Multi-waste-based pavement patching material and preparation method thereof

Abstract

The invention discloses a multielement waste-based pavement patching material and a preparation method thereof, and the multielement waste-based pavement patching 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 an alkaline waste liquid exciting agent, 5-8% of a chemical thickening time control agent and 16-20% of mixing water. The preparation method comprises the following steps. A1, preparing an alkaline waste liquid exciting agent and a chemical thickening time control agent; a2, fully mixing and uniformly stirring the slag, the regenerated micro powder, the shell powder, the alkaline waste liquid exciting agent, the chemical thickening time control agent and the mixing water to obtain the multi-waste-based pavement patching material. The invention has the characteristics of high flowability, high early strength, simple process, low cost, environmental friendliness and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of road surface repair, and in particular to a multi-waste-based road surface repair material and a preparation method thereof. Background Art

[0002] Under the combined effects of load and environment, existing cement concrete pavements have suffered severe damage and are in urgent need of repair. Cement-based pavement repair materials, made from cement, mineral admixtures, fine aggregate, chemical admixtures, and water, offer advantages such as high fluidity, early high strength, and minimal expansion. They can effectively repair damaged areas and extend the service life of existing cement concrete pavements.

[0003] Multi-waste-based cementitious materials generally refer to cementitious material systems prepared through chemical activation of multiple wastes. Compared to cement-based materials, multi-waste-based cementitious materials have low production costs and low carbon emissions. However, due to limitations in reactivity and activation mechanisms, multi-waste-based cementitious materials often suffer from poor workability, slow early strength development, and limited mechanical properties, making them impractical for on-site construction and difficult to meet the performance requirements of pavement repair materials. In an 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 these ultrafine powders, the fluidity control of the all-solid waste cementitious material is significantly more difficult. Furthermore, the 3d compressive strength of the all-solid waste cementitious material is only 6.8MPa to 17.8MPa, and the 7d compressive strength is only 23.7MPa to 29.7MPa. These low mechanical properties make it difficult to rapidly open the repaired pavement and ensure long-term service.

[0004] Therefore, how to improve fluidity and enhance mechanical properties is an urgent problem that needs to be solved when using 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 the present invention is to provide a multi-waste-based pavement repair material and a preparation method thereof, which has the characteristics of high fluidity, high early strength, simple process, low cost, and environmental friendliness.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

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

[0008] In the early stage of the multi-waste-based pavement repair material, after alkali excitation, a large number of short rod-shaped crystals are formed in the repair material as the structural skeleton, and the gel-like products attached around the crystals are responsible for filling, ensuring the early performance of the repair material; in the later stage, during the long-term reaction process, the crystals and the gel products are fully overlapped, which promotes the densification of the microstructure and ensures the mechanical properties of the repair material.

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

[0010] The regenerated micropowder is immersed in a tannic acid solution with a concentration of 0.01 to 0.1 mol / L for 12 to 24 hours. The adsorption and chemical bonding of tannic acid's phenolic hydroxyl groups effectively shields the regenerated micropowder from its negative effects on the fluidity of the cementitious material. After immersion in the tannic acid solution with a concentration of 0.01 to 0.1 mol / L for 12 to 24 hours, the regenerated micropowder can improve the fluidity of the cementitious material.

[0011] The shell powder is soaked in a 0.5-5% by mass silane coupling agent solution for 8-12 hours. The shell powder's biomass water-locking effect can improve the water retention of the cementitious material, but it can also create weak interfacial areas. 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% by mass silane coupling agent solution for 8-12 hours, the shell powder can improve the water retention of the cementitious material.

[0012] The specific surface area of the activated carbon in the alkaline waste liquid activator is 800 to 1200 m 2 / g, the average particle size of nano titanium dioxide is 50 to 100 nm. (The specific surface area of activated carbon is 800 to 1200 m 2 / g, the average particle size of nano titanium dioxide is 50-100nm, which can quickly achieve the harmlessness of desulfurization waste liquid through physical adsorption and ultraviolet photocatalysis, thereby preparing alkaline waste liquid activator.

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

[0014] A1. Preparation of alkaline waste liquid activator and chemical coagulant;

[0015] A2. Slag, recycled micropowder, shell powder, alkaline waste liquid activator, chemical coagulant, and mixing water are fully mixed and stirred to obtain the multi-waste-based pavement repair material.

