Carbonized recycled aggregate high-strength pervious concrete and preparation method thereof

Abstract

This invention provides a high-strength permeable concrete using carbonized recycled aggregate and its preparation method, comprising the following raw materials: 300-500 parts by weight of cement, 100-200 parts by weight of fly ash, 80-150 parts by weight of silica fume, 400-600 parts by weight of river sand, 1500-2500 parts by weight of the aggregate, 20-40 parts by weight of water-reducing agent, and 100-200 parts by weight of mixing water. The aggregate includes carbonized recycled concrete aggregate. Compared with existing technologies, this invention effectively solves the problem of poor load-bearing performance of recycled aggregate, effectively improves recycled aggregate through carbonization, broadens the application scenarios of high-strength permeable concrete using carbonized recycled aggregate, provides a solution for mitigating carbon emissions, and promotes the large-scale resource recycling of urban construction solid waste.

Description

Technical Field

[0001] This invention relates to the field of construction solid waste recycling technology, specifically to a high-strength permeable concrete made from recycled aggregate, its preparation method, and its application. Background Technology

[0002] Permeable concrete, also known as porous concrete or no-fines concrete, is a type of porous, lightweight concrete made by mixing aggregates (gravel), cement, reinforcing agents, and water in a specific ratio. Permeable concrete features a honeycomb structure with evenly distributed pores, formed by coarse aggregates coated with a thin layer of cement paste that bonds them together. This results in permeable concrete being breathable, permeable to water, and lightweight. Furthermore, permeable concrete pavement is a green building material that reduces the urban heat island effect, absorbs road noise, promotes rainwater runoff, and purifies water. Therefore, as a rainwater management device, permeable concrete pavement effectively controls urban rainwater runoff, making it a preferred permeable product in urban construction.

[0003] Currently, one of the challenges in the road construction industry is improving the strength of permeable bricks. To overcome this bottleneck, researchers have been using techniques such as adding polyacrylamide to adjust film-forming ability and adding steel fibers and surface coating slurry to reinforce aggregates to increase the strength of permeable concrete. However, since permeable concrete is inherently a porous system, how to prepare permeable concrete by reinforcing aggregates with cement paste while simultaneously ensuring its permeability remains a challenge. This approach not only increases construction costs and difficulty but also hinders its large-scale application in the road construction industry. Summary of the Invention

[0004] This invention provides a high-strength permeable concrete using carbonized recycled aggregate and its preparation method, effectively solving the technical challenge of low strength in permeable concrete caused by recycled aggregate, promoting the application of recycled concrete aggregate in permeable concrete preparation, and expanding the resource utilization pathways of carbonization technology. To achieve the above objectives, the technical solution of this invention is as follows.

[0005] This invention provides a high-strength permeable concrete using carbonized recycled aggregate, comprising the following raw materials:

[0006] The mixture comprises 300-500 parts by weight of cement, 100-200 parts by weight of fly ash, 80-150 parts by weight of silica fume, 400-600 parts by weight of river sand, 1500-2500 parts by weight of the aggregate, 20-40 parts by weight of water-reducing agent, and 100-200 parts by weight of mixing water, wherein the aggregate includes carbonized recycled concrete aggregate.

[0007] Furthermore, the aggregate content of the carbonized recycled concrete is not less than 50% of the aggregate.

[0008] Furthermore, the method for preparing carbonized recycled concrete aggregate includes:

[0009] The recycled aggregate is placed in a pressure tank and carbonized under conditions of 0.1 MPa pressure, 25°C temperature, 70% humidity and 99% carbon dioxide concentration to obtain carbonized recycled concrete aggregate.

[0010] Furthermore, the particle size of the recycled aggregate is 2–10 mm.

[0011] Furthermore, the particle size of the river sand is 0.5 mm to 1.18 mm.

[0012] Furthermore, the ratio of mixing water to water-reducing agent ranges from 0.18 to 0.20.

[0013] Furthermore, the cement is ordinary Portland cement.

[0014] Furthermore, the recycled aggregate is prepared from urban waste road aggregate.

