CN112897937B - A kind of composite modified cold patch asphalt mixture and preparation method thereof - Google Patents

Abstract

The invention discloses a composite modified cold patch asphalt mixture and its preparation method. 3.5-7%, waste tire rubber powder 1-3%, swelling agent 3-9%, diluent 15-20%; mineral materials include: diabase, limestone and basalt mineral powder. The compound modified asphalt is obtained by pre-swelling rubber powder, pre-processing rubber powder; shearing and curing; diluting to obtain cold patching asphalt, and then mixing with ore to obtain cold patching asphalt mixture. The cold patched asphalt mixture of the invention not only has high initial and forming strength and water resistance, but also has certain high temperature stability, short forming time and balanced high and low temperature performance. The cold feed material has strong adaptability to the environment and can meet all-weather construction requirements. The molding time is short and the molding strength is high, which can meet the requirements of rapid opening of traffic after pothole repair.

Description

A kind of composite modified cold patch asphalt mixture and preparation method thereof

technical field

The invention relates to the technical field of road pothole repair, in particular to a composite modified cold patch asphalt mixture and a preparation method thereof.

Background technique

Potholes are one of the common road diseases. If they are not dealt with in time, there will often be a "domino" effect, causing large-scale damage to the road surface of the corresponding road section, which seriously affects the driving safety and the stability of the overall structure of the road surface. Therefore, pit repairing technology, as the most common daily maintenance work in the maintenance department, has been widely valued by the industry both in foreign countries and in China. The traditional pit repair mainly adopts the hot mix asphalt repair method, which has the advantages of mature preparation technology and excellent material properties. It is difficult to meet the requirements of all-weather construction with the repairing technology of feeding pits. In addition, the locations of road potholes are mostly scattered and small in area, which leads to increased construction cost of repairing with hot mix and poor economic benefits. To sum up, it is often difficult to repair the potholes in the pavement in time, which in turn induces other pavement diseases and seriously affects the service life of the pavement.

Cold patch asphalt mixture is an asphalt mixture that is pre-heated, mixed and stored and can be used at room temperature. The cold patching asphalt mixture has low construction cost, does not require large-scale supporting equipment, can be used in cold areas and rainy seasons, and is not restricted by the construction environment. And other issues. However, there are also some problems with the cold patch itself, the most prominent of which is that the material properties are worse than that of the hot patch. At present, the method of adding modifiers to the patch is mainly used to develop high-performance modified asphalt for pit repair. The mixture, by this method, has stronger water stability, low temperature resistance and good cohesion.

CN107805300A (application publication date March 16, 2018) patented an environmentally friendly solvent, cold feed and its preparation method. The solvent is obtained from animal fat or vegetable fat and polyol through a catalytic reaction of a catalyst, using high-efficiency shearing Asphalt cold rehydration is prepared by cutting method.

CN103193417A (application publication date July 10, 2013) patent invented a kind of urea-formaldehyde-based asphalt pavement rapid cold repair material, the material is based on urea-formaldehyde resin, by adding formaldehyde absorber, compound modifier, curing agent and other additives Modified asphalt was synthesized, and a pavement cold repair material was prepared based on the modified asphalt.

CN110317003A (application publication date October 11, 2019) patented a kind of saturated hydrocarbon and styrene-butadiene liquid rubber compound modified asphalt cold patch material and its preparation method, the material through the saturated hydrocarbon and styrene-butadiene liquid rubber to 70# petroleum Asphalt is compound modified, and surfactant is added to further catalyze the performance of the modifier. This material has good adhesion to asphalt concrete, cement concrete, metal and wooden pavement.

CN106751976A (application publication date May 31, 2017) patent invented a road cold feed material and its preparation method, the modifier selected for the cold feed material is acrylate. This road cold patch is aimed at pothole repairs in low temperature environments.

The above invention mainly improves the low temperature performance, strength and water resistance of cold patched asphalt mixture, but ignores that cold patched asphalt mixture should have higher initial strength, shorter molding time and certain high temperature stability. The problem of secondary damage of repaired pits and grooves still exists in practical projects, which seriously affects the service life of cold feeding materials and hinders the popularization and application of cold feeding materials in practical projects.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned defects in the prior art, the purpose of the present invention is to provide a composite modified cold patch asphalt mixture and a preparation method thereof. The cold patch asphalt mixture not only has high initial and forming strength, water resistance, At the same time, it has certain high temperature stability and balanced high and low temperature performance. The cold feed material has strong adaptability to the environment and can meet all-weather construction requirements. The molding time is short and the molding strength is high, which can meet the requirements of rapid opening of traffic after pothole repair.

