Solid-waste-based self-excitation foam concrete and preparation method thereof

Abstract

The invention relates to solid waste-based self-excitation foam concrete which is characterized by comprising the following raw materials in parts by mass: 1-2 parts of a composite foaming agent, 40-60 parts of a composite precursor, 40-60 parts of an alkaline excitation material, 0.1-0.2 part of polypropylene fiber and water, and the mass ratio of water to glue is 0.45-0.55. The mineral activity of the waste incineration bottom slag, the fly ash and the granulated blast furnace slag powder is excited through the solid waste-based alkaline exciting agent, the compressive strength of the material is remarkably improved by adding the polypropylene fiber, the dry density and the heat conductivity coefficient meet expected requirements, the cost is saved, energy is saved, the environment is protected, and a new direction is provided for recycling application of industrial solid waste.

Description

Technical Field

[0001] The present invention relates to the technical field of foamed concrete, and in particular to a solid waste-based self-exciting foamed concrete and a preparation method thereof. Background Art

[0002] Foamed concrete is a lightweight, heat-insulating, fire-resistant, sound-insulating and frost-resistant concrete material, which has been widely used in building engineering for roof slope finding, toilet backfilling and floor heating backfilling, etc., replacing the traditional backfilling method, not only reducing the structural self-weight, but also having fast construction and excellent performance. The conventional method is to make foam with a foaming agent, and then mix it with a certain proportion of water, cement, admixtures and additives to make a slurry, and then pour and solidify it. The use of traditional cementitious materials such as cement increases carbon emissions.

[0003] Bottom ash from waste incineration is the main product after waste incineration, and there are problems of insufficient utilization and consumption of waste incineration bottom ash; in addition, in industrial production, solid wastes such as red mud, carbide slag, granulated blast furnace slag, and fly ash are directly stacked or landfilled outdoors, resulting in problems of occupying land, secondary pollution and insufficient utilization.

[0004] To solve the above problems, the present invention proposes a solid waste-based self-exciting foamed concrete and a preparation method thereof. Summary of the Invention

[0005] The purpose of the present invention is to provide a solid waste-based self-exciting foamed concrete and a preparation method thereof for the problems in the prior art that traditional cementitious materials such as cement are used in foamed concrete, and the utilization and consumption of solid wastes are insufficient.

[0006] The technical solution of the present invention is as follows:

[0007] A solid waste-based self-exciting foamed concrete, including raw materials and mass parts: composite foaming agent (1-2 parts), composite precursor (40-60 parts), alkaline activation material (40-60 parts), polypropylene fiber (0.1-0.2 parts) and water, and the water-cementitious material mass ratio is 0.45-0.55.

[0008] Preferably: The composite foaming agent is composed of a compound foaming agent and a foam stabilizer, wherein the compound foaming agent is composed of one or several of sodium dodecyl sulfate, α-olefin sulfonate, and animal protein foaming agent, and the foam stabilizer is polyvinyl alcohol or sorbitan monooleate.

[0009] Preferably: The concentration of the composite foaming agent is 10 g / L.

[0010] Preferably: The composite foaming agent is compounded according to the mass ratio of animal protein foaming agent to sodium dodecyl sulfate of 1:0.5-4.

[0011] Preferably, the dosage of the foam stabilizer is 1% of the animal protein foaming agent.

[0012] By adopting the above technical solution, adding animal protein into a solution where sodium dodecyl sulfate has not reached the critical micelle concentration can further reduce the surface tension of the solution. According to the film elasticity theory, when an external force causes local thinning and stretching of the liquid film, the surface tension gradient between the thinned area and the non-thinned area increases, prompting the surface layer molecules and the entrained bottom liquid in the non-thinned area to flow towards the thinned area, thereby preventing further thinning of the film. The compounding of the two can increase the electrostatic repulsion force between the inner and outer layers of the foam surface, making it difficult for the liquid between the two surfactant molecular films to drain. Therefore, through the compounding of the animal protein foaming agent and sodium dodecyl sulfate, the foaming performance of the foaming agent is significantly improved, effectively reducing the foam settlement distance and bleeding water volume. Polyvinyl alcohol is a high molecular compound with good water solubility. It can not only increase the viscosity of the liquid phase and prevent liquid film drainage, but also form a high-strength interfacial film, so it has a good foam stabilizing effect.

