Preparation method of recycled concrete aggregate thermal insulation non-burning brick
By treating recycled concrete aggregate with calcium bicarbonate and using modified fly ash cenospheres, combined with other raw materials, non-fired bricks were prepared, solving the problems of mechanical strength and water absorption of recycled concrete aggregate in non-fired bricks, and achieving improvements in strength and thermal insulation performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- QINGDAO XINZHOU HUANKE BUILDING MATERIALS CO LTD
- Filing Date
- 2024-02-18
- Publication Date
- 2026-06-09
Smart Images
Figure CN118026614B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of non-fired brick preparation technology, and in particular to a method for preparing non-fired bricks with recycled concrete aggregate insulation. Background Technology
[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.
[0003] Non-fired bricks are a new type of building material. Compared with ordinary sintered bricks, non-fired bricks are more environmentally friendly because they do not require mining and firing processes. Studies show that the comprehensive energy consumption for the production of non-fired bricks is between 600 and 900 kg of standard coal per 10,000 standard bricks, only half that of sintered bricks. Furthermore, non-fired bricks have advantages such as high strength, good frost resistance, low water absorption, and sound insulation, leading to their increasingly widespread use in the construction industry. They can be used to build partition walls, load-bearing walls, soundproof walls, and protective walls. Moreover, the main raw material for non-fired bricks is various industrial solid wastes, promoting the resource utilization of industrial solid waste. Therefore, using non-fired bricks to replace sintered bricks can bring significant social, economic, and environmental benefits. Currently, non-fired bricks have become a substitute for traditional sintered bricks, solid bricks, and steam-cured concrete.
[0004] Recycled concrete aggregate is obtained by processing waste concrete from construction waste and is currently one of the important ways to utilize construction waste resources. Statistics show that tens of billions of tons of natural sand and gravel aggregate are consumed globally each year. Using recycled concrete aggregate to completely or partially replace natural aggregate in the production of non-fired bricks not only helps conserve natural aggregate resources but also alleviates the resulting environmental problems. However, compared to natural aggregates, recycled concrete aggregates have more internal defects and higher breakage values, resulting in lower strength. Furthermore, recycled concrete aggregates have a higher water absorption rate than natural aggregates, which can hinder the hydration reaction of cement in concrete, reducing the amount of cementitious products generated. These issues lead to insufficient mechanical strength in non-fired bricks made from recycled concrete aggregates, affecting their application. Summary of the Invention
[0005] To address the aforementioned problems, this invention discloses a method for preparing thermally insulating, non-fired bricks using recycled concrete aggregates. This method effectively reduces the adverse effects of recycled concrete aggregates on the mechanical properties of the non-fired bricks, and the non-fired bricks prepared by this invention also possess excellent thermal insulation properties. To achieve the above objectives, this invention discloses the following technical solutions.
[0006] A method for preparing a recycled concrete aggregate insulating non-fired brick includes the following steps:
[0007] (1) The recycled concrete coarse aggregate is immersed in a saturated calcium bicarbonate solution. After the immersion is completed, the coarse aggregate is removed and dried to obtain pretreated coarse aggregate for later use.
[0008] (2) Take the following raw materials: 45-62 parts by weight of slag powder, 18-25 parts by weight of silicate cement, 6-10 parts by weight of fly ash cenospheres, 30-40 parts by weight of the pretreated coarse aggregate, 55-70 parts by weight of sand, and 1-2 parts by weight of water-reducing agent. Mix the above raw materials evenly, then add mixing water at a water-cement ratio of 0.18-0.22. After mixing evenly, press the resulting mixture into brick blanks and cure them naturally to obtain unfired bricks.
