阅读说明：本技术 碳化硅改性沥青混凝土的制备方法 (Preparation method of silicon carbide modified asphalt concrete ) 是由 刘小明 赵昱 魏子奇 颜大雄 朱志辉 吴小龙 张道凯 于 2019-10-11 设计创作，主要内容包括：本发明公开了一种碳化硅改性沥青混凝土的制备方法,采用化学气相沉积法在碳化硅纤维上镀3-5nm厚的铁膜,再将镀膜后的碳化硅纤维掺入沥青中；按照级配设计进行配料,将加热的集料置于搅拌锅中,搅拌90s,将改性后的沥青倒入搅拌锅中,搅拌90s；将矿粉放入烘箱中加热至170℃,然后将加热的矿粉倒入搅拌锅进行搅拌,直至拌合均匀,将拌好的沥青混合料进行装模、击实、脱模,制成碳化硅改性沥青混凝土。本方法其制备工艺简单、操作安全,所制备出的沥青混凝土加热效果与加热速率明显提高,同时还提高了沥青混凝土的强度。(The invention discloses a preparation method of silicon carbide modified asphalt concrete, which comprises the steps of plating an iron film with the thickness of 3-5nm on silicon carbide fibers by a chemical vapor deposition method, and doping the silicon carbide fibers after film plating into asphalt; mixing materials according to a grading design, placing the heated aggregate into a stirring pot, stirring for 90s, pouring the modified asphalt into the stirring pot, and stirring for 90 s; and putting the mineral powder into an oven to be heated to 170 ℃, then pouring the heated mineral powder into a stirring pot to be stirred until the mineral powder is uniformly mixed, and filling, compacting and demoulding the mixed asphalt mixture to prepare the silicon carbide modified asphalt concrete. The method has simple preparation process and safe operation, and the prepared asphalt concrete has obviously improved heating effect and heating rate and simultaneously improves the strength of the asphalt concrete.)

1. The preparation method of the silicon carbide modified asphalt concrete is characterized by comprising the following steps:

step S1: soaking the silicon carbide fiber in an acetone solution for 2 hours, taking out and cleaning the silicon carbide fiber by using distilled water;

step S2: putting the silicon carbide fiber into a drying oven, and drying at 100 ℃ for 2 hours;

step S3: plating an iron film with the thickness of 3-5nm on the dried silicon carbide fiber by adopting a chemical vapor deposition method;

step S4: heating the asphalt to 160 ℃, doping the coated silicon carbide fiber into the asphalt, and fully stirring by using a high-speed shearing instrument to obtain modified asphalt;

step S5: putting the cleaned aggregate into a drying oven, and drying at 105 +/-5 ℃ to constant weight;

step S6: proportioning according to a grading design, then putting the proportioned aggregate into an oven, and heating to 170 ℃;

step S7: heating the stirring pot to 163 ℃, then placing the heated aggregate in the stirring pot, and stirring for 90 s;

step S8: pouring the modified asphalt into a stirring pot, and stirring for 90 s;

step S9: putting the mineral powder into an oven, heating to 170 ℃, then pouring the heated mineral powder into a stirring pot for stirring until the mineral powder is uniformly mixed, and keeping the asphalt mixture in a required mixing range;

step S10: and (3) putting the mould into an oven, heating to 105 ℃, filling the mixed asphalt mixture into the mould at the temperature of 145 ℃, compacting and demoulding according to the technical specification requirement to prepare the silicon carbide modified asphalt concrete.

2. The method for preparing silicon carbide modified asphalt concrete according to claim 1, wherein the length of the silicon carbide fiber is 1-3 mm.

3. The method as claimed in claim 1, wherein the chemical vapor deposition process in step S3 comprises heating carbonyl iron to 155 ℃ at a temperature increasing rate of 15-20 ℃/min, and coating with Ar gas as carrier gas at a flow rate of 100 and 300 sccm.

4. The method for preparing the silicon carbide modified asphalt concrete according to claim 1, wherein AH-70 asphalt is adopted as the asphalt, and the mass ratio of the asphalt to the aggregate is 5%.

5. The method of claim 1, wherein in step S4, the silicon carbide fiber coated with the coating is blended in an amount of 2-5% by mass of the asphalt.

