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

Abstract

The invention discloses a multi-solid waste interface collaborative optimization regenerant and a preparation method of a regenerated asphalt mixture thereof, and belongs to the technical field of road material regeneration. In order to solve the problems that a traditional single regenerant is insufficient in performance improvement, low in solid waste utilization rate and high in carbon emission, citric acid is used for activating steel slag powder to enhance the reactivity of the steel slag powder and fatty acid methyl ester (FAME) ester groups, and a silane coupling agent is used for modifying waste tire rubber powder to improve the interfacial compatibility of the waste tire rubber powder with steel slag and asphalt; lignosulfonate stabilizes FAME, reduces interfacial tension of FAME and improves dispersibility of FAME, and then three-component interface collaborative optimization is achieved. According to the invention, the rigid reinforcing effect of the steel slag powder, the elastic recovery characteristic of the rubber powder and the regeneration function of the FAME are fully utilized, and a gradient temperature mixing process is combined to form a'rigid reinforcing-elastic buffering-dynamic regeneration 'synergistic mechanism. The composite regenerant can recover the viscosity, rheology and other characteristics of the aged asphalt, improve the high and low temperature and other comprehensive pavement performance of the regenerated asphalt mixture, and achieve the purposes of multi-element solid waste recycling and low carbonization.

Description

Technical Field

[0001] The present invention belongs to the technical field of road material recycling, and specifically relates to a preparation method of a multi-solid waste interface synergistic regenerant and a preparation method of recycled asphalt mixture. Background Art

[0002] The asphalt pavement recycling technology is a key way to alleviate resource consumption and environmental pollution in the road engineering field, and is the core link to achieve the sustainable development of transportation infrastructure. The core challenge lies in how to efficiently restore the performance of aged asphalt and improve the mechanical durability of recycled mixtures, while reducing the dependence on natural resources and carbon emissions. Traditional asphalt recycling technologies mostly rely on single or two-component regenerants (such as oils or polymers, etc.), and it is difficult to meet the comprehensive performance requirements of aged asphalt mixtures. For example, although oil-based regenerants can restore the ductility of aged asphalt, the high-temperature viscosity drops significantly, resulting in the deterioration of the rutting resistance of the mixture; although solid wastes such as steel slag and waste tire rubber powder have the potential to enhance performance, when directly applied, due to disadvantages such as poor interfacial bonding and insufficient activity, it is easy to cause segregation and swelling cracking of asphalt mixtures, which instead exacerbates the performance degradation. In addition, existing technologies mostly focus on the modification of single solid waste, and do not solve the problem of interfacial incompatibility in the co-modification of multiple solid wastes, resulting in low resource utilization rate and limited improvement in comprehensive performance. Therefore, the present invention realizes the interfacial bonding and functional complementarity of the three components of steel slag-rubber powder-bio-oil through a multi-solid waste interface synergistic-gradient process integration technical path, and overcomes the three major problems of low efficiency of solid waste utilization, single performance of regenerants, and high carbon emissions, providing an innovative solution for high-performance low-carbon recycling technologies. Summary of the Invention

[0003] The present invention aims to solve the technical problems of insufficient improvement of the performance of traditional single regenerants, low utilization rate of solid wastes, and high carbon emissions, and provides a multi-solid waste interface synergistic regenerant and a preparation method of recycled asphalt mixture.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention aims to provide a preparation method of a multi-solid waste interface synergistic regenerant, including the following steps:

[0006] Step 1: Mix steel slag powder with citric acid solution, stir at 50°C to 70°C for 40 min to 80 min, filter, and dry.

[0007] Step 2: Mix fatty acid methyl ester (FAME) with sodium lignosulfonate solution, and stir at 40°C to 60°C for 20 min to 40 min.

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

[0009] Step 4: Mix the steel slag powder after being treated in Step 1 with the FAME after being treated in Step 2, stir at 120°C - 130°C for 15 min - 25 min. Subsequently, add the rubber powder after being treated in Step 3, raise the temperature to 160°C - 180°C and continue stirring for 25 min - 35 min, then raise the temperature to 185°C - 195°C and continue stirring for 8 min - 12 min to obtain the regenerant.

