A multi-element waste-based pavement repair material and a method of preparing the same

Abstract

The application discloses a multi-waste-based road pavement repairing material and a preparation method thereof. The multi-waste-based road pavement repairing material comprises the following components in percentage by weight: 30-38% of slag, 12-17% of regenerated micro powder, 10-18% of shell powder, 10-15% of alkaline waste liquid activator, 5-8% of chemical setting regulator and 16-20% of mixing water. The preparation method comprises the following steps: A1, preparing the alkaline waste liquid activator and the chemical setting regulator; and A2, mixing and stirring the slag, the regenerated micro powder, the shell powder, the alkaline waste liquid activator, the chemical setting regulator and the mixing water to obtain the multi-waste-based road pavement repairing material. The multi-waste-based road pavement repairing material has the characteristics of large fluidity, high early strength, simple process, low cost and environmental friendliness.

Description

Technical Field

[0001] This invention relates to the field of road repair technology, specifically to a multi-element waste-based road repair material and its preparation method. Background Technology

[0002] Under the combined effects of load and environment, existing cement concrete pavements have suffered severe damage and urgently need repair. Cement-based pavement repair materials, prepared using cement, mineral admixtures, fine aggregates, chemical additives, and water, possess advantages such as high fluidity, early high strength, and micro-expansion, effectively repairing damaged areas and extending the service life of existing cement concrete pavements.

[0003] Multi-waste-based cementitious materials generally refer to cementitious material systems prepared by chemically activating various wastes. Compared with cement-based materials, multi-waste-based cementitious materials have the characteristics of low production cost and low carbon emissions. However, due to limitations in reactivity and activation principles, multi-waste-based cementitious materials often suffer from poor workability, slow early strength development, and limited mechanical properties, making them unsuitable for on-site construction and unable to meet the performance requirements of road repair materials. In the invention patent (CN202310882549.7), an all-solid waste cementitious material was prepared using ultrafine powders such as slag powder, steel slag powder, and desulfurized gypsum. Due to the high water demand of ultrafine powders, the flowability control of the all-solid waste cementitious material is significantly increased. In addition, the 3-day compressive strength of the all-solid waste cementitious material is only 6.8MPa to 17.8MPa, and the 7-day compressive strength is only 23.7MPa to 29.7MPa. The low mechanical properties make it difficult to achieve rapid traffic opening and long-term service of repaired road surfaces.

[0004] Therefore, improving fluidity and enhancing mechanical properties are urgent problems to be solved for the application of multi-waste-based cementitious materials in cement concrete pavement repair projects. Summary of the Invention

[0005] In order to overcome the above technical problems, the purpose of this invention is to provide a multi-element waste-based road repair material and its preparation method. The material and method have the characteristics of high fluidity, high early strength, simple process, low cost and environmental friendliness.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A multi-component waste-based road repair material comprises the following components by weight percentage: 30-38% slag, 12-17% recycled micro powder, 10-18% shell powder, 10-15% alkaline waste liquid activator, 5-8% chemical coagulant regulator, and 16-20% mixing water.

[0008] In the early stages, after alkali activation, a large number of short rod-shaped crystals are formed in the multi-element waste-based pavement repair material, which serve as a structural framework. The gel-like products attached to the crystals are responsible for filling and ensuring the early performance of the repair material. In the later stages, during the long-term reaction process, the crystals and gel products fully overlap, which promotes the densification of the microstructure and ensures the mechanical properties of the repair material.

[0009] The slag has an MgO content of 6–13%. (MgO content is an important parameter characterizing the hydration activity of slag. When the MgO content is 6–13%, the slag can be rapidly activated without any risk to volume stability.)

[0010] The regenerated micropowder is soaked in a tannic acid solution with a concentration of 0.01–0.1 mol / L for 12–24 hours. The adsorption and chemical bonding of the phenolic hydroxyl groups in tannic acid can effectively shield the negative effects of the regenerated micropowder on the flowability of the cementitious material. After soaking in a tannic acid solution with a concentration of 0.01–0.1 mol / L for 12–24 hours, the regenerated micropowder can improve the flowability of the cementitious material.

[0011] The shell powder is soaked in a 0.5–5% (w / w) silane coupling agent solution for 8–12 hours. The biomass water-locking effect of the shell powder can improve the water retention of the cementitious material, but it can also create weak interfacial zones. The alkyl hydrolysis and condensation of the silane coupling agent in an alkaline environment can effectively improve interfacial properties. After soaking in a 0.5–5% (w / w) silane coupling agent solution for 8–12 hours, the shell powder can improve the water retention of the cementitious material.

