CN1807514A - Method for preparing modified asphalt mixture using waste and old tyre and hybrid method - Google Patents

Abstract

This invention relates to the field of engineering material technical, and it is specificly related to the method for preparing a kind of modified bituminous mixture with worn tyre. It is made as follows: mill worn tyre to powder, mix the owder with base bitumen and agitate to get rubber bitumen; gap-graded aggregate, screen the aggregates and get coarse, fine aggregates; mix rubber particles with the coarse and fine aggregates, agitate, then add rubber bitumen and agitate, lastly add powdered ore and mix to get needed production. This invention blends dry and wet processes together to exert each advantage sufficiently, and attained both the aims of consumping much worn tyre and improve pavement performance. With this invention, we can greatly improve high and low temperature behavior of bitumen and its mixture, we can longer pavement life and abate environmental pollution. The pavement paved by this mixture has the behavior of lowering traffic noise. Popularization of this achievement is economic, society, environmental and engineering benefit.

Description

Method for preparing modified asphalt mixture by using waste tires by mixing method

technical field

The invention belongs to the technical field of road engineering materials, and in particular relates to a method for preparing modified asphalt mixture by using waste tires through a mixing method.

Background technique

With the rapid development of my country's automobile industry and the improvement of people's living standards, the number of automobiles has increased rapidly year by year, and our country will face the problem of dealing with a large number of waste tires. According to statistics, the number of waste tires in my country reached 80 million in 2002, increasing at an annual rate of 12%. By 2005, it will reach 120 million. Such large-scale waste tires will bring huge environmental pressure to society. Therefore, it is imminent to find a way out for waste tires.

At present, the main ways to dispose of waste tires in the world are stacking (or landfill), burning and recycling. Among them, the application of waste rubber powder in road construction has become the focus of research and application in all countries in the world, and it is also the best choice for a large number of waste tires. The technologies for applying waste rubber powder to asphalt pavement are mainly divided into two categories: wet method and dry method, both of which have their own advantages and disadvantages. Although the dry process has obvious advantages in rubber particle size, rubber dosage and mixing equipment, most of the research in the world focuses on the wet process. The main reason is that the performance of the test road paved by the dry process is unstable. , while the wet process has obtained more satisfactory performance.

According to the patent novelty search, there is no report on the method of preparing asphalt mixture by using dry and wet mixing methods at home and abroad at present.

Contents of the invention

The object of the present invention is to propose a method for preparing modified asphalt mixture by using waste tires and using a mixing method, which can dispose of waste tire rubber in large quantities, improve road performance and reduce road traffic noise.

The method that the present invention proposes utilizes waste tire to adopt mixing method to prepare modified asphalt mixture, and its specific steps are as follows:

(1) Preparation of rubber asphalt:

Pulverize and grind waste tires at room temperature to obtain 60-80 mesh fine rubber powder, mix and stir the fine rubber powder with matrix asphalt to obtain rubber asphalt; the mixing time is 45-75 minutes, and the temperature is controlled at 185-195°C , the addition of fine rubber powder is 10-20% of the mass of base asphalt;

(2) Screening of aggregates:

Using broken grading aggregates, the aggregates are screened, and when the aperture of the sieve is 0.075-2.36mm, fine aggregate is obtained; when the aperture of the sieve is 4.75-16mm, coarse aggregate is obtained;

(3) Mixing of rubber particles and aggregate mixture:

When mixing at the construction site, mix the rubber particles of 1-3mm with the coarse aggregate and fine aggregate obtained in step (2), the dry mixing time is 8-12 seconds, and the temperature is controlled at 175-185°C. The amount of particles added is 2.0-2.5% of the total mass of coarse and fine aggregates;

When mixing in the laboratory, mix the rubber particles of 1-3mm with the coarse aggregate and fine aggregate obtained in step (2), the dry mixing time is 8-12 seconds, the temperature is controlled at 170-180°C, the rubber The amount of particles added is 2.0-2.5% of the total mass of coarse and fine aggregates;

(4) Preparation of rubber modified asphalt mixture:

Add the rubber asphalt obtained in step (1) to the construction site product obtained in step (3) for mixing, the mixing time is 15-20 seconds, and the mixing temperature is 170-180 ° C, then add mineral powder and mix, The mixing time is 20-25 seconds, and the mixing temperature is 170-180°C to obtain the desired product;

Add the rubber asphalt obtained in step (1) to the laboratory product obtained in step (3) for mixing, the mixing time is 50-75 seconds, the mixing temperature is 160-170 °C, and then add mineral powder and mix , the mixing time is 50-75 seconds, and the mixing temperature is 160-170°C to obtain the desired product;

Wherein, the addition amount of rubber asphalt is 6.2-6.8% of the total mass of coarse and fine aggregates, and the addition amount of mineral powder is 8-12% of the total mass of coarse and fine aggregates.

