CN113735545A

CN113735545A - Concrete product containing phosphogypsum fly ash cement and preparation method thereof

Info

Publication number: CN113735545A
Application number: CN202111226043.8A
Authority: CN
Inventors: 刘丽娟; 李山山; 马红青; 唐永波
Original assignee: Jiangsu Efful Science And Technology Co ltd
Current assignee: Jiangsu Efful Science And Technology Co ltd
Priority date: 2021-10-21
Filing date: 2021-10-21
Publication date: 2021-12-03

Abstract

The invention provides a concrete product containing phosphogypsum fly ash cement and a preparation method thereof, wherein the concrete product comprises the following raw materials in parts by weight: 130 portions of ardealite, 215 portions of fly ash, 45 portions to 80 portions of silicate cement, 850 portions of sand, 950 portions of pebbles, 1050 portions of water and 165 portions of sand. The concrete product of the invention utilizes the process waste resource and reduces the cement consumption, which is beneficial to environmental protection. The preparation method comprises the following steps: adding water into phosphogypsum and part of silicate cement for wet grinding to obtain phosphogypsum slurry, and filtering and concentrating to obtain phosphogypsum mud; mixing and stirring the phosphogypsum mud, the fly ash, the residual silicate cement, the sand, the stones and the water, pressing or pouring into a concrete product, and finally performing product maintenance treatment. The preparation method does not need calcination, and can be used for producing concrete products by direct wet grinding, thereby improving the strength of concrete and shortening the setting time of the concrete products.

Description

Concrete product containing phosphogypsum fly ash cement and preparation method thereof

Technical Field

The invention belongs to the technical field of concrete preparation, and relates to a concrete product containing phosphogypsum fly ash cement and a preparation method thereof.

Background

In construction, concrete is one of the most widely used and used building materials, consuming approximately 40 billion cubic meters every year, and among them, cement is one of the important materials constituting concrete, accounting for about 1/6 of the total amount of concrete. The raw materials for cement production are mainly limestone, coal and electric power are fuel and power for production, and the production of cement needs to consume a large amount of energy. Along with the rapid development of society, the importance of environmental protection is increasingly prominent, so that the use amount of cement in the preparation process of concrete needs to be reduced, a large amount of fly ash, phosphogypsum, ground blast furnace slag or other industrial waste residues can be doped, and the use amount of cement is reduced; or the use of recycled materials, such as crushed concrete and industrial waste residues, reduces the resource consumption. In a word, the resources are recycled as much as possible, and the energy consumption for producing concrete in unit volume is reduced.

Phosphogypsum is solid waste residue produced in the production process of wet-process phosphoric acid, when the phosphoric acid is produced by adopting a wet-process, every 1 ton of phosphoric acid is produced with 4.5-5 tons of phosphogypsum, and the phosphogypsum mainly contains calcium sulfate dihydrate, a small amount of chlorosilicate, fluoride, iron-aluminum compound, organic matter and the like. The annual phosphogypsum emission amount of China is more than 8000 million tons, the accumulation of a large amount of phosphogypsum not only occupies land resources, but also harmful components such as soluble phosphorus, fluoride and the like can diffuse and permeate to the surrounding environment in the accumulation process, and potential safety and environmental protection hazards exist. Resource utilization of phosphogypsum is always a research hotspot of scholars at home and abroad, and researchers put forward that phosphogypsum replaces part of cementing materials to be used for preparing phosphogypsum cement concrete, so that the phosphogypsum can be recycled, the use amount of cement can be reduced, and the energy consumption is reduced.

Fly ash, also called fly ash, is a solid waste emission collected from a chimney of a coal-fired power plant by an electrostatic precipitation device, and has a main chemical composition of SiO₂、Al₂O₃And Fe₂O₃The annual production amount is close to 6 hundred million tons, and the method is a resource with potential value.