[0015] Another aspect of the present invention discloses a method for preparing the above-mentioned high-strength permeable concrete using carbonized recycled aggregate, comprising:

[0016] Step 1: The recycled aggregate obtained by crushing the urban waste road aggregate is then screened to obtain recycled concrete aggregate of a specified particle size; after completion, the aggregate is separated to obtain pretreated recycled aggregate.

[0017] Step 2: Place the recycled aggregate into a pressure tank for carbonation to obtain carbonized recycled concrete aggregate.

[0018] Step 3: Mix the raw materials evenly according to the specified mixing time, and then press them into shape to obtain permeable concrete.

[0019] Furthermore, it also includes step 4: the permeable concrete is cured at room temperature for 28 days to obtain high-strength permeable concrete with carbonized recycled aggregate.

[0020] Compared with existing technologies, this invention effectively solves the problem of poor stress performance of recycled aggregates. It utilizes carbonization to effectively improve recycled aggregates, broadens the application scenarios of carbonized recycled aggregate high-strength permeable concrete, provides solutions for mitigating carbon emissions, and promotes the large-scale resource recycling of urban construction solid waste. Attached Figure Description

[0021] Figure 1 These are samples of carbonized recycled concrete aggregates from Examples 1-4 and Comparative Examples 1-4.

[0022] Figure 2 This is a schematic diagram of the pressure molding process for permeable concrete.

[0023] Figure 3This is a flowchart of the preparation process of high-strength permeable concrete using carbonized recycled aggregate according to the present invention. Detailed Implementation

[0024] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the implementation cases of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] This invention provides a high-strength permeable concrete using carbonized recycled aggregate, comprising the following raw materials:

[0027] The mixture comprises 300-500 parts by weight of cement, 100-200 parts by weight of fly ash, 80-150 parts by weight of silica fume, 400-600 parts by weight of river sand, 1500-2500 parts by weight of the aggregate, 20-40 parts by weight of water-reducing agent, and 100-200 parts by weight of mixing water, wherein the aggregate includes carbonized recycled concrete aggregate.

[0028] Optionally, the aggregate content of the carbonized recycled concrete is not less than 50% of the aggregate.

[0029] Optionally, the method for preparing carbonized recycled concrete aggregate includes:

[0030] The recycled aggregate is placed in a pressure tank and carbonized under conditions of 0.1 MPa pressure, 25°C temperature, 70% humidity and 99% carbon dioxide concentration to obtain carbonized recycled concrete aggregate.

[0031] Specifically, the recycled aggregate has a particle size of 2–10 mm.

[0032] Optionally, the particle size of the river sand is 0.5 mm to 1.18 mm.

[0033] Optionally, the ratio of mixing water to water-reducing agent is in the range of 0.18 to 0.20.

[0034] Optionally, the cement is ordinary Portland cement.

[0035] Specifically, the recycled aggregate is prepared from urban waste road aggregate.

[0036] This invention also provides a method for preparing high-performance carbonized recycled aggregate high-strength permeable concrete, comprising:

[0037] Add cement, fly ash, silica fume, sand, and water-reducing agent to the mixer, then mix slowly for 3 minutes and quickly for 3 minutes.

[0038] Add recycled aggregate and continue stirring for 3 minutes;

[0039] The molding mold for the mixture is made of steel mold, and a press is used to press it into shape under a load of 1 MPa. The mixture must be spread twice and compacted once.

[0040] To further illustrate the embodiments and effects of the present invention, embodiments 1-4 are listed below.

[0041] Example 1

[0042] A high-strength permeable concrete using carbonized recycled aggregate and its preparation method include the following steps:

[0043] (1) The recycled aggregate obtained by crushing urban waste road aggregate is then screened to obtain recycled concrete aggregate with an aggregate particle size of 2.36-5mm; after completion, the aggregate is separated to obtain pretreated recycled concrete aggregate.

[0044] (2) The pretreated recycled concrete aggregate was placed in a pressure tank and carbonized for 24 hours under the conditions of pressure of 0.1 MPa, temperature of 25℃, humidity of 70% and carbon dioxide concentration of 99% to obtain carbonized recycled concrete aggregate.

