Multi-solid waste interface synergistic regenerating agent and preparation method of regenerated asphalt mixture thereof

Abstract

This invention discloses a multi-solid waste interface synergistic optimization regenerator and its preparation method for recycled asphalt mixtures, belonging to the field of road material recycling technology. This invention addresses the problems of insufficient performance improvement, low solid waste utilization, and high carbon emissions associated with traditional single regenerators. It achieves synergistic optimization of the three-component interface by: activating steel slag powder with citric acid to enhance its reactivity with fatty acid methyl ester (FAME); modifying waste tire rubber powder with a silane coupling agent to improve its interfacial compatibility with steel slag and asphalt; and stabilizing FAME with lignin sulfonate to reduce its interfacial tension and improve dispersibility. This invention fully utilizes the rigidity-enhancing effect of steel slag powder, the elastic recovery characteristics of rubber powder, and the regeneration function of FAME, combined with a gradient temperature mixing process, to form a synergistic mechanism of "rigid reinforcement - elastic buffer - dynamic regeneration." This composite regenerator can restore the viscosity and rheological properties of aged asphalt, improve the comprehensive road performance of recycled asphalt mixtures at high and low temperatures, and achieve the goals of multi-component solid waste resource utilization and low carbon emissions.

Description

Technical Field

[0001] This invention belongs to the field of road material recycling technology, specifically, it relates to a method for preparing a multi-solid waste interface synergistic regenerator and a method for preparing recycled asphalt mixture. Background Technology

[0002] Asphalt pavement recycling technology is a key approach to alleviating resource consumption and environmental pollution in the road engineering field, and a core element in achieving sustainable development of transportation infrastructure. Its core challenge lies in how to efficiently restore the performance of aged asphalt and improve the mechanical durability of recycled mixtures, while simultaneously reducing dependence on natural resources and carbon emissions. Traditional asphalt recycling technologies often rely on single or two-component recyclers (such as oils or polymers), making it difficult to meet the comprehensive performance requirements of aged asphalt mixtures. For example, while oil-based recyclers can restore the ductility of aged asphalt, their viscosity drops significantly at high temperatures, leading to a deterioration in the mixture's rutting resistance. Although solid wastes such as steel slag and waste tire rubber powder have reinforcing potential, their direct application suffers from poor interfacial bonding and insufficient activity, easily causing asphalt mixture segregation, expansion, and cracking, thus exacerbating performance degradation. Furthermore, existing technologies often focus on modifying single solid wastes, failing to address the interfacial incompatibility issues in the synergistic modification of multiple solid wastes, resulting in low resource utilization and limited overall performance improvement. To this end, this invention achieves interfacial bonding and functional complementarity of the three components of steel slag, rubber powder, and bio-oil through a multi-solid waste interface synergy-gradient process integration technology path, overcoming the three major challenges of inefficient solid waste utilization, single performance of regenerators, and high carbon emissions, and providing an innovative solution for high-performance low-carbon regeneration technology. Summary of the Invention

[0003] This invention addresses the technical problems of insufficient performance improvement, low solid waste utilization, and high carbon emissions associated with traditional single regenerators, and provides a method for preparing multi-solid waste interface synergistic regenerators and their recycled asphalt mixtures.

[0004] To address the aforementioned technical problems, the present invention adopts the following technical solution:

[0005] The purpose of this invention is to provide a method for preparing a multi-solid waste interface synergistic regenerator, comprising the following steps:

[0006] Step 1: Mix steel slag powder with citric acid solution, stir at 50℃~70℃ for 40min~80min, filter, and dry;

[0007] Step 2: Mix fatty acid methyl ester (FAME) with sodium lignosulfonate solution and stir at 40℃~60℃ for 20min~40min;

[0008] Step 3: Mix waste tire rubber powder with KH-550 silane coupling agent solution, stir at 60℃~80℃ for 30min~50min, and then dry.

[0009] Step 4: Mix the steel slag powder treated in Step 1 with the FAME treated in Step 2, and stir at 120℃~130℃ for 15min~25min. Then, add the adhesive powder treated in Step 3, raise the temperature to 160℃~180℃ and continue stirring for 25min~35min. Then raise the temperature to 185℃~195℃ and continue stirring for 8min~12min to obtain the regenerator.