CN103755248B discloses phosphogypsum concrete and a preparation process thereof, wherein the raw materials comprise 19.5-97.5 kg of phosphogypsum, 292.5-370.5 kg of cement, 7.8-8.97 kg of water reducing agent, 150-165 kg of water, 880-960 kg of sand and 870-960 kg of stones in terms of each cubic meter of phosphogypsum concrete. The process uses the phosphogypsum to replace part of cement to prepare the phosphogypsum concrete, and solves the problem of stacking of the phosphogypsum. CN112062529A discloses gypsum-based foam concrete with a large amount of phosphogypsum and a preparation method thereof, wherein the gypsum-based foam concrete comprises the following components in parts by weight: 540 parts of ardealite 198-containing material, 0-360 parts of cement, 0.4-3.5 parts of fiber, 0.1-0.75 part of retarder, 0-3 parts of water reducer, 5-13.8 parts of foaming agent, 5-7 parts of foam stabilizer, 0-0.9 part of catalyst and 420 parts of water 160-containing material. The preparation method ensures that the phosphogypsum has the gelling property, replaces cement with the same amount of phosphogypsum, and improves the utilization rate of the industrial byproduct phosphogypsum. However, the utilization rate of the phosphogypsum in the patent is low, and the doping amount of the cement is high.

Therefore, it is highly desirable to develop a method for preparing concrete, which can improve the utilization rate of industrial waste resources such as phosphorous slag and fly ash, reduce the amount of cement used, reduce environmental pollution, fully exert the effect of industrial waste, and reduce the production cost of concrete.

Disclosure of Invention

In order to solve the technical problems, the invention provides a concrete product containing phosphogypsum and fly ash cement and a preparation method thereof.

In order to achieve the technical effect, the invention adopts the following technical scheme:

the invention provides a concrete product containing phosphogypsum fly ash cement, which comprises the following raw materials in parts by weight: 130 portions of ardealite, 215 portions of fly ash, 45 portions to 80 portions of silicate cement, 850 portions of sand, 950 portions of pebbles, 1050 portions of water and 165 portions of sand.

The weight portion of the phosphogypsum is 130-240 parts, such as 130 parts, 140 parts, 150 parts, 160 parts, 170 parts, 180 parts, 190 parts, 200 parts, 210 parts, 220 parts, 230 parts or 240 parts, etc., but is not limited to the enumerated values, and other unrecited values in the numerical range are also applicable.

The fly ash is 125-215 parts by weight, such as 125 parts, 135 parts, 145 parts, 155 parts, 165 parts, 175 parts, 185 parts, 195 parts, 205 parts or 215 parts, but not limited to the recited values, and other values not recited in the numerical range are also applicable.

The silicate cement is 45-80 parts by weight, such as 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts or 80 parts, but not limited to the recited values, and other values not recited in the numerical range are also applicable.

The sand is present in an amount of 650-850 parts by weight, such as 650 parts, 700 parts, 750 parts, 800 parts or 850 parts, but is not limited to the recited values, and other values not recited within the numerical range are equally applicable.

The stone is 1050 parts by weight, such as 950 parts, 960 parts, 970 parts, 980 parts, 990 parts, 1000 parts, 1010 parts, 1020 parts, 1030 parts, 1040 parts or 1050 parts, and the like, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.

The water is present in an amount of 145-165 parts by weight, for example 145 parts, 150 parts, 155 parts, 160 parts or 165 parts, but is not limited to the recited values, and other values not recited within the numerical range are equally applicable.

The concrete product of the invention takes the industrial waste residue phosphogypsum and the fly ash as main raw materials, and is doped with a small amount of silicate cement, thereby fully improving the utilization rate of process waste resources, saving energy and land resources, reducing the consumption of cement and lowering the production cost; wherein, the sand and the stones play a role of a framework, and the phosphogypsum, the fly ash and the silicate cement jointly form a cementing material which plays a role of cementing the sandstone.

As a preferable technical scheme of the invention, the concrete product comprises the following raw materials in parts by weight: 140 portions of ardealite, 145 portions of fly ash, 195 portions of silicate cement, 55 portions to 75 portions of sand, 720 portions of sand, 1020 portions of pebble and 150 portions of water.

As a preferable technical scheme of the invention, the raw materials of the concrete product also comprise a water reducing agent.

Preferably, the phosphogypsum, the fly ash, the silicate cement and the water reducing agent form a cementing material.