[0013] Preferably, the composite precursor is composed of granulated blast furnace slag (60 - 75 parts by mass), fly ash (10 - 20 parts by mass), bottom slag from waste incineration (10 - 25 parts by mass), coagulant (1 part by mass), and water reducer (1 part by mass); the bottom slag from waste incineration is the residue obtained after recovering metals from the bottom slag generated by a waste incineration plant, aging in an open environment, and sieving; the coagulant is white granular Na2CO3, and the water reducer is brown powdery naphthalene-based water reducer; the granulated blast furnace slag is commercially available S95 grade granulated blast furnace slag powder; the fly ash is commercially available secondary fly ash.

[0014] The composite precursor prepared from granulated blast furnace slag, fly ash, and bottom slag from waste incineration can adjust the incorporation ratio according to the composition of the solid waste, and rationally configure the Si - Al - O ratio in the precursor, enabling it to fully participate in the alkali activation reaction, and at the same time making full use of solid waste. The addition of the coagulant can increase the reaction rate and shorten the initial setting and final setting times. The addition of the water reducer can improve fluidity, reduce water consumption, and increase the strength of the foam concrete.

[0015] Preferably, the alkaline activation material is composed of carbide slag (60 - 75 parts) and red mud (25 - 40 parts).

[0016] Preferably, the particle sizes of the carbide slag and red mud are ≤ 0.075 mm.

[0017] By adopting the above technical solution, the alkaline activator is composed of carbide slag and red mud. The carbide slag mainly contains Ca(OH)2 and its aqueous solution is strongly alkaline. The red mud contains a large amount of strongly alkaline chemical substances, and its pH value is still 11.25 - 11.50 after being diluted 10 times. By mixing carbide slag and red mud, the alkalinity of the alkaline activator for the water-mixed material can be adjusted to ensure that the activity of the composite precursor can be activated.

[0018] Preferably, the polypropylene fiber has a length of 6 - 19 mm and a diameter of 0.02 - 0.04 mm.

[0019] The present invention also provides a method for preparing the above solid waste-based self-activating foamed concrete, which includes the following steps:

[0020] S1. Weigh the granulated blast furnace slag, fly ash, municipal solid waste incineration bottom ash, coagulant, and water reducer in dry state according to the proportion and put them into a powder mixer for mixing to obtain a uniform composite precursor mixture;

[0021] S2. Weigh the carbide slag and red mud in dry state according to the proportion, put them into a mixer, add water according to the proportion and stir evenly to obtain an alkaline activator;

[0022] S3. Put the polypropylene fiber and the composite precursor obtained in S1 into a mixer and stir evenly to obtain a mixed slurry; meanwhile, put the composite foaming agent into a foaming machine and mix it with water at a ratio of 1:20 to obtain stable and uniform foam;

[0023] S4. Put the stable and uniform foam obtained in S3 into the alkaline activator obtained in S2 according to the proportion, and stir to obtain the solid waste-based self-activating foamed concrete;

[0024] Preferably, the mixing time in step S1 is not less than 3 minutes;

[0025] Preferably, the stirring time in step S2 is not less than 5 minutes;

[0026] Preferably, the stirring time in step S3 is 3 - 5 minutes;

[0027] Preferably, the stirring temperature of the foaming machine in step S3 is 40 - 50 °C and the stirring time is 5 - 7 minutes;

[0028] Preferably, the stirring time in step S4 is 3 - 5 minutes.

[0029] Municipal solid waste incineration bottom ash (MSWIBA) is the main product after garbage incineration. The main compounds are oxides, hydroxides, and carbonates. Among them, the contents of SiO2, Al2O3, and CaO account for about 70% of the total mass of the bottom ash, belonging to the typical CaO - SiO2 - Al2O3 chemical system and having similar hydration activity to cement, fly ash, granulated blast furnace slag, etc.