[0012] The activated carbon in the alkaline waste liquid activator has a specific surface area of ​​800–1200 m². 2 / g, the average particle size of nano-titanium dioxide is 50-100nm. (The specific surface area of ​​activated carbon is 800-1200m²) 2 The average particle size of nano-titanium dioxide is 50-100 nm. It can rapidly render desulfurization wastewater harmless through physical adsorption and ultraviolet photocatalysis, thereby preparing an alkaline wastewater activator.

[0013] A method for preparing a multi-element waste-based road repair material includes the following steps:

[0014] A1. Preparation of alkaline waste liquid activators and chemical coagulants;

[0015] A2. The slag, recycled micro powder, shell powder, alkaline waste liquid activator, chemical coagulant regulator, and mixing water are thoroughly mixed and stirred evenly to obtain the multi-element waste-based road repair material.

[0016] In A1, the preparation of the alkaline waste liquid activator includes the following steps:

[0017] The desulfurization waste liquid generated during the purification of coke oven gas in a coking plant is simply filtered; activated carbon is added and stirred at 20-40℃ for 1-2 hours; then, it is subjected to ultraviolet light intensity of 10-15 mW / cm². 2 Under certain conditions, nano-titanium dioxide is added and stirred at room temperature for 2-4 hours to obtain the alkaline waste liquid activator.

[0018] The obtained alkaline waste liquid activator has the characteristics of high pH value and high sulfate content, which can quickly activate the reactivity of slag.

[0019] In the above technical solution, optionally, the mass ratio of the desulfurization waste liquid, the activated carbon, and the nano-titanium dioxide is (80-90):(4-8):(6-12). Through the physical adsorption of activated carbon and the ultraviolet photocatalytic effect of nano-titanium dioxide, the desulfurization waste liquid can be rapidly rendered harmless, thereby preparing an alkaline waste liquid activator.

[0020] In A1, the preparation of the chemical setting agent includes the following steps:

[0021] The chemical setting regulator is obtained by stirring polycarboxylate superplasticizer, lithium acetate, and sodium acetate at pH 4–6 and temperature 60–80°C for 8–16 hours. The electrostatic repulsion and steric hindrance effects of polycarboxylate superplasticizer can effectively improve the flowability of the repair material, while the solubilizing effects of lithium acetate and sodium acetate can effectively accelerate the setting and hardening of the repair material.

[0022] The mass ratio of the polycarboxylate superplasticizer, the lithium acetate, and the sodium acetate is (70-80):(15-20):(5-10).

[0023] The beneficial effects of this invention are:

[0024] (1) This invention replaces traditional alkaline activators with alkaline waste liquid activators derived from the coking industry, and replaces natural fine aggregates with recycled micro powder and shell powder, which significantly reduces material production costs and carbon emissions. The waste utilization rate of repair materials is 100%, the carbon emissions are 231-263 kg / t, and the production cost is 264-312 RMB / t, thus realizing the recycling of building materials.

[0025] (2) This invention uses highly active slag as a precursor and alkaline waste liquid with high pH value and high sulfate content as an activator. Combined with the CSH crystal nuclei provided by the regenerated micro powder and the solubilizing effect of lithium acetate and sodium acetate in the chemical coagulating agent, the crystal gel products are rapidly induced to be generated, so as to achieve early high strength of the repair material.

[0026] Furthermore, the adsorption and complexation of dissolved ions by the surface-active groups of shell powder modified with polycarboxylate superplasticizer, tannic acid-modified recycled micro powder, and silane coupling agent significantly delays the alkali activation process, achieving high flowability of the repair material. The initial flowability of the repair material is 350-380 mm, the initial setting time is 32-47 min, the 1-day compressive strength is 41-47 MPa, the 1-day flexural strength is 6.3-7.7 MPa, and the 1-day bond strength with reference concrete is 1.3-1.6 MPa.

[0027] (3) The present invention has a simple process, excellent performance, and environmental friendliness, and is suitable for large-scale promotion. Attached image description:

[0028] Figure 1 This is a SEM image of the repair material of the present invention. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the embodiments.

[0030] This invention provides a multi-component waste-based road repair material, comprising the following components by weight percentage: 30-38% slag, 12-17% recycled micro powder, 10-18% shell powder, 10-15% alkaline waste liquid activator, 5-8% chemical coagulant regulator, and 16-20% mixing water.

