Stirring process of fiber reinforced asphalt mixture

Abstract

The invention relates to the technical field of road materials, in particular to a stirring process of a fiber reinforced asphalt mixture. The preparation method comprises the following steps: heating asphalt, and mixing the heated asphalt with a binder to obtain a mixture A; adding aggregate and mineral powder into the mixture A, and shearing to obtain a mixture B; and finally, adding fibers into the mixture B, and stirring under a vacuum condition to obtain the fiber-reinforced asphalt mixture. According to the method, the fibers and the asphalt mixture are mixed under vacuum, the fibers can be more uniformly dispersed in the asphalt mixture under the action of negative pressure, and the phenomenon of fiber agglomeration is avoided, so that the reinforcing effect of the fibers is better exerted, and the durability of the prepared fiber asphalt mixture is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of road materials, in particular to a stirring process of fiber-reinforced asphalt mixture. BACKGROUND

[0002] Asphalt mixture is a kind of pavement construction material mixed by asphalt, mineral powder, coarse and fine aggregate and binder, which is usually used as material for road construction and maintenance. In recent years, with the rapid development of road engineering, the quantity and especially the quality of asphalt mixture is required higher and higher. However, in some areas, especially in the mountainous areas with bad weather, the asphalt pavement is subjected to the combined action of environment and load, and a series of diseases such as deformation and cracking exist in the asphalt pavement. Adding an appropriate amount of fiber to the asphalt mixture can effectively improve the durability of the asphalt pavement. The fiber added to the asphalt mixture plays the role of reinforcement, adsorption and adhesion, which can effectively improve the high-temperature stability and low-temperature stability and other road performance of the asphalt mixture. Although the addition of fiber can significantly improve the performance of the asphalt mixture, there are still many deficiencies in the actual application of the existing technology. For example, the uniformity of fiber dispersion in the mixing process is difficult to control, and fiber agglomeration phenomenon is easy to occur; the existing technology usually modifies the surface of the fiber to improve its dispersion in asphalt, but the preparation method is complex, and there are many problems such as high cost, low efficiency and complicated operation. Therefore, how to provide a new stirring process of fiber-reinforced asphalt mixture, which can improve the dispersion of fiber without modifying the fiber, and thus increase the strength of the asphalt pavement, has become a technical problem to be solved in the field. SUMMARY

[0003] The purpose of the present application is to provide a stirring process of fiber-reinforced asphalt mixture, which has the effect of effectively improving the uniformity of fiber dispersion and the performance of asphalt mixture.

[0004] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical scheme:

[0005] The present application provides a stirring process of fiber-reinforced asphalt mixture, comprising the following steps:

[0006] 1) After heating the asphalt and mixing with the binder, a mixture A is obtained;

[0007] 2) The aggregate and mineral powder are added to the mixture A, and shearing is performed to obtain a mixture B;

[0008] 3) The fiber is added to the mixture B, and stirring is performed under vacuum conditions to obtain a fiber-reinforced asphalt mixture.

[0009] Optionally, the asphalt includes base asphalt, petroleum asphalt or modified asphalt; the temperature of the heated asphalt is 150-185℃.

[0010] Optionally, the binder comprises styrene-isoprene-styrene polymer or styrene-ethylene-butadiene-styrene polymer; the asphalt amount is 20-50% of the mass of the binder.

[0011] Optionally, the aggregate is basalt aggregate; the basalt aggregate comprises aggregate one, aggregate two and aggregate three, the particle size of the aggregate one is 10-20mm, the particle size of the aggregate two is 5-10mm, and the particle size of the aggregate three is 0-3mm; the mineral powder is lime powder; the particle size of the mineral powder is less than 0.1mm.

[0012] Optionally, the mass ratio of the aggregate one, the aggregate two, the aggregate three and the mineral powder is 9-11:9-11:10-12:1; the asphalt amount is 3-6% of the total mass of the basalt aggregate and the mineral powder.

[0013] Optionally, the speed of shearing is 1000-3000r / min, and the time is 10-60min.

[0014] Optionally, the amount of the fiber is 2-6% of the mass of the mixture B.