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

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

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

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

[0014] Further limit that the steel slag powder after being treated in Step 1 and the FAME after being treated in Step 2 are mixed in a mass ratio of 1:(0.3 - 0.8).

[0015] Further limit that the mass ratio of the rubber powder after being treated in Step 3 to the steel slag powder after being treated in Step 1 is 1:(0.6 - 1.6).

[0016] Another object of the present invention is to provide a preparation method of a regenerated asphalt mixture with a multi-solid waste interface synergistic regenerant, including the following steps:

[0017] Step (1) Heating treatment: Heat the recycled old asphalt mixture (RAP), new basalt coarse and fine aggregates, new limestone mineral powder, and new SBS modified asphalt at 150°C - 180°C for 2 - 5 hours respectively;

[0018] Step (2) Mixing treatment: Mix the SBS modified asphalt, RAP material, basalt coarse and fine aggregates, limestone mineral powder, and the composite regenerant prepared by the method according to any one of claims 1 - 6 according to the asphalt mixture gradation at 165°C - 185°C;

[0019] Step (3) Compaction treatment: Transfer the mixture to a forming mold and compact it at 135°C - 155°C.

[0020] Further limit that, by the total mass percentage of the recycled asphalt mixture, the mixing ratio of SBS modified asphalt is 4% - 8%, the mixing ratio of RAP material is 20% - 40%, the mixing ratio of basalt coarse and fine aggregates is 55% - 75%, the mixing ratio of limestone mineral powder is 5% - 10%, and the mixing ratio of the composite regenerant is 4% - 8%.

[0021] Further limit that the asphalt mixture gradation includes one or more of AC - 13 type, SMA - 13 type, AC - 16 type, and SMA - 16 type.

[0022] In the present invention, the reactivity of steel slag powder with the ester group of fatty acid methyl ester (FAME) is enhanced by citric acid activation, the interfacial compatibility of waste tire rubber powder with steel slag and asphalt is improved by silane coupling agent modification, and the interfacial tension of FAME is reduced and its dispersibility is improved by lignosulfonate stabilization, thereby realizing the synergistic optimization of the three - component interface. The present invention makes full use of the rigid strengthening effect of steel slag powder, the elastic recovery characteristics of rubber powder, and the regeneration function of FAME, and combines with the gradient temperature mixing process to form a "rigid reinforcement - elastic buffer - dynamic regeneration" synergistic mechanism. This composite regenerant can restore the viscosity and rheological properties of aged asphalt, improve the comprehensive road - using properties such as high and low temperature of the recycled asphalt mixture, and achieve the goals of resource utilization and low - carbonization of multiple solid wastes.

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

[0024] (1) Advantages of the synergistic preparation of the composite regenerant: After the steel slag powder is activated by citric acid, active calcium silicate gel is generated on the surface, enhancing the chemical bonding with the ester group of FAME and the carbon dioxide sequestration ability; the mechanical bite with steel slag and the chemical compatibility with asphalt of the rubber powder are improved through the chemical bonding action of the silane coupling agent; after FAME is stabilized by lignosulfonate, a micelle structure is formed, reducing the interfacial tension and delaying oxidation. In addition, the three components are integrated in stages through the gradient temperature process. At the low - temperature stage, the steel slag and FAME form a rigid - regeneration complex, and at the high - temperature stage, the rubber powder melts and embeds to construct an elastic network, finally realizing a multi - level synergistic modification mechanism of "rigid strengthening - elastic buffer - dynamic regeneration".

[0025] (2) Advantages of improving the comprehensive performance of recycled asphalt mixture: The synergistic modification effect of the composite regenerant endows the recycled mixture with multiple performance advantages. The rigid skeleton of steel slag powder and the elastic network of crumb rubber synergistically inhibit the high-temperature rutting deformation and low-temperature thermal shrinkage cracks of asphalt mixture; the dynamic regeneration ability of FAME restores the rheology of aged asphalt, and lignosulfonate strengthens the bonding of aggregate-asphalt interface, significantly improving the water damage resistance and fatigue resistance of asphalt mixture. In addition, the high proportion of solid waste resource utilization greatly reduces the consumption of natural aggregates and carbon emissions. The recycled mixture prepared by the composite regenerant has excellent high and low temperature stability, durability and environmental benefits, can meet the long-life pavement requirements under harsh environments such as heavy traffic and extreme climate, and promote the green and low-carbon transformation of road engineering. Detailed implementation manners

[0026] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, and at the same time do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can also be made. These all belong to the protection scope of the present invention.