[0031] like Figure 1 As shown, in the early stage (left figure), after alkali activation, a large number of short rod-shaped crystals are formed in the repair material as a structural framework, while the gel-like products attached to the crystals are responsible for filling, thus ensuring the early performance of the repair material; in the later stage (right figure), during the long-term reaction process, the crystals and gel products overlap fully, promoting the densification of the microstructure, thus ensuring the mechanical properties of the repair material.

[0032] Furthermore, the MgO content of the slag is 6-13%. MgO content is an important parameter characterizing the hydration activity of slag; the higher the MgO content, the higher the alkalinity of the system and its hydration activity. However, when the MgO content is too high, it can easily lead to poor stability of the cementitious material. Experiments in this invention demonstrate that when the MgO content is 6-13%, the slag can hydrate rapidly in the early stages without any stability risk.

[0033] Furthermore, the regenerated micropowder is soaked in a tannic acid solution with a concentration of 0.01–0.1 mol / L for 12–24 hours. The complex composition of the regenerated micropowder can easily lead to poor flowability of the cementitious material. By modifying the regenerated micropowder with tannic acid, the adsorption and chemical bonding of phenolic hydroxyl groups can effectively shield the negative effects of the regenerated micropowder on the flowability of the cementitious material. Experimental results of this invention demonstrate that soaking the regenerated micropowder in a tannic acid solution with a concentration of 0.01–0.1 mol / L for 12–24 hours can improve the flowability of the slurry.

[0034] Furthermore, the shell powder is soaked in a 0.5–5% (w / w) silane coupling agent solution for 8–12 hours. Shell powder can improve the water retention of cementitious materials through the water-locking effect of biomass, thereby preventing water bleeding. However, shell powder easily leads to weak interfacial properties, while the alkyl hydrolysis and condensation of the silane coupling agent in an alkaline environment can effectively improve interfacial properties. Experiments of this invention demonstrate that soaking shell powder in a 0.5–5% (w / w) silane coupling agent solution for 8–12 hours improves the water retention of cementitious materials.

[0035] Furthermore, the specific surface area of ​​the activated carbon in the alkaline waste liquid activator is 800–1200 m². 2 The average particle size of nano-titanium dioxide is 50–100 nm. The harmlessness of desulfurization wastewater is key to the preparation of alkaline wastewater activators. This invention utilizes the high specific surface area of ​​activated carbon to physically adsorb harmful substances in the desulfurization wastewater; and then chemically degrades these harmful substances through the photocatalytic reaction of nano-titanium dioxide under ultraviolet light, thus synergistically achieving the harmlessness of the desulfurization wastewater. Experimental demonstrations show that the specific surface area of ​​activated carbon is 800–1200 m² / g. 2 The average particle size of nano-titanium dioxide (50-100 nm) can rapidly and effectively render desulfurization wastewater harmless, thus enabling the preparation of an alkaline wastewater activator. Based on its high pH value and high sulfate content, the alkaline wastewater activator can rapidly activate the reactivity of slag.

[0036] This invention replaces traditional alkaline activators with alkaline waste liquid activators derived from the coking industry, and replaces natural fine aggregates with recycled micro powder and shell powder, significantly reducing material production costs and carbon emissions. The waste utilization rate of the repair materials is 100%, with carbon emissions of 231-263 kg / t and production costs of 264-312 RMB / t, thus realizing the recycling of building materials.

[0037] Another object of the present invention is to provide a method for preparing the multi-element waste-based road repair material as described above, comprising the following steps:

[0038] A1. Preparation of alkaline waste liquid activators and chemical coagulants;

[0039] A2. The slag, recycled micro powder, shell powder, alkaline waste liquid activator, chemical coagulant regulator, and mixing water are thoroughly mixed and stirred evenly to obtain the multi-element waste-based road repair material.

[0040] Furthermore, the preparation method of the alkaline waste liquid activator includes: simply filtering the desulfurization waste liquid generated during the purification of coke oven gas in a coking plant; adding activated carbon and stirring at 20-40℃ for 1-2 hours; then, under ultraviolet light intensity of 10-15 mW / cm². 2 Under certain conditions, nano-titanium dioxide is added and stirred at room temperature for 2-4 hours to obtain the alkaline waste liquid activator. Desulfurization waste liquid, as an industrial byproduct of coking plants, contains thiosulfate, thiocyanate, and suspended sulfur, which are harmful components that must be removed. The alkaline waste liquid activator is prepared by filtering out suspended sulfur, physical adsorption of thiosulfate and thiocyanate by activated carbon, and photocatalytic degradation of thiosulfate and thiocyanate into non-toxic and harmless sulfate and cyanate ions under ultraviolet light conditions, thus achieving the harmless treatment of the desulfurization waste liquid. The mass ratio of the desulfurization waste liquid, the activated carbon, and the nano-titanium dioxide is (80-90):(4-8):(6-12).