[0045] (3) Mix 404 parts by weight of cement, 173 parts by weight of fly ash, 110 parts by weight of silica fume, 531 parts by weight of river sand, 870 parts by weight of pretreated recycled concrete aggregate, 870 parts by weight of carbonized recycled concrete aggregate, 27 parts by weight of water-reducing agent and 123 parts by weight of mixing water evenly for the specified mixing time, and then press and mold to obtain permeable concrete.

[0046] The permeable concrete described in this embodiment was prepared into test specimens and cured in a water curing chamber for 28 days. Then, the compressive strength of the specimens was tested according to the "Technical Specification for Application of High-Strength Permeable Concrete with Carbonated Recycled Aggregate" (CJJT-253-2016), and the test result was 28.02 MPa.

[0047] Example 2

[0048] A high-strength permeable concrete using carbonized recycled aggregate and its preparation method include the following steps:

[0049] (1) The recycled aggregate obtained by crushing urban waste road aggregate is then screened to obtain recycled concrete aggregate with an aggregate particle size of 2.36-5mm; after completion, the aggregate is separated to obtain pretreated recycled concrete aggregate.

[0050] (2) The pretreated recycled concrete aggregate was placed in a pressure tank and carbonized for 24 hours under the conditions of pressure of 0.1 MPa, temperature of 25℃, humidity of 70% and carbon dioxide concentration of 99% to obtain carbonized recycled concrete aggregate.

[0051] (3) Mix 404 parts by weight of cement, 173 parts by weight of fly ash, 110 parts by weight of silica fume, 531 parts by weight of river sand, 1740 parts by weight of the carbonized recycled concrete aggregate, 27 parts by weight of water-reducing agent and 123 parts by weight of mixing water evenly and mix for the specified time. After pressing and molding, permeable concrete is obtained.

[0052] The permeable concrete described in this embodiment was prepared into test specimens and cured in a water curing chamber for 28 days. Then, the compressive strength of the specimens was tested according to the "Technical Specification for Application of High-Strength Permeable Concrete with Carbonated Recycled Aggregate" (CJJT-253-2016), and the test result was 32.74 MPa.

[0053] Example 3

[0054] A high-strength permeable concrete using carbonized recycled aggregate and its preparation method include the following steps:

[0055] (1) The recycled aggregate obtained by crushing urban waste road aggregate is then screened to obtain recycled concrete aggregate with an aggregate particle size of 5-10mm; after completion, the aggregate is separated to obtain pretreated recycled concrete aggregate.

[0056] (2) The pretreated recycled concrete aggregate was placed in a pressure tank and carbonized for 24 hours under the conditions of pressure of 0.1 MPa, temperature of 25℃, humidity of 70% and carbon dioxide concentration of 99% to obtain carbonized recycled concrete aggregate.

[0057] (3) Mix 404 parts by weight of cement, 173 parts by weight of fly ash, 110 parts by weight of silica fume, 531 parts by weight of river sand, 1111 parts by weight of pretreated recycled concrete aggregate, 1111 parts by weight of carbonized recycled concrete aggregate, 27 parts by weight of water-reducing agent and 123 parts by weight of mixing water evenly and mix for the specified time. After pressing and molding, permeable concrete is obtained.

[0058] The permeable concrete described in this embodiment was prepared into test specimens and cured in a water curing chamber for 28 days. Then, the compressive strength of the specimens was tested according to the "Technical Specification for Application of High-Strength Permeable Concrete with Carbonated Recycled Aggregate" (CJJT-253-2016), and the test result was 25.49 MPa.

[0059] Example 4

[0060] A high-strength permeable concrete using carbonized recycled aggregate and its preparation method include the following steps:

[0061] (1) The recycled aggregate obtained by crushing urban waste road aggregate is then screened to obtain recycled concrete aggregate with an aggregate particle size of 5-10mm; after completion, the aggregate is separated to obtain pretreated recycled concrete aggregate.

[0062] (2) The pretreated recycled concrete aggregate was placed in a pressure tank and carbonized for 24 hours under the conditions of pressure of 0.1 MPa, temperature of 25℃, humidity of 70% and carbon dioxide concentration of 99% to obtain carbonized recycled concrete aggregate.