The present invention is achieved through the following technical solutions.

The invention provides a composite modified cold patch asphalt mixture, comprising the following mixture ratio of cold patch asphalt raw materials and mineral materials according to the mass ratio of 1:19:

The cold patch asphalt includes: asphalt 70-75%, polyurethane 3.5-7%, waste tire rubber powder 1-3%, swelling agent 3-9%, diluent 15-20%;

Mineral materials include: diabase, limestone and basalt ore fines.

For the above-mentioned technical scheme, the present invention also has a further preferred scheme:

Preferably, the asphalt is matrix asphalt.

Preferably, the swelling agent is diesel oil or kerosene.

Preferably, the diluent is one or more mixtures of kerosene, diesel and gasoline.

Preferably, the mineral material includes diabase with a particle size of 9.5-13.2 mm, limestone with a particle size of 0.075-4.75 mm, and basalt ore powder with a particle size of less than 0.075 mm.

Preferably, the diabase accounts for 5.6-17.6% of the mineral material; limestone accounts for 1.4-30.2% of the mineral material; and basalt powder accounts for 4% of the mineral material.

The present invention further provides a preparation method of composite modified cold patch asphalt mixture, comprising the following steps:

A. Pre-swell 1-3% waste tire rubber powder and 3-9% swelling agent in a ratio of 1:3-1:4 according to the mass ratio to obtain pre-swollen rubber powder;

B. heating the pre-swollen rubber powder obtained in the step A, stirring at a shearing speed to prepare the pre-treated rubber powder;

C. adding the pretreated rubber powder obtained in step B to 70-75% base asphalt at 120-130°C, raising the temperature to 170-185°C, and shearing;

D. Then stop the heating, maintain the temperature between 130 and 135 ° C, add 3.5 to 7% of polyurethane, shear at a shear rate, and cure in an oven to obtain a composite modified asphalt;

E. The cured composite modified asphalt is cooled to below 65°C, 15-20% of diluent is added to the composite modified asphalt, and the cold patched asphalt is prepared after stirring evenly;

F. Mix the cold patch asphalt and mineral aggregate prepared in step D at a mass ratio of 1:19 for 120-240s to obtain a cold patch asphalt mixture.

Preferably, in the step A, pre-swelling is performed at 60-80° C. for 3-5 hours;

In the step B, the pre-swollen rubber powder is heated to 220-260° C. and stirred at a shearing speed of 300-500 rpm for 0.3-0.5 h.

Preferably, in step C, the temperature is raised to 170-185° C. within 3-5 min, and sheared at a shear rate of 4000-5000 rpm for 0.5-1 h.

Preferably, in step D, shearing is performed at a shear rate of 2000-3000 rpm for 0.3-0.5 h, and finally placed in an oven at 80-100° C. for 2-3 h.

The present invention has the following beneficial effects due to taking the above technical solutions:

The invention makes full use of the good high-temperature performance of the waste tire rubber powder and the excellent low-temperature performance and strength of the polyurethane. The two are added to the 70# matrix asphalt by a high-speed shearing instrument, and the composite modification is carried out. asphalt. The diluent is then added to the composite modified asphalt to obtain the parent cold patch asphalt. Then, the ore powder content is used as the control index to optimize the grading of the ore material, and finally the cold patch asphalt and the ore aggregate are fully mixed to obtain a cold patch asphalt mixture with excellent performance.

Since the selected polyurethane is a moisture-curing material, it can be cured within 0.5 to 1 hour in contact with air at room temperature. Therefore, the cold patching asphalt with polyurethane has a shorter curing time than the cold patching asphalt without polyurethane, which can meet the requirements of fast curing. The need for open traffic. Waste tire rubber powder has a huge output in my country, low price, low carbon and environmental protection. When it is used in modified asphalt, it has excellent high temperature performance, good viscosity, and also has the advantages of water resistance and noise reduction. The two composite modified asphalts take into account the advantages of both and make up for the unbalanced high and low temperature performance caused by single modification, and improve the road performance of the cold patch asphalt mixture.