[0030] The alkaline activator material composed of carbide slag and red mud is strongly alkaline after being mixed with water, and can stimulate the mineral activity of the composite precursor. The silicate dissolves in the strong alkaline environment to form an ion body, and then the alkali enters the interior of the vitreous body, and the interior begins to dissolve, forming silicate gel on the surface and inside of the vitreous body, and finally the system dehydrates and hardens.

[0031] Advantages of the present invention: The present invention provides a solid waste-based self-exciting foamed concrete, which uses industrial solid waste as the basic raw material, uniformly mixes it with foam, and by adjusting the mixing ratio between the raw materials, enables each raw material to play its role together. Compared with the prior art, the prepared foamed concrete has the following advantages:

[0032] The foamed concrete provided by the present invention does not use cement, water glass, and sodium hydroxide during preparation. The mineral activity of the bottom slag of waste incineration, fly ash, and granulated blast furnace slag powder is stimulated by a solid waste-based alkaline activator. By adding polypropylene fiber, the compressive strength of the material is significantly improved, and the dry density and thermal conductivity meet the expected requirements, saving costs, energy conservation and environmental protection, and providing a new direction for the resource utilization of industrial solid waste.

[0033] The foamed concrete prepared by the present invention is light, porous, and also has material properties such as good heat preservation, heat insulation, fire resistance, and frost resistance. It has good physical and mechanical properties and is an excellent building energy-saving material. It can replace traditional backfill materials, solve the problems of insufficient utilization and consumption of industrial solid waste in the prior art, open up a new field for the resource utilization of industrial solid waste, and improve the utilization rate and utilization quality of industrial solid waste such as the bottom slag of waste incineration, fly ash, and granulated blast furnace slag. Specific embodiments

[0034] The present invention will be further described in detail below with reference to the embodiments. It can be understood that the specific embodiments described herein are only used to explain the related invention, rather than limiting the invention. It should be noted that, without conflict, the embodiments, comparative examples, and features in the embodiments and comparative examples of the present invention can be combined with each other.

[0035] Embodiment

[0036] This embodiment provides a solid waste-based self-exciting foamed concrete, the raw materials of which include a composite foaming agent, a composite precursor, an alkaline activator material, polypropylene fiber, and water.

[0037] The composite foaming agent is composed of a compound foaming agent and a foam stabilizer. The compound foaming agent is compounded by an animal protein foaming agent and sodium dodecyl sulfate at a mass ratio of 1:0.7; the foam stabilizer is sorbitan monooleate, and preferably the dosage of sorbitan monooleate is 1% of the animal protein foaming agent; the preferred concentration of the composite foaming agent is 10 g / L.

[0038] The composite precursor is mixed by 70 parts of granulated blast furnace slag, 10 parts of fly ash, 20 parts of bottom ash from waste incineration, 1 part of coagulant, and 1 part of water reducer;

[0039] The alkaline activating material is mixed by 60 parts of carbide slag and 40 parts of red mud;

[0040] The mass ratio of the composite precursor to the alkaline activating material is 1:1.45;

[0041] The water-binder ratio is 0.48.

[0042] The preparation method of the foamable concrete provided in this example includes the following steps:

[0043] S1. Weigh the granulated blast furnace slag, fly ash, bottom ash from waste incineration, coagulant, and water reducer in dry state according to the proportion and put them into a powder mixer for mixing. The mixing time is 3 minutes to obtain a uniform composite precursor mixture;

[0044] S2. Weigh the carbide slag and red mud in dry state according to the proportion, put them into a mixer, add water according to the proportion and stir evenly. The stirring time is 5 minutes;

[0045] S3. Put the composite precursor obtained in S1 into a mixer, and the stirring time is 4 minutes to obtain a uniform slurry; meanwhile, put the composite foaming agent into a foaming machine and mix it with water at a ratio of 1:20. The stirring temperature of the foaming machine is 45 °C and the stirring time is 7 minutes to obtain stable and uniform foam;

[0046] S4. Put the stable and uniform foam obtained in S3 into the slurry mixer obtained in S2 according to the proportions of Examples 1 - 6 shown in Table 1. The foam volume to the mass ratio of the uniform slurry is different for Examples 1 - 6. Stir for 4 minutes to obtain a solid waste-based self-activating foam concrete after stirring.

