A highly phosphorus gypsum-based all-solid waste permeable concrete and its preparation method

Abstract

The present invention discloses a highly phosphorus gypsum-based all-solid waste permeable concrete. The raw material composition is calculated by weight percentage: 25-30% of phosphorus gypsum-based cement slurry, 65-70% of phosphorus gypsum-based aggregate balls, 1-1.5% of water reducer, and the balance is water; the phosphorus gypsum-based cement slurry is a cement paste formed by wet grinding phosphorus gypsum, slag, waste slurry from a ready-mix plant and water; the phosphorus gypsum-based aggregate balls are circular artificial coarse aggregates with continuous gradation formed by granulating the phosphorus gypsum-based cement slurry through a granulator and then naturally cured; the permeable concrete obtained by the preparation method of the present invention enhances its water permeability while having mechanical properties equivalent to those of common permeable concrete, has a lower cost and is more environmentally friendly; at the same time, it solves the problems of serious stockpiling and difficult treatment of various solid wastes such as phosphorus gypsum, waste slurry from a ready-mix plant and slag, and conducts comprehensive resource utilization on them.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to a phosphogypsum-based permeable concrete and a preparation method thereof. Background Art

[0002] Phosphogypsum is an industrial solid waste generated during the production of phosphoric acid by treating phosphate rock with sulfuric acid. Approximately 4 to 5 tons of phosphogypsum are produced for every 1 ton of phosphoric acid produced. Currently, the disposal of phosphogypsum is generally used for making cement retarders, building gypsum boards, etc. It needs to be dried and adjusted before application, with high utilization costs and low comprehensive utilization rates, which are insufficient to consume the accumulated phosphogypsum, resulting in a gradually increasing annual stockpile and occupying a large amount of land. Phosphogypsum contains impurities such as soluble phosphorus and soluble fluorine, and long-term stacking will pollute the environment. Therefore, it is extremely urgent to improve the comprehensive utilization rate of phosphogypsum and achieve the reduction, increase, removal, and storage of phosphogypsum. Premixed plant waste slurry is a solid waste generated during the production of concrete. Usually, it is transported to landfills for disposal. Only a very small part of premixed plants will recycle and precipitate it for reuse. Premixed plant waste slurry is often strongly alkaline, and arbitrary stacking will pollute the environment and damage the ecosystem. It can also be treated by neutralizing its alkalinity with acidic substances, but the disposal cost will increase sharply. Slag is a by-product during the blast furnace ironmaking process. If not effectively utilized, it will occupy a large amount of land. The above industrial solid wastes are not only difficult to dispose of in terms of stockpiling, but also pollute the environment and the ecosystem. Therefore, a permeable concrete that combines multiple solid wastes, has a simple process, and a low cost is proposed to solve this series of problems.

[0003] As early as 12 years ago, the concept of "sponge city" was first proposed, that is, the city can store natural precipitation like a sponge and utilize the stored water when needed. However, with the acceleration of the urbanization construction process, more and more areas are covered by steel-concrete structures and various impermeable roads and ground, resulting in a significant increase in the burden on the urban drainage system and prone to urban road waterlogging problems. As an important part of sponge city construction, permeable concrete can quickly infiltrate rainwater into the ground, reduce the pressure of urban internal drainage, and has the advantages of keeping the underground soil moist, improving the road surface environment, and absorbing vehicle noise. However, permeable concrete usually requires a large amount of cement for pouring, and the preparation of cement clinker requires two grinding and one burning, which is not conducive to the current green ecological development concept. Therefore, preparing a new type of environmentally friendly and low-energy-consuming permeable concrete to solve the stockpiling problems of various solid wastes and promote the further construction and development of sponge cities has become an urgent technical problem to be solved. Summary of the Invention

[0004] One of the objectives of the present invention is to provide a highly phosphorus gypsum-based all-solid waste permeable concrete and its preparation method, which enhances the permeable performance while having comparable mechanical properties to common permeable concretes, with lower cost and environmental friendliness; the second objective is to solve the problem of serious stockpiling and difficult treatment of various solid wastes such as phosphorus gypsum, waste slurry from ready-mixed plants, and slag, and to comprehensively utilize them for resource recovery.