In the present invention, the stirring method described in step (1) can adopt one of high-speed shearing device stirring or other mechanical stirring devices.

In the present invention, the high-speed shearing device refers to placing the base asphalt in a kettle and heating it to 185-195°C, inserting the high-speed shearing device into the asphalt and starting it, and controlling the speed at 1000-3000 revolutions per minute to reduce the quality of the asphalt 10-20% fine rubber powder is slowly added to the asphalt, if necessary, an appropriate amount of additives can be added, and the rubber asphalt is prepared after stirring for about 60 minutes.

In the present invention, the mechanical stirring device is a stirring head similar to an electric fan (the length of the blade is about 20 cm), which is driven by a motor and can rotate in both positive and negative directions. Put the base asphalt in a kettle and heat it to 185-195°C, insert the mechanical stirring device into the asphalt and start it, the speed is controlled at 1000-2000 rpm, and slowly add 10-20% fine rubber powder into the asphalt , if necessary, add an appropriate amount of additives, stir for about 60 minutes, and the rubber asphalt is prepared.

In the present invention, among the aggregates, the coarse aggregate can be rolled by one of the hard rocks such as diabase, basalt, andesite, and the particle shape should be nearly cubic, and the needle flake content should not exceed 10 %; Fine aggregates can be made of alkaline rocks, such as limestone and dolomite rolled gravel.

In the present invention, the mineral powder is finely ground limestone or dolomite, and the content of particles smaller than 0.075mm should be greater than 80%.

In the present invention, additives may be added in step (1).

In the present invention, described additive can adopt one kind such as Vita coupling agent, sulfur, phenol disulfide, and dosage depends on variety, and wherein the addition of Vita coupling agent is 3-5% of rubber powder quality, sulfur, sulfur, The amount of phenol disulfide added is 0.8-1.2% of the rubber powder mass.

The rubber asphalt mixture obtained in the present invention is used for paving road surfaces.

The modified asphalt mixture prepared by the method of the present invention can be tested by double-sided compaction with a Marshall instrument, that is, a sample is compacted 75 times on both sides with a Marshall instrument, and the compaction temperature is controlled at 140-150°C.

In the present invention, the asphalt mixture adopts specially designed broken-graded aggregates, and the passing rate of the 2.36mm and 4.75mm sieve holes is adjusted according to the amount of coarse and fine waste tire rubber powder and the design porosity of the asphalt mixture . The mix ratio design of the mixture adopts the Marshall method, double-sided compaction is 75 times, and the oil-stone ratio (OAC) is mainly determined according to the void ratio of 4%.

The present invention proposes a method of combining the two processes (called a hybrid method) to give full play to their respective advantages and achieve the dual purposes of consuming a large amount of waste tires and improving road performance.

Research shows that the invention can greatly improve the high and low temperature performance of asphalt and asphalt mixture, prolong the service life of the road surface, and can process a large number of waste tires to reduce environmental pollution. The pavement paved with this mixture also has the effect of reducing road traffic noise. The popularization and application of the results has economic, social, environmental and engineering benefits.

Description of drawings

Fig. 1 is a schematic diagram of the modified asphalt mixture by the waste tire rubber mixing method of the present invention.

Figure 2 is a graph showing the relationship between the penetration of rubber asphalt and temperature.

Fig. 3 is the aggregate gradation curve diagram in embodiment 1.

Detailed ways

The present invention is further illustrated below by way of examples.

Example 1: Preparation of rubber-modified asphalt mixture at the construction site

(1) Preparation of rubber asphalt

The base asphalt is AH-70 asphalt, and its technical indicators are shown in Table 1. The fine rubber powder is crushed and ground from waste tires at room temperature to obtain 80-mesh fine rubber powder with a relative density of 1.15.

Table 1 Technical indicators of AH-70 asphalt index Relative Density(15℃) Penetration (25℃, 0.1mm) Softening point (℃) Ductility (15℃, cm) Test value specification value 1.029- 6960-80 49.5≥43 ＞150≥100

The AH-70 asphalt is heated to 190°C, the amount of fine rubber powder is determined to be 15% of the mass of the base asphalt, and the mixing temperature is controlled at 190°C-195°C. Use a high-speed shearing device to mix for 15 minutes, and the stirring speed is 1500 rpm, so that the fine rubber powder is evenly dispersed in the base asphalt, and then continue to stir for 45 minutes, so that the fine rubber powder and the base asphalt can fully react at high temperature, reaching Desired binder properties. Table 2 is the performance index test results of 80 mesh rubber asphalt,

Table 2 Test results of performance indicators of 80 mesh rubber asphalt index Penetration (0.1mm) Viscosity (Pa·s) Softening point (℃) Elastic recovery (25℃, %) test value 15℃20 25°C47 30℃66 120℃6.1 135°C 2.7 150℃1.3 60 68

It can be seen from Table 2 that the softening point of rubber asphalt is 10.5°C higher than that of base asphalt, indicating that the addition of fine rubber powder can significantly improve the high temperature performance of base asphalt. From the relationship curve between penetration P and temperature T in Figure 2, it can be seen that the slope of rubber asphalt (ie, penetration sensitivity coefficient A) is smaller than that of base asphalt, which means that rubber asphalt is less sensitive to temperature changes, and its temperature Good stability.

(2) Aggregate screening configuration

The mixture adopts a dense structure with broken gradation skeleton. In order to avoid the interference of rubber particles on the coarse aggregate skeleton, the 2.36-4.75mm aggregate is completely interrupted to provide enough space for rubber particles. The determined aggregate synthesis grading curve is shown in Figure 3. Diabase is used as the coarse aggregate, and the physical indexes of the stone are listed in Table 3, all of which meet the requirements of construction technical specifications. The nominal maximum particle size of the aggregate is 13.2mm. For example, based on 1000kg of aggregate, the particle sizes of coarse aggregate are 16mm, 13.2mm, 9.5mm, and 4.75mm respectively. 40 kg of coarse aggregate with a particle size of 13.2-16mm, 290 kg of coarse aggregate with a particle size of 9.5-13.2mm, 410 kg of coarse aggregate with a particle size of 4.75-9.5mm, and a particle size of 2.36-4.75mm The coarse aggregate is 0 kg; the fine aggregate is limestone, and the particle diameters of the fine aggregate are 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm, 0.075mm, and the particle diameter is 1.18-2.36mm. 70 kg, 20 kg of fine aggregate with a particle size of 0.6-1.18 mm, 20 kg of fine aggregate with a particle size of 0.3-0.6 mm, 20 kg of fine aggregate with a particle size of 0.15-0.3 mm, and a particle size of 0.075 -0.15mm fine aggregate is 20 kg; mineral powder is made of limestone or dolomite after grinding, and the amount of mineral powder added is 11%, which is 110 kg.

Table 3 Physical indicators of mineral materials Stone technical indicators test value Required value ^* Coarse Aggregate Fine Aggregate Mineral Powder Relative Apparent Density Relative Gross Bulk Density Crushing Value (%) Los Angeles Abrasion Rate (%) Needle-like Particle Content (%) Water Absorption (%) Relative Apparent Density Relative Apparent Density 2.7212.67611.210.880.72.7002.715 Not less than 2.50- not more than 26 not more than 28 not more than 10 not more than 2 not less than 2.50-

In the dry process, prepare 1-3mm rubber particles with a relative density of 1.13, and the dosage of the rubber particles is 2% of the total mass of the aggregate.

(3) Preparation of modified asphalt mixture by waste rubber mixing method

Add 1-3mm rubber particles into the mixing tank and mix with coarse aggregate and fine aggregate. The dry mixing time is 8-12 seconds, and the temperature is controlled at 175-185°C. Then add rubber-modified asphalt, wet mix for 15-20 seconds, add mineral powder and continue mixing for 20-25 seconds. Loading and transporting the material to the construction site for paving.

(4) Sampling is carried out in the laboratory, and the Marshall method test is carried out. Double-sided compaction is performed 75 times, and the compaction temperature is controlled at 140-150°C. The molded specimens were subjected to Marshall and other related tests. Table 4 is the laboratory Marshall test results.

Table 4 Marshall test test results craft technical indicators Porosity/% VMA/% VFA/% Stability/KN Flow value/mm OAC/% hybrid approach 4.2 17.2 76 7.3 4.2 6.8

The performance of the waste tire rubber mixing method modified asphalt mixture mainly includes high temperature stability, low temperature crack resistance and water stability, which are evaluated by rutting test, low temperature split test and freeze-thaw split test respectively. The test results are shown in Table 5 .