[0009] Compared with the prior art, the above-mentioned technical solution of the present invention has the following beneficial effects:
[0010] This invention involves placing recycled concrete aggregate used in the preparation of unfired bricks in a saturated calcium bicarbonate solution and allowing it to stand, thereby allowing the calcium bicarbonate to penetrate into the pores and cracks of the recycled concrete aggregate. When this recycled concrete aggregate is used to prepare unfired bricks, the calcium hydroxide, a hydration product produced after the silicate cement hydration, enters the recycled concrete aggregate and reacts with the calcium bicarbonate to form calcium carbonate particles and water. On one hand, the calcium carbonate particles can fill and compact the pores and cracks of the recycled concrete aggregate, thereby reducing the water absorption rate and crushing value of the recycled concrete aggregate and improving the mechanical strength of the unfired bricks. On the other hand, the formed water can replenish the moisture in the unfired bricks, thus overcoming the problem of insufficient cement hydration and deterioration of the mechanical strength of the unfired bricks due to the additional water absorption of the recycled concrete aggregate. Simultaneously, the unfired bricks of this invention also contain fly ash cenospheres, which have good thermal insulation properties, thereby improving the thermal insulation performance of the unfired bricks. Attached Figure Description
[0011] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention and do not constitute an undue limitation of the invention. The embodiments of the invention are described in detail below with reference to the accompanying drawings, wherein:
[0012] Figure 1 The image shows a sample of the recycled concrete coarse aggregate used in Example 1 below.
[0013] Figure 2 The graph shows the thermal conductivity of the slurry prepared in Example 1 below. Detailed Implementation
[0014] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.
[0015] In some more specific embodiments, in step (1) of the above preparation method, the ratio of the recycled concrete coarse aggregate to the saturated calcium bicarbonate solution is 1g:20-30ml.
[0016] In some more specific embodiments, in step (1) of the above preparation method, the impregnation time is 40 to 70 minutes, so that the saturated calcium bicarbonate solution can fully penetrate into the recycled concrete coarse aggregate.
[0017] In some more specific embodiments, in step (1) of the above preparation method, the drying method includes any one of natural air drying, heat drying, etc. Optionally, the natural air drying time is 1 to 3 days. The heat drying temperature is 50 to 75°C, and the time is 2 to 3 hours.
[0018] In some more specific embodiments, in step (2) of the above preparation method, the water-reducing agent includes any one of polycarboxylate water-reducing agents, naphthalene-based water-reducing agents, lignin sulfonate water-reducing agents, etc.
[0019] In some more specific embodiments, in step (2) of the above preparation method, the pressing pressure is 20-35 MPa and the holding time is 1-3 min.
[0020] Preferably, in step (2) of the above preparation method, the fly ash cenospheres are pretreated by the following method: the fly ash cenospheres are mixed evenly with an alkaline solution and heated to a set temperature and kept warm. Then, the fly ash cenospheres are separated, mixed with saturated lime water, and subjected to a hydrothermal reaction under ultrasonic oscillation conditions. The solid product is separated and dried to obtain the modified fly ash cenospheres.
[0021] Fly ash cenospheres are lightweight and float on water, exhibiting poor compatibility and wettability. Therefore, when added to unfired bricks, they are difficult to mix thoroughly with the raw materials and mixing water, resulting in significant agglomeration and uneven distribution, which negatively impacts the brick's insulation performance. To address this, this invention modifies the fly ash cenospheres, improving their compatibility with the raw materials and mixing water, thereby enhancing both the insulation performance and mechanical strength of the unfired bricks. This is because treatment with a strong alkaline solution disrupts the inert network structures (Si-O-Si, Si-O-Al, Al-O-Al, etc.) on the surface of the fly ash cenospheres, causing the silicon-oxygen tetrahedra and aluminum-oxygen tetrahedra to depolymerize and form ionic active monomers (such as Al(OH)). 4- Si(OH) 3-(etc.). When the above-mentioned fly ash cenospheres are further treated with saturated lime water, the active monomers on their surface react with calcium hydroxide to form hydrated calcium silicate and hydrated calcium aluminate products. These products have good hydrophilic properties, thereby significantly increasing the compatibility between fly ash cenospheres and various raw materials and mixing water, improving the dispersibility of fly ash cenospheres, and improving the thermal insulation performance of unfired bricks. At the same time, the hydrated calcium silicate and hydrated calcium aluminate products on the surface of fly ash cenospheres are of the same type of substance as the hydrated calcium silicate and hydrated calcium aluminate produced by the hydration of cement components in unfired bricks, thereby making the bond between the fly ash cenospheres and the unfired brick matrix tighter and improving the strength of unfired bricks.