Preferably, the water reducing agent is present in an amount of 0-0.5% by mass of the cementitious material, such as 0, 0.1%, 0.2%, 0.3%, 0.4%, or 0.5%, but not limited to the recited values, and other values within the range of values are equally applicable, preferably 0.2-0.4%.

In the invention, the cementing material may not contain a water reducing agent.

In the invention, the main chemical component of the phosphogypsum is CaSO₄·2H₂O。

In the invention, the main chemical component of the fly ash comprises SiO₂、Al₂O₃CaO and Fe₂O₃。

In the invention, the fly ash has wide sources, is solid waste emission generated in the production of coal-fired power plants, and has low cost.

As a preferred embodiment of the present invention, the portland cement includes any one or at least two combinations of portland cement, portland slag cement, portland fly ash cement, portland pozzolana cement, composite portland cement, or portland limestone cement, and the combinations are typically, but not limited to: the combination of ordinary portland cement and portland slag cement, the combination of fly ash portland cement and pozzolanic portland cement, or the combination of pozzolanic portland cement and composite portland cement, and the like.

In the invention, the main chemical components of the common silicate cement comprise tricalcium silicate, dicalcium silicate, tricalcium aluminate, tetracalcium aluminoferrite and gypsum.

As a preferred embodiment of the present invention, the above-mentionedThe water reducing agent comprises a BASF polycarboxylic acid type water reducing agent,

(II) any one or combination of at least two of a polycarboxylic acid high-efficiency water-reducing agent or a combined polycarboxylic acid water-reducing agent, typical but non-limiting examples of which are: BASF polycarboxylic acid type water reducing agent and

(II) combination of polycarboxylic acid high-efficiency water reducing agent,

(II) a combination of a polycarboxylic acid high-efficiency water reducing agent and a combined polycarboxylic acid water reducing agent, a combination of a BASF polycarboxylic acid type water reducing agent and a combined polycarboxylic acid water reducing agent, and the like.

The invention also provides a preparation method of the concrete product, which comprises the following steps:

(1) adding water into phosphogypsum and part of silicate cement for wet grinding to obtain phosphogypsum slurry, and filtering and concentrating to obtain phosphogypsum mud;

(2) and (2) mixing and stirring the phosphogypsum mud obtained in the step (1) with fly ash, the rest silicate cement, sand, stones and water, pressing or pouring into a concrete product, and finally performing product maintenance treatment.

The preparation method provided by the invention does not need calcination, and can be used for producing concrete products by direct wet grinding, thereby improving the strength of the concrete and shortening the setting time of the concrete.

In the invention, in the step (1), part of silicate cement is added into the phosphogypsum to neutralize acid substances in the phosphogypsum, so that the early strength of the concrete prepared from the phosphogypsum is improved. A large amount of needle-shaped calcium sulphoaluminate hydrate and amorphous calcium silicate hydrate minerals are formed on the surfaces of the phosphogypsum particles and among the particles, so that higher strength is generated, and the phosphogypsum particles play a role of a cementing material; in the cementing material, the phosphogypsum is excessive, one part of the phosphogypsum plays the role of a skeleton, and the other part of the phosphogypsum participates in chemical reaction to form a series of new hydration products. In the phosphogypsum wet-grinding modification process, silicate cement is hydrated to generate substances such as calcium hydroxide, the calcium hydroxide reacts with phosphorus and fluorine impurities in the phosphogypsum to generate inert substances, and the weakening effect of the phosphorus and fluorine impurities on intermolecular force of a cementing material is reduced, so that the setting time is shortened, and the strength of a concrete product can be improved; the phosphogypsum wet grinding modification converts acidic phosphogypsum into alkalinity, can meet the alkalinity required by the hydration of the fly ash in a short time, and effectively provides external conditions for the hydration of the fly ash.

In addition, a small amount of silicate cement is doped, a small amount of hydration product crystal nuclei can be formed in the phosphogypsum slurry, the hydration product crystal nuclei are uniformly distributed in the phosphogypsum slurry through wet grinding, and then after the fly ash and the silicate cement are added, the hydration product grows around the crystal nuclei, so that microcracks are blocked, pores of a cement hardened body are filled, the density of the cement hardened body is increased, and the strength of a concrete product is improved.

