Anti-rutting drainage ultrathin overlay asphalt mixture and preparation method thereof
Technical Field
The invention relates to an anti-rutting drainage ultrathin overlay asphalt mixture and a preparation method thereof, belonging to the technical field of road maintenance.
Background
With the continuous development of economy and the increasing of urbanization process, traffic load is increased year by year, so that the performance requirements of people on roads are higher and higher. In rainy days, the incidence rate of road accidents is far greater than that in sunny days, serious accidents such as chain rear-end collisions and water drift occur frequently, and the main reason of high accidents is that the friction coefficient of the road surface is obviously reduced due to a large amount of water accumulated on the road, and the braking distance is greatly prolonged. Therefore, it is reasonable to use the drainage ultrathin overlay with large structural void ratio and obvious road surface drainage effect as the upper layer of the asphalt pavement.
The drainage ultrathin overlay asphalt mixture is easy to be damaged by water to peel off, loosen and the like due to the existence of larger communication gaps, and the temperature is rapidly increased and the modulus and the shear strength of the mixture are rapidly reduced after the mixture is directly contacted with strong sunlight in summer because the drainage ultrathin overlay asphalt mixture is positioned on the uppermost layer of a pavement structure. If the anti rutting ability of ultra-thin overlay bituminous mixture of drainage is not enough, just the road surface just produces easily such diseases as wave, lapse, rutting under the repeated action of driving load, influences the skid resistance performance on travelling comfort and road surface, causes the threat to driving safety. If the anti-rutting capability of the ultrathin overlay asphalt mixture is better, the ultra-thin overlay asphalt mixture can bear the action of driving load, effectively reduce the diseases such as rutting and the like of the lower-layer asphalt mixture, and because the ultrathin overlay asphalt mixture has good flatness and anti-sliding performance, the driving comfort and the safety of the road surface are improved.
Therefore, the method has important practical significance for deeply researching the improvement of the anti-rutting capability of the drainage ultrathin overlay asphalt mixture.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a preparation method of an anti-rutting drainage ultrathin overlay asphalt mixture.
In order to achieve the purpose, the invention adopts the technical scheme that: a preparation method of a drainage ultrathin overlay asphalt mixture comprises the following steps:
(1) preparing raw materials: aggregate, asphalt and filler;
(2) dividing aggregates into coarse aggregates and fine aggregates, determining the densities of the coarse aggregates, the fine aggregates, the filler and the asphalt, and determining the proportion of the coarse aggregates and the fine aggregates in the gradation, the void ratio of the drainage ultrathin overlay asphalt mixture and the mass percentage of the asphalt by adopting a volume method;
(3) finishing the grading design of the drainage ultrathin overlay asphalt mixture according to the mass proportion of coarse and fine aggregates and the Fowler series, and adding key sieve pores of a sieve;
(4) and determining the optimal asphalt mass percentage content of the drainage ultrathin overlay asphalt mixture to obtain the drainage ultrathin overlay asphalt mixture.
According to the preparation method provided by the invention, the asphalt mixture is subjected to optimized grading design by adopting a volume method, the embedding force among coarse aggregates and the stability of a framework space network structure can be improved, and the prepared water-draining ultrathin overlay asphalt mixture has stronger capacity of resisting permanent deformation.
As a preferred embodiment of the preparation method of the present invention, in step (1), the aggregate is diabase, the asphalt is high-viscosity asphalt (provided by shell asphalt company, ltd), and the filler is alkaline limestone ore powder (for removing impurities from the ore powder); the diabase comprises 3-5mm and 5-10mm of broken stone and 0-3mm of stone chips.
As a preferred embodiment of the preparation method of the present invention, in the step (2), the coarse aggregate has a gross bulk density of 2.90g/cm3Bulk density in the tamped state of 1.72g/cm3(ii) a The fine aggregate has an apparent relative density of 2.93g/cm3(ii) a The relative density of the asphalt is 1.023g/cm3The relative density of the filler is 2.864g/cm3。
As a preferable embodiment of the preparation method, in the step (2), the voidage of the drainage ultrathin overlay asphalt mixture is 18-23%, and the asphalt content is 3.9-5.1% by mass.
