Recycled concrete based on asphalt multi-source waste and preparation method

Abstract

The invention discloses recycled concrete based on asphalt multi-source waste and a preparation method, and belongs to the technical field of concrete materials. The recycled concrete based on the asphalt multi-source waste comprises 50-70 parts of recycled asphalt mixture particles, 5-10 parts of new asphalt, 0.5-3 parts of a curing agent, 10-20 parts of basalt macadam and 10-20 parts of asphalt station recycled powder. The recycled asphalt mixture particles comprise 20-30% of recycled asphalt mixture particles with the particle size of less than 5mm and 70-80% of recycled asphalt mixture particles with the particle size of 5-15mm; the recycled asphalt mixture particles with the particle size smaller than 5 mm are pretreated before being used. By preparing a chitosan-RAP (particle size less than 5mm)-sodium alginate compound, the modified RAP material has better compatibility with other aggregates, can better play the role of an asphalt material, reduces the use amount of new asphalt, enhances the strength of the asphalt, improves the crack resistance and fatigue resistance of the asphalt, comprehensively utilizes solid wastes and reduces the production cost under the condition that the use amount of the RAP material is relatively high. Therefore, the method has application value.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of concrete materials, and particularly relates to a regenerated concrete based on asphalt multi-source waste and a preparation method. BACKGROUND

[0002] In recent years, with the rapid development of economy, the highway construction develops rapidly. With the vigorous promotion of green highway construction, energy-saving and environment-friendly technology has become the main development trend in the field of highway construction and maintenance. At the same time, with the basic completion of highway network, the highway industry has entered an era of maintenance and repair as the main, construction as the auxiliary, and due to the excellent characteristics of micro-surfacing preventive maintenance technology such as rapidness, economy and high efficiency, it has been widely applied.

[0003] In the process of highway maintenance, the treatment of waste asphalt mixture generated by milling old pavement has always been a difficult problem. According to incomplete statistics, about 12% of asphalt pavement in China needs to be repaired and maintained every year, and the amount of waste generated by these repairs and maintenance is as high as 200 million tons, and most of the waste has not been effectively utilized. The large accumulation of RAP materials not only occupies land resources, but also pollutes the local environment after the action of wind and rain, and then a large amount of funds needs to be invested for environmental pollution control, which is not cost-effective from the perspective of social and economic benefits, and does not conform to the new concept of saving, intensive and green development in China. With the gradual enhancement of people's environmental protection consciousness and the gradual maturity of micro-surfacing technology, people began to apply solid waste to micro-surfacing technology, so the micro-surfacing preventive maintenance technology based on fine separation of RAP was used, and different amounts of RAP with different particle sizes were reasonably used through cold recycling technology, which greatly improved the utilization rate of solid waste and had broad application prospects.

[0004] From the feasibility of using RAP with different contents in micro-surfacing technology, Poursoltani Mostafa et al. studied the feasibility of using almost 100% RAP instead of virgin aggregate (VA) in micro-surfacing, and evaluated the use value of RAP content of 69% and 43%, and the study found that the mixture containing RAP needs 1% more asphalt than the mixture containing VA. Anping Wang et al. determined the optimum asphalt content (OAC) of RAP mixture and the effectiveness of rejuvenator on the performance of asphalt mixture micro-surfacing, and the results showed that the OAC decreases with the increase of RAP content, the addition of RAP can improve the mixing time and improve the moisture resistance and skid resistance performance, and has good environmental and engineering value. Willis et al. studied the crack resistance of plant-mixed hot recycled mixture with 40% RAP content, and found that the crack resistance was not significantly different from that of new asphalt mixture. Studies have shown that when the RAP-SBS content is 30%, the crack resistance is close to that of the original mixture, but the anti-aging performance is poor. McDaniel pointed out that when the RAP content is relatively high, the performance of asphalt mixture is not significantly different from that of new asphalt mixture. However, in the case of high RAP content, the addition of RAP increases the strength of the recycled material, which is prone to cracking.

[0005] The asphalt mixing station processes asphalt, stone, binder and the like into asphalt mixture according to a certain mixing ratio, wherein the asphalt mixing is an important process for forming the asphalt mixture, and in this process, the raw materials pass through multiple links such as transportation, conveying, mixing, heating and the like, and a large amount of dust particles seriously polluting the environment are generated, which are usually less than 0.075 mm in particle size and are called recycled dust, simply referred to as recycled powder or old powder. At present, the recycled powder of the asphalt station is generally treated as waste, and has not been effectively recycled. SUMMARY

[0006] In view of the problems in the prior art, the present application provides a recycled concrete based on asphalt multi-source waste and a preparation method. The present application processes RAP material, does not increase the use amount of asphalt when adding a high content, cooperates with other waste materials, realizes green environmental protection, enhances the strength of asphalt, and improves the crack resistance and fatigue resistance.