[0041] Further, the preparation method of the chemical setting regulator includes: stirring polycarboxylate superplasticizer, lithium acetate, and sodium acetate at pH = 4-6 and temperature of 60-80℃ for 8-16 hours to obtain the chemical setting regulator. By grafting lithium acetate and sodium acetate onto the surface of polycarboxylate superplasticizer molecules, the flowability of the repair material can be effectively improved based on the electrostatic repulsion and steric hindrance effect of polycarboxylate superplasticizer; at the same time, the solubilizing effect of lithium acetate and sodium acetate can effectively accelerate the setting and hardening of the repair material. The mass ratio of polycarboxylate superplasticizer, lithium acetate, and sodium acetate is (70-80):(15-20):(5-10).

[0042] This invention uses highly active slag as a precursor and alkaline wastewater with high pH and high sulfate content as an activator. Combined with CSH crystal nuclei provided by recycled micropowder and the solubilizing effects of lithium acetate and sodium acetate in the chemical setting regulator, it rapidly induces the formation of a crystalline gel product, achieving early high strength in the repair material. Furthermore, by utilizing the adsorption and complexation of dissolved ions on the surface active groups of shell powder modified with polycarboxylate superplasticizer, tannic acid, and silane coupling agent, the alkali activation process is significantly delayed, achieving high flowability in the repair material. The initial flowability of the repair material is 350–380 mm, the initial setting time is 32–47 min, the 1-day compressive strength is 41–47 MPa, the 1-day flexural strength is 6.3–7.7 MPa, and the 1-day bond strength with reference concrete is 1.3–1.6 MPa.

[0043] Based on the above embodiments, the present invention is further illustrated below in conjunction with the preparation method of the multi-element waste-based pavement repair material. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed according to the manufacturer's recommended conditions. Unless otherwise stated, percentages and parts are calculated by mass.

[0044] Table 1. Raw material parameters and proportions of the alkaline waste liquid activator in Examples 1-6

[0045] Example number 1 2 3 4 5 6 Desulfurization wastewater usage (%) 88 90 83 80 87 86 Activated carbon dosage (%) 5 4 6 8 4 8 <![CDATA[Specific surface area of activated carbon (m 2 / g)]]> 970 1200 800 890 1150 1050 Activated carbon stirring temperature (°C) 25 40 30 35 30 20 Activated carbon stirring time (h) 1.2 2.0 1.9 1.0 1.6 1.4 <![CDATA[Ultraviolet light intensity (mW / cm 2 )]]> 15 14 12 10 13 11 Nano titanium dioxide dosage (%) 7 6 11 12 9 6 Average particle size of nano-titanium dioxide (mm) 50 75 85 60 100 90 Stirring time for nano-titanium dioxide (h) 3.7 3.3 2.0 2.9 4.0 3.1

[0046] Table 2. Raw material parameters and proportions of chemical setting agents in Examples 1-6

[0047] Example number 1 2 3 4 5 6 Reaction pH environment 5.5 5.0 4.0 6.0 4.5 5.0 Reaction temperature (°C) 80 60 70 60 70 80 Polycarboxylate superplasticizer dosage (%) 76 70 80 77 73 74 Lithium acetate dosage (%) 18 20 15 16 18 18 Sodium acetate (%) 6 20 5 7 9 8

[0048] Table 3. Raw material parameters and proportions of the multi-component waste-based pavement repair materials in Examples 1-6

[0049]

[0050]

[0051] During implementation, alkaline waste liquid activator is prepared according to the technical scheme in Table 1, chemical setting agent is prepared according to the technical scheme in Table 2, and slag, recycled micro powder, shell powder, alkaline waste liquid activator, chemical setting agent, and mixing water are thoroughly mixed and stirred evenly according to the technical scheme in Table 3 to obtain multi-element waste-based road repair material.

[0052] The performance of the multi-component waste-based pavement repair materials prepared in Examples 1-6 was tested, and the results are shown in Table 4. The relevant tests were conducted in accordance with JT / T 1211.1-2018 "Rapid Repair Materials for Cement Concrete in Highway Engineering - Part 1: Cement-Based Repair Materials".

