All-solid-waste pervious concrete and preparation method thereof

Abstract

The invention provides all-solid-waste pervious concrete and a preparation method thereof, and the all-solid-waste pervious concrete is prepared from the following raw materials in parts by mass: 65-70 parts of waste concrete recycled coarse aggregate, 20-25 parts of activated coal gangue composite precursor, 5-15 parts of solid alkaline material and water. The mass of the solid alkaline material accounts for 20-30% of the mass of the activated coal gangue composite precursor, and the mass of the water accounts for 30-40% of the mass of the activated coal gangue composite precursor; the activated coal gangue composite precursor specifically comprises the following components in parts by weight: 60-75 parts of activated coal gangue; 10 to 20 parts of fly ash; 10-25 parts of granulated blast furnace slag powder; and 1-2 parts of a water reducing agent. The solid alkaline material specifically comprises the following components in parts by weight: 10-20 parts of flaky sodium hydroxide; 30-40 parts of instant sodium silicate; and 40-60 parts of alkaline residue micro powder. The pervious concrete with high strength and good water permeability is prepared.

Description

Technical Field

[0001] This application relates to the technical field of solid waste utilization, and particularly relates to a fully solid waste permeable concrete and a preparation method thereof. Background Art

[0002] Permeable concrete is an important part of sponge city construction. It has the characteristics of many pores, water permeability and air permeability, and is widely used in sidewalks and parking lots. Commercially available permeable concrete uses cement as a gelling material and natural crushed stone as an aggregate, consuming mineral resources and increasing carbon emissions.

[0003] In industrial production, solid wastes such as coal gangue, fly ash, granulated blast furnace slag powder, and alkali slag are generated and stacked in the open air, occupying land and polluting the environment. The treatment of waste concrete generated in the civil construction industry is difficult, and there is an urgent need for resource utilization. Summary of the Invention

[0004] The purpose of this application is to provide a fully solid waste permeable concrete and a preparation method thereof for the problems of insufficient utilization and consumption of solid wastes in the prior art.

[0005] In the first aspect, this application provides a fully solid waste permeable concrete. Calculated by mass fraction, the raw materials include 65 - 75 parts of recycled coarse aggregate of waste concrete, 20 - 30 parts of activated coal gangue composite precursor, 5 - 10 parts of solid alkaline material, and water;

[0006] The activated coal gangue composite precursor specifically includes the following components by weight: 60 - 75 parts of activated coal gangue; 10 - 20 parts of fly ash; 10 - 25 parts of granulated blast furnace slag powder; 1 - 2 parts of water reducing agent.

[0007] The solid alkaline material specifically includes the following components by weight: 10 - 20 parts of flaky sodium hydroxide; 30 - 40 parts of instant sodium silicate; 40 - 60 parts of alkali slag fine powder.

[0008] Further, the recycled coarse aggregate of waste concrete is the product after the waste concrete is crushed and screened. The particle size range of the recycled coarse aggregate of waste concrete is 5 - 10 mm, the crushing value is less than 10%, and the micro powder content is less than 1%.

[0009] Further, the activated coal gangue is the powder obtained by calcining washed coal gangue at 800 - 1000 °C, grinding it finely and screening it with a particle size less than 0.075 mm.

[0010] Further, the granulated blast furnace slag powder is commercially available S95 grade granulated blast furnace slag powder.

[0011] Further, the fly ash is commercially available secondary fly ash.

[0012] Further, the water reducing agent is commercially available polycarboxylic acid high-performance water reducing agent.

[0013] Further, the flaky sodium hydroxide is commercially available flaky sodium hydroxide with a purity of 98%.

[0014] Further, the instant soluble sodium silicate is commercially available instant soluble sodium silicate with a purity of 95%.

[0015] Further, the alkali residue fine powder is an alkaline waste residue discharged during the production of alkali and alkali treatment in industrial production, and the pH value of its 10-fold aqueous solution by mass ratio is greater than 11.

[0016] In a second aspect, the present application also provides a method for preparing the above-mentioned all-solid waste permeable concrete, including the following steps:

[0017] S1. Weigh the flaky sodium hydroxide, instant soluble sodium silicate and alkali residue fine powder in a dry state according to the proportion, put them into a powder mixer for mixing to obtain a uniform solid alkaline material;

[0018] S2. Weigh the activated coal gangue, fly ash, granulated blast furnace slag powder and water reducer in a dry state according to the proportion, put them into a powder mixer for mixing to obtain a uniform activated coal gangue composite precursor;

[0019] S3. Put the solid alkaline material obtained in S1 into a concrete mixer, add water according to the proportion and stir evenly;

[0020] S4. Put the activated coal gangue composite precursor obtained in S2 into the mixer in S3 according to the proportion and stir evenly;

[0021] S5. Put the recycled coarse aggregate of waste concrete into the mixer in S4 according to the proportion and stir evenly to obtain the finished product of all-solid waste permeable concrete.

[0022] Further, the mixing time in step S1 is not less than 3 minutes, and the rotation speed is 20 - 30 rpm / min.

[0023] Further, the stirring time in step S2 is not less than 5 minutes, and the rotation speed is 20 - 30 rpm / min.

[0024] Further, the stirring time in step S3 is 3 - 5 minutes.

[0025] Further, the stirring time in step S4 is 3 - 5 minutes.

[0026] Further, the stirring time in step S5 is 2 - 3 minutes.

[0027] Coal gangue is a solid waste discharged during the coal mining process and coal washing process. High-temperature calcination can remove the carbon component in coal gangue and the hydroxyl groups contained in kaolinite, and the Si—O structure and Al—O tetrahedral structure change, generating more Al 2 O3 , SiO 2 , greatly improving the activation degree of coal gangue. The addition of fly ash and granulated blast furnace slag powder can adjust the fluidity and early strength of permeable concrete.

[0028] Alkaline materials can stimulate the mineral activity of the activated coal gangue composite precursor. When the alkali contacts the activated coal gangue composite precursor particles, OH - reacts with the silicate on the surface of fly ash particles, and the -Si-O-Si- or -Si-O-Al- in the silicate breaks, releasing active ions such as Si 4+ and Al 3+ etc., and at the same time forms different complexes, such as [Al(OH)4] - , [Al(OH)6] 3- , [SiO(OH)3] - , [SiO(OH)2] 2- and [SiO3(OH)] 3- . These substances are not stable and will further react with each other to form low-polymer gels. The low polymers combine with each other to form high-polymer gels with a three-dimensional network structure. Finally, the gels gradually harden to form cementitious materials.

[0029] Advantages of this application: This application proposes a fully solid waste permeable concrete. This permeable concrete uses activated coal gangue as the basic raw material, uniformly mixes it with fly ash, granulated blast furnace slag powder, solid alkaline materials and water, and uses recycled coarse aggregate of waste concrete as the support. Each raw material plays its role together. Compared with the prior art, the fully solid waste permeable concrete prepared has the following advantages:

[0030] (1) The permeable concrete provided in this application does not use cement during preparation. By stimulating the mineral activity of activated coal gangue, fly ash, granulated blast furnace slag powder, etc. with alkaline materials, the material strength and water permeability rate meet the expected requirements, saving costs, being energy-saving and environment-friendly, and providing a new direction for the resource utilization of solid waste;

[0031] (2) The permeable concrete provided in this application does not use natural aggregates during preparation, reducing the utilization of natural resources.

[0032] (3) All materials in the permeable concrete provided in this application are solids except water during preparation, and the preparation equipment are all common equipment. The manufacturing method is simple and is convenient for large-scale production. Description of the Drawings

[0033] Figure 1 It is a schematic flow chart of the preparation method of the fully solid waste permeable concrete in the embodiment of the present invention. Detailed Embodiments

[0034] The present application will be further described in detail below in conjunction with embodiments. It can be understood that the specific embodiments described herein are only used to explain the relevant invention and not to limit the invention. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0035] An embodiment of the present application provides a fully solid waste permeable concrete, the raw materials of which include waste concrete recycled coarse aggregate, activated coal gangue composite precursor, solid alkaline material and water.

[0036] The raw material ratio of the activated coal gangue composite precursor is shown in Table 1.

[0037] Table 1 Raw material table of activated coal gangue composite precursor (by weight)

[0038]

[0039]

[0040] The raw material ratio of the solid alkaline material is shown in Table 2.

[0041] Table 2 Raw material table of solid alkaline material (by weight)

[0042] Raw material Alkaline material 1 Alkaline material 2 Alkaline material 3 Alkaline material 4 Flake sodium hydroxide 10％ 10％ 15％ 20％ Instant sodium silicate 30％ 35％ 35％ 40％ Alkali residue fine powder 60％ 55％ 50％ 40％

[0043] In Examples 1 to 50 of the present application, the raw material ratios for preparing the fully solid waste permeable concrete are shown in Table 3.

[0044] Table 3 Raw material ratio table of fully solid waste permeable concrete in Examples 1 to 50 (by weight)

[0045]

[0046]

[0047] Furthermore, the waste concrete recycled coarse aggregate is the product of waste concrete after crushing and screening, the particle size range of the waste concrete recycled coarse aggregate is 5 - 10 mm, the crushing value is less than 10%, and the micro powder content is less than 1%.

[0048] Furthermore, the activated coal gangue is the powder obtained by calcining washed coal gangue at 800 - 1000 °C, grinding it finely and then screening with a particle size less than 0.075 mm.

[0049] Furthermore, the granulated blast furnace slag powder is commercially available S95 grade granulated blast furnace slag powder.

[0050] Furthermore, the fly ash is commercially available secondary fly ash.

[0051] Furthermore, the water reducing agent is a commercially available polycarboxylate high-performance water reducing agent.

[0052] Further, the flake sodium hydroxide is commercially available flake sodium hydroxide with a purity of 98%.

[0053] Further, the instant soluble sodium silicate is commercially available instant soluble sodium silicate with a purity of 95%.

[0054] Further, the alkali residue fine powder is the alkaline waste residue discharged during the production of alkali and alkali treatment in industrial production, and the pH value of the 10-fold aqueous solution by mass ratio is greater than 11.

[0055] The preparation method includes the following steps (see the specific flow chart in Figure 1 ):

[0056] S1. Weigh the flake sodium hydroxide, instant soluble sodium silicate and alkali residue fine powder in a dry state according to the proportion, put them into a powder mixer for mixing, with a mixing time of 2 minutes and a rotation speed of 20 - 30 rpm / min to obtain a uniform solid alkaline material;

[0057] S2. Weigh the activated coal gangue, fly ash, granulated blast furnace slag powder and water reducer in a dry state according to the proportion, put them into a powder mixer for mixing, with a stirring time of 5 minutes and a rotation speed of 20 - 30 rpm / min to obtain a uniform activated coal gangue composite precursor;

[0058] S3. Put the solid alkaline material obtained in S1 into a concrete mixer, add water according to the proportion and stir evenly, with a stirring time of 4 minutes;

[0059] S4. Put the activated coal gangue composite precursor obtained in S2 into the mixer in S3 according to the proportion and stir evenly, with a stirring time of 4 minutes;

[0060] S5. Put the recycled coarse aggregate of waste concrete into the mixer in S4 according to the proportion and stir evenly to obtain the finished product of all-solid waste permeable concrete, with a stirring time of 2 minutes;

[0061] S6. Put the permeable concrete prepared in each example into a mold of 100mm×100mm×100mm for molding to make test blocks. After standard curing for 28 days, test the slump, initial setting time, compressive strength and water permeability coefficient of the permeable concrete.

[0062] Performance Test

[0063] Performance tests were conducted on the finished all-solid waste pervious concrete products prepared in Examples 1-50. Among them, the slump and initial setting time were tested in accordance with the Standard Test Method for Performance of Ordinary Concrete Mixtures GBT 50080-2016, the compressive strength was tested in accordance with the Standard Test Method for Mechanical Properties of Ordinary Concrete GB / T500-81-2002, and the permeability coefficient was tested in accordance with the Technical Specification for Permeable Cement Concrete Pavement CJJ / T135-2009 (2023 Edition); the specific test results are shown in Table 4.

[0064] Table 4 Performance Test Results of Examples 1-50

[0065]

[0066]

[0067]

[0068] It can be seen from Table 4 that the all-solid waste pervious concrete provided by this application has the following characteristics:

[0069] (1) The 28-day compressive strength > 20 Mpa, meeting the strength required for the surface layer material;

[0070] (2) The slump is less than 50 mm, and the initial setting time > 120 min, having good workability and facilitating construction;

[0071] (3) The permeability coefficient > 2, meeting the permeability requirements.