[0007] The present application is realized by the following technical solutions: In a first aspect, the present application provides a recycled concrete based on asphalt multi-source waste, which comprises the following raw materials by weight: recycled asphalt mixture particles 50-70 parts, new asphalt 5-10 parts, solidifying agent 0.5-3 parts, basalt crushed stone 10-20 parts, and asphalt station recycled powder 10-20 parts. The recycled asphalt mixture particles comprise 20-30% recycled asphalt mixture particles with a particle size of less than 5 mm and 70-80% recycled asphalt mixture particles with a particle size of 5-15 mm. The regenerated asphalt mixture particles with a particle size less than 5 mm are pretreated before use.

[0008] Further, the pretreatment method of the regenerated asphalt mixture particles with a particle size less than 5 mm is as follows: (1) chitosan is dissolved, (3-mercaptopropyl) trimethoxysilane is added, and after being uniformly mixed, hydrothermal reaction is carried out at 150-180 DEG C for 4-6 h, and after the reaction is completed, filtration, washing and drying are carried out to obtain a chitosan grafting product; (2) the chitosan grafting product, the regenerated asphalt mixture particles with a particle size less than 5 mm and sodium alginate are mixed, and after being heated to 120-140 DEG C, stirring is carried out for 0.5-1 h to obtain a regenerated asphalt mixture particle modification product with a particle size less than 5 mm, and the pretreatment is completed.

[0009] Further, in step (1), chitosan is dissolved by using a sodium hydroxide-methanol-DMF mixed solvent, the volume ratio of methanol and DMF in the sodium hydroxide-methanol-DMF mixed solvent is 1:1-3, and the mass percentage concentration of sodium hydroxide is 20-40%.

[0010] Further, in step (1), the mass ratio of chitosan and (3-mercaptopropyl) trimethoxysilane is 1:0.05-0.2.

[0011] Further, in step (2), the mass ratio of the chitosan grafting product, the regenerated asphalt mixture particles with a particle size less than 5 mm and sodium alginate is 1:5-10:1-2.

[0012] Further, the new asphalt is No. 70 asphalt or SBS modified asphalt; and the curing agent is one of sodium alginate, acrylamide and sodium bisulfite.

[0013] Further, the particle size of the basalt macadam is 5-10 mm; and the particle size of the asphalt station recycling powder is less than 1 mm.

[0014] In the second aspect of the present application, a preparation method of the regenerated concrete based on asphalt multi-source waste is provided, and specifically, the regenerated asphalt mixture particles and basalt macadam are uniformly mixed at 160-180 DEG C, and then the asphalt station recycling powder, new asphalt and curing agent are added and heated, and stirring is continuously carried out for 2-5 min to obtain the regenerated concrete based on asphalt multi-source waste.

[0015] Compared with the prior art, the present application has the following beneficial effects: (1) The present application prepares chitosan-RAP (particle size <5mm)-sodium alginate compound, (3-mercaptopropyl) trimethoxysilane is grafted to chitosan, and a cross-linked network structure is formed by sodium alginate and RAP, the modified RAP material has better compatibility with other aggregate, can better play the role of asphalt material, reduces the use amount of new asphalt, in the case that the use amount of RAP material is high, the strength of asphalt is enhanced, the crack resistance and fatigue resistance are improved, and the service life is prolonged; (2) The present application adds asphalt station recovery powder in the preparation process of the recycled concrete based on asphalt multi-source waste, the asphalt station recovery powder can replace the mineral powder and better play a role, and the compatibility of the recovery powder with other components of the concrete is better, a dense structure is formed, the impermeability of the concrete material is improved, and the solidification strength is improved; the present application comprehensively utilizes solid waste, changes waste into treasure, and has popularization value. DETAILED DESCRIPTION

[0016] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and are not used to limit the scope of the present application. The experimental methods not specified in the following examples are usually carried out according to conventional conditions or according to the conditions recommended by the manufacturers.

[0017] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as familiar to those skilled in the art. The reagents or raw materials used in the present application can be purchased through a conventional route, and the reagents or raw materials used in the present application are used according to the conventional mode in the art or according to the product instructions, unless otherwise specified.

[0018] In the present application, the asphalt content in the recycled asphalt mixture particles with a particle size of less than 5mm is 8.3%, and the asphalt content in the recycled asphalt mixture particles with a particle size of 5-15mm is 1.47%; the parts in the following examples and comparative examples are weight parts; the new asphalt in the following examples and comparative examples is SBS modified asphalt; the particle size of the basalt macadam is 5-10mm, and the particle size of the asphalt station recovery powder is less than 1mm.

