Warm-mixed composite modified asphalt and preparation method thereof
Technical Field
The invention belongs to the technical field of road materials, and particularly relates to warm-mixed composite modified asphalt and a preparation method thereof.
Background
The low-temperature season time in the northwest region is long, the pavement task of the asphalt pavement needs to be completed within a set construction period, the construction of the asphalt mixture pavement needs to be performed in the low-temperature season, and the warm-mixed asphalt technology is one of effective ways for solving the low-temperature construction of the asphalt pavement.
Warm mix asphalt originated in europe and was first proposed by the international asphalt pavement society of the earliest 2000 years. According to the warm mixing mechanism of warm-mixed asphalt, the warm-mixed asphalt technology can be divided into the following four types: (1) organic additive method: adding a low-melting-point organic additive into the mixture, changing the viscosity-temperature characteristic of the asphalt from the chemical perspective, and mainly using synthetic wax and low-molecular-weight ester compounds, wherein representative products are Sasobit synthetic wax and HON warm-mixing modifier; (2) a foamed asphalt method: firstly, adding a soft cementing material with the temperature of 100-120 ℃ into an aggregate, stirring to achieve good coating, foaming an extremely hard cementing material, and then adding the foamed cementing material into the pre-coated aggregate, so that the soft cementing material and the foamed hard cementing material play a role in reducing the viscosity of the cementing material, and the construction temperature is reduced; (3) surfactant method: also called Evotherm technology, can be directly added into the asphalt mixture for mixing, and can also be used for preparing warm-mixed asphalt mixture by adopting modified asphalt. In addition, the artificial synthetic zeolite can be directly added into the mixture to enable the cementing material to generate a foaming effect, so that the mixing temperature of the asphalt mixture is reduced, and the warm mixing effect is achieved.
However, the common warm-mix asphalt is difficult to meet the increasing traffic load demand, so the research on the warm-mix composite modified asphalt has important social and economic values. The invention adopts a composite modification technology, utilizes different modifiers to carry out composite modification on different modification effects of high and low temperature performances of the asphalt, fully exerts respective characteristics and advantages, supplements the modifiers with each other, can simultaneously improve the high and low temperature performances of the asphalt cement, reduces the compaction temperature, reduces the compaction times, reduces the cost and simultaneously reduces the emission of pollutants.
Disclosure of Invention
The warm-mix composite modified asphalt has good temperature sensing performance, storage stability and high temperature performance, and the asphalt mixture of the invention needs low compaction temperature and few compaction times, reduces energy consumption, saves resources and increases the driving comfort and durability of the road surface.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
the warm-mix composite modified asphalt comprises the following components in parts by weight: 100 parts of matrix asphalt, 3-5 parts of modifier, 1-3 parts of warm mixing agent and 2-3 parts of stabilizer.
The invention has the further improvement that the matrix asphalt is any one of the matrix asphalt of the brocade 90# and the imported matrix asphalt of SK90# and the corresponding index meets the technical Specification for constructing the asphalt pavement of the highway.
The invention has the further improvement that the saturated fraction of the matrix asphalt of the Spiranthus nitens No. 90 is 16.3 percent, the aromatic fraction is 44.6 percent, the colloid content is 26.5 percent, and the asphaltene content is 12.4 percent; the inlet SK90# base asphalt has the saturation fraction of 21.4%, the aroma fraction of 36.8%, the colloid fraction of 41.9% and the asphaltene fraction of 5.8%.
The invention is further improved in that the modifier is any one or a mixture of more than two of styrene-butadiene-styrene block copolymer, styrene-butadiene rubber and ethylene-vinyl acetate copolymer, wherein the styrene-butadiene-styrene block copolymer is abbreviated as SBS, the styrene-butadiene rubber is abbreviated as SBR, and the ethylene-vinyl acetate copolymer is abbreviated as EVA.
The further improvement of the invention is that the SBS modifier has the particle length of less than 10mm, the molecular weight of 5000-16000 and the density of 0.94-1.13g/cm3;
The SBR modifier is white powder, the fineness of the powder is less than 40 meshes, and the molecular weight of the powder is 20-30;
the EVA modifier is a closed cell structure, the molecular weight is 1800-2200, and the density is 0.92-0.98g/cm3。
The invention further improves that the warm-mixing agent is any one of Sasobit, Evotherm and HON.
The invention has the further improvement that the Sasobit warm mixing agent is a powdery material, the average molecular weight is about 1100g/mol, and the melting point is higher than 90 ℃;
the Evotherm warm mixing agent is a dark yellow brown viscous liquid, the density is about 1.006, and the boiling point is about 98 ℃;
the HON warm mixing agent is white powder material with the density of about 0.5g/cm3The melting point is about 115 ℃.
A preparation method of warm-mixed composite modified asphalt comprises the following steps:
1) taking the following raw materials in parts by mass: 100 parts of asphalt, 3-5 parts of modifier, 1-3 parts of warm mixing agent and 2-3 parts of stabilizer for later use;
2) heating the matrix asphalt to 160-170 ℃, slowly adding the modifier, and shearing for 20 minutes by using a high-speed shearing machine, wherein the shearing speed is 4000 r/min;
3) stirring for 30 minutes by using a stirrer at the temperature of 150-160 ℃ to enable the mixture to swell; then continuously shearing for 20 minutes at the temperature of 170-180 ℃;
4) adjusting the temperature to 140-150 ℃, adding 2% of a stabilizer, and continuing shearing for ten minutes;
5) and finally, slowly adding a warm-mixing agent at the temperature of 150-160 ℃ and shearing at a low speed for 10 minutes to prepare the warm-mixing composite modified asphalt.
The invention has the following beneficial technical effects:
the warm-mixed composite modified asphalt provided by the invention has the following technical advantages:
(1) the molecular chain of the modifier can be broken under the action of strong external force of the shearing machine, a large amount of fragments can be generated along with the breaking process, the molecular weight is greatly reduced, and the particles of the modifier are dispersed more finely, so that the modifier can be better dissolved in the asphalt. Meanwhile, the surface of the broken modifier particles has strong surface acting force, so that light components in the asphalt can be adsorbed, the flow of asphalt molecules is restrained, and the high-temperature deformation resistance of the asphalt is improved.
(2) The warm-mixed composite modified asphalt reduces the viscosity of asphalt cement due to the melting of the modifier, thereby improving the compaction effect of the asphalt mixture under the low-temperature condition, simultaneously, the aging of the asphalt cement in the construction process is weakened due to the reduction of the construction temperature, and the warm-mixed composite modified asphalt has positive significance for prolonging the service life of the pavement.
(3) The warm-mixed composite modified asphalt can solve the problem that the asphalt mixture is difficult to compact due to too fast temperature loss in construction in a low-temperature environment, and can prolong the construction period of the asphalt mixture. And the compaction temperature is reduced, so that the compaction work is reduced, the energy consumption is reduced, and the resources are saved.
(4) The warm-mix composite modified asphalt modifier has good compatibility with the matrix asphalt, forms a stable space network structure inside, and is not easy to float upwards, so that the storage stability of the modified asphalt is improved.
(5) The whole preparation process of the warm-mixed composite modified asphalt does not need professional equipment, is simple and easy to operate, only needs to be operated according to the description of the invention, and greatly reduces various cost expenses.
The preparation method of the warm-mixed composite modified asphalt provided by the invention has the following technical advantages:
(1) the whole preparation process of the warm-mixed composite modified asphalt does not need special equipment, is simple and easy to operate, only needs to be operated according to the description of the invention, and greatly reduces various cost expenses.
(2) The warm-mixing agent with good compatibility with the asphalt and the SBS modifier is adopted in the preparation process of the warm-mixing composite modified asphalt, and the warm-mixing agent can be rapidly and uniformly dispersed in the asphalt, so that the shearing and development time is reduced, the energy consumption is reduced, and the smoke dust is reduced.
Detailed Description
The present invention will be further illustrated with reference to the following examples.
Example 1
Heating 100 parts of base asphalt to 170 ℃, slowly adding 3 parts of styrene-butadiene-styrene block copolymer (SBS) modifier, and shearing at a high speed of 4000r/min for 20 minutes; then stirring for 30 minutes at the temperature of 150 ℃ to swell the mixture; then continuing shearing at 170 ℃ for 20 minutes; adjusting the temperature to about 150 ℃, adding 2 parts of stabilizer, and continuing shearing for ten minutes; finally, 2 portions of Sasobit warm-mixing agent are added, stirred at a low speed of 160 ℃ until no obvious floating particles exist, and then sheared for ten minutes at a speed of 2000r/min, and the warm-mixing composite modified asphalt is obtained.
Example 2
Heating 100 parts of base asphalt to 170 ℃, slowly adding 4 parts of Styrene Butadiene Rubber (SBR) modifier, and shearing at a high speed of 4000r/min for 20 minutes; then stirring for 30 minutes at the temperature of 155 ℃ to swell the mixture; then shearing is continued for 20 minutes at 175 ℃; adjusting the temperature to about 140 ℃, adding 3 parts of stabilizer, and continuing shearing for ten minutes; finally, adding 1 part of Evotherm warm-mix agent, stirring at low speed at 150 ℃ until no obvious floating particles exist, and shearing at the speed of 2000r/min for ten minutes to obtain the warm-mix composite modified asphalt.
Example 3
Taking 100 parts of base asphalt, heating to 165 ℃, slowly adding 5 parts of SBS modifier, and shearing at high speed of 4000r/min for 20 minutes; then stirring for 30 minutes at the temperature of 150 ℃ to swell the mixture; then continuing to shear at 160 ℃ for 20 minutes; adjusting the temperature to about 150 ℃, adding 2 parts of stabilizer, and continuing shearing for ten minutes; and finally, adding 1 part of HON warm-mixing agent, stirring at a low speed of 150 ℃ until no obvious floating particles exist, and shearing at a speed of 2000r/min for ten minutes to obtain the warm-mixing composite modified asphalt.
Example 4
Taking 100 parts of matrix asphalt, heating to 160 ℃, slowly adding 3 parts of ethylene-vinyl acetate copolymer (EVA) modifier, and shearing at a high speed of 4000r/min for 20 minutes; then stirring for 30 minutes at the temperature of 155 ℃ to swell the mixture; then shearing is continued for 20 minutes at 175 ℃; adjusting the temperature to about 150 ℃, adding 3 parts of stabilizer, and continuing shearing for ten minutes; finally, 2 portions of Sasobit warm-mixing agent are added, stirred at a low speed of 155 ℃ until no obvious floating particles exist, and then sheared for ten minutes at a speed of 2000r/min, and the warm-mixing composite modified asphalt is obtained.
Example 5
Taking 100 parts of base asphalt, heating to 165 ℃, slowly adding 4 parts of SBS modifier, and shearing at high speed of 4000r/min for 20 minutes; then stirring for 30 minutes at the temperature of 160 ℃ to swell the mixture; then continuing to shear at 180 ℃ for 20 minutes; adjusting the temperature to about 150 ℃, adding 2 parts of stabilizer, and continuing shearing for ten minutes; finally, 3 portions of Sasobit warm mixing agent is added, stirred at low speed at 160 ℃ until no obvious floating particles exist, and then sheared for ten minutes at the speed of 2000r/min, and the warm mixing composite modified asphalt is obtained.
Comparative example 1
The base asphalt is heated to 165 ℃.
Comparative example 2
Taking 100 parts of base asphalt, heating to 165 ℃, slowly adding 5 parts of SBS modifier, and shearing at high speed for 20 minutes, wherein the shearing speed is 4000 r/min; then stirring for 30 minutes at the temperature of 160 ℃ to swell the mixture; then continuing to shear at the temperature of 175 ℃ for 20 minutes; and adjusting the temperature to about 150 ℃, adding 3 parts of stabilizer, and continuously shearing for ten minutes to obtain the SBS modified asphalt.
The modified asphalt and the warm-mixed composite modified asphalt prepared by the above examples and comparative examples have good storage stability, and the penetration, softening point, ductility and viscosity tests are performed on the modified asphalt and the warm-mixed composite modified asphalt, the operation process is performed according to technical specifications of tests on asphalt and asphalt mixtures for highway engineering, and the specific test results are shown in the following table:
the test results of the above examples can show that the addition of the warm-mix agent does not have particularly great influence on the penetration, softening point and ductility of the asphalt. The Sasobit and HON warm-mixing agent can effectively reduce the viscosity of the asphalt and further reduce the construction temperature of the asphalt and the mixture; although the Evotherm warm-mixing agent has an unobvious viscosity reducing effect on asphalt, the surface activity effect of the Evotherm warm-mixing agent can also effectively reduce the construction temperature of asphalt and a mixture.
The modified asphalt and the warm-mixed composite modified asphalt prepared by the above examples and comparative examples are subjected to mixture tests, and the mixing temperature and the compaction forming temperature have the following specific results:
the results show that the warm-mixing agent can reduce the construction temperature of the asphalt, reduce energy consumption, facilitate the mixing, the paving and the rolling of the asphalt mixture and improve the construction workability.
The above is a further detailed description of the present invention according to specific preferred embodiments, and the specific embodiments of the present invention should not be considered as limited thereto, and the skilled person should be considered as falling within the scope of the claims as filed in the present invention if he or she wants to make several simple deductions or substitutions on the premise of the inventive concept. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.