6. The method for preparing silicon carbide modified asphalt concrete according to claim 1, wherein limestone is used as the aggregate, and the particle composition is 11mm to 16mm in particle size accounting for 23.2% of the total mass of the mineral aggregate, 5mm to 11mm in particle size accounting for 25% of the total mass of the mineral aggregate, and 0mm to 5mm in particle size accounting for 47% of the total mass of the mineral aggregate.

7. The method for preparing the silicon carbide modified asphalt concrete according to claim 1, wherein the mineral powder is limestone, and accounts for 4.8% of the total mass of the mineral material.

Technical Field

The invention belongs to the technical field of pavement engineering materials, and relates to a preparation method of silicon carbide modified asphalt concrete.

Background

Asphalt concrete pavements are becoming larger and larger worldwide and are increasing. Under the long-term action of load and natural factors, various performances of the asphalt concrete pavement are gradually reduced, and the pavement is subjected to fatigue failure. Therefore, maintenance of asphalt concrete pavement is essential to ensure sufficient strength and rigidity, sufficient stability, durability and surface flatness during operation of the asphalt concrete pavement. The traditional asphalt concrete repairing technology has the problems of large consumption of manpower and material resources, low working efficiency, poor repairing effect and the like. Therefore, the method for improving the disease problem of the asphalt concrete by finding a reasonable method has important practical significance, and the silicon carbide modified asphalt concrete with the intelligent repairing function can just solve the problems.

The tiny cracks of the asphalt pavement are realized through the self-repairing function of the asphalt. The self-repairing speed of the traditional asphalt concrete is low, the effect is not good enough, and the self-repairing capability of the asphalt concrete modified by the wave-absorbing material can be greatly improved. However, for traditional wave-absorbing materials such as steel fibers, when the external temperature is too high and the sunlight is strong, the steel fiber asphalt concrete is used as a good conductor, and the steel fiber asphalt concrete is easy to absorb heat and raise the temperature, so that the internal temperature of the asphalt concrete is higher, diseases such as wheel tracks are easy to generate, and the aging of the internal structure is accelerated. And the silicon carbide is not easy to absorb heat, so that the problems are not worried about. For the magnetic wave-absorbing material, the magnetic metal powder is easy to rust and passivate, so that the wave-absorbing capability is poor, and the pavement is easy to loose, crack and other diseases due to poor wettability with asphalt. Therefore, the traditional wave-absorbing material can not enable the asphalt concrete to achieve ideal repairing effect. The problems can be avoided by using the silicon carbide modified asphalt concrete under the action of microwaves, so that the asphalt concrete has excellent self-repairing capability.

Although the electrical loss material such as graphite and metal powder has high conductivity and large attenuation coefficient, the material is electrically consumed under ideal conditionsThe efficiency of converting magnetic energy into heat energy is high. However, due to the impedance mismatch with air, electromagnetic waves are difficult to enter the surface of the material, thereby forming reflected waves, and thus the high-conductivity material is difficult to become a microwave absorbing material. On the contrary, for some mutually insulated fibers and conductive fibers, the conductance loss is more because of a certain resistance. Therefore, a good conductor is not the best choice when selecting an electrically lossy material, and conversely, a semiconductor material with certain insulating properties is selected to be more reliable and efficient in generating heat energy by virtue of its resistive loss. The silicon carbide material is used as a semiconductor material, has adjustable conductivity within a certain range, is easy to match impedance with air, and is an excellent wave-absorbing material. But the pure silicon carbide material has higher resistance which can reach 10⁹-10¹⁰Omega cm, less dielectric loss, difficult to achieve the ideal wave absorbing effect, and can be used for coating the silicon carbide material. Magnetic materials or elements are introduced to adjust the dielectricity and reduce the resistivity to achieve the required wave-absorbing effect, so that the wave-absorbing material with wider frequency absorption range is prepared. The excellent wave-absorbing performance of the silicon carbide subjected to coating treatment greatly increases the wave-absorbing performance of the asphalt concrete, thereby improving the self-repairing capability of the asphalt concrete. The silicon carbide material has the characteristics that the silicon carbide is subjected to film coating treatment to change the dielectric property and improve the wave absorbing performance, and meanwhile, the silicon carbide is used as a modified material for improving the microwave absorbing performance of asphalt concrete aiming at the problem of repairing the current asphalt pavement diseases.