[0019] Example 1 (1) Pretreatment of recycled asphalt mixture particles 1) Chitosan is dissolved in a sodium hydroxide-methanol-DMF mixed solvent (the volume ratio of methanol and DMF in the sodium hydroxide-methanol-DMF mixed solvent is 1:3, and the mass percentage concentration of sodium hydroxide is 28%), (3-mercaptopropyl) trimethoxysilane (the mass ratio of chitosan and (3-mercaptopropyl) trimethoxysilane is 1:0.2) is added, the mixture is uniformly mixed, and then hydrothermal reaction is carried out at 160℃ for 5h, after the reaction is completed, filtration, washing and drying are carried out to obtain a chitosan graft product; 2) The chitosan grafting product, the regenerated asphalt mixture particles with a particle size less than 5 mm, and sodium alginate are mixed, and the mass ratio of the chitosan grafting product, the regenerated asphalt mixture particles with a particle size less than 5 mm, and sodium alginate is 1:8:1.5. After mixing, heating is performed to 135°C, and stirring is performed for 40 min to obtain a regenerated asphalt mixture particle modified product, and the pretreatment is completed.

[0020] (2) The above-mentioned 30 parts of the regenerated asphalt mixture particle modified product with a particle size less than 5 mm and 70 parts of the regenerated asphalt mixture particles with a particle size of 5-15 mm are mixed to obtain the regenerated asphalt mixture particles; (3) 60 parts of the regenerated asphalt mixture particles and 15 parts of basalt gravel are heated to 175°C and uniformly mixed, and then 15 parts of asphalt station recycling powder, 8 parts of new asphalt, and 2 parts of curing agent acrylamide are added, and stirring is continuously performed for 5 min to obtain the recycled concrete based on asphalt multi-source waste materials.

[0021] Example 2 (1) The pretreatment of the regenerated asphalt mixture particles is the same as that in step (1) of the example; (2) The above-mentioned 20 parts of the regenerated asphalt mixture particle modified product with a particle size less than 5 mm and 80 parts of the regenerated asphalt mixture particles with a particle size of 5-15 mm are mixed to obtain the regenerated asphalt mixture particles; (3) 50 parts of the regenerated asphalt mixture particles and 20 parts of basalt gravel are heated to 180°C and uniformly mixed, and then 15 parts of asphalt station recycling powder, 10 parts of new asphalt (SBS modified asphalt), and 2 parts of curing agent acrylamide are added, and stirring is continuously performed for 5 min to obtain the recycled concrete based on asphalt multi-source waste materials.

[0022] Example 3 (1) The pretreatment of the regenerated asphalt mixture particles is the same as that in step (1) of the example; (2) The above-mentioned 25 parts of the regenerated asphalt mixture particle modified product with a particle size less than 5 mm and 75 parts of the regenerated asphalt mixture particles with a particle size of 5-15 mm are mixed to obtain the regenerated asphalt mixture particles; (3) 55 parts of the regenerated asphalt mixture particles and 20 parts of basalt gravel are heated to 170°C and uniformly mixed, and then 20 parts of asphalt station recycling powder, 6 parts of new asphalt, and 2 parts of curing agent sodium alginate are added, and stirring is continuously performed for 2-5 min to obtain the recycled concrete based on asphalt multi-source waste materials.

[0023] Example 4 (1) The pretreatment of the regenerated asphalt mixture particles is the same as that in step (1) of the example; (2) The above-mentioned 30 parts of the regenerated asphalt mixture particle modified product with a particle size less than 5 mm and 70 parts of the regenerated asphalt mixture particles with a particle size of 5-15 mm are mixed to obtain the regenerated asphalt mixture particles; (3) 65 parts of recycled asphalt mixture particles and 10 parts of basalt gravel were heated to 160°C and uniformly mixed, and then 20 parts of asphalt station recycling powder, 10 parts of new asphalt (SBS modified asphalt), and 2 parts of curing agent acrylamide were added, and stirring was continued for 2-5 min to obtain recycled concrete based on asphalt multi-source waste materials.

[0024] Comparative Example 1 Unlike Example 1, no pretreatment of recycled asphalt mixture particles was performed in Comparative Example 1; specifically: (1) 30 parts of recycled asphalt mixture particles with a particle size of less than 5 mm and 70 parts of recycled asphalt mixture particles with a particle size of 5-15 mm were mixed to obtain recycled asphalt mixture particles; (2) 60 parts of recycled asphalt mixture particles and 15 parts of basalt gravel were heated to 175°C and uniformly mixed, and then 15 parts of asphalt station recycling powder, 8 parts of new asphalt, and 2 parts of curing agent acrylamide were added, and stirring was continued for 5 min to obtain recycled concrete based on asphalt multi-source waste materials.