[0027] Example 1:

[0028] Example 1 reveals the influence of the regenerant prepared by interface synergistic optimization on the performance of recycled asphalt binder.

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

[0030] In this Example 1, a composite regenerant is prepared through the following interface synergistic optimization process of steel slag powder activation treatment, FAME stabilization modification treatment, crumb rubber surface modification treatment, and gradient temperature mixing.

[0031] 1) Steel slag powder activation treatment: Mix steel slag powder with a particle size less than 75 μm and a citric acid solution with a mass concentration of 6% at a mass ratio of 1:4, stir at 60 °C for 60 minutes, filter, and dry in an oven at 110 °C;

[0032] 2) FAME stabilization modification treatment: Mix fatty acid methyl ester (FAME) refined from waste cooking oil and a lignosulfonate solution with a mass concentration of 1.5% at a mass ratio of 1:0.2, and stir at 60 °C for 30 minutes;

[0033] 3) Crumb rubber surface modification treatment: Mix waste tire crumb rubber with a particle size less than 375 μm and a KH-550 silane coupling agent solution with a mass concentration of 3% at a mass ratio of 1:0.8, stir at 70 °C for 40 minutes, and dry for standby;

[0034] 4) Gradient temperature mixing: First, mix the steel slag powder after the activation treatment in step 1) and the FAME after the stabilization treatment in step 2) at a mass ratio of 1:0.5, and stir at 120 °C for 20 minutes; Subsequently, add the rubber powder after the modification treatment in step 3) (the added mass ratio 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 to 190 °C and continue stirring for 10 minutes to obtain the composite regenerant.

[0035] (2) Regenerant of Comparative Case 1

[0036] Comparative Case 1 is improved based on the steps in (1) above, that is, the steel slag powder is not subjected to activation treatment, and only untreated steel slag powder is used, and the remaining steps are the same as those in (1) above to prepare the regenerant of Comparative Case 1.

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

[0038] 2) - 3) The steps are the same as those in (1) above;

[0039] 4) Gradient temperature mixing: First, mix the untreated steel slag powder in step 1) and the FAME after the stabilization treatment in step 2) at a mass ratio of 1:0.5, and stir at 120 °C for 20 minutes; Subsequently, add the rubber powder after the modification treatment in step 3) (the added mass ratio 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 to 190 °C and continue stirring for 10 minutes to obtain the regenerant of Comparative Case 1.

[0040] (3) Regenerant of Comparative Case 2

[0041] Comparative Case 2 is improved based on the steps in (1) above, that is, the rubber powder is not subjected to surface modification treatment, and only untreated rubber powder is used, and the remaining steps are the same as those in (1) above to prepare the regenerant of Comparative Case 2.

[0042] 1) - 2) The steps are the same as those in (1) above;

[0043] 3) Untreated rubber powder: Dry the waste tire rubber powder with a particle size less than 375 μm at 70 °C for standby;

[0044] 4) Gradient temperature mixing: First, mix the steel slag powder after the activation treatment in step 1) and the FAME after the stabilization treatment in step 2) at a mass ratio of 1:0.5, and stir at 120 °C for 20 minutes; Subsequently, add the untreated rubber powder in step 3) (the added mass ratio 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 to 190 °C and continue stirring for 10 minutes to obtain the regenerant of Comparative Case 2.

[0045] (4) Regenerant of Comparative Case 3

[0046] Comparative Case 3 is improved on the basis of the steps in (1) above, that is, the gradient temperature mixing process is not adopted, and the remaining steps are the same as those in (1) above to prepare the regenerant of Comparative Case 3.