The coarse and fine aggregates are divided according to the standard (JTG E42-2005 Highway engineering aggregate test Specification), aggregates with the grain size of more than or equal to 2.36mm are coarse aggregates, and aggregates with the grain size of less than 2.36mm are fine aggregates. The proportion of the coarse and fine aggregates in the grading is changed according to different selected grading, and when the porosity of the drainage ultrathin overlay asphalt mixture is 18-23% and the asphalt mass percentage is 3.9-5.1%, the proportion of the coarse and fine aggregates in the grading can be obtained.
As a preferred embodiment of the preparation method of the present invention, in step (2), the coarse and fine aggregate proportion is determined by a volume method, and specifically, the mass percentage of the coarse and fine aggregates is obtained by formulas ① and ②:
①qc+qf+qp=100;
③VCADRC=(1-ρ/ρb)х100
wherein q isc、qf、qp、qaRespectively the mass percentage of coarse aggregate, fine aggregate, mineral powder and asphalt, VCADRCIs the coarse aggregate porosity (%), VCA obtained according to formula ③DRCVv is the design porosity (%), and ρ is the bulk density (g/cm) of the coarse aggregate in the compacted state3);ρbIs the bulk density of the coarse aggregate synthetic wool; rhoafIs the apparent relative density (g/cm) of the fine aggregate3);ρaIs the relative density (g/cm) of the asphalt3);ρfIs the relative density (g/cm) of the ore powder3)。
As a preferred embodiment of the preparation method of the present invention, in the step (3), the fowler series design is specifically as follows:
wherein P is the aggregate passage percentage (%) for the mesh size d; d is the mesh size (mm); d is the maximum particle size (mm) of the aggregate; n is an index, n is more than or equal to 0.3 and less than or equal to 0.5.
As a preferred embodiment of the preparation method of the present invention, in the step (3), the gradation of the drainage ultra-thin overlay asphalt mixture is as follows:
mesh/mm
|
13.2
|
9.5
|
8
|
6.7
|
4.75
|
2.36
|
1.18
|
0.6
|
0.3
|
0.15
|
0.075
|
Through rate/%)
|
100
|
94.8
|
86.2
|
72.7
|
20.9
|
15.4
|
13.4
|
10.7
|
7.6
|
6.1
|
5 |
。
As a preferred embodiment of the production method of the present invention, in the step (3), the mesh opening size of the screen is 13.2mm, 9.5mm, 8.0mm, 6.7mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm or 0.075 mm.
As a preferred embodiment of the preparation method of the invention, in the step (3), the key screen holes added into the screen are specifically operated by adding two key screen holes with the hole diameter of 6.7mm and 8mm between the screen holes with the hole diameter of 4.75mm-9.5 mm.
As a preferred embodiment of the preparation method, in the step (4), determining the optimal asphalt mass percentage of the drainage ultrathin overlay asphalt mixture by adopting a leakage and scattering comprehensive experiment method; the optimal asphalt mass percentage content of the drainage ultrathin overlay asphalt mixture is 4.5%.
A high-temperature track test, a low-temperature small beam bending test, a water immersion Marshall test, a freeze-thaw splitting test and a construction depth test are adopted as a conventional pavement performance test.
The invention also aims to provide the drainage ultrathin overlay asphalt mixture prepared by the preparation method.
The drainage ultrathin overlay asphalt mixture improves the high-temperature stability and the anti-rutting capability of the asphalt mixture.
Compared with the prior art, the invention has the beneficial effects that:
(1) according to the preparation method of the drainage ultrathin overlay asphalt mixture, the prepared asphalt mixture has the advantages of large void ratio, more indirect contacts of coarse aggregates, good structural stability of a framework space network, strong embedding and squeezing force among frameworks, good drainage performance and anti-rutting capability, difficulty in occurrence of diseases such as cracks, ruts and pits on the pavement, and improvement of driving comfort and safety;
(2) the drainage ultrathin overlay asphalt mixture prepared by the preparation method can effectively improve the high-temperature stability and the anti-rutting capability of the drainage ultrathin overlay asphalt mixture;
(3) the drainage ultrathin overlay asphalt mixture prepared by the preparation method provided by the invention has the advantages that the high-temperature stability, the low-temperature crack resistance, the water damage resistance and the skid resistance meet the standard requirements, and because the drainage performance and the track resistance are better, the defects such as cracks, tracks, pits and the like are not easy to occur on the pavement, the drainage ultrathin overlay asphalt mixture provided by the invention is applied to the pavement, and the driving comfort and the safety can be improved.
