CN110615631A

CN110615631A - Method for controlling concrete volume stability by comprehensively utilizing industrial waste residues

Info

Publication number: CN110615631A
Application number: CN201910254450.6A
Authority: CN
Inventors: 吴凯; 范鹏
Original assignee: Suzhou Chongyushan New Material Technology Co Ltd
Current assignee: Suzhou Chongyushan New Material Technology Co Ltd
Priority date: 2019-04-01
Filing date: 2019-04-01
Publication date: 2019-12-27

Abstract

The invention belongs to the technical field of new materials and environmental protection. The invention relates to a technology for utilizing solid wastes such as waste incineration fly ash, desulfurized gypsum, phosphogypsum and the like and producing an expanding agent for stabilizing the volume of concrete. The technology comprises the following two steps: (1) the method comprises the following steps of (1) obtaining sulphoaluminate clinker taking anhydrous calcium sulphoaluminate and dicalcium silicate as main minerals by heating and insulating waste incineration fly ash, desulfurized gypsum, limestone and bauxite as raw materials in an electric furnace; (2) the sulphoaluminate clinker, the desulfurized gypsum and the phosphogypsum are ground together to prepare the expanding agent, and the expanding agent can compensate the volume shrinkage of concrete in different degrees according to different types and compositions of materials, so that the expanding agent has the function of stabilizing the volume change of the concrete.

Description

Method for controlling concrete volume stability by comprehensively utilizing industrial waste residues

Technical Field

The invention belongs to the technical field of new materials and environmental protection, and relates to a technology for utilizing solid wastes such as waste incineration fly ash, desulfurized gypsum, phosphogypsum and the like and producing an expanding agent for stabilizing the volume of concrete.

Background

The concrete expanding agent is an additive which can expand a certain volume of concrete due to chemical action in the hardening process after being doped into the concrete. The crack control of concrete is a major technical problem which has been long dedicated to the concrete engineering industry, and the shrinkage compensation effect of the expanding agent is the most common method for controlling the concrete crack in the engineering at present.

The concrete expanding agent has wide application, and is mainly used in shrinkage-compensating concrete, filling expanded concrete, grouting material and self-stress concrete. The concrete expanding agent is also commonly used as a raw material of a waterproof agent, and the technical requirements of the concrete on water reduction, retardation, water prevention, expansion and the like can be simultaneously met by compounding the expanding agent with a water reducing agent, a retarder and the like.

Currently, calcium sulfoaluminatesThe expanding agent is a very commonly used one, and the reason for the expansion energy is due to the formation of calcium sulfoaluminate hydrate (ettringite). Because of the effective utilization of resources and energy and environmental problems, people pay high attention to the method, and the strategy of sustainable development is advocated. Because the used alumina, limestone, gypsum and the like are natural minerals and natural resources are nonrenewable resources, which threatens increasingly tense resources, the search for substitutes of the natural resources is a trend of the development of the current building material industry.

The municipal waste incineration fly ash belongs to dangerous waste due to the fact that the municipal waste incineration fly ash contains total dioxins (PCDDs) and total furans (PCDFs) and heavy metals with high leaching concentration, and meanwhile, the main chemical component in the incineration fly ash belongs to CaO-SiO₂－Al₂O₃(Fe₂O₃) The system has pollution and resource utilization of the incineration fly ash. The annual treatment cost of burning fly ash into dangerous waste landfills is over 200 million yuan. In addition to cost concerns, hazardous waste landfills present other problems. At present, the construction of domestic waste incineration plants in China far exceeds the construction pace of dangerous waste landfills, and a large amount of waste incineration fly ash is generated every day, and a proper way for going out is urgently needed to be found, so that how to safely and effectively treat and utilize the waste incineration fly ash becomes an environmental and social problem which is urgently needed to be solved. The treatment of incineration fly ash at home and abroad focuses on harmless treatment, such as melt solidification, cement asphalt solidification and the like, but the resource property of the incineration fly ash cannot be utilized.