[0022] In some more specific embodiments, the ratio of fly ash celery beads to alkaline solution is 1g:8-15ml. Optionally, the alkaline solution includes at least one of sodium hydroxide solution and potassium hydroxide solution. The concentration of the alkaline solution is 1.5-3mol / L.
[0023] In some more specific embodiments, the set temperature is 40–55°C and the holding time is 60–90 min.
[0024] In some more specific embodiments, the ratio of fly ash cenospheres to saturated lime water is 1g:5-10ml.
[0025] In some more specific embodiments, the hydrothermal reaction is carried out at a temperature of 160–200°C for 3–4.5 hours. Optionally, the ultrasonic power of the ultrasonic oscillation is 300–500 W.
[0026] In some more specific embodiments, the solid product is dried at a temperature of 90–130°C for 1–2 hours.
[0027] The technical solution of the present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0028] Example 1
[0029] A method for preparing a recycled concrete aggregate insulating non-fired brick includes the following steps:
[0030] (1) After crushing the waste building concrete, the particles with a diameter of 5-15mm are screened out to obtain recycled concrete coarse aggregate (refer to...). Figure 1 The recycled concrete coarse aggregate was mixed with a saturated calcium bicarbonate solution at a ratio of 1g:25ml and stirred until homogeneous, then impregnated for 60 minutes. After completion, the recycled concrete coarse aggregate was filtered out and dried in an oven at 75°C for 2 hours to obtain modified recycled concrete coarse aggregate.
[0031] (2) Take the following raw materials: 55 parts by weight of slag powder with a particle size of 300 mesh, 22 parts by weight of 42.5 ordinary Portland cement, 8.5 parts by weight of fly ash cenospheres, 36 parts by weight of the modified recycled concrete coarse aggregate of this embodiment, 65 parts by weight of sand, and 1.5 parts by weight of polycarboxylate superplasticizer (water reduction rate of 22%). The sand is river sand with a continuous gradation of 0.2-1.0 mm particle size.
[0032] (3) Add the above raw materials to a mixer and dry mix for 5 minutes. Then, add mixing water at a water-cement ratio of 0.2 and mix for 3 minutes. Pour the resulting slurry into a mold for pressing (pressure 30 MPa, holding time 2.5 minutes). After completion, allow the resulting brick blanks to cure naturally for 28 days. During the curing period, spray water once every 24 hours, just enough to wet the surface of the brick blanks. The resulting recycled concrete aggregate insulating non-fired brick is then obtained.
[0033] 1. The compressive strength of the unfired bricks prepared in this embodiment was tested according to the "Test Methods for Masonry Bricks" (GB / T 2542-2012), and the result was 28.62 MPa.
[0034] 2. According to the "Standard for Thermal Conductivity Testing" (GB / T10294-2008), the slurry prepared in this embodiment was made into a specimen, and then the thermal conductivity was tested using a thermal conductivity meter (model DR-3030, manufactured by Beijing Hangjian Huaye Technology Development Co., Ltd.) (see reference). Figure 2 The result was 0.47 W / (m·K).
[0035] Example 2
[0036] A method for preparing a recycled concrete aggregate insulating non-fired brick includes the following steps:
[0037] (1) After crushing the waste building concrete, the particles with a diameter of 5-15 mm are screened out to obtain recycled concrete coarse aggregate. The recycled concrete coarse aggregate is mixed with a saturated calcium bicarbonate solution at a ratio of 1g:20ml and stirred evenly, and then impregnated for 40 minutes. After completion, the recycled concrete coarse aggregate is filtered out and air-dried naturally for 1 day to obtain modified recycled concrete coarse aggregate.