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

[0048] 4) Normal temperature mixing: First, mix the steel slag powder after activation treatment in step (1) and the FAME after stabilization treatment in step (2) at a mass ratio of 1:0.5, and stir at 170 °C for 20 minutes; subsequently, add the powdered rubber after modification treatment in step (3) (the added mass ratio to the steel slag powder is 1:1), heat up 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 regenerant of Comparative Case 3.

[0049] (5) Performance test

[0050] According to the JTG E20-2011 specification, the penetration, ductility at 5 °C, softening point, and dynamic viscosity at 60 °C are used to evaluate the influence of the above composite regenerant, the regenerant of Comparative Case 1, the regenerant of Comparative Case 2, and the regenerant of Comparative Case 3 on the properties of aged asphalt. The results are shown in Table 1. It can be seen from Table 1 that the incorporation of different regenerants can significantly improve the high and low temperature flow properties of asphalt binder. Compared with the composite regenerated asphalt, the softening point and ductility of the regenerated asphalt of Comparative Case 1 become smaller, which indicates that the citric acid activation treatment can significantly improve the esterification reaction efficiency of steel slag and FAME, and form calcium soap to enhance the interfacial bonding between the two. Compared with the composite regenerated asphalt, the ductility of the regenerated asphalt of Comparative Case 2 decreases significantly, which indicates that the surface modification of powdered rubber with silane coupling agent can reduce the polarity difference between powdered rubber and other substances and improve the interfacial compatibility. Compared with the composite regenerated asphalt, the penetration and ductility at 5 °C of the regenerated asphalt of Comparative Case 3 become smaller, and the dynamic viscosity at 60 °C becomes larger, which indicates that the composite regenerant prepared by the interface synergistic optimization of steel slag activation-rubber powder modification-FAME treatment and the gradient temperature mixing process of the present invention can significantly restore and improve the high and low temperature properties and viscosity of aged asphalt.

[0051] Table 1 Asphalt performance test

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

[0053] Example 2:

[0054] Example 2 reveals the influence of the composite regenerant on the properties of the regenerated asphalt mixture.

[0055] (1) Preparation of the regenerated asphalt mixture containing the composite regenerant

[0056] In this Example 2, the composite regenerated asphalt mixture is prepared based on the composite regenerant prepared in Example 1.

[0057] First, according to the total mass percentage of the recycled asphalt mixture, mix new SBS modified asphalt (mixing ratio 5%), RAP material (mixing ratio 22%), new basalt coarse and fine aggregates (mixing ratio 62%), new limestone mineral powder (mixing ratio 6%), and composite regenerant (mixing ratio 5%) according to the AC-16 type asphalt mixture gradation; subsequently, subject the above mixture to treatment processes with heating temperatures of 150°C to 180°C, mixing temperatures of 165°C to 185°C, and compaction temperatures of 135°C to 155°C to obtain the composite recycled asphalt mixture.

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

[0059] In this Example 2, based on Example 1, a comparative recycled asphalt mixture was prepared using the comparative regenerant of Case 3.

[0060] First, according to the total mass percentage of the recycled asphalt mixture, mix new SBS modified asphalt (mixing ratio 5%), RAP material (mixing ratio 22%), new basalt coarse and fine aggregates (mixing ratio 62%), new limestone mineral powder (mixing ratio 6%), and comparative regenerant (mixing ratio 5%) according to the AC-16 type asphalt mixture gradation; subsequently, subject the above mixture to treatment processes with heating temperatures of 150°C to 180°C, mixing temperatures of 165°C to 185°C, and compaction temperatures of 135°C to 155°C to obtain the comparative recycled asphalt mixture.

[0061] (3) Performance testing

[0062] According to the JTG E20-2011 specification, the high-temperature rutting resistance test, low-temperature beam bending test, and four-point bending fatigue test were used to test the effects of the composite regenerant and the comparative regenerant on the high-temperature performance, low-temperature performance, and fatigue resistance performance of the recycled asphalt mixture. The results are shown in Table 2. It can be seen from Table 2 that compared with the comparative regenerant, the composite regenerant makes the low-temperature bending strain and fatigue resistance life of the aged asphalt mixture larger, which indicates that the composite regenerant prepared by the present invention can significantly improve the low-temperature performance and fatigue resistance performance of the recycled asphalt mixture; for the dynamic stability, both the composite regenerant and the comparative regenerant make the dynamic stability of the aged asphalt mixture smaller, but the composite regenerant makes the dynamic stability of the aged asphalt mixture larger.