The flue gas desulfurization technology in China mainly comprises a wet desulfurization process, a dry desulfurization process, a semi-dry desulfurization process and the like, wherein the application proportion of the wet desulfurization process is as high as 85%. However, the wet desulfurization process using limestone-gypsum method has the consequence that a large amount of desulfurized gypsum is piled up and decomposed to cause secondary pollution, which brings harm to climate, soil, plants and human health. In addition, the byproduct gypsum in the production process of many chemical enterprises is accumulated and damaged as well. At present, the desulfurized gypsum and gypsum which is a chemical byproduct, such as phosphogypsum, exceed 1 hundred million tons. How to dispose of the industrial waste is an urgent problem to be solved by governments of various countries.

Disclosure of Invention

The invention aims to provide a method for controlling the volume stability of concrete by comprehensively utilizing industrial waste residues.

In order to achieve the above purpose, the solution of the invention is as follows: in the invention, the production of the novel concrete expanding agent comprises two processes of calcining the sulphoaluminate clinker and grinding the sulphoaluminate clinker and the gypsum.

The sulphoaluminate clinker is prepared by taking waste incineration fly ash, desulfurized gypsum, phosphogypsum, limestone and bauxite as raw materials, heating to 1200-1250 ℃ at a heating rate of 20-30 ℃/min in an electric furnace, and then preserving heat for 1-2 hours. The main mineral of the clinker isC₂S and C₄AF, which can be controlled by the following method (recipe).

The quality of the sulphoaluminate clinker should meet the relevant regulations in sulphoaluminate cement (GB 20472-2006): i.e. Al in the clinker₂O₃％≥30.0％；SiO₂Less than or equal to 10.5 percent, and the 3d compressive strength of the sulphoaluminate cement clinker is more than or equal to 55 MPa. Such quality can be controlled by the following method.

The raw material formula of the sulphoaluminate clinker is as follows (mass ratio):

waste incineration fly ash: 10% -18%; limestone: 30% -40%; desulfurized gypsum: 15% -25%; phosphogypsum: 15% -25%; bauxite: 25 to 32 percent.

The main mineral composition of the sulphoaluminate clinker is as follows (mass ratio):

55％～75％；C₂S：15％～30％；C₄AF：3％～6％。

in the novel concrete expanding agent, the mass ratio of the sulphoaluminate is controlled as follows: 45-55 percent of the desulfurized gypsum and 45-55 percent of the desulfurized gypsum. In the production, the sulphoaluminate clinker and the desulfurized gypsum are jointly ground to reach the specific surface area of (300-400) m²/kg。

The expanding agent has the action principle thatReacting with gypsum to produce ettringite (C)₃A·CaSO₄·32H₂O), causing micro-expansion of the concrete. Under the above ratio conditions, the effect of swelling can be exhibited to the maximum extent. If the gypsum content is more than 55%, the setting time is too short and the expansion is insufficient; and if the amount of the gypsum is less than 45%, insufficient gypsum may be caused,can not completely participate in the reaction and can not generate ettringite to the maximum extent, thereby causing the waste of clinker. Within the above ratio ranges, the setting time is generally shorter as the gypsum content is larger, and tables 4 and 5 are shown in detail.

Due to the adoption of the scheme, the invention has the beneficial effects that:

the invention comprehensively utilizes solid wastes such as waste incineration fly ash, desulfurized gypsum and the like to completely replace natural gypsum and partially replace non-renewable mineral resources such as limestone, bauxite and the like, and the total substitution rate of the wastes in the produced novel concrete expanding agent reaches over 50 percent. The method can reduce the serious burden and treatment cost of fly ash, desulfurized gypsum and the like on the environment because of not being utilized while ensuring the performance of products, and has good economic and social benefits.

Detailed Description

The present invention will be further described with reference to the following examples.

The main raw materials used in the test comprise desulfurized gypsum, waste incineration fly ash, limestone and alumina. The main chemical components of the raw materials are shown in Table 1

TABLE 1 chemical composition of raw materials%

Calculating the ingredients according to the designed mineral clinker composition: garbage ash: 15 percent; limestone: 36 percent; desulfurized gypsum: 19 percent; alumina: 30 percent. The raw materials in the proportion are calcined in an electric furnace at the temperature rise rate of 30 ℃/min for 1 hour at 1200 ℃, and then taken out for quenching. The chemical composition of the sulfoaluminate clinker is shown in table 2, and the physical properties of the sulfoaluminate clinker are shown in table 3.

TABLE 2 major chemical composition/% of sulfoaluminate clinker

TABLE 3 Primary physical Properties of the sulphoaluminate Clinker

The calcined sulphoaluminate clinker and the desulfurized gypsum are jointly ground to specific surface area of (320-360) m²The novel expanding agent can be prepared by/kg, and two formulas (mass ratio) for preparing the expanding agent are selected:

sulphoaluminate clinker: 45 percent; desulfurized gypsum: 55 percent;

② sulphoaluminate clinker: 50 percent; desulfurized gypsum: 50 percent.

③ sulphoaluminate clinker: 55 percent; desulfurized gypsum: 45 percent of

Sulphoaluminate clinker: 55 percent; phosphogypsum: 45 percent of

P.O 42.5.5 ordinary portland cement was blended with 10% and 12% of an expanding agent, and the results of tests conducted in accordance with "concrete expanding agent" (JC/T476-2001) are shown in tables 4 and 5.

TABLE 4 physical properties of concrete with 10% of expanding agent

TABLE 5 physical Properties of concrete with 12% of swelling agent

Claims

1. A method for controlling the volume stability of concrete by comprehensively utilizing industrial waste residues is characterized by comprising the following steps: the method comprises the following two steps:

(1) the method comprises the following steps of (1) obtaining sulphoaluminate clinker taking anhydrous calcium sulphoaluminate and dicalcium silicate as main minerals by heating and insulating waste incineration fly ash, desulfurized gypsum, limestone and bauxite as raw materials in an electric furnace;

(2) the sulphoaluminate clinker, the desulfurized gypsum and the phosphogypsum are ground together to prepare the expanding agent, and the expanding agent can compensate the volume shrinkage of concrete in different degrees according to different types and compositions of materials, so that the expanding agent has the function of stabilizing the volume change of the concrete.

2. The process and method of claim 1, wherein: in the step (1), the raw materials are heated to 1200-1250 ℃ in an electric furnace at a heating rate of 20-30 ℃/min, and then heat preservation is carried out for 1-2 h to obtain sulphoaluminate clinker;

in the step (2), the sulphoaluminate clinker, the desulfurized gypsum and the phosphogypsum are ground together until the specific surface area is 300-400 m²/kg。

3. The method of claim 1, wherein: the formula of the raw material of the sulphoaluminate clinker in the step (1) is as follows (mass ratio):

waste incineration fly ash: 10% -18%; limestone: 30% -40%; desulfurized gypsum: 15% -25%; phosphogypsum: 15% -25%; bauxite: 25 to 32 percent;

the quality ratio of the sulphoaluminate clinker in the step (2) is controlled as follows: 45-55 percent of the desulfurized gypsum and 45-55 percent of the desulfurized gypsum. Mixing the raw materials according to the proportionThen putting the mixture into a ball mill for common grinding until the specific surface area is more than 250m²/kg。

4. The method of claim 1, wherein: the quality requirement of the sulphoaluminate clinker obtained by the step (1) is as follows: wherein Al is₂O₃％≥30.0％；SiO₂Less than or equal to 10.5 percent, and the 3d compressive strength of the sulphoaluminate cement clinker is more than or equal to 55 MPa.

5. The method for preparing a concrete expansive agent according to claim 1, wherein:

the main mineral composition of the sulphoaluminate clinker obtained by the step (1) is as follows (mass ratio):

C₂S：15％～40％；C₄AF：1％～3％；C₁₂A₇：1％～7％。