[0015] Optionally, the fiber comprises natural fiber, polymer fiber or inorganic nanofiber.

[0016] Optionally, the vacuum degree of the vacuum condition is -0.05 to -0.08MPa.

[0017] Optionally, the speed of stirring is 300-600r / min, and the time is 5-20min.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] The stirring process of the fiber-reinforced asphalt mixture provided by the present application adds the fiber into the asphalt mixture and stirs under the vacuum condition, so that the fiber is more uniformly dispersed in the asphalt mixture by the negative pressure effect, the fiber agglomeration phenomenon is avoided, the reinforcing effect of the fiber is better, and the durability of the prepared fiber asphalt mixture is greatly improved. DETAILED DESCRIPTION

[0020] The various exemplary embodiments of the present application will be described in detail below, which should not be considered as limiting the present application, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present application.

[0021] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Additionally, for a range of values of, for example, the upper limit and lower limit of a range of values are included in the range. Each intermediate value of the stated range and each smaller range that falls within the stated range are also included in the present application. The upper and lower limits of these smaller ranges can independently be included or excluded in the range.

[0022] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned herein are incorporated by reference to disclose and describe in full the methods and / or materials which are described therein. In the case of conflict between the present specification and any document incorporated herein by reference, the present specification will control.

[0023] Many modifications and variations of the present application described in the specification are possible without departing from the scope or spirit of the application. Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application. The specification and examples are illustrative only.

[0024] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having", "contains", "containing", or variations thereof, are intended to be open-ended terms that mean including, but not limited to.

[0025] The raw materials used in the present application can be obtained commercially or prepared by prior art.

[0026] The present application provides a mixing process of fiber reinforced asphalt mixture, comprising the following steps:

[0027] 1) After heating the asphalt, mix the asphalt with the binder to obtain mixture A;

[0028] 2) Add the aggregate and the mineral powder into the mixture A, and perform shearing to obtain mixture B;

[0029] 3) Add the fiber into the mixture B, and perform mixing under vacuum condition to obtain the fiber reinforced asphalt mixture.

[0030] The present application first heats the asphalt, which refers to the process of converting the solid asphalt into a flowing state.

[0031] The mixing method of the asphalt and the binder is not particularly limited in the present application, as long as the asphalt and the binder can be uniformly mixed.

[0032] In the embodiment of the present application, the asphalt comprises base asphalt, petroleum asphalt or modified asphalt, preferably base asphalt or petroleum asphalt, and further preferably base asphalt; the temperature of the heated asphalt is 150-185°C, preferably 155-180°C, further preferably 160-175°C, and more preferably 165-170°C.

[0033] In the embodiment of the present application, the binder comprises styrene-isoprene-styrene polymer or styrene-ethylene-butadiene-styrene polymer, and preferably styrene-isoprene-styrene polymer; the asphalt content is 20-50% of the mass of the binder, preferably 25-45%, further preferably 30-40%, and more preferably 34-35%.

[0034] In the present application, during the shearing mixing process, the binder phase uniformly coats the surface of the fibers through thermoplastic flow, forming a physical anchoring effect.

[0035] In the embodiment of the present application, the aggregate is basalt aggregate; the basalt aggregate comprises aggregate one, aggregate two and aggregate three, the particle size of aggregate one is 10-20 mm, the particle size of aggregate two is 5-10 mm, and the particle size of aggregate three is 0-3 mm; the mineral powder is lime powder; the particle size of the mineral powder is less than 0.1 mm.

[0036] In the present application, the coarse particle size particles of aggregate one constitute the main skeleton structure of the mixture, the intermediate particle size particles of aggregate two fill the voids between the coarse aggregate, and the fine particle size particles of aggregate three further compact the internal pores of the mixture, forming a continuous gradation dense skeleton. The fine particles of lime powder uniformly wrap the surface of the aggregate through adsorption, forming a stable asphalt-mineral powder interface film, and at the same time, the alkaline components react with the acidic substances in the asphalt, enhancing the interfacial adhesion. The hard characteristics of basalt aggregate combined with multi-level particle size distribution reduce the internal porosity of the mixture, providing physical support for the uniform dispersion of fibers and avoiding the agglomeration of fibers due to excessively large voids.