[0072] Comprehensively analyzing the performance test results of Examples 1-50, with the increase in the dosage of coarse aggregate, the concrete strength decreased slightly, but not significantly, but it would lead to an increase in the permeability coefficient. The performance test results of the examples show that when the mass fraction of coarse aggregate is 65% - 70%, the permeability rate and strength requirements can be met. The components of alkaline materials have certain effects on the slump, initial setting time, compressive strength, and permeability coefficient of pervious concrete. Alkali slag micro-powder can improve strength and increase the permeability rate, but it will increase costs and should be considered overall. The greater the dosage of granulated blast furnace slag powder in the activated coal gangue composite precursor, the higher the strength, but it will increase costs.

[0073] In this article, specific examples are used to illustrate the principles and implementation manners of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application. The above is only the preferred implementation manner of the present application. It should be noted that due to the limitation of literal expression and objectively there are infinite specific structures, for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements, refinements or changes can be made, or the above technical features can be combined in an appropriate manner; these improvements, refinements, changes or combinations, or directly applying the concept and technical solution of the invention to other occasions without improvement, shall all be regarded as the protection scope of the present application.

Claims

1. A full solid waste permeable concrete, characterized in that: The raw materials include 65-70 parts of recycled coarse aggregate from waste concrete, 20-25 parts of activated coal gangue composite precursor, 5-15 parts of solid alkaline material and water, in terms of mass proportion; The mass of the solid alkaline material accounts for 20-30% of the mass of the activated coal gangue composite precursor, and the mass of water accounts for 30-40% of the mass of the activated coal gangue composite precursor; The activated coal gangue composite precursor specifically includes the following components in parts by weight: 60-75 parts of activated coal gangue; 10-20 parts of fly ash; 10-25 parts of granulated blast furnace slag powder; 1-2 parts of water reducing agent; The solid alkaline material specifically comprises the following components in parts by weight: 10-20 parts of flaky sodium hydroxide; 30-40 parts of instant sodium silicate; and 40-60 parts of alkaline residue powder.

2. The all-solid waste permeable concrete according to claim 1, characterized in that: The recycled coarse aggregate is the product of crushing and screening waste concrete. The particle size of the recycled coarse aggregate is 5-10 mm, the crushing value is less than 10%, and the powder content is less than 1%.

3. The all-solid waste permeable concrete according to claim 1, characterized in that: The activated coal gangue is water-washed coal gangue calcined at 800-1000° C., ground into powder with a particle size of less than 0.075 mm after sieving.

4. The all-solid waste permeable concrete according to claim 1, characterized in that: The granulated blast furnace slag powder is commercially available S95 grade granulated blast furnace slag powder.

5. The all-solid waste permeable concrete according to claim 1, characterized in that: The fly ash is commercially available secondary fly ash.

6. The all-solid waste permeable concrete according to claim 1, characterized in that: The water reducing agent is a commercially available polycarboxylic acid high performance water reducing agent.

7. The all-solid waste permeable concrete according to claim 1, characterized in that: The flaky sodium hydroxide is commercially available flaky sodium hydroxide with a purity of 98%.

8. The all-solid waste permeable concrete according to claim 1, characterized in that: The instant sodium silicate is commercially available, with a purity of 95%.

9. A method for preparing all-solid waste permeable concrete according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: S1. Weigh dry flaky sodium hydroxide, instant sodium silicate and alkaline residue powder in proportion and put them into a powder mixer for mixing to obtain a uniform solid alkaline material; S2, weighing dry activated coal gangue, fly ash, granulated blast furnace slag powder, and water reducing agent in proportion, and putting them into a powder mixer for mixing to obtain a uniform activated coal gangue composite precursor; S3, putting the solid alkaline material obtained in S1 into a concrete mixer, adding water in proportion and stirring evenly; S4, adding the activated coal gangue composite precursor obtained in S2 into the mixer S3 in proportion and stirring evenly; S5. Add the recycled coarse aggregate from waste concrete into the S4 mixer in proportion and mix them evenly to obtain a finished product of all-solid waste permeable concrete.

10. The method for preparing all-solid waste permeable concrete according to claim 9, characterized in that: The stirring time in step S2 is not less than 5 minutes, and the rotation speed is 20-30 rpm / min; the stirring time in step S3 is 3 to 5 minutes; the stirring time in step S4 is 3 to 5 minutes; and the stirring time in step S5 is 2 to 3 minutes.

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