When the rubber powder is in contact with the asphalt, it will absorb the light components in the asphalt to make the two melt. If the amount is too large, some rubber powder will not be able to be mixed with the asphalt, but will be dispersed in the asphalt with obvious rubber particles. The moduli of the two are different, and a large strain will be generated in the tensile direction when tensioned at low temperature, so stress concentration occurs at the interface between the two, which weakens the cohesive force between the asphalts, which reflects the reduction of the macroscopic properties of the asphalt, that is, the ductility. By pre-processing the rubber powder, the invention increases the content of the rubber powder in the asphalt, avoids the problem that some of the rubber powder and the asphalt cannot be mixed due to an excessively large content, thereby better exerting the modification effect.

The initial strength of the prepared composite modified cold patch asphalt mixture is not less than 5KN, the forming strength is not less than 9KN, the dynamic stability at 40°C is not less than 2600 times/mm, and the dynamic stability at 60°C is not less than 1400 times/mm , the tensile strain at failure is not less than 2100με, the residual stability of water immersion is not less than 70%, the mass loss rate is not more than 12%, and the time to reach the theoretical forming strength is not more than 5d.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention and constitute a part of this application, and do not constitute an improper limitation of the present invention. In the accompanying drawings:

Fig. 1 is the sectional view of the rubber powder modified asphalt ductility die without pre-swelling;

Figure 2 is a sectional view of the pre-swelled rubber powder modified asphalt ductility die.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The exemplary embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

The preparation method of composite modified cold patch asphalt mixture of the present invention comprises the following steps:

A. First, pre-swell 1-3% waste tire rubber powder and 3-9% swelling agent at a ratio of 1:3 at 60-80°C for 3-5 hours to obtain pre-swollen rubber powder;

B. The pre-swollen rubber powder obtained in step A is heated to 220～260 ℃, and the pretreated rubber powder is prepared by stirring at a shear speed of 300～500rpm for 0.3～0.5h;

C. The pretreated rubber powder obtained in step B is added to the 70-75% 70# base asphalt at 120-130°C, the temperature is raised to 170-185°C within 3-5min, and a high-speed shearing instrument is used to Shear at a shear rate of 4000-5000rpm for 0.5-1h;

D. Then stop heating, maintain the temperature between 130-135°C, add 3.5-7% polyurethane (PU), shear at a shear rate of 2000-3000rpm for 0.3-0.5h, and finally put in 80-100°C After curing in the oven for 2 to 3 hours, the composite modified asphalt is obtained, as shown in Figure 2;

E. The cured composite modified asphalt is cooled to below 65°C, 14-20% diluent is added to the composite modified asphalt, and the cold patched asphalt is prepared after stirring evenly;

F. The cold patched asphalt prepared in step D is graded with the mineral aggregates in Table 1, and mixed with a mass ratio of 1:19 for 120-240s to obtain a cold patched asphalt mixture.

A specific example is given below to further illustrate the preparation method of the present invention, wherein the shear temperature, shear rate, curing time and curing temperature of each embodiment are unchanged.

Example 1

A. First, pre-swell 2% of waste tire rubber powder and 6% of swelling agent at a ratio of 1:3 at 80°C for 4 hours to obtain pre-swollen rubber powder;

B. The pre-swollen rubber powder obtained in step A is heated to 260 ° C, and the pre-treated rubber powder is prepared by stirring at a shear rate of 300 rpm for 0.4 h;

C. Add the pretreated rubber powder obtained in step B to the 70% 70# base asphalt at 120°C, raise the temperature to 170-185°C within 3-5min, use a high-speed shearing instrument, at 4000-5000rpm The shear rate shearing 0.5 ~ 1h;

D. Then stop heating, maintain the temperature between 130-135°C, add 7% polyurethane (PU), shear at a shear rate of 2000-3000rpm for 0.3-0.5h, and finally put it into an oven at 80-100°C Preserving for 2-3 hours to obtain composite modified asphalt;

E. The cured composite modified asphalt is cooled to below 65°C, 15% thinner is added to the composite modified asphalt, and the cold patched asphalt is prepared after stirring evenly;

F. The cold patched asphalt prepared in step D is graded with the mineral aggregates in Table 1, and mixed with a mass ratio of 1:19 for 120-240s to obtain a cold patched asphalt mixture.