[0016] In A1, the preparation of the alkaline waste liquid stimulant comprises the following steps:

[0017] The desulfurization waste liquid generated during the coking plant's coke oven gas purification process was simply filtered; activated carbon was added and stirred at 20-40°C for 1-2 hours; then, the mixture was irradiated with ultraviolet light at an intensity of 10-15 mW / cm 2 Under the conditions of , nano titanium dioxide is added and stirred at room temperature for 2 to 4 hours; the alkaline waste liquid activator can be obtained.

[0018] The alkaline waste liquid activator obtained has the characteristics of high pH value and high sulfate content, which can quickly activate the reaction activity 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). The physical adsorption of the activated carbon and the ultraviolet photocatalytic effect of the nano-titanium dioxide can quickly render the desulfurization waste liquid harmless, thereby preparing the alkaline waste liquid activator.

[0020] In A1, the preparation of the chemical coagulant comprises the following steps:

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

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

[0023] Beneficial effects of the present invention:

[0024] (1) The present invention replaces the traditional alkaline activator with an alkaline waste liquid activator from the coking industry, and replaces the natural fine aggregate with recycled micropowder and shell powder, which significantly reduces the material production cost and carbon emissions. The waste utilization rate of the repair material 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) The present invention uses highly active slag as a precursor and alkaline waste liquid with a high pH value and a high sulfate content as an activator, combined with the CSH crystal nuclei provided by the regenerated micropowder and the dissolution-promoting effect of lithium acetate and sodium acetate in the chemical coagulant, to quickly induce the formation of a crystal gel product, thereby achieving early high strength of the repair material.

[0026] Furthermore, the surface active groups of polycarboxylate superplasticizer, tannic acid-modified recycled micropowder, and silane coupling agent-modified shell powder adsorb and complex dissolved ions, significantly delaying the alkali excitation process and achieving high fluidity for the repair material. The repair material has an initial fluidity of 350-380 mm, an initial setting time of 32-47 minutes, a one-day compressive strength of 41-47 MPa, a one-day flexural strength of 6.3-7.7 MPa, and a one-day bond strength with baseline concrete of 1.3-1.6 MPa.

[0027] (3) The present invention has simple process, excellent performance, and is environmentally friendly, and is suitable for large-scale promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a SEM schematic diagram of the repair material of the present invention. DETAILED DESCRIPTION

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

[0030] The present invention provides a multi-waste-based pavement repair material, which comprises the following components, calculated by weight percentage: 30-38% of slag, 12-17% of recycled micropowder, 10-18% of shell powder, 10-15% of alkaline waste liquid activator, 5-8% of chemical coagulant, and 16-20% of mixing water.

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

[0032] Furthermore, the MgO content of the slag is 6-13%. MgO content is a key parameter in characterizing slag hydration activity: higher MgO content increases the alkalinity of the system and its hydration activity. However, excessively high MgO content can lead to poor stability of the cementitious material. Experiments conducted in the present invention demonstrate that when the MgO content is 6-13%, the slag can rapidly hydrate at an early stage without any stability risks.

[0033] Furthermore, the regenerated micropowder is soaked in a tannic acid solution at a concentration of 0.01 to 0.1 mol / L for 12 to 24 hours. The complex composition of regenerated micropowder can easily lead to poor fluidity in 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 fluidity of the cementitious material. Experiments in the present invention demonstrate that soaking the regenerated micropowder in a tannic acid solution at a concentration of 0.01 to 0.1 mol / L for 12 to 24 hours can improve the fluidity of the slurry.

[0034] Furthermore, the shell powder is soaked in a silane coupling agent solution with a mass fraction of 0.5-5% for 8-12 hours. Shell powder can improve the water retention of the cementitious material through the water-locking effect of biomass, thereby avoiding water bleeding. However, shell powder can easily lead to weak interfacial properties, while the alkyl hydrolysis and condensation of the silane coupling agent in an alkaline environment can effectively improve the interfacial properties. The present invention's experiments demonstrate that after soaking in a silane coupling agent solution with a mass fraction of 0.5-5% for 8-12 hours, shell powder can improve the water retention of the cementitious material.

