A method for preparing a water permeable brick by using dry desulfurization ash-waste concrete recycled powder-waste clay brick powder-steel slag-mixing station wastewater

Abstract

This invention discloses a method for preparing permeable bricks using dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, and batching plant wastewater. The raw materials are: 10-20 parts dry desulfurization ash; 10-20 parts recycled waste concrete powder; 5-10 parts waste clay brick powder; 50-70 parts steel slag; 10-20 parts batching plant wastewater; and 0.05-0.15 parts starch dextrin. The steel slag, 1 / 10 of the batching plant wastewater, and starch dextrin are weighed according to the proportions and placed in a mixer for 3-5 minutes to pre-wet and coat the steel slag aggregate. Then, the dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, and 9 / 10 of the batching plant wastewater are added and the mixture is stirred for another 2-3 minutes. The mixture is poured into brick molds, compacted under a pressure of 5-10 MPa, demolded, covered with geotextile, and cured for 7-14 days. The product of this invention can be used for paving sidewalks and non-heavy-load traffic surfaces, as well as for courtyard wall construction and decoration.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a method for preparing permeable bricks using dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, and wastewater from a mixing plant. Background Technology

[0002] Permeable pavement has been a major form of road surface in my country's "sponge city" development over the past 5-10 years. Permeable materials are those through which water can easily flow under its own weight without pressure. The preparation methods for permeable cement concrete and permeable asphalt concrete mainly involve mixing cement slurry or asphalt slurry with coarse aggregate in a certain proportion, then pouring the mixture to create concrete with large interconnected pores. Using this mix ratio, the concrete is poured into brick molds to produce permeable bricks. Permeable bricks can be used not only for paving roads, such as sidewalks or low-traffic-load pavements, but also for building courtyard walls, which are not only aesthetically pleasing but also allow climbing vines to retain rainwater.

[0003] In addition, a large amount of solid waste has high emissions, low resource utilization, or low value. For example, the dry desulfurization ash produced during the sintering process of steel plants or the removal of sulfur dioxide in the flue gas circulating bed of power plants has an annual by-product of 20-30 million tons, most of which is difficult to utilize, and a small amount is used to produce low-strength blocks. Another example is that after waste concrete is crushed and screened, generally only the useful recycled coarse aggregate and recycled fine aggregate are collected for the production of recycled concrete, while the fine powder is often discarded without being utilized due to its low hydration reaction activity. Summary of the Invention

[0004] Based on this, the purpose of this invention is to provide a method for preparing permeable bricks using dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, and wastewater from concrete mixing plants. This method utilizes the resources of dry desulfurization ash, recycled powder from waste concrete processed from construction sites, waste clay brick powder from waste clay brick processing, steel slag from steel plants, and wastewater from concrete mixing plants, turning waste into treasure.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] This invention provides a permeable brick, which is composed of dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, wastewater from a mixing plant, and starch dextrin. The weight proportions of each component are as follows:

[0007]

[0008]

[0009] Preferably, the weight proportions of each component of the permeable brick are as follows:

[0010]

[0011] Preferably, the dry desulfurization ash is a mixture of calcium oxide, calcium hydroxide, and calcium trioxide produced during the sulfur dioxide removal process in the sintering process of steel plants or the flue gas circulating bed of power plants. This mixture contains calcium sulfite hemihydrate, calcium sulfite dihydrate, and calcium sulfate dihydrate, and is mixed with fly ash. The SO3 content is not less than 30.0%, and the specific surface area is not less than 300 m². 2 / kg.

[0012] Preferably, the waste concrete recycled powder is the powder obtained by crushing and screening waste concrete to remove coarse and fine aggregates, with a 0.08mm square hole sieve residue of no more than 8.0%, CaO content of no less than 40%, and SiO2 content of no less than 20%.

[0013] Preferably, the waste clay powder is a powder obtained by crushing and screening waste clay bricks, with a 0.08mm square hole sieve residue of no more than 3.0%, CaO content of no less than 10%, SiO2 content of no less than 40%, and Al2O3 content of no less than 15%.

[0014] Preferably, the steel slag is waste slag from steel plants, with a particle size of 5-15mm, qualified autoclaving stability, f-CaO content not exceeding 2.0%, and MgO content not exceeding 10%.

