pouring and statically releasing the mixed slurry to obtain a hardened aerated concrete blank: The mixture slurry is poured into the mold; Then let it stand still for 2-4 hours at 45-55℃; The hardened aerated concrete blank is obtained.

6. The method for preparing aerated concrete using recycled concrete aggregate as described in claim 5, characterized in that, In the step of cutting and autoclaving the hardened aerated concrete blank to obtain the finished aerated concrete product: The hardened aerated concrete blank was subjected to vacuum treatment for 0.5 hours; The temperature is raised to 180-195℃ and 1.2-1.5MPa within 2-3 hours; Perform constant temperature and pressure curing treatment for 6-10 hours; Cool the room to room temperature within 2-3 hours; Finally, the aerated concrete product is obtained.

7. An apparatus for preparing aerated concrete using recycled concrete aggregate, applied to the method for preparing aerated concrete using recycled concrete aggregate as described in claim 1, characterized in that, It includes a pretreatment module, a batching and mixing module, a molding and static stopping module, and a cutting and curing module. The batching and mixing module is connected to the pretreatment module, the molding and static stopping module is connected to the batching and mixing module, and the cutting and curing module is connected to the molding and static stopping module.

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