[0035] Furthermore, the specific surface area of the activated carbon in the alkaline waste liquid activator is 800 to 1200 m 2 / g, the average particle size of nano titanium dioxide is 50-100nm. The harmlessness of desulfurization waste liquid is the key to the preparation of alkaline waste liquid activator. The high specific surface area of activated carbon is used to physically adsorb harmful substances in desulfurization waste liquid; the harmful substances in desulfurization waste liquid are chemically degraded by the photocatalytic reaction of nano titanium dioxide under ultraviolet conditions, and the harmlessness of desulfurization waste liquid is achieved synergistically. The experiment of the present invention proves that the specific surface area of activated carbon is 800-1200m 2 / g, and nano-titanium dioxide with an average particle size of 50-100nm, can quickly and effectively achieve harmlessness in desulfurization wastewater, thereby preparing alkaline wastewater activator. Due to its high pH value and high sulfate content, the alkaline wastewater activator can quickly stimulate the reactivity of slag.

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

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

[0038] A1. Preparation of alkaline waste liquid activator and chemical coagulant;

[0039] A2. Slag, recycled micropowder, shell powder, alkaline waste liquid activator, chemical coagulant, and mixing water are fully mixed and stirred to obtain the multi-waste-based pavement repair material.

[0040] Furthermore, the preparation method of the alkaline waste liquid activator includes: simply filtering the desulfurization waste liquid generated in the process of purifying coke oven gas in a coking plant; adding activated carbon and stirring at 20-40°C for 1-2 hours; then, irradiating the waste liquid under ultraviolet light with an intensity of 10-15 mW / cm 2 Under the conditions of , nano titanium dioxide is added and stirred at room temperature for 2 to 4 hours; the alkaline waste liquid activator can be obtained. Desulfurization waste liquid is an industrial by-product of coking plants. The thiosulfate, thiocyanate, and suspended sulfur contained therein are harmful components that must be removed. By filtering out the suspended sulfur, physically adsorbing the thiosulfate and thiocyanate on activated carbon, and photocatalytically reacting the nano titanium dioxide under ultraviolet light to degrade the thiosulfate and thiocyanate into non-toxic and harmless sulfate and cyanate, the alkaline waste liquid activator is prepared by completing the harmlessness of the desulfurization waste liquid. The mass ratio of the desulfurization waste liquid, the activated carbon, and the nano titanium dioxide is (80 to 90):(4 to 8):(6 to 12).

[0041] Furthermore, a method for preparing a chemical setting agent includes stirring a polycarboxylate superplasticizer, lithium acetate, and sodium acetate at a pH of 4-6 and a temperature of 60-80°C for 8-16 hours to obtain the chemical setting agent. By grafting lithium acetate and sodium acetate onto the surface of the polycarboxylate superplasticizer molecules, the electrostatic repulsion and steric hindrance of the polycarboxylate superplasticizer effectively improve the fluidity of the repair material. Simultaneously, the solubilizing effect of lithium acetate and sodium acetate effectively accelerates the setting and hardening of the repair material. The mass ratio of the 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 a high pH and high sulfate content as an activator. Combined with the CSH crystal nuclei provided by the regenerated micropowder and the dissolution-promoting effects of lithium acetate and sodium acetate in the chemical setting agent, it rapidly induces the formation of a crystal-gel product, achieving early, high-strength repair material. Furthermore, the adsorption and complexation of dissolved ions by the surface active groups of polycarboxylate water-reducing agents, tannic acid-modified regenerated micropowder, and silane coupling agent-modified shell powder significantly slows the alkaline activation process, achieving high fluidity for the repair material. The repair material has an initial fluidity of 350-380 mm, an initial setting time of 32-47 minutes, a 1-day compressive strength of 41-47 MPa, a 1-day flexural strength of 6.3-7.7 MPa, and a 1-day bond strength with benchmark concrete of 1.3-1.6 MPa.

[0043] Based on the above examples, the present invention is further described below in conjunction with methods for preparing multi-component waste-based pavement repair materials. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit its scope. Experimental methods in the following examples, where specific conditions are not specified, generally follow those recommended by the manufacturer. Unless otherwise noted, percentages and parts are calculated by mass.

[0044] Table 1 Raw material parameters and ratios of alkaline waste liquid activators in Examples 1-6

[0045] Example No. 1 2 3 4 5 6 Desulfurization waste liquid consumption (%) 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 (℃) 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 Nano-titanium dioxide stirring time (h) 3.7 3.3 2.0 2.9 4.0 3.1

[0046] Table 2 Raw material parameters and ratios of chemical coagulants in Examples 1-6

[0047] Example No. 1 2 3 4 5 6 Reaction pH environment 5.5 5.0 4.0 6.0 4.5 5.0 Reaction temperature (℃) 80 60 70 60 70 80 Polycarboxylate water reducer 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 ratios of multi-waste-based pavement repair materials in Examples 1-6

[0049]

[0050]

[0051] During the implementation process, the alkaline waste liquid activator is prepared according to the technical scheme of Table 1, the chemical coagulant is prepared according to the technical scheme of Table 2, and the slag, recycled micropowder, shell powder, alkaline waste liquid activator, chemical coagulant, and mixing water are fully mixed and stirred according to the technical scheme of Table 3 to obtain a multi-waste-based pavement repair material.