[0015] Preferably, the wastewater from the mixing plant is the wastewater collected after cleaning the concrete mixer and concrete transport vehicles at the mixing plant, with a suspended solids content of no more than 5% and a pH value of no less than 7.0 and no more than 13.5.

[0016] Preferably, the starch dextrin is a white powder with a viscosity of 5,000-20,000 MPa.s.

[0017] This invention also provides a method for preparing permeable bricks using dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, and batching plant wastewater, comprising the following steps:

[0018] (1) Weigh out steel slag, 1 / 10 of the batching plant wastewater and starch dextrin according to the proportion, put them into the mixer, and mix for 3-5 minutes to pre-wet and coat the steel slag aggregate with slurry. Then add dry desulfurization ash, waste concrete recycled powder, waste clay brick powder and 9 / 10 of the batching plant wastewater, put them into the mixer, and continue mixing for 2-3 minutes to obtain the mixture.

[0019] (2) Pour the mixture into a brick mold, apply a pressure of 5-10 MPa, compact it, demold it, cover it with geotextile, and cure it for 7-14 days to obtain the final product.

[0020] In the permeable bricks of this invention, the recycled waste concrete powder is mainly composed of about 80% cement stone hardened slurry powder, with another 20% stone powder, and contains a small amount of unhydrated cement. The wastewater from the mixing plant contains a small amount of cement slurry. These cement components hydrate to form hydrated calcium silicate, calcium hydroxide, and hydrated calcium sulfoaluminate; on the other hand, they will co-activate the clay brick powder with the dry desulfurization ash. The main principle is as follows: the dry desulfurization ash, mainly composed of calcium sulfate dihydrate, calcium sulfite hemihydrate, and calcium sulfite dihydrate, formed by the reaction of calcium oxide and calcium hydroxide with SO3 in flue gas, and containing a small amount of unreacted calcium oxide and calcium hydroxide, activates the active silica and active alumina in the recycled waste concrete powder and waste clay brick powder. Through hydration, hydrated calcium silicate and high-sulfur hydrated calcium sulfoaluminate are formed, contributing to the setting, hardening, and strength development of the slurry. The residual calcium oxide and calcium hydroxide in the dry desulfurization ash participate in the formation of high-sulfur hydrated calcium sulfoaluminate. The flue gas from dry desulfurization in power plants also contains a small amount of fly ash. Fly ash itself has pozzolanic activity, reacting with calcium sulfate dihydrate, calcium sulfite hemihydrate, calcium sulfite dihydrate, calcium oxide, and calcium hydroxide to form hydrated calcium silicate and high-sulfur hydrated calcium sulfoaluminate, which contribute to the setting, hardening, and strength development of the slurry. The high-sulfur hydrated calcium sulfoaluminate crystals overlap and interweave, while the hydrated calcium silicate gel fills the pores formed by these crystal overlaps and interweaving, generating strength. With prolonged wet curing time, more and more hydration products are generated, the structure becomes denser, the pore size becomes finer, and the strength increases.

[0021] In the preparation method of permeable bricks of the present invention, the steel slag is premixed with concrete in step (1) to increase the water viscosity on the surface of the steel slag particles, so that the slurry can easily adhere to the surface of the steel slag particles when they are mixed together. In step (2), pressure molding is used to ensure the compactness of the point contact between the steel slag particles and to solidify the residual pressure in the permeable brick, thereby further improving the compressive strength of the permeable brick.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] (1) This invention addresses the challenges of treating and utilizing dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, and wastewater from mixing plants. It organically combines these materials and, in conjunction with the current demand for permeable bricks in sponge city construction, develops a method for preparing permeable bricks using dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, and wastewater from mixing plants. This method can be used directly in concrete mixing plants to establish production lines and carry out production. The products can be used for paving sidewalks and non-heavy-load traffic surfaces, as well as for courtyard wall construction and decoration, and have broad application prospects.

[0024] (2) This invention does not add cement separately, but utilizes the cement components contained in the wastewater and waste concrete powder of the mixing plant, and makes large-volume use of dry desulfurization ash that is difficult to dispose of, and co-disposes of waste clay brick powder and steel slag. It takes advantage of the high hardness of steel slag particles, which not only has a high waste utilization rate and effectively saves natural resources, but also has the advantage of reducing carbon, which is conducive to energy conservation, emission reduction and carbon tax reduction. Attached Figure Description

[0025] Figure 1 The image shows a sample of permeable bricks produced using dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, and wastewater from a mixing plant, as shown in the example.