In the invention, the silicate cement added in the step (2) provides an alkaline environment for the hydration of the cementing material, promotes the breakage of Si-O, Al-O bond of the fly ash, improves the early hydration reaction rate of the fly ash, and generates cementitious products such as hydrated calcium silicate and hydrated aluminum silicate; while phosphogypsum provides SO₄ ^2-In Ca²⁺With active Al dissolved in liquid phase₂O₃The reaction generates stable ettringite which is beneficial to Ca²⁺Diffusing into the fly ash particles and reacting with the internal active Al₂O₃And SiO₂Reacting to improve the activity excitation degree of the fly ash; and the subsequent maintenance condition is assisted, so that the structure of the fly ash glass body network is easier to damage, and the active Al₂O₃And SiO₂More easily dissolved out, thereby accelerating the formation of hydration products.

In a preferred embodiment of the present invention, the mass ratio of the partial silicate cement of step (1) to the phosphogypsum is 0.01-0.02, for example, 0.01, 0.012, 0.014, 0.016, 0.018 or 0.02, but not limited to the values listed, and other values within the range of values are also applicable.

Preferably, the mass ratio of the total mass of the phosphogypsum and partial silicate cement to the water in the step (1) is (5.5-6.5):4, for example, 5.5:4, 5.7:4, 5.9:4, 6.1:4, 6.3:4, or 6.5:4, etc., but not limited to the enumerated values, and other values in the numerical range are also applicable.

Preferably, the specific surface area of the phosphogypsum slurry obtained in the step (1) is more than 350m²/kg, for example, may be 355m²/kg，360m²/kg，365m²/kg，370m²/kg，375m²/kg or 380m²And/kg, etc., but are not limited to the values listed, other values within the numerical range are equally applicable.

Preferably, the phosphogypsum slurry of step (1) has a solids content of 55-65%, for example 55%, 57%, 59%, 61%, 63% or 65%, etc., but is not limited to the values recited, and other values within the range of values are equally applicable.

Preferably, the phosphogypsum paste of step (1) has a solids content of 75-85%, which may be, for example, 75%, 77%, 79%, 81%, 83% or 85%, etc., but is not limited to the values listed, and other values within the range of values are equally applicable.

As a preferable technical scheme of the invention, the step (2) further comprises mixing and stirring the water reducing agent, the phosphogypsum mud obtained in the step (1), the fly ash, the residual silicate cement, the sand, the gravel and the water.

As a preferable aspect of the present invention, the product maintenance treatment includes: standing for 0-1 day after the concrete product is formed, heating to 50-75 ℃ for steaming for 1-3 days, taking out the concrete product, soaking in water for 0-1 day, and sealing with plastic cloth.

As a preferred technical scheme of the invention, the preparation method comprises the following steps:

(1) adding water to the phosphogypsum and part of silicate cement for wet grinding until the specific surface area is more than 350m²The mass ratio of the partial silicate cement to the phosphogypsum is 0.01-0.02, and the mass ratio of the total mass of the phosphogypsum and the partial silicate cement to the water is (5.5-6.5):4, obtaining phosphogypsum slurry with the solid content of 55-65%, and filtering and concentrating to obtain phosphogypsum mud with the solid content of 75-85%;

(2) and (2) uniformly mixing and stirring the phosphogypsum mud obtained in the step (1) with fly ash, the rest silicate cement, sand, stones, a water reducing agent and water, pressing or pouring into a concrete product, standing for 0-1 day after the concrete product is formed, heating to 50-75 ℃, steaming for 1-3 days, taking out the product, soaking in water for 0-1 day, and sealing with plastic cloth.

Compared with the prior art, the invention has the following beneficial effects:

(1) the concrete product prepared by the invention has the characteristics of hydraulicity and high strength, and the industrial waste residue phosphogypsum and the fly ash are used as main raw materials, so that the raw materials are easy to obtain, the cost is low, and the concrete product is suitable for large-scale popularization;

(2) the preparation method is simple, does not need calcination, can be used for producing concrete products by direct wet grinding, can improve the early strength of the concrete products, shortens the coagulation time of the concrete products, has low energy consumption in the preparation process, does not discharge pollutants such as carbon dioxide, nitric oxide, sulfur trioxide, dust and the like, realizes green production, meets the requirement of circular economy, and has higher social benefit.