[0038] (2) Take the following raw materials: 60 parts by weight of slag powder with a particle size of 250 mesh, 25 parts by weight of 42.5 ordinary Portland cement, 10 parts by weight of fly ash cenospheres, 40 parts by weight of the modified recycled concrete coarse aggregate of this embodiment, 70 parts by weight of sand, and 2 parts by weight of polycarboxylate superplasticizer (water reduction rate of 20%). The sand is river sand with a continuous gradation of particle size of 0.2 to 1.0 mm.
[0039] (3) Add the above raw materials to a mixer and dry mix for 5 minutes. Then, add mixing water at a water-cement ratio of 0.18 and mix for 3 minutes. Pour the resulting slurry into a mold for pressing (pressure 20 MPa, holding time 3 minutes). After completion, allow the resulting brick blanks to cure naturally for 28 days. During the curing period, spray water once every 24 hours, just enough to wet the surface of the brick blanks. The resulting recycled concrete aggregate insulating non-fired brick is then obtained.
[0040] 1. The compressive strength of the unfired bricks prepared in this embodiment was tested according to the "Test Methods for Masonry Bricks" (GB / T 2542-2012), and the result was 29.75 MPa.
[0041] 2. The slurry prepared in this embodiment was made into a specimen according to the "Standard for Thermal Conductivity Testing" (GB / T10294-2008), and then the thermal conductivity was tested using a thermal conductivity meter (model DR-3030, produced by Beijing Hangjian Huaye Technology Development Co., Ltd.). The result was 0.52 W / (m·K).
[0042] Example 3
[0043] A method for preparing a recycled concrete aggregate insulating non-fired brick includes the following steps:
[0044] (1) After crushing the waste building concrete, the particles with a diameter of 5-15 mm are screened out to obtain recycled concrete coarse aggregate. The recycled concrete coarse aggregate is mixed with a saturated calcium bicarbonate solution at a ratio of 1g:30ml and stirred evenly, and then impregnated for 70 minutes. After completion, the recycled concrete coarse aggregate is filtered out and naturally air-dried for 3 days to obtain modified recycled concrete coarse aggregate.
[0045] (2) Fly ash cenospheres were mixed with 1.5 mol / L sodium hydroxide solution at a ratio of 1 g: 15 ml and stirred until homogeneous. The mixture was then heated in a water bath to 40°C and held for 90 min. The fly ash cenospheres were then filtered out and mixed with saturated lime water at a ratio of 1 g: 10 ml. A hydrothermal reaction was then carried out under ultrasonic oscillation conditions. The hydrothermal reaction temperature was 160°C, the reaction time was 4.5 hours, and the ultrasonic power was 300 W. The solid product was then filtered out and dried in an oven at 130°C for 1 hour to obtain modified fly ash cenospheres.
[0046] (3) Take the following raw materials: 45 parts by weight of slag powder with a particle size of 250 mesh, 18 parts by weight of 42.5 ordinary Portland cement, 6 parts by weight of modified fly ash cenospheres in this embodiment, 30 parts by weight of modified recycled concrete coarse aggregate in this embodiment, 55 parts by weight of sand, and 1.0 part by weight of polycarboxylate superplasticizer (water reduction rate of 25%). The sand is river sand with a continuous gradation of particle size of 0.3 to 1.0 mm.
[0047] (4) Add the above raw materials to the mixer and dry mix for 5 minutes. Then, add mixing water at a water-cement ratio of 0.22 and mix for 2 minutes. Pour the resulting slurry into the mold for pressing (pressure 25 MPa, holding time 1.5 minutes). After completion, allow the brick blanks to cure naturally for 28 days. During the curing period, spray water once every 24 hours, just enough to wet the surface of the brick blanks. The resulting recycled concrete aggregate insulating non-fired brick is then obtained.
[0048] 1. The compressive strength of the unfired bricks prepared in this embodiment was tested according to the "Test Methods for Masonry Bricks" (GB / T 2542-2012), and the result was 36.87 MPa.