[0025] Comparative Example 2 Unlike Example 1, no pretreatment of recycled asphalt mixture particles was performed in Comparative Example 1, but chitosan and sodium alginate were modified and directly added as concrete raw materials for the preparation of concrete. The specific method is as follows: (1) Chitosan-sodium alginate modified product 1) Chitosan was dissolved in a sodium hydroxide-methanol-DMF mixed solvent (the volume ratio of methanol and DMF in the sodium hydroxide-methanol-DMF mixed solvent was 1:3, and the mass percentage concentration of sodium hydroxide was 28%), (3-mercaptopropyl)trimethoxysilane was added (the mass ratio of chitosan and (3-mercaptopropyl)trimethoxysilane was 1:0.2), and after uniform mixing, hydrothermal reaction was carried out at 160°C for 5h. After the reaction was completed, filtration, washing, and drying were performed to obtain a chitosan grafted product; 2) The chitosan grafted product, polyvinyl alcohol, and sodium alginate were mixed, and the mass ratio of chitosan grafted product, polyvinyl alcohol, and sodium alginate was 1:8:1.5. After mixing, heating was performed to 135°C, and stirring was performed for 40 min to obtain a chitosan-sodium alginate modified product.

[0026] (2) 30 parts of recycled asphalt mixture particles with a particle size of less than 5 mm and 70 parts of recycled asphalt mixture particles with a particle size of 5-15 mm were mixed to obtain recycled asphalt mixture particles; (3) 60 parts of recycled asphalt mixture particles, 5 parts of chitosan-sodium alginate modified product, and 15 parts of basalt gravel were heated to 175°C and uniformly mixed, and then 15 parts of asphalt station recycling powder, 8 parts of new asphalt, and 2 parts of curing agent acrylamide were added, and stirring was continued for 5 min to obtain recycled concrete based on asphalt multi-source waste materials.

[0027] Comparative Example 3 (1) Pretreatment of recycled asphalt mixture particles 1) Dissolve chitosan in a sodium hydroxide-methanol-DMF mixed solvent (the volume ratio of methanol and DMF in the sodium hydroxide-methanol-DMF mixed solvent is 1:3, and the mass percentage concentration of sodium hydroxide is 28%), add (3-mercaptopropyl) trimethoxysilane (the mass ratio of chitosan and (3-mercaptopropyl) trimethoxysilane is 1:0.2), mix uniformly, and then hydrothermally react at 160°C for 5h. After the reaction is completed, filter, wash, and dry to obtain a chitosan grafted product; 2) Mix the chitosan grafted product, recycled asphalt mixture particles (30 parts of recycled asphalt mixture particles with a particle size of less than 5mm and 70 parts of recycled asphalt mixture particles with a particle size of 5-15mm), and sodium alginate. The mass ratio of chitosan grafted product, recycled asphalt mixture particles, and sodium alginate is 1:8:1.5. After mixing, heat to 135°C and stir for 40min to obtain a recycled asphalt mixture particle modified product, and the pretreatment is completed.

[0028] (3) Heat 60 parts of pretreated recycled asphalt mixture particles and 15 parts of basalt macadam to 175°C, mix uniformly, then add 15 parts of asphalt station recycling powder, 8 parts of new asphalt, and 2 parts of curing agent acrylamide, and continue to stir for 5min to obtain recycled concrete based on asphalt multi-source waste.

[0029] Concrete performance test: (1) Penetration: tested according to GB / T4509-2010 "Determination of Penetration of Asphalt"; (2) Freeze-thaw splitting residual strength ratio: determined according to the method of T0729-2000 in JTJ052-2000 "Test Code for Asphalt and Asphalt Mixture in Highway Engineering"; (3) Immersed Marshall residual stability: determined according to T0709-2000 "Marshall Stability Test of Asphalt Mixture"; (4) Dynamic stability: determined according to T0719-2011 in JTGE20-2011 "Test Code for Asphalt and Asphalt Mixture in Highway Engineering"; (5) Fatigue test: determined according to NFP98-261-1 "Determination of Fatigue Resistance of Asphalt Mixture Part 1: Constant Deflection Bending Change Test".