Detailed Description

For the purpose of facilitating an understanding of the present invention, the present invention will now be described by way of examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1

The embodiment provides a preparation method of a concrete product containing phosphogypsum fly ash cement, which comprises the following steps:

(1) adding water to wet-grind the phosphogypsum and part of PO42.5 cement until the specific surface area is 500m²Per kg, the mass ratio of the part of PO42.5 cement to the phosphogypsum is 0.015, and the mass ratio of the total mass of the phosphogypsum and the part of PO42.5 cement to the water is 6: 4; obtaining phosphogypsum slurry with the solid content of 62%, and filtering and concentrating to obtain phosphogypsum mud with the solid content of 82%;

(2) and (2) mixing and stirring the phosphogypsum mud obtained in the step (1) with fly ash, the rest PO42.5 cement, sand, pebbles, a BASF polycarboxylic acid type water reducing agent and water uniformly, pressing or pouring into a concrete product, standing for 1 day after the concrete product is formed, heating to 65 ℃, steaming for 1 day, taking out the product, soaking in water for 1 day, and sealing with plastic cloth.

Example 2

(1) grinding the ardealite: adding water to wet-grind the phosphogypsum and part of slag portland cement until the specific surface area is 465m²The mass ratio of the part of Portland slag cement to the phosphogypsum is 0.01, and the mass ratio of the total mass of the phosphogypsum and the part of Portland slag cement to the water is 5.5: 4; obtaining phosphogypsum slurry with the solid content of 59.7 percent, and filtering and concentrating to obtain phosphogypsum mud with the solid content of 79.5 percent;

(2) the phosphogypsum mud obtained in the step (1) is mixed with fly ash, residual slag portland cement, stones, sand,

And (II) mixing and stirring the polycarboxylic acid high-efficiency water reducing agent and water uniformly, pressing or pouring into a concrete product, standing for 1 day after the concrete product is formed, raising the temperature to 65 ℃, steaming for 1 day, taking out the product, soaking in water for 1 day, and sealing by using plastic cloth.

Example 3

(1) adding water to wet-grind the phosphogypsum and part of the pozzolanic portland cement until the specific surface area is 455m²The mass ratio of the part of the pozzolanic portland cement to the phosphogypsum is 0.02, and the mass ratio of the total mass of the phosphogypsum to the part of the pozzolanic portland cement to the water is 6.5: 4; obtaining phosphogypsum slurry with solid content of 63.2%, filtering and concentrating to obtain phosphogypsum mud with solid content of 81.5%;

(2) and (2) mixing and stirring the phosphogypsum mud obtained in the step (1) with fly ash, the rest of pozzolanic silicate cement, stones, sand, the combined polycarboxylic acid water reducing agent and water uniformly, pressing or pouring into a concrete product, standing for 1 day after the concrete product is formed, heating to 65 ℃, steaming for 1 day, taking out the product, soaking in water for 1 day, and sealing with plastic cloth.

Example 4

This example provides a method for preparing a concrete product containing phosphogypsum fly ash cement, which is different from example 1 in the content of each component in step (2), and the content of each component is shown in table 1.

Example 5

Example 6

This example provides a method for preparing a concrete product containing phosphogypsum-fly ash cement, which is the same as that of example 1 except that no water reducing agent is added in step (2).

Comparative example 1

This comparative example provides a method of making a concrete product comprising a phosphogypsum-fly ash cement, which is otherwise identical to that of example 1 except that no fly ash is added in step (2).

Comparative example 2

This comparative example provides a method of making a concrete product comprising a phosphogypsum fly ash cement, which is otherwise identical to that of example 1 except that no remaining PO42.5 cement is added in step (2).

Specific formulations for 10L concrete articles prepared in examples 1-5 are shown in Table 1.

TABLE 1

The test methods and results of the above examples and comparative examples are as follows:

the testing method of the slump refers to GB/T50080-2016 Standard test method for the performance of common concrete mixtures;

the test method of the compressive strength refers to GB/T50081-2019 'test method standard of concrete physical and mechanical properties'.