Table 5 Performance test results of rubber asphalt mixture craft Dynamic stability/(times/mm) TSR/% Low temperature rupture stiffness modulus/MPa hybrid approach 4672 89 694

It can be seen from Table 5 that the dynamic stability of the asphalt mixture modified by the waste tire rubber mixing method is relatively high, indicating that it has good high temperature stability. The low temperature failure modulus of the mixing method is small, so the low temperature crack resistance of the asphalt mixture is very good. The water stability of the mixing method fully meets the requirements of the specification, which shows that the water stability of the modified asphalt mixture by the waste rubber mixing method is good.

Example 2: Preparation of rubber-modified asphalt mixture in the laboratory

The coarse aggregate that adopts in the present embodiment is basalt, and the Vita joint agent of 5% (the mass number of rubber powder) is mixed in the preparation process of rubber asphalt, all the other raw materials are identical with embodiment 1, and the adding of Vita joint agent promotes The rubber powder is chemically combined with the bitumen to reduce the precipitation of the rubber powder.

(1) Preparation of rubber asphalt

The dosage of fine rubber powder is 15% of the mass of asphalt, and the dosage of Vita coupling agent is 5% of the mass of rubber powder. The mixing temperature is controlled at 185°C-190°C. First use a high-speed shearing device to mix for 20 minutes, and the stirring speed is 3000 rpm, so that the fine rubber powder and Vita coupling agent are evenly dispersed in the base asphalt, and then continue to stir for 40 minutes to make them fully react at high temperature. to achieve the desired bond properties. Table 6 shows the performance index test results of 80 mesh rubber asphalt added with 5% Vita coupling agent.

Table 6 Performance indicators of 80 mesh rubber asphalt after adding Vita coupling agent index Penetration (25℃, 0.1mm) Viscosity (Pa·s) Softening point (℃) test value 46 120℃10.8 135°C4.3 150℃2.2 64.5

Compared with the rubber asphalt without Vita coupling agent in Example 1, the penetration does not change much, but the softening point and viscosity are considerably improved.

(2) Preparation of modified asphalt mixture by waste rubber mixing method

In the mixing method, the amount of rubber particles is still 2% of the total mass of the aggregate, and the nominal maximum particle size of the aggregate is 13.2 mm. The proportion of the aggregate used is listed in Table 7.

Table 7 Mixing ratio of aggregate materials Material 9.75-13.2mm gravel 4.75-9.5mm gravel 0-2.36mm stone chips mineral powder Proportion(%) 37 38 15 10

The mixing temperature in the laboratory is controlled at 170-180°C. In order to disperse the rubber particles evenly, the dry mixing time is 8-12 seconds, then add rubber asphalt for wet mixing for 1 minute, and finally add mineral powder and mix for 1 minute. The oil-stone ratio (OAC) is determined according to the porosity of 4%.

(3) Sampling performance test

The volume parameters of the mixture were determined by the Marshall method, and both sides were compacted 75 times. Table 8 is the laboratory test results.

Table 8 Marshall test test results craft technical indicators Porosity/% VMA/% VFA/% Stability/KN Flow value/mm OAC/% hybrid approach 4.0 17.4 77 7.9 4.0 6.8

Compared with the rubber asphalt without adding Vita coupling agent in Example 1, the Marshall stability is improved, the flow value is slightly decreased, and the OAC is not greatly affected.

The performance of the waste tire rubber mixing method modified asphalt mixture also includes high temperature stability, low temperature crack resistance and water stability, which are evaluated by rutting test, low temperature split test and freeze-thaw split test respectively. The test results are shown in Table 9 .

Table 9 Performance test results of rubber asphalt mixture craft Dynamic stability/(times/mm) TSR/% Low temperature rupture stiffness modulus/MPa hybrid approach 4805 90 702

It can be seen from Table 9 that the dynamic stability and TSR of the rubber asphalt mixture added with Vita coupling agent have increased, indicating that its high temperature stability and water stability have been further improved; the change of the low temperature failure stiffness modulus of the mixture It is very small, indicating that Vita coupling agent has little effect on the low temperature performance of rubber asphalt mixture.