[0010] Further specified, the particle size of the steel slag powder is less than 75 μm, and the mass concentration of the citric acid solution is 5% to 8%.

[0011] Further specifying, the mass ratio of steel slag powder to citric acid solution is 1:(3-5).

[0012] Further specified, the concentration of sodium lignosulfonate solution is 1% to 2%, and the mass ratio of FAME to sodium lignosulfonate solution is 1:(0.1 to 0.3).

[0013] Further specified, the particle size of waste tire rubber powder is less than 375μm, the mass concentration of KH-550 silane coupling agent solution is 2% to 3%, and the mass ratio of waste tire rubber powder to KH-550 silane coupling agent solution is 1:(0.8 to 1.2).

[0014] Further specified, the steel slag powder after step 1 treatment and the FAME after step 2 treatment are mixed at a mass ratio of 1:(0.3~0.8).

[0015] Further specified, the mass ratio of the adhesive powder after step 3 to the steel slag powder after step 1 is 1:(0.6~1.6).

[0016] Another objective of this invention is to provide a method for preparing recycled asphalt mixture using a multi-solid waste interface synergistic regenerator, comprising the following steps:

[0017] Step (1) Heat treatment: Heat the aged asphalt mixture recycled material (RAP), new basalt coarse and fine aggregates, new limestone mineral powder, and new SBS modified asphalt at 150℃~180℃ for 2~5 hours respectively.

[0018] Step (2) Mixing treatment: SBS modified asphalt, RAP material, basalt coarse and fine aggregates, limestone mineral powder, and composite recycling agent prepared by any one of claims 1-6 are mixed at 165℃~185℃ according to the asphalt mixture gradation.

[0019] Step (3) Compaction treatment: Transfer the mixture to the molding mold and compact it at 135℃~155℃.

[0020] Further specifying, by the total mass percentage of the recycled asphalt mixture, the proportion of SBS modified asphalt is 4% to 8%, the proportion of RAP material is 20% to 40%, the proportion of basalt coarse and fine aggregates is 55% to 75%, the proportion of limestone mineral powder is 5% to 10%, and the proportion of the composite recycling agent is 4% to 8%.

[0021] Further specifying, the asphalt mixture gradation includes one or more of the following types: AC-13, SMA-13, AC-16, and SMA-16.

[0022] This invention enhances the reactivity of steel slag powder with fatty acid methyl ester (FAME) by activating it with citric acid, improves the interfacial compatibility of waste tire rubber powder with steel slag and asphalt by modifying it with a silane coupling agent, and stabilizes FAME with lignin sulfonate to reduce its interfacial tension and improve its dispersibility, thereby achieving synergistic optimization of the three-component interface. This invention fully utilizes the rigidity-enhancing effect of steel slag powder, the elastic recovery characteristics of rubber powder, and the regeneration function of FAME, combined with a gradient temperature mixing process, to form a synergistic mechanism of "rigid reinforcement - elastic buffer - dynamic regeneration". This composite regenerator can restore the viscosity and rheological properties of aged asphalt, improve the comprehensive road performance of recycled asphalt mixtures at high and low temperatures, and achieve the goals of diversified solid waste resource utilization and low carbonization.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) Advantages of synergistic preparation of composite regenerator: After steel slag powder is activated by citric acid, active calcium silicate gel is generated on the surface, which enhances the chemical bonding with FAME ester groups and the carbon dioxide sequestration capacity; the rubber powder improves the mechanical interlocking with steel slag and the chemical compatibility with asphalt through the chemical bonding effect of silane coupling agent; after FAME is stabilized by lignin sulfonate, it forms a micelle structure, which reduces interfacial tension and delays oxidation. In addition, the three components are integrated in stages through a gradient temperature process. At low temperature, steel slag and FAME form a rigid-regenerated composite. At high temperature, the rubber powder melts and embeds to build an elastic network, ultimately realizing a multi-level synergistic modification mechanism of "rigid enhancement-elastic buffer-dynamic regeneration".