TABLE 2

From table 2, the following points can be derived: will be provided with

(1) Compared with the embodiment 5, the embodiment 1 has the advantages that the fly ash is added in a small amount, so that the strength of the prepared concrete product is reduced; comparing example 1 with example 6, the strength of the prepared concrete product is reduced without adding the water reducing agent.

(2) Comparing the example 1 with the comparative example 1, because the fly ash is not added in the step (2), a small amount of hydration product crystal nuclei are formed in the phosphogypsum slurry, but the hydration products growing around the crystal nuclei are less, and pores appear in the slurry, so that the strength of the obtained concrete product is reduced; comparing example 1 with comparative example 2, because the remaining PO42.5 cement is not added in step (2), the hydration activity of the fly ash can not be fully excited, so that the slurry structure is loose, and the strength of the prepared concrete product is reduced.

In conclusion, the invention takes the industrial waste residue phosphogypsum and the fly ash as main raw materials, and is doped with a small amount of silicate cement, the prepared concrete product has the characteristics of high hydraulicity and high strength, the phosphogypsum and the fly ash are easy to obtain and have low cost, and simultaneously, the cement consumption is reduced, and the production cost is reduced; the preparation method is simple, calcination is not needed, the concrete product is directly produced by wet grinding, the early strength of the concrete product can be improved, and the setting time of the concrete product is shortened.

The applicant states that the process flow of the present invention is illustrated by the above examples, but the present invention is not limited to the above process flow, i.e. it does not mean that the present invention must rely on the above process flow to be implemented. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims

1. The concrete product containing the phosphogypsum fly ash cement is characterized by comprising the following raw materials in parts by weight: 130 portions of ardealite, 215 portions of fly ash, 45 portions to 80 portions of silicate cement, 850 portions of sand, 950 portions of pebbles, 1050 portions of water and 165 portions of sand.

2. The concrete product of claim 1, wherein the concrete product comprises the following raw materials in parts by weight: 140 portions of ardealite, 145 portions of fly ash, 195 portions of silicate cement, 55 portions to 75 portions of sand, 720 portions of sand, 1020 portions of pebble and 150 portions of water.

3. The concrete article according to claim 1 or 2, wherein the raw materials of the concrete article further comprise a water reducing agent;

preferably, the phosphogypsum, the fly ash, the silicate cement and the water reducing agent form a cementing material;

preferably, the water reducing agent accounts for 0-0.5%, preferably 0.2-0.4% of the mass of the cementing material.

4. The concrete article of any one of claims 1 to 3, wherein the portland cement comprises any one or a combination of at least two of ordinary portland cement, portland slag cement, portland fly ash cement, portland pozzolan cement, composite portland cement, or portland limestone cement.

5. The concrete article of claim 3 or 4, wherein the water reducer comprises a water reducer of the BASF polycarboxylic acid type,

Any one or the combination of at least two of a polycarboxylic acid high-efficiency water reducing agent or a combined polycarboxylic acid water reducing agent.

6. A method for the preparation of a concrete article according to any one of claims 1 to 5, characterized in that it comprises the following steps:

7. The method according to claim 6, characterized in that the mass ratio of said partial silicate cement to said phosphogypsum of step (1) is 0.01-0.02;

preferably, the mass ratio of the total mass of the phosphogypsum and the partial silicate cement to the water in the step (1) is (5.5-6.5): 4;

preferably, the specific surface area of the phosphogypsum slurry obtained in the step (1) is more than 350m²/kg；

Preferably, the phosphogypsum slurry in the step (1) has the solid content of 55-65%;

preferably, the phosphogypsum mud of step (1) has a solid content of 75-85%.

8. The preparation method according to claim 6 or 7, wherein the step (2) further comprises mixing and stirring a water reducing agent and the phosphogypsum mud obtained in the step (1) with the fly ash, the residual silicate cement, the sand, the gravel and the water.

9. The production method according to any one of claims 6 to 8, wherein the article curing treatment comprises: standing for 0-1 day after the concrete product is formed, heating to 50-75 ℃ for steaming for 1-3 days, taking out the concrete product, soaking in water for 0-1 day, and sealing with plastic cloth.

10. The method of any one of claims 6 to 9, comprising the steps of: