CN115745536B - Ecological high-ductility cement-based rapid repair material prepared from calcined gangue powder and method - Google Patents

Abstract

The invention relates to the resource utilization of solid wastes in building materials, in particular to an ecological high-ductility cement-based rapid repair material prepared by calcining gangue powder and a method thereof; the material comprises the following raw materials in parts by mass: 496-938 parts of sulphoaluminate cement, 186-372 parts of calcined coal gangue powder, 134-372 parts of fly ash, 372-471 parts of river sand, 2.5-5.0 parts of water reducer, 12.4-37.2 parts of early strength agent, 335-397 parts of water and 18.2-26 parts of fiber; the ecological high-ductility cement-based rapid repair material prepared by the invention integrates high ductility, rapid hardening and early strength, obviously improves the defects of poor tensile deformation capacity and the like of the concrete of the road bridge deck pavement layer, can be used for rapid repair of the road bridge deck pavement layer with high efficiency, reduces the cracking risk of the concrete pavement layer, reduces the traffic blocking time, opens traffic as early as possible, and prolongs the service life of roads and bridges; on the other hand, the calcined gangue powder is used for partially replacing cement, so that the cement is saved, and the high-value utilization of the gangue can be promoted.

Description

Ecological high-ductility cement-based rapid repair materials prepared from calcined coal gangue powder and method

Technical field

The invention relates to the resource utilization of solid waste in building materials, and specifically relates to an ecological high-ductility cement-based rapid repair material and method prepared from calcined coal gangue powder.

Background technique

With the accelerated development of basic industries such as roads and bridges, the number of traffic vehicles and heavy-duty vehicles has gradually increased. Our country's road and bridge deck pavements mainly use asphalt concrete, which has poor tensile deformation resistance. Under repeated vehicle loads, the concrete road and bridge decks will be damaged. Once the concrete cracks, the cracks will rapidly worsen, and cracks and other diseases will appear in the road and bridge deck concrete pavement layers. After the road bridge deck cracks, harmful ions in the rainwater will seep into the reinforced concrete main beams and other substructures of the road bridge, affecting the service life of the road bridge. It will also reduce vehicle speed, affect comfort, and reduce transportation efficiency. Preparing a cement-based composite material that combines high ductility, quick hardening, and meets the strength level requirements of concrete pavement layers is of great significance for reducing cracking diseases of road and bridge pavement layers, opening up traffic as early as possible, and improving the efficiency of passenger and freight transportation.

Coal gangue is a kind of solid waste produced during coal preparation and washing. It is one of the largest industrial wastes in my country. The accumulation of coal gangue not only occupies land resources, but may also cause secondary disasters such as collapse, landslides, and spontaneous combustion, seriously threatening human life and safety. After spontaneous combustion or calcination, the silica and alumina content of coal gangue increases and becomes active, similar to cement cementitious materials. Partial replacement of cement with calcined coal gangue powder can save cement, strengthen the high-value utilization of solid waste coal gangue, and promote the "double carbon" action.

High-ductility cement-based composite materials are made by adding fibers to the cement-based material matrix. Through microscopic property control, the ultimate elongation under uniaxial tensile properties is no less than 0.5%, and the average crack width is no more than 200 μm. With reference to the microscopic design theory of high-ductility cement-based composite materials, an ecological high-ductility cement-based rapid repair material was prepared using fast-hardening sulfoaluminate cement and calcined coal gangue powder as cementing materials.

At present, the main way to quickly repair concrete pavement layers is to use fast-hardening concrete, but its tensile deformation ability is poor and it is easy to crack under the combined effects of temperature differences, shrinkage, vehicle loads, etc., treating the symptoms but not the root cause. The curing life of high-ductility cement-based composite materials is generally 28 days and cannot be directly used for rapid repair of road and bridge concrete pavements. Regarding the application of calcined coal gangue powder in concrete, it is shown in Table 1.

Table 1 Comparison of the current research status of existing invention patents

As can be seen from Table 1, existing research on the preparation of concrete from coal gangue powder mainly uses alkali to stimulate the activity of coal gangue powder to replace cement. However, it does not involve high ductility and rapid hardening, and cannot be used for rapid concrete paving in the field of road and bridge engineering. repair.

Contents of the invention

The invention overcomes the shortcomings of the prior art and provides an ecological high-ductility cement-based rapid repair material prepared from calcined coal gangue powder. The cement is partially replaced with calcined coal gangue powder, fly ash, early strength agent and river sand are added to prepare the matrix, and a certain amount of fiber is added. Through micro, meso and macro multi-scale interactive design, the material achieves high ductility, It hardens quickly and meets the strength grade requirements of concrete pavement layers on road and bridge decks, and provides a technical solution for rapid repair of concrete pavement layers on road and bridge decks. The ecological high-ductility cement-based rapid repair material of the invention can not only repair the concrete pavement layer of road and bridge decks, build a green and efficient transportation system, but also make high-value utilization of solid waste to promote green and low-carbon transportation.

In order to solve the above technical problems, the technical solution adopted by the present invention is: an ecological high-ductility cement-based rapid repair material prepared from calcined coal gangue powder, including raw materials with the following mass proportions: sulfoaluminate cement 496-938 parts, calcined coal gangue powder 186~372 parts, fly ash 134~372 parts, river sand 372~471 parts, water reducing agent 2.5~5.0 parts, early strength agent 12.4~37.2 parts, water 335~397 parts, fiber 18.2 parts ~26 servings.

Further, the particle size of the calcined coal gangue powder is 600 mesh to 1250 mesh, and the total mass content of alumina and silicon oxide in the calcined coal gangue powder is not less than 63.4%.

Further, the particle size of the river sand is 0.06~1.18mm, and the fineness modulus is 1.22~1.71.

Further, the early strengthening agent is one or a combination of anhydrous sodium sulfate and lithium carbonate.

Further, the fiber has a diameter of 20-40 μm, a length of 6-12 mm, an elastic modulus of 30-35 GPa, a tensile strength of at least 1000 MPa, and an ultimate elongation of 8-12%.

Further, the fiber is one or more of polyvinyl alcohol fiber, basalt fiber and polypropylene fiber.

The present invention also provides a method for preparing ecological high-ductility cement-based rapid repair materials using calcined coal gangue powder. If a solid water-reducing agent is used, the preparation steps are as follows:

1) Mix sulphoaluminate cement, calcined coal gangue powder, fly ash, water reducing agent, early strength agent, and river sand slowly, that is, the rotation speed is 140 rpm and the revolution speed is 62 rpm, and stir for 1 ~2 minutes;

2) Add water quickly, that is, the rotation speed is 285 rpm, the revolution speed is 125 rpm, and the mixture is stirred for 3 to 4 minutes;

3) Add fiber quickly, that is, the rotation speed is 285 rpm, the revolution speed is 125 rpm, and the mixing is done for 2 to 3 minutes;

4) Install the mold and remove the mold after curing it for 6 hours in a standard curing box.

The present invention also provides a method for preparing ecological high-ductility cement-based rapid repair materials using calcined coal gangue powder. If a liquid water-reducing agent is used, the preparation steps are as follows:

1) Mix sulphoaluminate cement, calcined coal gangue powder, fly ash, early strength agent, and river sand at slow speed, that is, the rotation speed is 140 rpm and the revolution speed is 62 rpm, and stir for 1 to 2 minutes;

2) Mix the water-reducing agent and water into the mixer quickly, that is, the rotation speed is 285 rpm and the revolution speed is 125 rpm, and stir for 3 to 4 minutes;

3) Add fiber quickly, that is, the rotation speed is 285 rpm, the revolution speed is 125 rpm, and the mixing is done for 2 to 3 minutes;

4) Install the mold and remove the mold after curing it for 6 hours in a standard curing box.

Furthermore, for the above two methods of using calcined coal gangue powder to prepare ecological high-ductility cement-based rapid repair materials, the entire material preparation process is controlled in 7 to 9 minutes.

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

1) Compared with the existing technology, the present invention has obvious characteristics of high ductility and rapid hardening, and can provide an effective method for concrete paving layers on road and bridge decks.

2) In terms of economic benefits, for cracked road and bridge concrete pavements, ecological high-ductility cement-based rapid repair materials are used to repair them, which fundamentally solves the diseases caused by the poor tensile deformation ability of asphalt concrete and reduces the risk of cracking of brittle concrete materials. Reduce the number of maintenance times, ensure the service life of road and bridge deck concrete, and reduce carbon emissions from the perspective of the entire life cycle.

3) In terms of social benefits, ecological high-ductility cement-based rapid repair materials are used to repair cracked concrete pavements on road and bridge decks to ensure the normal use of the concrete pavements on road and bridge decks, improve driving comfort, and improve people's quality of life; Traditional cracked concrete repair requires milling to damage the concrete. Using ecological high-ductility cement-based rapid repair materials can reduce the number of road and bridge deck repairs, reduce milling noise, and avoid disturbing residents.

4) In terms of ecological benefits, solid waste is used to calcine coal gangue powder to prepare ecological high-ductility cement-based rapid repair materials. The high-value utilization of solid waste can reduce the accumulation of solid waste, reduce environmental pollution, and promote the "double carbon" action; save Cement, reducing the high carbon emissions in the "two grinding and one burning" process of cement.

Description of the drawings

Figure 1 is a uniaxial tensile stress-strain curve of the ecological high-ductility cement-based rapid repair material in Example 1;

Figure 2 is a uniaxial tensile stress-strain curve of the ecological high-ductility cement-based rapid repair material in Example 2;

Figure 3 is a uniaxial tensile stress-strain curve of the ecological high-ductility cement-based rapid repair material in Example 3;

Figure 4 is a uniaxial tensile stress-strain curve of the ecological high-ductility cement-based rapid repair material in Example 4.

Figure 5 is a uniaxial tensile stress-strain curve of the ecological high-ductility cement-based rapid repair material in the comparative example.

Detailed ways

The present invention will be further described below in conjunction with specific examples.

Example 1

The mixing ratio of ecological high-ductility cement-based rapid repair materials in this embodiment is shown in Table 2:

Table 2 Material mix ratio (mass ratio)

cement Calcined coal gangue powder fly ash river sand Water reducing agent morning strength agent water fiber 496 372 372 372 5.0 37.2 335 26

The particle size of the above-mentioned calcined gangue powder is 1250 mesh, the mass content of alumina (Al ₂ O ₃ ) + silicon oxide (SiO ₂ ) is 95.5%; the particle size of river sand is 0.06~1.18mm, and the fineness modulus is 1.22; The early strength agent is lithium carbonate; the fiber is polyvinyl alcohol fiber, the length is 12mm, the elastic modulus is 35GPa, and the tensile strength is 1200MPa; the water-reducing agent is a liquid polycarboxylate water-reducing agent.

The preparation steps are as follows:

1) Stir sulphoaluminate cement, calcined coal gangue powder, fly ash, early strength agent lithium carbonate, and river sand at slow speed (rotation speed is 140 rpm, revolution speed is 62 rpm) for 2 minutes;

2) Mix the water-reducing agent and water into the mixer, and mix quickly (rotation speed is 285 rpm, revolution speed is 125 rpm) for 3 minutes;

3) Add fiber quickly (rotation speed is 285 rpm, revolution speed is 125 rpm) and stir for 2 minutes;

4) Install the mold, cure it in a standard curing box for 6 hours, then remove the mold and test the mechanical properties.

The entire process of preparation steps 1), 2), 3) and 4) takes 7 minutes.

Example 2

The mixing ratio of ecological high-ductility cement-based rapid repair materials in this embodiment is shown in Table 3:

Table 3 Material mix ratio (mass ratio)

cement Calcined coal gangue powder fly ash river sand Water reducing agent morning strength agent water fiber 620 310 310 397 4.2 31 360 23.4

The particle size of the above-mentioned calcined coal gangue powder is 1250 mesh, the mass content of alumina (Al ₂ O ₃ ) + silicon oxide (SiO ₂ ) is 89.2%; the particle size of river sand is 0.06~1.18mm, and the fineness modulus is 1.35; The early strength agent is anhydrous sodium sulfate; the fiber is polyvinyl alcohol fiber, the length is 8mm, the elastic modulus is 32GPa, and the tensile strength is 1100MPa; the water-reducing agent is a solid polycarboxylate water-reducing agent.

The preparation steps are as follows:

1) Put sulphoaluminate cement, calcined coal gangue powder, fly ash, water reducing agent, early strength agent anhydrous sodium sulfate, and river sand at a slow speed (the rotation speed is 140 rpm, the revolution speed is 62 rpm ) Stir for 1 minute;

2) Add water to the mixer and mix quickly (rotation speed is 285 rpm, revolution speed is 125 rpm) for 4 minutes;

3) Add fiber quickly (rotation speed is 285 rpm, revolution speed is 125 rpm) and stir for 3 minutes;

4) Install the mold, cure it in a standard curing box for 6 hours, then remove the mold and test the mechanical properties.

The entire process of preparation steps 1), 2), 3) and 4) takes 8 minutes.

Example 3

The mixing ratio of ecological high-ductility cement-based rapid repair materials in this embodiment is shown in Table 4:

Table 4 Material mix ratio (mass ratio)

cement Calcined coal gangue powder fly ash river sand Water reducing agent morning strength agent water fiber 868 186 186 415 3.7 24.8 384 20.8

The particle size of the above-mentioned calcined coal gangue powder is 800 mesh, the mass content of alumina (Al ₂ O ₃ ) + silicon oxide (SiO ₂ ) is 63.4%; the particle size of river sand is 0.06~1.18mm, and the fineness modulus is 1.62; The early strength agent is a composite of lithium carbonate and anhydrous sodium sulfate; the fiber is basalt fiber, the length is 6mm, the elastic modulus is 30GPa, and the tensile strength is 1100MPa; the water-reducing agent is a liquid polycarboxylate water-reducing agent.

The preparation steps are as follows:

1) Combine sulphoaluminate cement, calcined coal gangue powder, fly ash, early strength agent (lithium carbonate and anhydrous sodium sulfate), and river sand at a slow speed (rotation speed is 140 rpm, revolution speed is 62 rpm) minutes) stir for 2 minutes;

2) Mix the water-reducing agent and water into the mixer, and mix quickly (rotation speed is 285 rpm, revolution speed is 125 rpm) for 3 minutes;

3) Add fiber quickly (rotation speed is 285 rpm, revolution speed is 125 rpm) and stir for 3 minutes;

4) Install the mold, cure it in a standard curing box for 6 hours, then remove the mold and test the mechanical properties.

The entire process of preparation steps 1), 2), 3) and 4) takes 8 minutes.

Example 4

The mixing ratio of ecological high-ductility cement-based rapid repair materials in this embodiment is shown in Table 5:

Table 5 Material mix ratio (mass ratio)

cement Calcined coal gangue powder fly ash river sand Water reducing agent morning strength agent water fiber 938 268 134 471 2.5 12.4 397 18.2

The particle size of the above-mentioned calcined coal gangue powder is 600 mesh, the mass content of alumina (Al ₂ O ₃ ) + silicon oxide (SiO ₂ ) is 78.4%; the particle size of river sand is 0.06~1.18mm, and the fineness modulus is 1.71; The early strength agent is lithium carbonate; the fiber is a composite of polyvinyl alcohol fiber and polypropylene fiber. The length of polyvinyl alcohol fiber is 12mm, the length of polypropylene fiber is 8mm, the elastic modulus of polyvinyl alcohol fiber is 35GPa, and the tensile strength is 1200MPa. The elastic modulus of polypropylene fiber is 32GPa and the tensile strength is 1000MPa; the water-reducing agent is a solid polycarboxylate water-reducing agent.

The preparation steps are as follows:

1) Stir sulphoaluminate cement, calcined coal gangue powder, fly ash, water reducing agent, early strength agent lithium carbonate, and river sand at slow speed (rotation speed is 140 rpm, revolution speed is 62 rpm) 1 minute and 30 seconds;

2) Add water to the mixer and mix quickly (rotation speed is 285 rpm, revolution speed is 125 rpm) for 3 minutes;

3) Add fiber quickly (rotation speed is 285 rpm, revolution speed is 125 rpm) and stir for 3 minutes;

4) Install the mold, cure it in a standard curing box for 6 hours, then remove the mold and test the mechanical properties.

The entire process of preparation steps 1), 2), 3) and 4) lasts 7 minutes and 30 seconds.

Comparative ratio:

The mixing ratio of ecological high-ductility cement-based rapid repair materials in this comparative example is shown in Table 6:

Table 6 Material mix ratio (mass ratio)

cement fly ash river sand Water reducing agent morning strength agent water fiber 868 372 372 5.0 37.2 335 26

The particle size of the above-mentioned river sand is 0.06~1.18mm, the fineness modulus is 1.22; the early strength agent is lithium carbonate; the fiber is polyvinyl alcohol fiber, the length is 12mm, the elastic modulus is 35GPa, and the tensile strength is 1200MPa; the water-reducing agent It is a liquid polycarboxylate water-reducing agent.

The preparation steps are as follows:

1) Stir sulphoaluminate cement, fly ash, early strength agent lithium carbonate, and river sand at slow speed (rotation speed is 140 rpm, revolution speed is 62 rpm) for 2 minutes;

2) Mix the water-reducing agent and water into the mixer, and mix quickly (rotation speed is 285 rpm, revolution speed is 125 rpm) for 3 minutes;

3) Add fiber quickly (rotation speed is 285 rpm, revolution speed is 125 rpm) and stir for 2 minutes;

4) Install the mold, cure it in a standard curing box for 6 hours, then remove the mold and test the mechanical properties.

The entire process of preparation steps 1), 2), 3) and 4) takes 7 minutes.

Table 7 Compressive strength of ecological high-ductility cement-based rapid repair materials after standard curing for 6 hours

The compressive strength of the ecological high-ductility cement-based rapid repair materials in Examples 1 to 4 and the comparative example after standard curing for 6 hours is shown in Table 7. Although the partial replacement of cement with calcined coal gangue powder reduces the compressive strength of the repair material, However, the compressive strengths in Examples 1 to 4 are all greater than 40MPa, which meets the strength requirements of concrete pavement layers on road and bridge decks.

Table 8 Ultimate elongation of ecological high-ductility cement-based rapid repair materials after standard curing for 6 hours

Example Example 1 Example 2 Example 3 Example 4 Comparative ratio Ultimate elongation (%) 1.26 1.03 0.86 0.79 0.81 Improvement effect (%) 55.5 27.2 6.2 -2.5 --

Note: The improvement effect of ultimate elongation in Table 8 is compared based on the test results in the comparative example.

The ultimate elongation of the ecological high-ductility cement-based rapid repair materials in Comparative Examples 1 to 4 and Comparative Examples after standard curing for 6 hours is shown in Table 8. Partial replacement of cement with calcined coal gangue powder reduces the strength of the repair material. According to the high-ductility cement The micromechanical design method of matrix composite materials helps the fibers to be pulled out slowly when the matrix strength is low, which can increase the ultimate elongation of the repair material. It shows that calcined coal gangue powder can replace cement to prepare ecological high-ductility cement-based rapid repair materials. After reasonable mix ratio optimization design, it can ensure that the repair materials have high ductility while meeting the strength grade requirements, and can improve the high-value utilization of coal gangue. efficiency and save cement.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the art may think of changes or modifications within the technical scope disclosed in the present invention without creative efforts. All substitutions are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope defined by the claims.

Claims (3)

1. The ecological high-ductility cement-based rapid repair material prepared from calcined gangue powder is characterized by comprising the following raw materials in parts by mass: 496 parts of sulphoaluminate cement, 372 parts of calcined coal gangue powder, 372 parts of fly ash, 372 parts of river sand, 5.0 parts of water reducer, 37.2 parts of early strength agent, 335 parts of water and 26 parts of fiber; the particle size of the calcined coal gangue powder is 1250 meshes, and the sum of the mass contents of alumina and silica in the calcined coal gangue powder is 95.5 percent; the grain diameter of the river sand is 0.06-1.18 mm, and the fineness modulus is 1.22; the early strength agent is lithium carbonate; the fiber is polyvinyl alcohol fiber, the length is 12mm, the elastic modulus is 35GPa, and the tensile strength is 1200MPa; the water reducer is a liquid polycarboxylate water reducer.

2. The method for preparing the ecological high-ductility cement-based rapid repair material according to claim 1, wherein the preparation method comprises the following steps of:

1) The method comprises the steps of (1) slowly mixing sulphoaluminate cement, calcined gangue powder, fly ash, an early strength agent and river sand, namely, the rotation speed is 140 rpm, the revolution speed is 62 rpm, and stirring is carried out for 1-2 minutes;

2) Mixing the water reducer and water, adding the mixture into a stirrer, and stirring the mixture for 3 to 4 minutes, wherein the rotation speed is 285 rpm, and the revolution speed is 125 rpm;

3) Adding fiber quickly, namely, the rotation speed is 285 rpm, the revolution speed is 125 rpm, and stirring is carried out for 2-3 minutes;

4) And (5) die filling, curing in a standard curing box for 6 hours, and then removing the die.

3. The method for preparing the ecological high-ductility cement-based rapid repair material according to claim 2, wherein the whole preparation process of the material is controlled to be 7-9 minutes.