[0063] (3) Mix 404 parts by weight of cement, 173 parts by weight of fly ash, 110 parts by weight of silica fume, 531 parts by weight of river sand, 2065 parts by weight of carbonized recycled concrete aggregate, 27 parts by weight of water-reducing agent and 123 parts by weight of mixing water evenly and mix for the specified time. After pressing and molding, permeable concrete is obtained.

[0064] The permeable concrete described in this embodiment was prepared into test specimens and cured in a water curing chamber for 28 days. Then, the compressive strength of the specimens was tested according to the "Technical Specification for Application of High-Strength Permeable Concrete with Carbonated Recycled Aggregate" (CJJT-253-2016), and the test result was 28.81 MPa.

[0065] Comparative Example 1

[0066] The concrete preparation of Comparative Example 1 includes the following steps:

[0067] (1) The aggregate obtained by crushing natural aggregate is then screened to obtain natural aggregate with a particle size of 2.36-5mm; after completion, the aggregate is separated to obtain pretreated aggregate;

[0068] (2) The natural aggregate is placed at room temperature and pressure and used directly in the test.

[0069] (3) Mix 404 parts by weight of cement, 173 parts by weight of fly ash, 110 parts by weight of silica fume, 531 parts by weight of river sand, 1740 parts by weight of the reconcrete aggregate, 27 parts by weight of water-reducing agent and 123 parts by weight of mixing water evenly for the specified mixing time, and then press and mold to obtain permeable concrete.

[0070] The permeable concrete described in this embodiment was prepared into test specimens and cured in a water curing chamber for 28 days. Then, the compressive strength of the specimens was tested according to the "Technical Specification for Application of High-Strength Permeable Concrete with Carbonated Recycled Aggregate" (CJJT-253-2016), and the test result was 45.59 MPa.

[0071] Comparative Example 2

[0072] The concrete preparation of Comparative Example 2 includes the following steps:

[0073] (1) The aggregate obtained by crushing natural aggregate is then screened to obtain natural aggregate with a particle size of 5-10 mm; after completion, the aggregate is separated to obtain pretreated aggregate;

[0074] (2) The natural aggregate is placed at room temperature and pressure and used directly in the test.

[0075] (3) Mix 404 parts by weight of cement, 173 parts by weight of fly ash, 110 parts by weight of silica fume, 531 parts by weight of river sand, 2065 parts by weight of the natural aggregate, 27 parts by weight of water-reducing agent and 123 parts by weight of mixing water evenly for the specified mixing time, and then press and mold to obtain permeable concrete.

[0076] The permeable concrete described in this embodiment was prepared into test specimens and cured in a water curing chamber for 28 days. Then, the compressive strength of the specimens was tested according to the "Technical Specification for Application of High-Strength Permeable Concrete with Carbonated Recycled Aggregate" (CJJT-253-2016), and the test result was 37.17 MPa.

[0077] Comparative Example 3

[0078] The concrete preparation of Comparative Example 3 includes the following steps:

[0079] (1) The recycled aggregate obtained by crushing urban waste road aggregate is then screened to obtain recycled concrete aggregate with an aggregate particle size of 2.36-5mm; after completion, the aggregate is separated to obtain pretreated recycled concrete aggregate.

[0080] (2) Mix 404 parts by weight of cement, 173 parts by weight of fly ash, 110 parts by weight of silica fume, 531 parts by weight of river sand, 1740 parts by weight of pretreated recycled concrete aggregate, 27 parts by weight of water-reducing agent and 123 parts by weight of mixing water evenly and mix for the specified time. After pressing and molding, permeable concrete is obtained.

[0081] The permeable concrete described in this embodiment was prepared into test specimens and cured in a water curing chamber for 28 days. Then, the compressive strength of the specimens was tested according to the "Technical Specification for Application of High-Strength Permeable Concrete with Carbonated Recycled Aggregate" (CJJT-253-2016), and the test result was 26.92 MPa.

[0082] Comparative Example 4

[0083] The concrete preparation of Comparative Example 4 includes the following steps:

[0084] (1) The recycled aggregate obtained by crushing urban waste road aggregate is then screened to obtain recycled concrete aggregate with an aggregate particle size of 5-10mm; after completion, the aggregate is separated to obtain pretreated recycled concrete aggregate.

[0085] (2) Mix 404 parts by weight of cement, 173 parts by weight of fly ash, 110 parts by weight of silica fume, 531 parts by weight of river sand, 2065 parts by weight of pretreated recycled concrete aggregate, 27 parts by weight of water-reducing agent and 123 parts by weight of mixing water evenly and mix for the specified time. After pressing and molding, permeable concrete is obtained.

[0086] The permeable concrete described in this embodiment was prepared into test specimens and cured in a water curing chamber for 28 days. Then, the compressive strength of the specimens was tested according to the "Technical Specification for Application of High-Strength Permeable Concrete with Carbonated Recycled Aggregate" (CJJT-253-2016), and the test result was 24.98 MPa.

[0087] Comparative Example 5

[0088] The concrete preparation of Comparative Example 5 includes the following steps:

[0089] (1) The recycled aggregate obtained by crushing urban waste road aggregate is then screened to obtain recycled concrete aggregate with an aggregate particle size of 2.36-5mm; after completion, the aggregate is separated to obtain pretreated recycled concrete aggregate.

[0090] (2) The pretreated recycled concrete aggregate was placed in a pressure tank and carbonized for 24 hours under the conditions of pressure of 0.1 MPa, temperature of 25℃, humidity of 70% and carbon dioxide concentration of 99% to obtain carbonized recycled concrete aggregate.

[0091] (3) Mix 404 parts by weight of cement, 173 parts by weight of fly ash, 110 parts by weight of silica fume, 531 parts by weight of river sand, 1740 parts by weight of carbonized recycled concrete aggregate, 27 parts by weight of water-reducing agent and 123 parts by weight of mixing water evenly and mix for the specified time. Permeable concrete is obtained without pressure molding.

[0092] The permeable concrete described in this embodiment was prepared into test specimens and cured in a water curing chamber for 28 days. Then, the compressive strength of the specimens was tested according to the "Technical Specification for Application of Recycled Aggregate Permeable Concrete" (CJJT-253-2016), and the test result was 29.83 MPa.

[0093] Comparative Example 6

[0094] The concrete preparation of Comparative Example 6 includes the following steps:

[0095] (1) The recycled aggregate obtained by crushing urban waste road aggregate is then screened to obtain recycled concrete aggregate with an aggregate particle size of 5-10mm; after completion, the aggregate is separated to obtain pretreated recycled concrete aggregate.

[0096] (2) The pretreated recycled concrete aggregate was placed in a pressure tank and carbonized for 24 hours under the conditions of pressure of 0.1 MPa, temperature of 25℃, humidity of 70% and carbon dioxide concentration of 99% to obtain carbonized recycled concrete aggregate.

[0097] (3) Mix 404 parts by weight of cement, 173 parts by weight of fly ash, 110 parts by weight of silica fume, 531 parts by weight of river sand, 2065 parts by weight of carbonized recycled concrete aggregate, 27 parts by weight of water-reducing agent and 123 parts by weight of mixing water evenly and mix for the specified time. Permeable concrete is obtained without pressure molding.

[0098] The permeable concrete described in this embodiment was prepared into test specimens and cured in a water curing chamber for 28 days. Then, the compressive strength of the specimens was tested according to the "Technical Specification for Application of Recycled Aggregate Permeable Concrete" (CJJT-253-2016), and the test result was 25.59 MPa.

[0099] Performance testing

[0100] After 28 days of curing, the concrete in Examples 1-4 and Comparative Examples 1-4 underwent tests to measure the compressive strength, density, permeability coefficient, and effective porosity of the permeable concrete, referring to the "Technical Specification for Application of High-Strength Permeable Concrete with Carbonated Recycled Aggregate (CJJT-253-2016)". The test results are shown in the table below.