[0049] 2. The slurry prepared in this embodiment was made into a specimen according to the "Standard for Thermal Conductivity Testing" (GB / T10294-2008), and then the thermal conductivity was tested using a thermal conductivity meter (model DR-3030, produced by Beijing Hangjian Huaye Technology Development Co., Ltd.). The result was 0.33 W / (m·K).
[0050] Example 4
[0051] A method for preparing a recycled concrete aggregate insulating non-fired brick includes the following steps:
[0052] (1) Waste building concrete is crushed and screened to obtain particles with a particle size of 5-15 mm, thus obtaining recycled concrete coarse aggregate. The recycled concrete coarse aggregate is mixed with a saturated calcium bicarbonate solution at a ratio of 1 g: 20 ml and stirred evenly, then impregnated for 65 min. After completion, the recycled concrete coarse aggregate is filtered out and placed in an oven to dry at 50°C for 3 hours, thus obtaining modified recycled concrete coarse aggregate.
[0053] (2) Fly ash cenospheres were mixed with 3 mol / L sodium hydroxide solution at a ratio of 1 g: 8 ml and stirred until homogeneous. The mixture was then heated in a water bath to 55°C and held for 60 min. The fly ash cenospheres were then filtered out and mixed with saturated lime water at a ratio of 1 g: 5 ml. A hydrothermal reaction was then carried out under ultrasonic oscillation conditions. The hydrothermal reaction temperature was 200°C, the time was 3 hours, and the ultrasonic oscillation power was 500 W. The solid product was filtered out and dried in an oven at 90°C for 2 hours to obtain modified fly ash cenospheres.
[0054] (3) Take the following raw materials: 55 parts by weight of slag powder with a particle size of 250 mesh, 23 parts by weight of 42.5 ordinary Portland cement, 8 parts by weight of modified fly ash cenospheres in this embodiment, 35 parts by weight of modified recycled concrete coarse aggregate in this embodiment, 67 parts by weight of sand, and 1.8 parts by weight of sodium lignosulfonate water-reducing agent (water reduction rate of 15%). The sand is river sand with a continuous gradation of particle size of 0.3-1.0 mm.
[0055] (4) Add the above raw materials to the mixer and dry mix for 5 minutes. Then, add mixing water at a water-cement ratio of 0.22 and mix for 2 minutes. Pour the resulting slurry into the mold for pressing (pressure 35 MPa, holding time 1 minute). After completion, allow the brick blanks to cure naturally for 28 days. During the curing period, spray water once every 24 hours, just enough to wet the surface of the brick blanks. The resulting recycled concrete aggregate insulating non-fired brick is then obtained.
[0056] 1. The compressive strength of the unfired bricks prepared in this embodiment was tested according to the "Test Methods for Masonry Bricks" (GB / T 2542-2012), and the result was 38.31 MPa.
[0057] 2. The slurry prepared in this embodiment was made into a specimen according to the "Standard for Thermal Conductivity Testing" (GB / T10294-2008), and then the thermal conductivity was tested using a thermal conductivity meter (model DR-3030, produced by Beijing Hangjian Huaye Technology Development Co., Ltd.). The result was 0.31 W / (m·K).
[0058] Example 5
[0059] A method for preparing a recycled concrete aggregate insulating non-fired brick includes the following steps:
[0060] (1) After crushing the waste building concrete, the particles with a particle size of 5-15mm are screened out to obtain recycled concrete coarse aggregate.
[0061] (2) Take the following raw materials: 55 parts by weight of slag powder with a particle size of 300 mesh, 22 parts by weight of 42.5 ordinary Portland cement, 8.5 parts by weight of fly ash cenospheres, 36 parts by weight of recycled concrete coarse aggregate in this embodiment, 65 parts by weight of sand, and 1.5 parts by weight of polycarboxylate superplasticizer (water reduction rate of 22%). The sand is river sand with a continuous gradation of particle size of 0.2 to 1.0 mm.
[0062] (3) Add the above raw materials to a mixer and dry mix for 5 minutes. Then, add mixing water at a water-cement ratio of 0.2 and mix for 3 minutes. Pour the resulting slurry into a mold for pressing (pressure 30 MPa, holding time 2.5 minutes). After completion, allow the resulting brick blanks to cure naturally for 28 days. During the curing period, spray water once every 24 hours, just enough to wet the surface of the brick blanks. The resulting recycled concrete aggregate insulating non-fired brick is then obtained.
[0063] 1. The compressive strength of the unfired bricks prepared in this embodiment was tested according to the "Test Methods for Masonry Bricks" (GB / T 2542-2012), and the result was 21.54 MPa.
[0064] 2. The slurry prepared in this embodiment was made into a specimen according to the "Standard for Thermal Conductivity Testing" (GB / T10294-2008), and then the thermal conductivity was tested using a thermal conductivity meter (model DR-3030, produced by Beijing Hangjian Huaye Technology Development Co., Ltd.). The result was 0.49 W / (m·K).
[0065] Example 6
[0066] A method for preparing a recycled concrete aggregate insulating non-fired brick includes the following steps:
[0067] (1) After crushing the waste building concrete, the particles with a diameter of 5-15mm are screened out to obtain recycled concrete coarse aggregate. The recycled concrete coarse aggregate is mixed with clean water at a ratio of 1g:20ml and stirred evenly, and then soaked for 40min. After completion, the recycled concrete coarse aggregate is filtered out and air-dried naturally for 1 day to obtain modified recycled concrete coarse aggregate.
[0068] (2) Take the following raw materials: 60 parts by weight of slag powder with a particle size of 250 mesh, 25 parts by weight of 42.5 ordinary Portland cement, 10 parts by weight of fly ash cenospheres, 40 parts by weight of the modified recycled concrete coarse aggregate of this embodiment, 70 parts by weight of sand, and 2 parts by weight of polycarboxylate superplasticizer (water reduction rate of 20%). The sand is river sand with a continuous gradation of particle size of 0.2 to 1.0 mm.
[0069] (3) Add the above raw materials to a mixer and dry mix for 5 minutes. Then, add mixing water at a water-cement ratio of 0.18 and mix for 3 minutes. Pour the resulting slurry into a mold for pressing (pressure 20 MPa, holding time 3 minutes). After completion, allow the resulting brick blanks to cure naturally for 28 days. During the curing period, spray water once every 24 hours, just enough to wet the surface of the brick blanks. The resulting recycled concrete aggregate insulating non-fired brick is then obtained.
[0070] 1. The compressive strength of the unfired bricks prepared in this embodiment was tested according to the "Test Methods for Masonry Bricks" (GB / T 2542-2012), and the result was 23.06 MPa.
[0071] 2. The slurry prepared in this embodiment was made into a specimen according to the "Standard for Thermal Conductivity Testing" (GB / T10294-2008), and then the thermal conductivity was tested using a thermal conductivity meter (model DR-3030, produced by Beijing Hangjian Huaye Technology Development Co., Ltd.). The result was 0.54 W / (m·K).
[0072] Example 7
[0073] A method for preparing a recycled concrete aggregate insulating non-fired brick includes the following steps:
[0074] (1) Waste building concrete is crushed and screened to obtain particles with a particle size of 5-15 mm, thus obtaining recycled concrete coarse aggregate. The recycled concrete coarse aggregate is mixed with a saturated calcium bicarbonate solution at a ratio of 1 g: 20 ml and stirred evenly, then impregnated for 65 min. After completion, the recycled concrete coarse aggregate is filtered out and placed in an oven to dry at 50°C for 3 hours, thus obtaining modified recycled concrete coarse aggregate.
[0075] (2) Mix fly ash cenospheres with 3 mol / L sodium hydroxide solution at a ratio of 1 g: 8 ml and stir until homogeneous. Then heat in a water bath to 55°C and keep warm for 60 min. Filter out the fly ash cenospheres and dry them in an oven at 90°C for 2 hours to obtain modified fly ash cenospheres.