[0005] To achieve the above objectives, the following technical solutions are adopted:

[0006] A highly phosphorus gypsum-based all-solid waste permeable concrete, the raw material composition is calculated by weight percentage:

[0007] Phosphorus gypsum-based cement slurry 25 - 30%, phosphorus gypsum-based aggregate balls 65 - 70%, water reducing agent 1 - 1.5%, and the balance is water;

[0008] The phosphorus gypsum-based cement slurry is a cement paste formed by wet grinding phosphorus gypsum, slag, waste slurry from ready-mixed plants, and water;

[0009] The phosphorus gypsum-based aggregate balls are circular artificial coarse aggregates with a continuous gradation of 5 - 15 mm formed by granulating the phosphorus gypsum-based cement slurry with a disk granulator, and then naturally cured for 7 - 15 days.

[0010] According to the above scheme, the phosphorus gypsum contains 10 - 20% water, specific surface area > 400 m 2 / kg, and pH value is 1.8 - 4.5.

[0011] According to the above scheme, the slag is S95 slag, specific surface area > 400 m 2 / kg.

[0012] According to the above scheme, the waste slurry from the ready-mixed plant is a mixture of concrete waste slurry residue and water, and the mass ratio of water to dry waste slurry residue is 1:3; the main components of the waste slurry residue include SiO2 content of 37.4% - 48.6%, CaO content of 19.1 - 25.4%, Al2O3 content of 13.4 - 17.3%, Fe2O3 content of 4.2 - 5.6%, MgO content of 2.4 - 3.7%, Na2O content of 0.3 - 0.4%, and K2O content of 1.2 - 1.6%.

[0013] According to the above scheme, the water reducing agent is a polycarboxylate water reducing agent.

[0014] According to the above scheme, the composition of the phosphorus gypsum cement slurry is calculated by weight percentage: phosphorus gypsum 30 - 35%, slag 40 - 45%, waste slurry from ready-mixed plant 25 - 30%.

[0015] The preparation method of the above highly phosphorus gypsum-based all-solid waste permeable concrete includes the following steps:

[0016] Mix phosphogypsum, slag and waste slurry from the premix plant, and then pour the mixture into an ultrafine wet mill. Adjust the mass ratio of the mixture to zirconia balls to 1:2, with a rotation speed of 400 revolutions per minute, and grind for 10 minutes to obtain phosphogypsum-based cement slurry;

[0017] Put the phosphogypsum-based cement slurry into a disk granulator to form circular artificial coarse aggregates with a continuous gradation of 5 - 15 mm. Then, cure them naturally for 7 - 15 days to obtain phosphogypsum-based aggregate balls;

[0018] Wet the phosphogypsum-based aggregate balls with water, then mix them with phosphogypsum-based cement slurry, water and water reducer and stir evenly. Pour and cure them to form high-phosphogypsum-consuming all-solid-waste permeable concrete.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] (1) By consuming various solid wastes such as phosphogypsum, waste slurry from the premix plant, and slag, the high-phosphogypsum-consuming all-solid-waste permeable concrete prepared by the present invention has a compressive strength grade of up to C30, a water permeability coefficient of up to 14 mm / s, a porosity of 20%, and a splitting tensile strength of 4.2 MPa. The paved road has the advantage of absorbing urban noise.