[0025] (2) Advantages of Comprehensive Performance Improvement in Recycled Asphalt Mixtures: The synergistic modification effect of composite recycling agents endows recycled mixtures with multiple performance advantages. The rigid skeleton of steel slag powder and the elastic network of rubber powder synergistically inhibit high-temperature rutting deformation and low-temperature shrinkage cracks in asphalt mixtures. The dynamic recycling capacity of FAME restores the rheological properties of aged asphalt, and lignin sulfonate strengthens the bonding between aggregates and asphalt, significantly improving the water loss resistance and fatigue resistance of asphalt mixtures. In addition, the high proportion of solid waste resource utilization greatly reduces the consumption of natural aggregates and carbon emissions. Recycled mixtures prepared by composite recycling agents have excellent high and low temperature stability, durability, and environmental benefits, which can meet the long-life pavement requirements under harsh environments such as heavy traffic and extreme climates, and promote the green and low-carbon transformation of road engineering. Detailed Implementation

[0026] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, while not limiting the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0027] Example 1:

[0028] Example 1 reveals the effect of interface synergistic optimization on the performance of recycled asphalt binder.

[0029] (1) Preparation of composite regenerants based on interface synergistic optimization

[0030] In this embodiment 1, a composite regenerator was prepared through an interface synergistic optimization process involving steel slag powder activation treatment, FAME stabilization modification treatment, adhesive powder surface modification treatment, and gradient temperature mixing.

[0031] 1) Activation treatment of steel slag powder: Steel slag powder with a particle size of less than 75μm is mixed with a 6% citric acid solution at a mass ratio of 1:4, stirred at 60℃ for 60 minutes, filtered, and dried in an oven at 110℃.

[0032] 2) FAME stabilization and modification treatment: Fatty acid methyl ester (FAME) extracted from waste cooking oil is mixed with a 1.5% sodium lignosulfonate solution at a mass ratio of 1:0.2 and stirred at 60°C for 30 minutes.

[0033] 3) Surface modification treatment of rubber powder: Waste tire rubber powder with a particle size of less than 375μm is mixed with a 3% KH-550 silane coupling agent solution at a mass ratio of 1:0.8, stirred at 70℃ for 40 minutes, and dried for later use;

[0034] 4) Gradient temperature mixing: First, the activated steel slag powder from step 1) and the stabilized FAME from step 2) are mixed at a mass ratio of 1:0.5 and stirred at 120°C for 20 minutes; then, the modified adhesive powder from step 3) (the mass ratio of the added powder to the steel slag powder is 1:1) is added, the temperature is raised to 170°C and stirred for another 30 minutes; finally, the mixture of the above three is heated to 190°C and stirred for another 10 minutes to obtain the composite regenerator.

[0035] (2) Comparison with Case 1 Regenerant

[0036] Comparative Case 1 is an improvement on the steps in (1) above, that is, the steel slag powder is not activated, only untreated steel slag powder is used, and the remaining steps are the same as in (1) above, in order to prepare the regenerator of Comparative Case 1.

[0037] 1) Untreated steel slag powder: Dry steel slag powder with a particle size of less than 75μm in an oven at 110℃;

[0038] Steps 2) to 3) are the same as those in (1) above;

[0039] 4) Gradient temperature mixing: First, mix the untreated steel slag powder from step 1) with the stabilized FAME from step 2) at a mass ratio of 1:0.5 and stir at 120°C for 20 minutes; then, add the modified adhesive powder from step 3) (the mass ratio of the added powder to the steel slag powder is 1:1), raise the temperature to 170°C and continue stirring for 30 minutes; finally, raise the temperature of the mixture of the above three materials to 190°C and continue stirring for 10 minutes to obtain the regenerator of Comparative Case 1.

[0040] (3) Comparison with Case 2 Regenerant

[0041] Comparative Case 2 is an improvement on the steps in (1) above. That is, the surface of the adhesive powder is not modified, only the untreated adhesive powder is used, and the remaining steps are the same as in (1) above, in order to prepare the regenerator of Comparative Case 2.

[0042] Steps 1) to 2) are the same as those in (1) above;

[0043] 3) Untreated rubber powder: Waste tire rubber powder with a particle size of less than 375μm is dried at 70℃ for later use;

[0044] 4) Gradient temperature mixing: First, the activated steel slag powder from step 1) and the stabilized FAME from step 2) are mixed at a mass ratio of 1:0.5 and stirred at 120°C for 20 minutes; then, the untreated adhesive powder from step 3) (the mass ratio of the added powder to the steel slag powder is 1:1) is added, the temperature is raised to 170°C and stirred for another 30 minutes; finally, the mixture of the above three is heated to 190°C and stirred for another 10 minutes to obtain the regenerator of Comparative Case 2.