[0063] Table 2 Performance testing of asphalt mixture

[0064] Performance index Aged asphalt mixture Composite recycled asphalt mixture Comparative regenerant asphalt mixture Dynamic stability (times / mm) 9100 8800 8200 Low temperature bending strain (με) 2350 2980 2640 Anti-fatigue 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 above specific embodiments, and those skilled in the art can make various deformations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A preparation method of a multi-solid waste interface collaborative regenerant, characterized in that, It includes the following steps: Step 1: Mix steel slag powder with citric acid solution, stir at 50°C - 70°C for 40 min - 80 min, filter, and dry. Step 2: Mix fatty acid methyl ester (FAME) with sodium lignosulfonate solution, stir at 40°C - 60°C for 20 min - 40 min. Step 3: Mix waste tire rubber powder with KH-550 silane coupling agent solution, stir at 60°C - 80°C for 30 min - 50 min, and dry. Step 4: Mix the steel slag powder treated in Step 1 with the FAME treated in Step 2, stir at 120°C - 130°C for 15 min - 25 min. Subsequently, add the rubber powder treated in Step 3, raise the temperature to 160°C - 180°C and continue to stir for 25 min - 35 min, then raise the temperature to 185°C - 195°C and continue to stir for 8 min - 12 min to obtain the regenerant.

2. The method according to claim 1, characterized in that The particle size of the steel slag powder is less than 75 μm, the mass concentration of the citric acid solution is 5% - 8%, and the mass ratio of the steel slag powder to the citric acid solution is 1:(3 - 5).

3. The method according to claim 1, wherein The mass concentration of the sodium lignosulfonate solution is 1% - 2%, and the mass ratio of FAME to the sodium lignosulfonate solution is 1:(0.1 - 0.3).

4. The method according to claim 1, characterized in that The particle size of the waste tire rubber powder is less than 375 μm, the mass concentration of the KH-550 silane coupling agent solution is 2% - 3%, and the mass ratio of the waste tire rubber powder to the KH-550 silane coupling agent solution is 1:(0.8 - 1.2).

5. The method according to claim 1, wherein The steel slag powder treated in Step 1 and the FAME treated in Step 2 are mixed in a mass ratio of 1:(0.3 - 0.8).

6. The method according to claim 1, wherein The mass ratio of the rubber powder treated in Step 3 to the steel slag powder treated in Step 1 is 1:(0.6 - 1.6).

7. A preparation method of recycled asphalt mixture with a multi-solid waste interface synergistic regenerant, characterized in that, It includes the following steps: Step (1) Heating treatment: Heat the recycled asphalt pavement (RAP), new basalt coarse and fine aggregates, new limestone powder, and new SBS modified asphalt at 150°C - 180°C for 2 - 5 hours respectively. Step (2) Mixing treatment: Mix the SBS modified asphalt, RAP material, basalt coarse and fine aggregates, limestone powder, and the composite regenerant prepared by the method according to any one of claims 1 - 6 according to the asphalt mixture gradation at 165°C - 185°C. Step (3) Compaction treatment: Transfer the mixture to a forming mold and compact it at 135°C - 155°C.

8. The method according to claim 7, characterized in that By the total mass percentage of the recycled asphalt mixture, the mixing ratio of the SBS modified asphalt is 4% - 8%, the mixing ratio of the RAP material is 20% - 40%, the mixing ratio of the basalt coarse and fine aggregates is 55% - 75%, the mixing ratio of the limestone powder is 5% - 10%, and the mixing ratio of the composite regenerant is 4% - 8%.

9. The method according to claim 7, characterized in that the asphalt The mixture gradation includes one or more of AC-13 type, SMA-13 type, AC-16 type, and SMA-16 type.