Disclosure of Invention

In order to realize the purpose, the invention provides a preparation method of silicon carbide modified asphalt concrete, the heating effect and the heating rate of the prepared asphalt concrete are obviously improved, and the strength of the asphalt concrete is also improved; the preparation method has simple process and safe operation; the pavement repairing efficiency is high, and the repairing effect is obvious.

The technical scheme adopted by the invention is that the preparation method of the silicon carbide modified asphalt concrete comprises the following steps:

step S1: soaking the silicon carbide fiber in an acetone solution for 2 hours, taking out and cleaning the silicon carbide fiber by using distilled water;

step S2: putting the silicon carbide fiber into a drying oven, and drying at 100 ℃ for 2 hours;

step S3: plating an iron film with the thickness of 3-5nm on the dried silicon carbide fiber by adopting a chemical vapor deposition method;

step S4: heating the asphalt to 160 ℃, doping the coated silicon carbide fiber into the asphalt, and fully stirring by using a high-speed shearing instrument to obtain modified asphalt;

step S5: putting the cleaned aggregate into a drying oven, and drying at 105 +/-5 ℃ to constant weight;

step S6: proportioning according to a grading design, then putting the proportioned aggregate into an oven, and heating to 170 ℃;

step S7: heating the stirring pot to 163 ℃, then placing the heated aggregate in the stirring pot, and stirring for 90 s;

step S8: pouring the modified asphalt into a stirring pot, and stirring for 90 s;

step S9: putting the mineral powder into an oven, heating to 170 ℃, then pouring the heated mineral powder into a stirring pot for stirring until the mineral powder is uniformly mixed, and keeping the asphalt mixture in a required mixing range;

step S10: and (3) putting the mould into an oven, heating to 105 ℃, filling the mixed asphalt mixture into the mould at the temperature of 145 ℃, compacting and demoulding according to the technical specification requirement to prepare the silicon carbide modified asphalt concrete.

Further, the length of the silicon carbide fiber is 1-3 mm.

Further, in the step S3, the CVD method uses carbonyl iron as the coating material, the carbonyl iron is heated to 155 ℃ at a heating rate of 15-20 ℃/min, Ar gas is used as the carrier gas, and the flow rate of the carrier gas is 300sccm to perform coating.

Furthermore, AH-70 asphalt is adopted as the asphalt, and the mass ratio of the asphalt to the aggregate is 5%.

Further, in step S4, the silicon carbide fiber after coating is blended according to 1-5% of the mass of the asphalt.

Furthermore, the aggregate is limestone, and the particle size of 11-16 mm accounts for 23.2% of the total mass of the mineral aggregate, the particle size of 5-11 mm accounts for 25% of the total mass of the mineral aggregate, and the particle size of 0-5 mm accounts for 47% of the total mass of the mineral aggregate.

Furthermore, the mineral powder is limestone, and accounts for 4.8% of the total mass of the mineral aggregate.

The invention has the beneficial effects that: according to the invention, the wave absorbing performance of the silicon carbide fiber under the microwave action is fully combined, the asphalt concrete with the microwave absorbing performance is prepared, the heating effect and the heating rate of the asphalt concrete are obviously improved, and meanwhile, the strength of the asphalt concrete is also improved; the preparation method is simple in process and safe to operate, only a microwave heating vehicle is needed to heat the original pavement during pavement repair, the pavement repair efficiency is high, the repair effect is obvious, and time and labor are saved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a flow chart of the preparation of silicon carbide modified asphalt concrete;

FIG. 2 is a schematic representation of a silicon carbide modified asphalt concrete grading curve;

FIGS. 3a-b are schematic diagrams illustrating the analysis of dielectric loss and magnetic loss, respectively, of a silicon carbide fiber after coating;

FIG. 4 is a schematic representation of the reflection loss analysis of silicon carbide fibers after coating;

FIG. 5 is a schematic diagram showing the temperature change of asphalt concrete with different silicon carbide contents under microwave heating;

FIG. 6 is a graph showing the temperature rise rate of asphalt concrete with different silicon carbide contents under microwave heating;

fig. 7 is a schematic view of the infrared thermal imager radiation under microwave heating.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.