Example 2

A. First, pre-swell 3% waste tire rubber powder and 9% swelling agent at a ratio of 1:3 at 70°C for 5 hours to obtain pre-swollen rubber powder;

B. The pre-swollen rubber powder obtained in step A is heated to 240 ° C, and the pre-treated rubber powder is prepared by stirring at a shear rate of 500 rpm for 0.5 h;

C. Add the pretreated rubber powder obtained in step B to the 70% 70# base asphalt at 125°C, raise the temperature to 170-185°C within 3-5min, and use a high-speed shearing instrument at 4000-5000rpm The shear rate shearing 0.5 ~ 1h;

D. Then stop heating, maintain the temperature between 130-135°C, add 4% polyurethane (PU), shear at a shear rate of 2000-3000rpm for 0.3-0.5h, and finally put it into an oven at 80-100°C Preserving for 2-3 hours to obtain composite modified asphalt;

E. The cured composite modified asphalt is cooled to below 65°C, 14% thinner is added to the composite modified asphalt, and the cold patched asphalt is prepared after stirring evenly;

F. The cold patched asphalt prepared in step D is graded with the mineral aggregates in Table 1, and mixed with a mass ratio of 1:19 for 120-240s to obtain a cold patched asphalt mixture.

Example 3

A. First, pre-swell 1% of waste tire rubber powder and 4% of swelling agent at a ratio of 1:3 at 80 °C for 3 hours to obtain pre-swollen rubber powder;

B. The pre-swollen rubber powder obtained in step A is heated to 220 ° C, and the pre-treated rubber powder is prepared by stirring at a shear rate of 400 rpm for 0.3 h;

C. Add the pretreated rubber powder obtained in step B to the 75% 70# base asphalt at 130°C, raise the temperature to 170-185°C within 3-5min, and use a high-speed shearing instrument at 4000-5000rpm The shear rate shearing 0.5 ~ 1h;

D. Then stop heating, maintain the temperature between 130-135°C, add 3.5% polyurethane (PU), shear at a shear rate of 2000-3000rpm for 0.3-0.5h, and finally put it into an oven at 80-100°C Preserving for 2-3 hours to obtain composite modified asphalt;

E. The cured composite modified asphalt is cooled to below 65°C, 16.5% diluent is added to the composite modified asphalt, and the cold patched asphalt is prepared after stirring evenly;

F. The cold patched asphalt prepared in step D is graded with the mineral aggregates in Table 1, and mixed with a mass ratio of 1:19 for 120-240s to obtain a cold patched asphalt mixture.

Example 4

A. First, pre-swell 1% waste tire rubber powder and 3% swelling agent at a ratio of 1:3 at 70°C for 3.5 hours to obtain pre-swollen rubber powder;

B. The pre-swollen rubber powder obtained in step A is heated to 250 ° C, and the pre-treated rubber powder is prepared by stirring at a shear rate of 350 rpm for 0.5 h;

C. Add the pretreated rubber powder obtained in step B to the 72.5% 70# base asphalt at 125°C, raise the temperature to 170-185°C within 3-5min, and use a high-speed shearing instrument at 4000-5000rpm The shear rate shearing 0.5 ~ 1h;

D. Then stop heating, maintain the temperature between 130-135°C, add 3.5% polyurethane (PU), shear at a shear rate of 2000-3000rpm for 0.3-0.5h, and finally put it into an oven at 80-100°C Preserving for 2-3 hours to obtain composite modified asphalt;

E. The cured composite modified asphalt is cooled to below 65°C, 20% thinner is added to the composite modified asphalt, and the cold patched asphalt is prepared after stirring evenly;

F. The cold patched asphalt prepared in step D is graded with the mineral aggregates in Table 1, and mixed with a mass ratio of 1:19 for 120-240s to obtain a cold patched asphalt mixture.

The mineral composition is shown in Table 1.

Table 1 Cold patch asphalt mixture gradation

The performance comparison between the comparative example and the embodiment of the present invention is given below to further illustrate the effect of the present invention.

Comparative example: Two kinds of commercial cold patch asphalt mixtures with high sales volume were randomly selected.

Because there is no clear specification for cold patch asphalt mixture in my country, referring to research methods at home and abroad, the following common road performances are selected as evaluation indicators. The performance test results of the embodiment and the comparative example are shown in Table 2.

Table 2 Performance comparison

Note: The test method for initial strength and forming strength is Marshall stability test, and Marshall stability is used to express the strength.

The high temperature performance test method is the rutting test, and the high temperature performance is expressed by the dynamic stability.

The low temperature performance test method is low temperature splitting test, and the low temperature performance is characterized by the tensile strain at failure.