[0026] Figure 2 The image shows a real-life example of a courtyard wall constructed using permeable bricks made from dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, and wastewater from a mixing plant. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0028] The raw materials used in the following examples include dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, batching plant wastewater, and starch dextrin, wherein:

[0029] Dry desulfurization ash is produced during the sulfur dioxide removal process in the sintering process of steel plants or the flue gas circulating bed of power plants. It is generated by the reaction of calcium oxide and calcium hydroxide with sulfur trioxide, producing calcium sulfite hemihydrate, calcium sulfite dihydrate, and calcium sulfate dihydrate, or a mixture of the above substances and fly ash. The SO3 content is not less than 30.0%, and the specific surface area is not less than 300 m². 2 / kg.

[0030] Waste concrete recycled powder is the powder obtained after waste concrete has been crushed, screened, and coarse and fine aggregates have been removed. Its residue on a 0.08mm square hole sieve is no more than 8.0%, CaO content is no less than 40%, and SiO2 content is no less than 20%.

[0031] Waste clay powder is a powder obtained by crushing and screening waste clay bricks. Its residue on a 0.08mm square hole sieve is no more than 3.0%, CaO content is no less than 10%, SiO2 content is no less than 40%, and Al2O3 content is no less than 15%.

[0032] Steel slag is waste residue from steel plants. Its particle size is 5-15mm, its autoclaving stability is qualified, its f-CaO content is not greater than 2.0%, and its MgO content is not greater than 10%.

[0033] Wastewater from a batching plant is the wastewater collected after cleaning the concrete mixer and concrete transport trucks. Its suspended solids content is no more than 5%, and its pH value is no less than 7.0 and no more than 13.5.

[0034] Starch dextrin is a commercially available white powder with a viscosity of 5,000-20,000 MPa.s.

[0035] Example 1

[0036] This embodiment provides a method for preparing permeable bricks using dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, and batching plant wastewater. The weight ratio of each component is as follows: 10 parts dry desulfurization ash; 10 parts recycled waste concrete powder; 5 parts waste clay brick powder; 50 parts steel slag; 10 parts batching plant wastewater; and 0.05 parts starch dextrin. The preparation method is as follows: 1) Weigh the steel slag, batching plant wastewater, and starch dextrin according to the ratio, put them into a mixer and stir for 3 minutes, then add the dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, and 9 / 10 of the batching plant wastewater, and continue stirring for 2 minutes; 2) Pour the permeable brick mixture into a brick mold, apply a pressure of 5 MPa, compact, demold, cover with geotextile, and cure for 7 days to obtain the final product.

[0037] Example 2

[0038] This embodiment provides a method for preparing permeable bricks using dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, and batching plant wastewater. The weight ratio of each component is as follows: 15 parts dry desulfurization ash; 15 parts recycled waste concrete powder; 7 parts waste clay brick powder; 60 parts steel slag; 15 parts batching plant wastewater; and 0.08 parts starch dextrin. The preparation method is as follows: 1) Weigh the steel slag, batching plant wastewater, and starch dextrin according to the ratio, put them into a mixer and stir for 2 minutes, then add the dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, and 9 / 10 of the batching plant wastewater, and continue stirring for 4 minutes; 2) Pour the permeable brick mixture into a brick mold, apply a pressure of 7 MPa, compact, demold, cover with geotextile, and cure for 10 days.

[0039] Example 3

[0040] This embodiment provides a method for preparing permeable bricks using dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, and batching plant wastewater. The weight ratio of each component is as follows: 20 parts dry desulfurization ash; 20 parts recycled waste concrete powder; 10 parts waste clay brick powder; 70 parts steel slag; 20 parts batching plant wastewater; and 0.15 parts starch dextrin. The preparation method is as follows: 1) Weigh the steel slag, batching plant wastewater, and starch dextrin according to the ratio, put them into a mixer and stir for 5 minutes. Then add the dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, and 9 / 10 of the batching plant wastewater, and continue stirring for 3 minutes. 2) Pour the permeable brick mixture into a brick mold, apply a pressure of 10 MPa, compact, demold, cover with geotextile, and cure for 7 days.

[0041] The performance test results of the permeable bricks prepared in Examples 1 to 3 are shown in Table 1.

[0042] Table 1

[0043]

[0044] In summary, this invention organically combines dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, batching plant wastewater, and starch dextrin to prepare permeable bricks. This method can be directly used in concrete batching plants, establishing production lines and conducting production. The products are directly used for permeable pavements and residential courtyard construction. Furthermore, no additional cement is added. The cement components contained in the batching plant wastewater and waste concrete powder are utilized, along with a large amount of difficult-to-dispose-of dry desulfurization ash, and the waste clay brick powder and steel slag are co-processed. The high particle hardness of the steel slag is leveraged, resulting in a high waste utilization rate, effective conservation of natural resources, and carbon reduction advantages.

[0045] The above description is merely a preferred embodiment of the present invention, but the present invention should not be limited to the content disclosed in this embodiment. Therefore, any equivalent or modified versions made without departing from the spirit of the present invention fall within the scope of protection of the present invention.

Claims

1. A method for preparing permeable bricks using dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, and batching plant wastewater, characterized in that, The permeable brick is composed of dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, wastewater from the mixing plant, and starch dextrin. The weight proportions of each component are as follows: 10-20 parts of dry desulfurization ash; 10-20 parts of recycled waste concrete powder; 5-10 parts of waste clay brick powder; 50-70 parts steel slag; 10-20 portions of wastewater from the mixing plant; Starch dextrin 0.05-0.15 parts; The method includes the following steps: (1) Weigh out steel slag, 1 / 10 of the batching plant wastewater and starch dextrin according to the proportion, put them into the mixer, and stir for 3-5 minutes to pre-wet and coat the steel slag aggregate with slurry. Then add dry desulfurization ash, waste concrete recycled powder, waste clay brick powder and 9 / 10 of the batching plant wastewater, put them into the mixer, and continue to stir for 2-3 minutes to obtain the mixture. (2) The mixture is poured into a brick mold, pressure of 5-10 MPa is applied, compacted, demolded, covered with geotextile, and cured for 7-14 days to obtain the final product.

2. The method for preparing permeable bricks using dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, and batching plant wastewater according to claim 1, characterized in that, The weight proportions of each component of the permeable brick are as follows: 10-15 parts of dry desulfurization ash; 15-20 parts of recycled waste concrete powder; 5-8 parts of waste clay brick powder; 50-60 parts steel slag; 10-15 portions of wastewater from the mixing plant; Starch dextrin 0.05-0.10 parts.

3. The method for preparing permeable bricks using dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, and batching plant wastewater according to claim 1, characterized in that, The dry desulfurization ash is produced during the sulfur dioxide removal process in the sintering process of steel plants or the flue gas circulating bed of power plants. It is generated by the reaction of calcium oxide and calcium hydroxide with sulfur dioxide, producing a mixture containing calcium sulfite hemihydrate, calcium sulfite dihydrate, and calcium sulfate dihydrate, or a mixture of these components with fly ash. The SO3 content is not less than 30.0%, and the specific surface area is not less than 300 m². 2 / kg.

4. The method for preparing permeable bricks using dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, and batching plant wastewater according to claim 1, characterized in that, The recycled waste concrete powder is the powder obtained by crushing and screening waste concrete to remove coarse and fine aggregates. Its residue on a 0.08mm square hole sieve is no more than 8.0%, its CaO content is no less than 40%, and its SiO2 content is no less than 20%.

5. The method for preparing permeable bricks using dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, and batching plant wastewater according to claim 1, characterized in that, The waste clay brick powder is a powder obtained by crushing and screening waste clay bricks. Its residue on a 0.08 mm square hole sieve is no more than 3.0%, its CaO content is no less than 10%, its SiO2 content is no less than 40%, and its Al2O3 content is no less than 15%.

6. The method for preparing permeable bricks using dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, and batching plant wastewater according to claim 1, characterized in that, The steel slag is waste slag from steel plants, with a particle size of 5-15 mm, qualified autoclaving stability, f-CaO content not exceeding 2.0%, and MgO content not exceeding 10%.

7. The method for preparing permeable bricks using dry desulfurization ash, recycled waste concrete powder, waste clay brick powder, steel slag, and batching plant wastewater according to claim 1, characterized in that, The wastewater from the mixing plant is the wastewater collected after cleaning the concrete mixer and concrete transport vehicles. Its suspended solids content is no more than 5%, and its pH value is no less than 7.0 and no more than 13.5.

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