[0021] (2) By using various solid wastes to prepare high-phosphogypsum-consuming all-solid-waste permeable concrete, the present invention can effectively solve the problems of stacking and environmental pollution of solid wastes such as phosphogypsum, waste slurry from the premix plant, and slag. By using waste slurry from the premix plant as an alkali activator and adopting the wet grinding method to prepare phosphogypsum cement slurry, not only the specific surface area of each item is increased, the activity is improved, but also the drying process of phosphogypsum and waste slurry from the premix plant is eliminated. Without cement finished products, the resource consumption and pollution caused by cement firing are eliminated, and the cost and energy consumption are greatly reduced, with significant economic and environmental benefits.

[0022] (3) The aggregate balls prepared with phosphogypsum-based cement slurry have the characteristics of high strength and low water absorption. Since the boundaries where the aggregates contact the phosphogypsum-based cement paste belong to the same phase and there is no transition zone, there will be no bleeding phenomenon and no weak links, which can improve the strength and practicability of the concrete.

[0023] (4) Slag and waste slurry from the premix plant can modify phosphogypsum, neutralize the acidic residues in phosphogypsum, convert water-soluble phosphorus and fluorine into inert water-insoluble salts, and at the same time provide a good alkaline environment for the later hydration reaction, facilitating the production of more stable C-S-H gel and ettringite, and improving the strength of the permeable concrete. Specific Embodiments

[0024] The following examples further illustrate the technical solutions of the present invention, but do not limit the protection scope of the present invention.

[0025] The specific implementation provides a highly phosphorus gypsum-based all-solid waste permeable concrete, and the raw material composition is by weight percentage:

[0026] Phosphorus gypsum-based cement slurry 25-30%, phosphorus gypsum-based aggregate balls 65-70%, water reducing agent 1-1.5%, and the balance is water.

[0027] Meanwhile, a preparation method of the highly phosphorus gypsum-based all-solid waste permeable concrete is also provided, including the following steps:

[0028] Mix phosphorus gypsum, slag and waste slurry from the premixing plant, then pour them into an ultrafine wet mill, adjust the mass ratio of the mixture to zirconia balls to 1:2, rotate at 400 revolutions per minute, and grind for 10 minutes to obtain the phosphorus gypsum-based cement slurry;

[0029] Put the phosphorus gypsum-based cement slurry into a disk granulator, form circular artificial coarse aggregates with a continuous gradation of 5-15 mm, and then naturally cure them for 7-15 d to obtain the phosphorus gypsum-based aggregate balls;

[0030] Wet the phosphorus gypsum-based aggregate balls with water, mix them with the phosphorus gypsum-based cement slurry, water and water reducing agent and stir evenly, then pour and cure them to form the highly phosphorus gypsum-based all-solid waste permeable concrete.

[0031] Specifically, the composition of the phosphorus gypsum cement slurry is by weight percentage: phosphorus gypsum 30-35%, slag 40-45%, waste slurry from the premixing plant 25-30%.

[0032] The specific phosphorus gypsum has a water content of 10-20%, a specific surface area > 400 m 2 / kg, and a pH value of 1.8-4.5.

[0033] The slag uses S95 slag, and the specific surface area > 400 m 2 / kg.

[0034] The waste slurry from the premixing plant is a mixture of concrete waste slurry residue and water, and the dry mass ratio of water to waste slurry residue is 1:3; the main components of the waste slurry residue include SiO2 content of 37.4%-48.6%, CaO content of 19.1-25.4%, Al2O3 content of 13.4-17.3%, Fe2O3 content of 4.2-5.6%, MgO content of 2.4-3.7%, Na2O content of 0.3-0.4%, and K2O content of 1.2-1.6%.

[0035] The water reducing agent uses a polycarboxylate water reducing agent.

[0036] The components and contents by mass percentage of the highly phosphorus gypsum-based all-solid waste permeable concrete in Examples 1-5 are shown in Table 1.

[0037] Table 1

[0038]

[0039] The permeable concrete prepared in Examples 1 to 5 was tested for 28-day compressive strength and splitting tensile strength in accordance with the "Standard Test Method for Mechanical Properties of Ordinary Concrete GB / T 50081-2002", and the permeability coefficient and continuous porosity were tested in accordance with the "Technical Specification for Permeable Concrete Pavement CJJ135-2009". The test results are shown in Table 2.