[0076] (3) Take the following raw materials: 55 parts by weight of slag powder with a particle size of 250 mesh, 23 parts by weight of 42.5 ordinary Portland cement, 8 parts by weight of modified fly ash cenospheres in this embodiment, 35 parts by weight of modified recycled concrete coarse aggregate in this embodiment, 67 parts by weight of sand, and 1.8 parts by weight of sodium lignosulfonate water-reducing agent (water reduction rate of 15%). The sand is river sand with a continuous gradation of particle size of 0.3-1.0 mm.
[0077] (4) Add the above raw materials to the mixer and dry mix for 5 minutes. Then, add mixing water at a water-cement ratio of 0.22 and mix for 2 minutes. Pour the resulting slurry into the mold for pressing (pressure 35 MPa, holding time 1 minute). After completion, allow the brick blanks to cure naturally for 28 days. During the curing period, spray water once every 24 hours, just enough to wet the surface of the brick blanks. The resulting recycled concrete aggregate insulating non-fired brick is then obtained.
[0078] 1. The compressive strength of the unfired bricks prepared in this embodiment was tested according to the "Test Methods for Masonry Bricks" (GB / T 2542-2012), and the result was 32.28 MPa.
[0079] 2. The slurry prepared in this embodiment was made into a specimen according to the "Standard for Thermal Conductivity Testing" (GB / T10294-2008), and then the thermal conductivity was tested using a thermal conductivity meter (model DR-3030, produced by Beijing Hangjian Huaye Technology Development Co., Ltd.). The result was 0.42 W / (m·K).
[0080] Example 8
[0081] A method for preparing a recycled concrete aggregate insulating non-fired brick includes the following steps:
[0082] (1) After crushing the waste building concrete, the particles with a diameter of 5-15 mm are screened out to obtain recycled concrete coarse aggregate. The recycled concrete coarse aggregate is mixed with a saturated calcium bicarbonate solution at a ratio of 1g:30ml and stirred evenly, and then impregnated for 70 minutes. After completion, the recycled concrete coarse aggregate is filtered out and naturally air-dried for 3 days to obtain modified recycled concrete coarse aggregate.
[0083] (2) Fly ash cenospheres and saturated lime water were mixed at a ratio of 1g:10ml and subjected to a hydrothermal reaction under ultrasonic oscillation conditions. The hydrothermal reaction temperature was 160℃, the time was 4.5 hours, and the ultrasonic power of the ultrasonic oscillation was 300W. After filtration, the solid product was placed in an oven and dried at 130℃ for 1 hour to obtain modified fly ash cenospheres.
[0084] (3) Take the following raw materials: 45 parts by weight of slag powder with a particle size of 250 mesh, 18 parts by weight of 42.5 ordinary Portland cement, 6 parts by weight of modified fly ash cenospheres in this embodiment, 30 parts by weight of modified recycled concrete coarse aggregate in this embodiment, 55 parts by weight of sand, and 1.0 part by weight of polycarboxylate superplasticizer (water reduction rate of 25%). The sand is river sand with a continuous gradation of particle size of 0.3 to 1.0 mm.
[0085] (4) Add the above raw materials to the mixer and dry mix for 5 minutes. Then, add mixing water at a water-cement ratio of 0.22 and mix for 2 minutes. Pour the resulting slurry into the mold for pressing (pressure 25 MPa, holding time 1.5 minutes). After completion, allow the brick blanks to cure naturally for 28 days. During the curing period, spray water once every 24 hours, just enough to wet the surface of the brick blanks. The resulting recycled concrete aggregate insulating non-fired brick is then obtained.
[0086] 1. The compressive strength of the unfired bricks prepared in this embodiment was tested according to the "Test Methods for Masonry Bricks" (GB / T 2542-2012), and the result was 29.14 MPa.
[0087] 2. The slurry prepared in this embodiment was made into a specimen according to the "Standard for Thermal Conductivity Testing" (GB / T10294-2008), and then the thermal conductivity was tested using a thermal conductivity meter (model DR-3030, produced by Beijing Hangjian Huaye Technology Development Co., Ltd.). The result was 0.51 W / (m·K).