[0030] The performance test results of the recycled concrete based on asphalt multi-source waste prepared in Examples 1-4 and Comparative Examples 1-3 are shown in Table 1 below: Table 1 Performance test results of recycled concrete based on asphalt multi-source waste As can be seen from Table 1, the chitosan-RAP-sodium alginate composite formed by modifying the regenerated asphalt mixture particles with a particle size less than 5 mm, grafting chitosan with (3-mercaptopropyl) trimethoxysilane, and forming a cross-linked network structure with sodium alginate and RAP, the modified RAP material has better compatibility with other aggregates, can better play the role of asphalt material, reduce the use amount of new asphalt, and in the case of high use amount of RAP material, enhance the strength of asphalt, improve the crack resistance, stability and service life; the comparative example 3 simultaneously modifies the regenerated asphalt mixture particles with a particle size less than 5 mm and the regenerated asphalt mixture particles with a particle size of 5-15 mm, and the regenerated concrete based on asphalt multi-source waste material obtained has relatively large freeze-thaw splitting strength ratio and immersion Marshall residual stability parameters, but its dynamic stability and fatigue resistance are not good, and due to the use of more chitosan and sodium alginate, the proportion of RAP material is reduced, and the cost is increased.

[0031] The comparative example 1 does not pretreat the regenerated asphalt mixture particles, directly adds untreated RAP material in the concrete, and the addition amount of RAP material should not be too much, and when the proportion reaches that of the example 1, the overall performance is significantly reduced. The comparative example 2 does not pretreat the regenerated asphalt mixture particles, but modifies chitosan and sodium alginate, and directly adds them as the raw material of the concrete to prepare the concrete. This direct adding method has little effect on RAP, and when the addition amount of RAP is relatively large, it will affect the stability, service life and freeze-thaw splitting strength ratio of the final concrete.

Claims

1. A recycled concrete based on multi-source asphalt waste, characterized in that, The raw materials include the following parts by weight: 50-70 parts recycled asphalt mixture particles, 5-10 parts new asphalt, 0.5-3 parts curing agent, 10-20 parts basalt crushed stone, and 10-20 parts asphalt station recycled powder. The recycled asphalt mixture particles include 20-30% recycled asphalt mixture particles with a particle size of less than 5 mm and 70-80% recycled asphalt mixture particles with a particle size of 5-15 mm. The recycled asphalt mixture particles with a particle size of less than 5 mm are pretreated before use.

2. The recycled concrete based on multi-source asphalt waste according to claim 1, characterized in that, The pretreatment method for the recycled asphalt mixture particles smaller than 5mm is as follows: (1) Dissolve chitosan, add (3-mercaptopropyl)trimethoxysilane, mix evenly, and then hydrothermally react at 150~180℃ for 4~6h. After the reaction is completed, filter, wash and dry to obtain chitosan graft product. (2) Mix chitosan graft product, recycled asphalt mixture particles with a particle size of less than 5 mm and sodium alginate. After mixing, heat to 120~140℃ and stir for 0.5~1h to obtain modified recycled asphalt mixture particles with a particle size of less than 5 mm, thus completing the pretreatment.

3. The recycled concrete based on multi-source asphalt waste according to claim 2, characterized in that, In step (1), chitosan is dissolved in a sodium hydroxide-methanol-DMF mixed solvent. The volume ratio of methanol to DMF in the sodium hydroxide-methanol-DMF mixed solvent is 1:1~3, and the mass percentage concentration of sodium hydroxide is 20~40%.

4. The recycled concrete based on multi-source asphalt waste according to claim 2, characterized in that, In step (1), the mass ratio of chitosan to (3-mercaptopropyl)trimethoxysilane is 1:0.05~0.

2.

5. The recycled concrete based on multi-source asphalt waste according to claim 2, characterized in that, In step (2), the mass ratio of chitosan graft product, recycled asphalt mixture particles with a particle size of less than 5 mm, and sodium alginate is 1:5~10:1~2.

6. The recycled concrete based on multi-source asphalt waste according to claim 1, characterized in that, The new asphalt is No. 70 asphalt or SBS modified asphalt; the curing agent is one of sodium alginate, acrylamide, and sodium bisulfite.

7. The recycled concrete based on multi-source asphalt waste according to claim 1, characterized in that, The basalt crushed stone has a particle size of 5-10 mm; the asphalt station recycled powder has a particle size of less than 1 mm.

8. A method for preparing recycled concrete based on multi-source asphalt waste according to any one of claims 1 to 7, characterized in that, Mix recycled asphalt mixture particles and basalt crushed stone at 160~180℃ until uniform, then add recycled powder from asphalt plant, new asphalt and curing agent, and continue stirring for 2~5 minutes to obtain recycled concrete based on multi-source asphalt waste.

Images