[0037] In the embodiment of the present application, the mass ratio of aggregate one, aggregate two, aggregate three and mineral powder is 9-11:9-11:10-12:1, preferably 9.5-10.6:9.4-10.8:10.2-11.8:1, and further preferably 9.8-10:10-10.5:10.5-11:1; the asphalt content is 3-6% of the total mass of the basalt aggregate and mineral powder used, preferably 4-5%.

[0038] In the embodiment of the present application, the shearing speed is 1000-3000 r / min, preferably 1200-2800 r / min, further preferably 1500-2500 r / min, and more preferably 1800-2000 r / min; and the time is 10-60 min, preferably 15-55 min, further preferably 20-40 min, and more preferably 25-30 min.

[0039] In the present application, the aggregate and the mineral powder form a space skeleton structure in the matrix by shearing, avoiding the fibers from being mechanically wrapped by the mineral particles when added.

[0040] In the embodiment of the present application, the amount of the fiber is 2-6% of the mass of the mixture B, preferably 3-5%, and further preferably 3.5-4%.

[0041] The fiber in the present application can be synthetic or natural. The fiber includes natural fiber, polymer fiber or inorganic nanofiber, etc. The natural fiber includes wood fiber and bamboo fiber, etc. The polymer fiber includes aramid fiber, polypropylene fiber, propylene fiber or polyvinyl chloride fiber, etc. The inorganic nanofiber includes copper fiber, carbon fiber and glass fiber, etc. In the embodiment of the present application, the inorganic nanofiber is preferred, and the glass fiber is further preferred.

[0042] In the present application, the fiber is added to the mixture B, the stirring container is evacuated to reach a preset negative pressure condition, then the evacuation is stopped, and the stirring is started. The fiber reinforced asphalt mixture is obtained after the stirring is completed.

[0043] In the embodiment of the present application, the vacuum degree of the vacuum condition is -0.05 to -0.08 MPa, and preferably -0.06 to -0.07 MPa.

[0044] In the present application, when the vacuum degree is maintained at -0.05 to -0.08 MPa, the gas phase volume of the mixing system is compressed, the contact area between the fiber and the aggregate is increased, the fiber is more uniformly dispersed in the asphalt mixture, and the fiber forms a more stable three-dimensional network structure in the mixture, thereby enhancing the cohesion and toughness of the mixture and making the interlocking action between the aggregates more compact.

[0045] In the embodiment of the present application, the stirring speed is 300-600 r / min, preferably 350-550 r / min, and further preferably 400-500 r / min; and the time is 5-20 min, preferably 10-15 min.

[0046] The technical solutions provided by the present application will be described in detail below in combination with the embodiments, but they should not be understood as limiting the scope of the present application.

[0047] Example 1

[0048] 1) After heating the asphalt to 170℃, the asphalt is mixed with styrene-isoprene-styrene polymer, the asphalt is used in an amount of 20% of the mass of the styrene-isoprene-styrene polymer to obtain a mixture A;

[0049] 2) The basalt aggregate is divided into aggregate one, aggregate two and aggregate three according to the particle size, the particle size of the aggregate one is 10-20mm, the particle size of the aggregate two is 5-10mm, and the particle size of the aggregate three is 0-3mm; the aggregate one, the aggregate two, the aggregate three and the mineral powder are mixed in a mass ratio of 10:10.5:11:1, then the mixture A is added, so that the asphalt is used in an amount of 3% of the total mass of the basalt aggregate and the mineral powder, then the mixture is sheared at 2500r / min for 30min to obtain a mixture B;

[0050] 3) The glass fiber is added to the mixture B, the amount of the fiber is 3% of the mass of the mixture B, stirring is carried out under a vacuum degree of-0.05MPa, the stirring rate is 300r / min, and the stirring time is 15min to obtain the fiber reinforced asphalt mixture.

[0051] Example 2

[0052] The difference from Example 1 is only that the vacuum degree is-0.06MPa.

[0053] Example 3

[0054] The difference from Example 1 is only that the vacuum degree is-0.07MPa.