[0052] The performance of the multi-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-waste-based pavement repair materials in Examples 1-6

[0054] Example No. 1 2 3 4 5 6 Initial fluidity (mm) 350 370 380 360 350 360 Initial setting time (min) 37 42 36 32 47 41 1d compressive strength (MPa) 42 44 47 43 46 41 1d flexural strength (MPa) 6.3 6.6 7.2 7.1 7.7 6.9 1d bond strength with benchmark 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 pavement repair material prepared according to the technical solution of the present invention has an initial fluidity range of 350-380 mm, an initial setting time of 32-47 min, a 1d compressive strength of 41-47 MPa, a 1d flexural strength of 6.3-7.7 MPa, and a 1d bonding strength with the benchmark concrete of 1.3-1.6 MPa. In addition, the carbon emissions during the production process are 231-263 kg / t, and the production cost is 264-312 RMB / t.

[0056] In summary, the present invention utilizes slag, recycled micropowder, shell powder, alkaline waste liquid activator, chemical coagulant and mixing water to prepare a multi-waste-based pavement repair material, which has the advantages of high fluidity, high early strength and simple process. It not only meets the performance requirements of cement concrete pavement repair projects, but also complies with the concept of green, environmental protection and sustainable development.

[0057] Although embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not intended to limit the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A multi-waste-based road repair material, characterized in that: Calculated by weight percentage, it includes the following components: 30-38% of slag, 12-17% of recycled micropowder, 10-18% of shell powder, 10-15% of alkaline waste liquid activator, 5-8% of chemical coagulant, and 16-20% of mixing water.

2. The multi-waste-based road repair material according to claim 1, characterized in that: In the early stage of the multi-waste-based pavement repair material, after alkali excitation, a large number of short rod-shaped crystals are formed in the repair material as the structural skeleton, and the gel-like products attached around the crystals are responsible for filling, ensuring the early performance of the repair material; in the later stage, during the long-term reaction process, the crystals and the gel products are fully overlapped, promoting the densification of the microstructure and ensuring the mechanical properties of the repair material.

3. The multi-waste-based road repair material according to claim 1, characterized in that: The MgO content of the slag is 6-13%.

4. The multi-waste-based road repair material according to claim 1, characterized in that: The regenerated micropowder is soaked in a tannic acid solution with a concentration of 0.01 to 0.1 mol / L for 12 to 24 hours.

5. The multi-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 to 5% for 8 to 12 hours.

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

7. A method for preparing a multi-waste-based road repair material according to any one of claims 1 to 6, characterized in that: The steps include: A1. Preparation of alkaline waste liquid activator and chemical coagulant; A2. Slag, recycled micropowder, shell powder, alkaline waste liquid activator, chemical coagulant, and mixing water are fully mixed and stirred to obtain the multi-waste-based pavement repair material.

8. The method for preparing a multi-waste-based road repair material according to claim 7, characterized in that: In A1, the preparation of the alkaline waste liquid stimulant comprises the following steps: The desulfurization waste liquid generated during the coking plant's coke oven gas purification process was simply filtered; activated carbon was added and stirred at 20-40°C for 1-2 hours; then, the mixture was irradiated with ultraviolet light at an intensity of 10-15 mW / cm 2 Under the conditions of , adding nano titanium dioxide and stirring at room temperature for 2 to 4 hours; the alkaline waste liquid activator can be obtained; The mass ratio of the desulfurization waste liquid, the activated carbon and the nano titanium dioxide is (80-90):(4-8):(6-12).

9. The method for preparing a multi-waste-based road repair material according to claim 7, characterized in that: In A1, the preparation of the chemical coagulant comprises the following steps: The chemical setting agent is obtained by stirring a polycarboxylate water reducer, lithium acetate, and sodium acetate at a pH of 4 to 6 and a temperature of 60 to 80° C. for 8 to 16 hours; The mass ratio of the polycarboxylate water reducer, the lithium acetate, and the sodium acetate is (70-80):(15-20):(5-10).

Images