[0040] Table 2

[0041]

[0042] Combined with the analysis of Table 1 and Table 2, it can be obtained that the compressive strength of the high-phosphogypsum-based all-solid waste permeable concrete of the present invention can reach 30 MPa, the splitting tensile strength reaches 4.2 MPa, the continuous porosity exceeds 20%, and the permeability coefficient exceeds 14 mm / s; at the same time, when the mass ratio of the phosphogypsum-based cement slurry is relatively large, the strength is improved and the porosity is slightly reduced; when the mass ratio of the phosphogypsum-based aggregate balls is relatively large, the porosity is increased and the strength is slightly reduced. The above examples can all meet the application on permeable sidewalks and lightly loaded permeable concrete pavements.

[0043] A high-phosphogypsum-based all-solid waste permeable concrete and a preparation method thereof provided in the above embodiments of the present invention prepare permeable concrete by preparing cement slurry and spherical aggregates from various solid wastes such as phosphogypsum, and propose a new preparation process method. Through the wet grinding treatment of phosphogypsum, waste slurry from the premixing plant, and slag, the energy consumption is reduced, the problem of solid waste stacking is solved, and the production cost is greatly reduced.

Claims

1. A highly phosphorus gypsum-based all-solid waste permeable concrete, characterized in that The raw material composition is by weight percentage: 25-30% of phosphogypsum-based cement slurry, 65-70% of phosphogypsum-based aggregate balls, 1-1.5% of water reducing agent, and the balance is water; The phosphogypsum-based cement slurry is a cement paste formed by wet grinding of phosphogypsum, slag, and waste slurry from the premix plant; the composition of the phosphogypsum cement slurry is by weight percentage: 30-35% of phosphogypsum, 40-45% of slag, and 25-30% of waste slurry from the premix plant; The phosphogypsum-based aggregate balls are formed by granulating the phosphogypsum-based cement slurry through a granulator to form continuously graded circular artificial coarse aggregates, and then naturally cured; The phosphogypsum has a water content of 10 - 20%, a specific surface area > 400 m 2 / kg, and a pH value of 1.8 - 4.5; The slag is S95 slag with a specific surface area > 400 m 2 / kg; The waste slurry from the premix plant is a mixture of concrete waste slurry and water, where the mass ratio of water to dry waste slurry is 1:3; the main components of the waste slurry include 37.4%-48.6% of SiO2 content, 19.1-25.4% of CaO content, 13.4-17.3% of Al2O3 content, 4.2-5.6% of Fe2O3 content, 2.4-3.7% of MgO content, 0.3-0.4% of Na2O content, and 1.2-1.6% of K2O content.

2. The highly phosphorus gypsum-based all-solid waste permeable concrete according to claim 1, wherein The water reducing agent is a polycarboxylic acid water reducing agent.

3. The preparation method of the highly phosphorus gypsum-based all-solid waste permeable concrete according to claim 1, characterized in that It includes the following steps: Mix phosphogypsum, slag, and waste slurry from the premix plant and pour them into an ultra-fine wet mill, adjust the mass ratio of the mixture to zirconia balls to 1:2, rotate at 400 revolutions per minute, and grind for 10 minutes to obtain the phosphogypsum-based cement slurry; Put the phosphogypsum-based cement slurry into a disk granulator to form continuously graded circular artificial coarse aggregates of 5-15 mm, and then naturally cure them for 7-15 days to obtain the phosphogypsum-based aggregate balls; Wet the phosphogypsum-based aggregate balls with water, mix them with the phosphogypsum-based cement slurry, water, and water reducing agent and stir evenly, then pour and cure them to form a highly phosphorus gypsum-consuming all-solid waste permeable concrete.

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