[0055] Example 4

[0056] The difference from Example 1 is only that the vacuum degree is-0.08MPa.

[0057] Comparative Example 1

[0058] The difference from Example 1 is only that no vacuum is applied, and the glass fiber is directly stirred after being added to the mixture B.

[0059] According to JTG E20-2011 “Standard Test Methods of Asphalt and Asphalt Mixture for Highway Engineering”, the performance of the asphalt mixture obtained in Examples 1-4 and Comparative Example 1 is tested, and the results are shown in Table 1.

[0060] Table 1 Performance test results of the fiber reinforced asphalt mixture

[0061]

[0062] As can be seen from Table 1, after the addition of the fibers and stirring under vacuum, the high and low temperature performance and water stability of the asphalt mixture can be significantly improved. Compared with the comparative example 1 which is not stirred under vacuum, the high temperature performance of the asphalt mixture prepared in the examples 1-4 is more excellent; the dynamic stability of the comparative example 1 decreases significantly because when the amount of glass fiber added in the asphalt mixture system increases, a higher glass fiber content can cause the glass fiber to form clusters in the asphalt mixture, and the glass fiber is not uniformly dispersed, and when the mixture is subjected to load, stress concentration occurs, thereby reducing the high temperature performance of the asphalt mixture. Compared with the comparative example 1 which is not stirred under vacuum, the low temperature performance of the asphalt mixture prepared in the examples 1-4 is more excellent; the bending strength of the comparative example 1 decreases significantly because: too high a glass fiber content can adsorb a large amount of asphalt, so that the content of asphalt that effectively bonds the mixture gradually decreases, the adhesion decreases, and thus the anti-cracking ability of the mixture decreases. Compared with the comparative example 1 which is not stirred under vacuum, the water stability of the asphalt mixture prepared in the examples 1-4 is more excellent; the reason for the poor water stability of the comparative example is that the excessive glass fiber is not uniformly distributed, and if water enters during the freeze-thaw cycle, the dynamic water pressure formed under the action of external load reduces the strength of the mixture and the freeze-thaw splitting strength ratio decreases.

[0063] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, several improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A mixing process for fiber-reinforced asphalt mixtures, characterized in that, Includes the following steps: 1) After heating, asphalt is mixed with binder to obtain mixture A; 2) Add the aggregate and mineral powder to mixture A, and shear to obtain mixture B; 3) Add the fiber to mixture B and stir under vacuum to obtain fiber-reinforced asphalt mixture.

2. The stirring process according to claim 1, characterized in that, The asphalt includes base asphalt, petroleum asphalt, or modified asphalt; the temperature of the asphalt after heating is 150–185°C.

3. The stirring process according to claim 1, characterized in that, The binder comprises a styrene-isoprene-styrene polymer or a styrene-ethylene-butadiene-styrene polymer; the amount of asphalt used accounts for 20-50% of the mass of the binder.

4. The stirring process according to claim 1, characterized in that, The aggregate is basalt aggregate; the basalt aggregate includes aggregate one, aggregate two and aggregate three, the particle size of aggregate one is 10-20mm, the particle size of aggregate two is 5-10mm and the particle size of aggregate three is 0-3mm; the mineral powder is lime powder; the particle size of the mineral powder is less than 0.1mm.

5. The stirring process according to claim 1, characterized in that, The mass ratio of aggregate one, aggregate two, aggregate three and mineral powder is 9-11:9-11:10-12:1; the amount of asphalt used accounts for 3-6% of the total mass of basalt aggregate and mineral powder used.

6. The stirring process according to claim 1, characterized in that, The shearing speed is 1000-3000 r / min, and the time is 10-60 min.

7. The stirring process according to claim 1, characterized in that, The amount of fiber used accounts for 2 to 6% of the mass of mixture B.

8. The stirring process according to claim 1, characterized in that, The fibers include natural fibers, polymer fibers, or inorganic nanofibers.

9. The stirring process according to claim 1, characterized in that, The vacuum level of the vacuum condition is -0.05 to -0.08 MPa.

10. The stirring process according to claim 1, characterized in that, The stirring rate is 300–600 r / min, and the stirring time is 5–20 min.

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