[0045] (4) Comparison with Case 3 Regenerant

[0046] Comparative Case 3 is an improvement on the steps in (1) above, namely, the gradient temperature mixing process is not used, and the remaining steps are the same as in (1) above, in order to prepare the regenerator of Comparative Case 3.

[0047] Steps 1) to 3) are the same as those in (1) above;

[0048] 4) Mixing at normal temperature: First, mix the activated steel slag powder from step 1) and the stabilized FAME from step 2) at a mass ratio of 1:0.5 and stir at 170°C for 20 minutes; then, add the modified adhesive powder from step 3) (the mass ratio of the added powder to the steel slag powder is 1:1), raise the temperature to 170°C and continue stirring for 30 minutes; finally, continue stirring the mixture of the above three at 170°C for 10 minutes to obtain the regenerator of Comparative Case 3.

[0049] (5) Performance Testing

[0050] According to JTG E20-2011 standard, the effects of the above-mentioned composite recycling agents, comparative case 1 recycling agent, comparative case 2 recycling agent, and comparative case 3 recycling agent on the properties of aged asphalt were evaluated using penetration, ductility at 5℃, softening point, and dynamic viscosity at 60℃. The results are shown in Table 1. Table 1 shows that the incorporation of different recycling agents can significantly improve the high and low temperature flow properties of asphalt binders. Compared with composite recycled asphalt, the softening point and ductility of the recycled asphalt in comparative case 1 are lower, indicating that citric acid activation treatment can significantly improve the esterification reaction efficiency of steel slag and FAME, forming calcium soaps to enhance the interfacial bonding between the two. Compared with composite recycled asphalt, the ductility of the recycled asphalt in comparative case 2 is significantly reduced, indicating that silane coupling agent modification of the rubber powder surface can reduce the polarity difference between the rubber powder and other substances, improving interfacial compatibility. Compared to composite recycled asphalt, the recycled asphalt in Case 3 showed lower penetration and ductility at 5°C, but higher dynamic viscosity at 60°C. This indicates that the composite regenerator prepared by the present invention through interface synergistic optimization of steel slag activation-rubber powder modification-FAME treatment and gradient temperature mixing process can significantly restore and improve the high and low temperature performance and viscosity of aged asphalt.

[0051] Table 1 Asphalt Performance Tests

[0052] Asphalt type Needle penetration (0.1mm) Ductility at 5℃ (cm) Softening point (°C) Viscosity at 60℃ (Pa·s) Aged asphalt 38 12 78 36000 Composite recycled asphalt 55 27 71 24000 Comparison Case 1: Recycled Asphalt 57 24 69 25000 Comparison Case 2: Recycled Asphalt 56 21 67 27000 Comparison Case 3: Recycled Asphalt 49 19 64 30000

[0053] Example 2:

[0054] Example 2 reveals the effect of composite recycling agents on the performance of recycled asphalt mixtures.

[0055] (1) Preparation of recycled asphalt mixture containing composite recycling agent

[0056] This Example 2 is based on the composite recycling agent prepared in Example 1 to prepare a composite recycled asphalt mixture.

[0057] First, according to the total mass percentage of recycled asphalt mixture, new SBS modified asphalt (5%), RAP material (22%), new basalt coarse and fine aggregates (62%), new limestone mineral powder (6%), and composite recycling agent (5%) are mixed according to the AC-16 type asphalt mixture gradation. Then, the above mixture is subjected to a treatment process of heating temperature of 150℃~180℃, mixing temperature of 165℃~185℃, and compaction temperature of 135℃~155℃ to obtain composite recycled asphalt mixture.

[0058] (2) Preparation of recycled asphalt mixture containing comparative recycling agent

[0059] This Example 2 is based on the preparation of comparative recycled asphalt mixture using the recycling agent prepared in Example 1, compared to Example 3.

[0060] First, according to the total mass percentage of recycled asphalt mixture, new SBS modified asphalt (5%), RAP material (22%), new basalt coarse and fine aggregates (62%), new limestone mineral powder (6%), and comparative recycling agent (5%) are mixed according to the AC-16 type asphalt mixture gradation. Then, the above mixture is subjected to a treatment process of heating temperature of 150℃~180℃, mixing temperature of 165℃~185℃, and compaction temperature of 135℃~155℃ to obtain comparative recycled asphalt mixture.