[0047] Table 1 Mixing ratio table of Examples 1 - 6

[0048]

[0049] Performance test

[0050] The foam concrete prepared in Examples 1 - 6 is subjected to performance testing according to JG / T 266 - 2011 "Foam Concrete". The specific test results are shown in Table 2.

[0051] Table 2 Performance table of Examples 1 - 6

[0052]

[0053] As can be seen from Table 2, the solid waste-based self-exciting foamed concrete provided by the present invention has the following characteristics:

[0054] (1) The range of 28-day compressive strength is 0.58 - 0.87 Mpa, meeting the requirements of C1 grade foamed concrete;

[0055] (2) The dry density range is 435 - 658 kg·m -3 , and the thermal conductivity range is 0.0855 - 0.1534 W·(m·k) -1 , meeting the requirements of A07 grade foamed concrete;

[0056] (3) The water absorption range is 12.4 - 15.9%, meeting the requirements of W20 grade foamed concrete;

[0057] (4) With the increase of the foam content, it has a great influence on the thermal conductivity and compressive strength, and can significantly reduce its thermal conductivity. However, when the foam content of 10 kg of slurry in Example 5 is 44 L, the thermal conductivity is the smallest and the compressive strength is relatively high. It can be seen from the cross-sectional views of the foamed concrete specimens with different foam contents that when the foam content is 44 L, the pore diameter is significantly smaller than that of other specimens, and the pore size is relatively uniform, and the pore wall is relatively thick, so the heat insulation performance is the best and the compressive strength is relatively high.

[0058] The fiber quality and length affect Example

[0059] To determine the influence of the fiber mass and fiber length incorporated on the properties of foamed concrete, taking Example 5 as the reference, a comparative example was set up, and the proportions are shown in Table 3.

[0060] Table 3 Proportion table of Examples 51 - 55 of Example 5

[0061]

[0062] Performance test

[0063] According to JG / T 266 - 2011 "Foamed Concrete", the performance of the foamed concrete prepared in Example 5 and Examples 51 - 55 was tested. The flexural strength was carried out in accordance with "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671 - 2021). The specific test results are shown in Table 4.

[0064] Table 4 Performance table of Example 5 and Examples 51 - 55

[0065]

[0066]

[0067] As can be seen from Table 4, the fiber-reinforced waste-based self-exciting foamed concrete provided by the present invention has the following characteristics:

[0068] The incorporation of fibers reduces the compressive strength of foamed concrete, and the water absorption rate and thermal conductivity increase to some extent. However, all three parameters meet the requirements of JG / T 266-2011 "Foamed Concrete". The flexural strength is effectively improved. When the fiber length is 6 mm and the dosage is 0.2% of the sum of the masses of the composite precursor and the alkaline activator, the improvement of the flexural strength is obvious.

[0069] The present invention proposes a waste-based self-exciting foamed concrete. This foamed concrete uses industrial solid waste as the basic raw material, mixes it evenly with foam, and by adjusting the mixing ratio between the raw materials, enables each raw material to play its role together. The flexural performance of the foamed concrete is strengthened by fibers. Compared with the existing technology, the prepared foamed concrete has the following advantages:

[0070] The foamed concrete provided by the present invention does not use cement, water glass, or sodium hydroxide during preparation. The mineral activities of bottom ash from waste incineration, fly ash, and granulated blast furnace slag powder are excited by a waste-based alkaline activator. By adding polypropylene fibers, the compressive strength of the material is significantly improved, and the dry density and thermal conductivity meet the expected requirements, saving costs, energy, and protecting the environment, providing a new direction for the resource utilization of industrial solid waste.

[0071] The foamed concrete prepared by the present invention is lightweight and porous, and also has material characteristics such as good heat preservation, heat insulation, fire resistance, and frost resistance. It has good physical and mechanical properties and is an excellent building energy-saving material. It can replace traditional backfill materials, solve the problems of insufficient utilization and consumption of industrial solid waste existing in the prior art, open up a new field for the resource utilization of industrial solid waste, and improve the utilization rate and utilization quality of industrial solid waste such as bottom ash from waste incineration, fly ash, and granulated blast furnace slag.