[0101] Physical and mechanical properties of high-strength permeable concrete using carbonized recycled aggregate

[0102]

[0103] Comparing the test results of Examples 1-4 with those of Comparative Examples 1-4, the results show that the particle size performance of carbonized fine aggregate is better than that of carbonized coarse aggregate. As the replacement rate of carbonized recycled aggregate increases, the performance of permeable concrete improves. When the content of carbonized recycled aggregate is 100%, the 28-day compressive strength of permeable concrete prepared with aggregate particle sizes of 2.36-5mm and 5-10mm increases by 21.62% and 15.32%, respectively, effectively improving the mechanical properties while still ensuring that the permeability coefficient meets the specifications.

[0104] In addition, carbonization of recycled concrete aggregates can effectively fix carbon, as shown in the table below.

[0105]

[0106] In summary, the beneficial effects of the design method for high-performance carbonized recycled aggregate high-strength permeable concrete provided by this invention are as follows:

[0107] 1. The permeable concrete of the present invention uses construction waste aggregate as raw material, and after carbonization treatment, it is used as aggregate for permeable concrete, which alleviates the problem of degradation of the strength of permeable concrete by recycled aggregate.

[0108] 2. Based on the different road application scenarios, and using high-performance cement-based materials with low water-cement ratio, the four sets of examples significantly improved the mechanical properties and permeability of carbonized recycled aggregate high-strength permeable concrete by incorporating a high proportion of recycled concrete aggregate, meeting the application requirements. At the same time, the volume stability performance was guaranteed. In addition, the four sets of examples and the six sets of comparative examples showed that the performance of fine aggregate was stronger than that of coarse aggregate. Furthermore, the pressurization scheme of the present invention can effectively improve the compressive strength of concrete.

[0109] 3. By designing the mix proportion of high-strength permeable concrete with carbonized recycled aggregate, the influence of high-performance cement matrix and recycled aggregate content on the mechanical properties and volume stability of permeable concrete can be analyzed, thereby preparing a high-strength permeable concrete with carbonized recycled aggregate that achieves comprehensive mechanical properties, permeability, and volume stability.

[0110] 4. This invention broadens the application scenarios of high-strength permeable concrete with carbonized recycled aggregate, provides a solution for alleviating carbon emissions, and promotes the large-scale resource reuse of urban construction solid waste.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading this application specification, they can still modify or make equivalent substitutions to the specific implementation of the present invention, but these modifications or changes do not depart from the protection scope of the pending claims of the present invention.

Claims

1. A high-strength permeable concrete using carbonized recycled aggregate, characterized in that, The carbonized recycled aggregate high-strength permeable concrete includes the following raw materials: The mixture comprises 300-500 parts by weight of cement, 100-200 parts by weight of fly ash, 80-150 parts by weight of silica fume, 400-600 parts by weight of river sand, 1500-2500 parts by weight of aggregate, 20-40 parts by weight of water-reducing agent, and 100-200 parts by weight of mixing water. The aggregate is carbonized recycled concrete aggregate; the particle size of the carbonized recycled concrete aggregate is 2.36-5 mm; and the particle size of the river sand is 0.5 mm to 1.18 mm. The carbonized recycled concrete aggregate is prepared from urban waste road aggregate; the urban waste road aggregate is crushed to obtain recycled aggregate, and then screened to obtain recycled concrete aggregate of a specified particle size; after completion, the recycled concrete aggregate is separated to obtain pretreated recycled aggregate. The pretreated recycled aggregate is placed in a pressure tank and carbonized under the conditions of 0.1 MPa pressure, 25°C temperature, 70% humidity and 99% carbon dioxide concentration to obtain carbonized recycled concrete aggregate. The preparation method of the carbonized recycled aggregate high-strength permeable concrete is as follows: the raw materials are mixed evenly and stirred for a specified time, and then pressed and molded to obtain permeable concrete; the pressing is performed by a press with a load of 1 MPa; the permeable concrete is cured at room temperature for 28 days to obtain carbonized recycled aggregate high-strength permeable concrete.

2. The high-strength permeable concrete using carbonized recycled aggregate according to claim 1, characterized in that, The ratio of mixing water to water-reducing agent is in the range of 0.18 to 0.

20.

3. The high-strength permeable concrete using carbonized recycled aggregate according to claim 1, characterized in that, The cement is ordinary Portland cement.

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