[0053] Table 4 Performance parameters of multi-component waste-based pavement repair materials in Examples 1-6

[0054] Example number 1 2 3 4 5 6 Initial flowability (mm) 350 370 380 360 350 360 Initial setting time (min) 37 42 36 32 47 41 1-day compressive strength (MPa) 42 44 47 43 46 41 1-day flexural strength (MPa) 6.3 6.6 7.2 7.1 7.7 6.9 1-day bond strength with reference concrete (MPa) 1.3 1.6 1.5 1.6 1.5 1.4 Carbon emissions (kg / t) 238 242 261 263 249 231 Production cost (¥ / t) 313 264 279 305 288 277

[0055] As can be seen from Table 5, the initial flowability of the road repair material prepared according to the technical solution of the present invention is in the range of 350-380mm, the initial setting time is 32-47min, the 1-day compressive strength is 41-47MPa, the 1-day flexural strength is 6.3-7.7MPa, the 1-day bond strength with reference concrete is 1.3-1.6MPa, and the carbon emission during the production process is 231-263kg / t, and the production cost is 264-312￥ / t.

[0056] In summary, the multi-component waste-based pavement repair material prepared by this invention using slag, recycled micro powder, shell powder, alkaline waste liquid activator, chemical setting regulator and mixing water has advantages such as high fluidity, high early strength and simple process. It not only meets the performance requirements of cement concrete pavement repair projects, but also conforms to the concept of green environmental protection and sustainable development.

[0057] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A multi-element waste-based road repair material, characterized in that, By weight percentage, it includes the following components: 30-38% slag, 12-17% recycled micro powder, 10-18% shell powder, 10-15% alkaline waste liquid activator, 5-8% chemical coagulant regulator, and 16-20% mixing water; The regenerated micro powder is soaked in a tannic acid solution with a concentration of 0.01~0.1 mol / L for 12~24 hours; The preparation of the alkaline waste liquid activator includes the following steps: The desulfurization waste liquid generated during the purification of coke oven gas in a coking plant is simply filtered; activated carbon is added and stirred at 20-40℃ for 1-2 hours; then, it is subjected to ultraviolet light intensity of 10-15 mW / cm². 2 Under the specified conditions, nano-titanium dioxide is added and stirred at room temperature for 2-4 hours to obtain the alkaline waste liquid activator. The mass ratio of the desulfurization waste liquid, the activated carbon, and the nano-titanium dioxide is (80~90): (4~8): (6~12); The preparation of the chemical setting regulator includes the following steps: The chemical setting regulator can be obtained by stirring polycarboxylate superplasticizer, lithium acetate, and sodium acetate at pH 4-6 and temperature 60-80℃ for 8-16 hours. The mass ratio of the polycarboxylate superplasticizer, the lithium acetate, and the sodium acetate is (70~80): (15~20): (5~10).

2. The multi-element waste-based road repair material according to claim 1, characterized in that, The slag has an MgO content of 6-13%.

3. The multi-element waste-based road repair material according to claim 1, characterized in that, The shell powder is soaked in a silane coupling agent solution with a mass fraction of 0.5-5% for 8-12 hours.

4. The multi-element waste-based road repair material according to claim 1, characterized in that, The activated carbon in the alkaline waste liquid activator has a specific surface area of ​​800~1200 m². 2 / g, the average particle size of nano titanium dioxide is 50~100 nm.

5. A method for preparing a multi-element waste-based road repair material according to any one of claims 1-4, characterized in that, Includes the following steps: A1. Preparation of alkaline waste liquid activators and chemical coagulants; A2. The slag, recycled micro powder, shell powder, alkaline waste liquid activator, chemical coagulant regulator, and mixing water are thoroughly mixed and stirred evenly to obtain the multi-element waste-based road repair material.

6. The method for preparing a multi-element waste-based road repair material according to claim 5, characterized in that, In A1, the preparation of the alkaline waste liquid activator includes the following steps: The desulfurization waste liquid generated during the purification of coke oven gas in a coking plant is simply filtered; activated carbon is added and stirred at 20-40℃ for 1-2 hours; then, it is subjected to ultraviolet light intensity of 10-15 mW / cm². 2 Under the specified conditions, nano-titanium dioxide is added and stirred at room temperature for 2-4 hours to obtain the alkaline waste liquid activator. The mass ratio of the desulfurization waste liquid, the activated carbon, and the nano titanium dioxide is (80~90): (4~8): (6~12).

7. The method for preparing a multi-element waste-based road repair material according to claim 5, characterized in that, In A1, the preparation of the chemical setting agent includes the following steps: The chemical setting regulator can be obtained by stirring polycarboxylate superplasticizer, lithium acetate, and sodium acetate at pH 4-6 and temperature 60-80℃ for 8-16 hours. The mass ratio of the polycarboxylate superplasticizer, the lithium acetate, and the sodium acetate is (70~80): (15~20): (5~10).

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