[0072] In this article, specific examples are used to elaborate on the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention. The above is only the preferred implementation mode of the present invention. It should be noted that due to the limited nature of written expression and objectively existing 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, retouches, or changes can be made, or the above technical features can be combined in an appropriate manner; these improvements, retouches, changes, or combinations, or directly applying the concept and technical solution of the invention to other occasions without improvement, should all be regarded as the protection scope of the present invention.

Claims

1. A solid waste-based self-excited foamed concrete, characterized in that: The raw materials and their mass proportions are: composite foaming agent (1-2 parts), composite precursor (40-60 parts), alkaline excitation material (40-60 parts), polypropylene fiber (0.1-0.2 parts) and water, and the water-to-gel mass ratio is 0.45-0.

55.

2. A solid waste-based self-excited foamed concrete as claimed in claim 1, characterized in that: The composite foaming agent is composed of a compound foaming agent and a foam stabilizer, wherein the compound foaming agent is a mixture of one or more of sodium dodecyl sulfate, sodium α-olefin sulfonate, and animal protein foaming agents, and the foam stabilizer is polyvinyl alcohol or sorbitan monooleate.

3. The solid waste-based self-excited foamed concrete according to claim 1, characterized in that: The concentration of the composite foaming agent is 10 g / L.

4. The solid waste-based self-excited foamed concrete according to claim 2, characterized in that: The composite foaming agent is compounded with animal protein foaming agent and sodium lauryl sulfate in a mass ratio of 1:0.5-4.

5. The solid waste-based self-excited foamed concrete according to claim 2, characterized in that: The dosage of the foam stabilizer is 1% of the animal protein foaming agent.

6. The solid waste-based self-excited foamed concrete according to claim 1, characterized in that: The composite precursor is formed by mixing granulated blast furnace slag (60-75 parts by mass), fly ash (10-20 parts by mass), waste incineration bottom ash (10-25 parts by mass), a coagulant (1 part by mass), and a water reducer (1 part by mass); the waste incineration bottom ash is the residue obtained by recovering metals from the bottom ash produced by a waste incineration plant, which is matured in an open-air environment and sieved; the coagulant is white granular Na2CO3, and the water reducer is a brown powdery naphthalene-based water reducer; the granulated blast furnace slag is commercially available S95 grade granulated blast furnace slag powder; and the fly ash is commercially available secondary fly ash.

7. The solid waste-based self-excited foamed concrete according to claim 1, characterized in that: The alkaline exciting material is prepared by mixing carbide slag (60-75 parts) and red mud (25-40 parts).

8. The solid waste-based self-excited foamed concrete according to claim 1, characterized in that: The particle size of the carbide slag and red mud is ≤0.075mm.

9. The solid waste-based self-excited foamed concrete according to claim 1, characterized in that: The polypropylene fiber has a length of 6 to 19 mm and a diameter of 0.02 to 0.04 mm.

10. A method for preparing the solid waste-based self-excited foamed concrete according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Weigh dry granulated blast furnace slag, fly ash, waste incineration bottom ash, coagulant, and water reducing agent in proportion and put them into a powder mixer for mixing to obtain a uniform composite precursor mixture; S2, weighing dry carbide slag and red mud in proportion, putting them into a mixer, adding water in proportion and stirring evenly to obtain an alkaline excitation material; S3, putting the polypropylene fiber and the composite precursor obtained in S1 into a mixer, stirring evenly to obtain a mixed slurry; at the same time, putting the composite foaming agent into the foaming machine, mixing it with water at a ratio of 1:20 to obtain a stable and uniform foam; S4, adding the stable and uniform foam obtained in S3 into the alkaline excitation material obtained in S2 in proportion, and obtaining the solid waste-based self-excited foam concrete after stirring; Preferably, the mixing time in step S1 is not less than 3 minutes; Preferably, the stirring time in step S2 is not less than 5 minutes; Preferably, the stirring time in step S3 is 3 to 5 minutes; Preferably, the stirring temperature of the foaming machine in step S3 is 40-50° C., and the stirring time is 5-7 minutes; Preferably, the stirring time in step S4 is 3 to 5 minutes.

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