[0088] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for preparing a recycled concrete aggregate insulating non-fired brick, characterized in that, Including the following steps: (1) The recycled concrete coarse aggregate is immersed in a saturated calcium bicarbonate solution. After the immersion is completed, the coarse aggregate is removed and dried to obtain pretreated coarse aggregate for later use. (2) Take the following raw materials: 45-62 parts by weight of slag powder, 18-25 parts by weight of silicate cement, 6-10 parts by weight of fly ash cenospheres, 30-40 parts by weight of the pretreated coarse aggregate, 55-70 parts by weight of sand, and 1-2 parts by weight of water-reducing agent; mix the above raw materials evenly, then add mixing water according to the water-cement ratio of 0.18-0.22, mix evenly, press the formed slurry into brick blanks and cure naturally to obtain non-fired bricks; wherein: the fly ash cenospheres are pretreated by the following method: mix the fly ash cenospheres with alkaline solution evenly and heat to the set temperature and keep warm; then separate the fly ash cenospheres, mix them with saturated lime water and carry out hydrothermal reaction under ultrasonic oscillation conditions; after completing the separation of solid products, dry them to obtain modified fly ash cenospheres.
2. The method for preparing recycled concrete aggregate insulating non-fired bricks according to claim 1, characterized in that, In step (1), the ratio of recycled concrete coarse aggregate to saturated calcium bicarbonate solution is 1g:20~30ml.
3. The method for preparing recycled concrete aggregate insulating non-fired bricks according to claim 1, characterized in that, In step (1), the soaking time is 40~70 min.
4. The method for preparing recycled concrete aggregate insulating non-fired bricks according to claim 1, characterized in that, In step (1), the drying method includes either natural air drying or heat drying.
5. The method for preparing recycled concrete aggregate insulating non-fired bricks according to claim 4, characterized in that, The natural air-drying time is 1 to 3 days; the heating and drying temperature is 50 to 75°C, and the time is 2 to 3 hours.
6. The method for preparing recycled concrete aggregate insulating non-fired bricks according to claim 1, characterized in that, In step (2), the water-reducing agent includes any one of polycarboxylate water-reducing agent, naphthalene-based water-reducing agent, and lignin sulfonate water-reducing agent.
7. The method for preparing recycled concrete aggregate insulating non-fired bricks according to claim 1, characterized in that, In step (2), the pressing pressure is 20~35MPa and the holding time is 1~3min.
8. The method for preparing recycled concrete aggregate insulating non-fired bricks according to claim 1, characterized in that, In the pretreatment, the ratio of fly ash celery beads to alkaline solution is 1g:8~15ml.
9. The method for preparing recycled concrete aggregate insulating non-fired bricks according to claim 1, characterized in that, In the pretreatment, the alkaline solution includes at least one of sodium hydroxide solution and potassium hydroxide solution.
10. The method for preparing recycled concrete aggregate insulating non-fired bricks according to claim 1, characterized in that, In the pretreatment, the concentration of the alkaline solution is 1.5~3 mol / L.
11. The method for preparing recycled concrete aggregate insulating non-fired bricks according to claim 1, characterized in that, In the pretreatment, the temperature is set to 40~55℃ and the holding time is 60~90min.
12. The method for preparing recycled concrete aggregate insulating non-fired bricks according to claim 1, characterized in that, In the pretreatment, the ratio of fly ash celery beads to saturated lime water is 1g:5~10ml.
13. The method for preparing recycled concrete aggregate insulating non-fired bricks according to claim 1, characterized in that, In the pretreatment, the hydrothermal reaction temperature is 160~200℃ and the time is 3~4.5 hours.
14. The method for preparing recycled concrete aggregate insulating non-fired bricks according to claim 1, characterized in that, In the pretreatment, the ultrasonic power of the ultrasonic oscillation is 300~500W.
15. The method for preparing recycled concrete aggregate insulating non-fired bricks according to claim 1, characterized in that, In the pretreatment, the drying temperature of the solid product is 90~130℃, and the drying time is 1~2 hours.