Claims (9)

1, utilize junked tire to adopt hybrid system to prepare the method for modified asphalt mixture, it is characterized in that concrete steps are as follows:

(1) preparation rubber asphalt:

Junked tire pulverized at normal temperatures grind, obtain the thin rubber powder of 60-80 purpose, this thin rubber powder mixes, stirs with matrix pitch, obtains rubber asphalt; Mixing the system time is 45-75 minute, and temperature is controlled at 185-195 ℃, and the add-on of thin rubber powder is the 10-20% of matrix pitch quality;

The screening of (2) gathering materials:

The employing gap gradation gathers materials, and will gather materials and sieve, and when the aperture of sieve aperture is 0.075-2.36mm, obtains fine aggregate; When the aperture of sieve aperture is 4.75-16mm, obtain coarse aggregate;

(3) rubber grain and aggregate mix are mixed system:

When mixing system at the construction field (site), the coarse aggregate, the fine aggregate that obtain in rubber grain and the step (2) with 1-3mm mix, and the dry mixing time is 8-12 second, and temperature is controlled at 175-185 ℃, and the add-on of rubber grain is 2.0-2.5% thick, the fine aggregate total mass;

Or when mixing system in the laboratory, the coarse aggregate, the fine aggregate that obtain in rubber grain and the step (2) with 1-3mm mix, and the dry mixing time is 8-12 second, and temperature is controlled at 170-180 ℃, the add-on of rubber grain be slightly, the 2.0-2.5% of fine aggregate total mass;

(4) preparation of rubber modified asphalt compound:

Mix system with adding the rubber asphalt that obtains in the step (1) in the working-yard product that obtains in the step (3), mixing the system time is 15-20 second, and mixing the system temperature is 170-180 ℃, adding breeze then mixes and stirs, mixing time is 20-25 second, and mixing and stirring temperature is 170-180 ℃, obtains desired product;

Or mix system with adding the rubber asphalt that obtains in the step (1) in the laboratory product that obtains in the step (3), mixing the system time is 50-75 second, mixing the system temperature is 160-170 ℃, adding breeze then mixes and stirs, mixing time is 50-75 second, mixing and stirring temperature is 160-170 ℃, obtains desired product;

Wherein, the add-on of rubber asphalt is 6.2-6.8% thick, the fine aggregate total mass, and the breeze add-on is 8-12% thick, the fine aggregate total mass.

2, adopt hybrid system to prepare the method for modified asphalt mixture according to the described junked tire that utilizes of claim 1, it is characterized in that mixing described in the step (1) the system method and take a kind of of high-speed shearing device system of mixing or mechanical stirring device.

3, adopt hybrid system to prepare the method for modified asphalt mixture according to the described junked tire that utilizes of claim 2, it is characterized in that described high-speed shearing device refers to place a still to be heated to 185-195 ℃ matrix pitch, insert in the pitch high-speed shearing device and startup, rotating speed is controlled at 1000-3000 rev/min, and thin rubber powder is added in the pitch.

4, adopt hybrid system to prepare the method for modified asphalt mixture according to the described junked tire that utilizes of claim 2, it is characterized in that described mechanical stirring device refers to place a still to be heated to 185-195 ℃ matrix pitch, insert in the pitch mechanical stirring device and startup, rotating speed is controlled at 1000-2000 rev/min, and thin rubber powder is added in the pitch.

5, adopt hybrid system to prepare the method for modified asphalt mixture according to the described junked tire that utilizes of claim 1, it is characterized in that coarse aggregate adopts a kind of of diabase, basalt, andesite, particle shape is similar to cube, and faller gill shape content is lower than 10%; Fine aggregate adopts a kind of of limestone, dolomite.

6, adopt hybrid system to prepare the method for modified asphalt mixture according to the described junked tire that utilizes of claim 1, it is characterized in that described breeze adopts a kind of in the stone flour of being worn into by limestone or dolomite, its less than the 0.075mm granule content greater than 80%.

7, adopt hybrid system to prepare the method for modified asphalt mixture according to the described junked tire that utilizes of claim 1, it is characterized in that in step (1), adding additive.

8, adopt hybrid system to prepare the method for modified asphalt mixture according to the described junked tire that utilizes of claim 7, it is characterized in that he connects a kind of of agent, sulphur, phenol disulphide to described additive for dimension, tie up him and connect the 3-5% that the agent add-on is the rubber powder quality, sulphur, phenol disulphide add-on are respectively the 0.8-1.2% of rubber powder quality.

9, a kind ofly utilize junked tire to adopt hybrid system to prepare the rubber-asphalt mixture that rubber modified asphalt obtains according to claim 1 to be used for the making pavement of road.

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