[0061] (3) Performance Testing

[0062] The effects of composite rejuvenator and comparative rejuvenator on the high-temperature performance, low-temperature performance, and fatigue resistance of recycled asphalt mixtures were tested according to the JTG E20-2011 standard using high-temperature rutting resistance test, low-temperature beam bending test, and four-point bending fatigue test. The results are shown in Table 2. Table 2 shows that, compared with the comparative rejuvenator, the composite rejuvenator resulted in greater low-temperature bending strain and fatigue life of the aged asphalt mixture. This indicates that the composite rejuvenator prepared in this invention can significantly improve the low-temperature performance and fatigue resistance of recycled asphalt mixtures. Regarding dynamic stability, both the composite rejuvenator and the comparative rejuvenator decreased the dynamic stability of the aged asphalt mixture, but the composite rejuvenator resulted in greater dynamic stability.

[0063] Table 2 Asphalt Mixture Performance Tests

[0064] Performance indicators Aged asphalt mixture Composite recycled asphalt mixture Comparison of regenerated asphalt mixtures Dynamic stability (cycles / mm) 9100 8800 8200 Low-temperature bending strain (με) 2350 2980 2640 Fatigue resistance life (times) 32000 52000 43000

[0065] The specific embodiments of the present invention have been described above. It should be noted that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing a multi-solid waste interface synergistic regenerator, characterized in that, Includes the following steps: Step 1: Mix steel slag powder with citric acid solution, stir at 50℃~70℃ for 40min~80min, filter, and dry; Step 2: Mix fatty acid methyl ester (FAME) with sodium lignosulfonate solution and stir at 40℃~60℃ for 20min~40min; Step 3: Mix waste tire rubber powder with KH-550 silane coupling agent solution, stir at 60℃~80℃ for 30min~50min, and dry. Step 4: Mix the steel slag powder treated in Step 1 with the FAME treated in Step 2, and stir at 120℃~130℃ for 15min~25min. Then, add the adhesive powder treated in Step 3, raise the temperature to 160℃~180℃ and continue stirring for 25min~35min. Then raise the temperature to 185℃~195℃ and continue stirring for 8min~12min to obtain the regenerator. The particle size of the steel slag powder is less than 75μm, the mass concentration of the citric acid solution is 5%~8%, and the mass ratio of steel slag powder to citric acid solution is 1:(3~5). The concentration of sodium lignosulfonate solution is 1%~2% by mass, and the mass ratio of FAME to sodium lignosulfonate solution is 1:(0.1~0.3). The particle size of the waste tire rubber powder is less than 375μm, the mass concentration of the KH-550 silane coupling agent solution is 2%~3%, and the mass ratio of waste tire rubber powder to KH-550 silane coupling agent solution is 1:(0.8~1.2). The steel slag powder processed in step 1 is mixed with the FAME processed in step 2 at a mass ratio of 1:(0.3~0.8); The mass ratio of the adhesive powder after step 3 to the steel slag powder after step 1 is 1:(0.6~1.6).

2. A method for preparing recycled asphalt mixture containing a multi-solid waste interface synergistic regenerator, characterized in that, Includes the following steps: Step (1) Heat treatment: Heat the aged asphalt mixture recycled material (RAP), new basalt coarse and fine aggregates, new limestone mineral powder, and new SBS modified asphalt at 150℃~180℃ for 2~5 hours respectively. Step (2) Mixing treatment: SBS modified asphalt, RAP material, basalt coarse and fine aggregates, limestone mineral powder, and the multi-solid waste interface synergistic regenerator prepared by the method described in claim 1 are mixed at 165℃~185℃ according to the asphalt mixture gradation. Step (3) Compaction treatment: Transfer the mixture to the molding mold and compact it at 135℃~155℃; The total mass percentage of the recycled asphalt mixture is 100%, that is, the blending ratio of SBS modified asphalt is 4%~8%, the blending ratio of RAP material is 20%~40%, the blending ratio of basalt coarse and fine aggregates is 55%~75%, the blending ratio of limestone mineral powder is 5%~10%, and the blending ratio of the multi-solid waste interface synergistic regeneration agent is 4%~8%.

3. The method according to claim 2, characterized in that the asphalt The mixture gradation includes one or more of the following types: AC-13, SMA-13, AC-16, and SMA-16.