The water stability test method is the water immersion Marshall test, and the water stability test is characterized by the water immersion residual stability.

The cohesion test method is the cohesion test, and the cohesion is characterized by the mass loss rate.

It can be seen from Table 2 that the initial strength of the four examples is not less than 5KN, the forming strength is not less than 9KN, the dynamic stability at 40°C is not less than 2600 times/mm, and the dynamic stability at 60°C is not less than 1400 times/mm , the tensile strain at failure is not less than 2100με, the residual stability of water immersion is not less than 70%, the mass loss rate is not more than 12%, and the time to reach the theoretical forming strength is not more than 5d. Compared with the two commercial cold patch asphalt mixtures, the composite modified cold patch asphalt mixture prepared by the invention has excellent performance.

It can be seen from Figure 1 and Figure 2 that the two kinds of rubber powder have different compatibility with asphalt under the same dosage. The pretreated rubber powder can increase the amount of rubber powder in the asphalt, so as to better exert the modification effect.

The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solutions disclosed in the present invention, those skilled in the art can make some substitutions and modifications to some of the technical features according to the disclosed technical contents without creative work. Modifications, replacements and modifications are all within the protection scope of the present invention.

Claims (7)

1. a preparation method of composite modified cold patch asphalt mixture, is characterized in that, comprises the following steps: A. Pre-swell 1-3% waste tire rubber powder and 3-9% swelling agent in a ratio of 1:3-1:4 according to the mass ratio to obtain pre-swollen rubber powder; B. heating the pre-swollen rubber powder obtained in the step A, stirring at a shearing speed to prepare the pre-treated rubber powder; C. adding the pretreated rubber powder obtained in step B to 70-75% base asphalt at 120-130°C, raising the temperature to 170-185°C, and shearing; D. Then stop the heating, maintain the temperature between 130 and 135 ° C, add 3.5 to 7% polyurethane, shear at a shear rate, and cure in an oven to obtain a composite modified asphalt; E. The cured composite modified asphalt is cooled to below 65°C, 15-20% diluent is added to the composite modified asphalt, and the cold patched asphalt is prepared after stirring evenly; F. the cold patch asphalt and mineral aggregate prepared in the step D are mixed with a mass ratio of 1:19 to obtain a cold patch asphalt mixture; Mixing the cold patching asphalt raw material and the mineral material according to the mass ratio of 1:19 to obtain the composite modified cold patching asphalt mixture; Described swelling agent is diesel oil or kerosene; The diluent is one or more mixtures of kerosene, diesel and gasoline; The mineral material includes diabase with a particle size of 9.5-13.2 mm, limestone with a particle size of 0.075-4.75 mm, and basalt ore powder with a particle size of less than 0.075 mm; The initial strength is not less than 5KN, the forming strength is not less than 9KN, the dynamic stability at 40°C is not less than 2600 times/mm, the dynamic stability at 60°C is not less than 1400 times/mm, the tensile strain at failure is not less than 2100με, water immersion The residual stability is not less than 70%, the mass loss rate is not more than 12%, and the time to reach the theoretical forming strength is not more than 5d. 2 . The method for preparing a composite modified cold patch asphalt mixture according to claim 1 , wherein the asphalt is matrix asphalt. 3 . 3. the preparation method of a kind of composite modified cold patch asphalt mixture according to claim 1, is characterized in that, described diabase accounts for 5.6～17.6% of mineral material material; limestone accounts for 1.4～30.2% of mineral material material ; Basalt ore powder accounts for 4% of the mineral material. 4 . The preparation method of composite modified cold patch asphalt mixture according to claim 1 , wherein, in the step A, pre-swelling is performed at 60-80° C. for 3-5 hours; 5 . In the step B, the pre-swollen rubber powder is heated to 220-260° C. and stirred at a shearing speed of 300-500 rpm for 0.3-0.5 h. 5 . The preparation method of composite modified cold patch asphalt mixture according to claim 1 , wherein in step C, the temperature is raised to 170-185° C. within 3-5 min, and the shearing speed is 4000-5000 rpm. The shear rate shears 0.5～1h. 6. The preparation method of composite modified cold patch asphalt mixture according to claim 1, characterized in that, in step D, shearing at a shear rate of 2000-3000rpm for 0.3-0.5h, and finally putting in 80-100 Incubate in an oven at ℃ for 2 to 3 hours. 7. A composite modified cold patch asphalt mixture prepared by the method of any one of claims 1-6.

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