Drawings
FIG. 1 is a flow chart of a preparation process of the anti-rutting drainage ultrathin overlay asphalt mixture.
Detailed Description
To better illustrate the objects, aspects and advantages of the present invention, the present invention will be further described with reference to specific examples.
Example 1
The embodiment of the invention provides a preparation method of an anti-rutting drainage ultrathin overlay asphalt mixture, which comprises the following steps:
(1) preparing raw materials: aggregate (10mm diabase macadam), high-viscosity asphalt (provided by Shell asphalt Co., Ltd.), and alkaline limestone ore powder (for removing impurities in the ore powder);
(2) the aggregate was divided into coarse aggregate and fine aggregate, and the densities of coarse aggregate, fine aggregate, filler and asphalt were determined (the gross bulk density of coarse aggregate was 2.90 g/cm)3Bulk density in the tamped state of 1.72g/cm3(ii) a The fine aggregate has an apparent relative density of 2.93g/cm3(ii) a The relative density of the high-viscosity asphalt is 1.023g/cm3The relative density of the alkaline limestone mineral powder is 2.864g/cm3) Determining the mass proportion of the coarse and fine aggregates by a volume method, and specifically obtaining the mass percentage of the coarse and fine aggregates by a formula ① and a formula ②:
①qc+qf+qp=100;
③VCADRC=(1-ρ/ρb)х100;
wherein q isc、qf、qp、qaRespectively the mass percentage of coarse aggregate, fine aggregate, mineral powder and asphalt, VCADRCPorosity (%) of the coarse aggregate, Vv a design porosity (%), and ρ a bulk density (g/cm) of the coarse aggregate in a compacted state3);ρbIs the bulk density of the coarse aggregate synthetic wool; rhoafIs the apparent relative density (g/cm) of the fine aggregate3);ρaIs the relative density (g/cm) of the asphalt3);ρfIs the relative density (g/cm) of the ore powder3) (ii) a The void ratio of the drainage ultrathin overlay asphalt mixture and the mass percentage of the asphalt; the dosage q of the mineral powderp5%, the target void ratio Vv is 20%, the amount q of asphalt used isa5% by mass of coarse aggregate, q, according to the formulae ① and ②c84.6 percent of fine aggregate by mass percentage content qf10.4% of VCA according to formula ③DRCIs 40.7%;
(3) finishing the grading design of the drainage ultrathin overlay asphalt mixture according to the proportion of coarse and fine aggregates and the Fowler series, and adding key sieve pores of a sieve; the Fowler series design is specifically as follows:
wherein P is the aggregate passage percentage (%) for the mesh size d; d is the mesh size (mm); d is the maximum particle size (mm) of the aggregate; n is an index; p and D are as described in table 1 below, D ═ 10mm, n ═ 0.5;
the gradation of the drainage ultrathin overlay asphalt mixture is shown in the following table 1:
TABLE 1 gradation of ultra-thin overlay asphalt mixture with water-drainage
Mesh/mm
|
13.2
|
9.5
|
8
|
6.7
|
4.75
|
2.36
|
1.18
|
0.6
|
0.3
|
0.15
|
0.075
|
Through rate/%)
|
100
|
94.8
|
86.2
|
72.7
|
20.9
|
15.4
|
13.4
|
10.7
|
7.6
|
6.1
|
5 |
(4) Determining the optimal asphalt mass percentage content of the drainage ultrathin overlay asphalt mixture to obtain the drainage ultrathin overlay asphalt mixture; the optimum asphalt dosage of the ultrathin overlay asphalt mixture is determined by selecting a leakage and scattering comprehensive test method, 5 groups of asphalt mixtures with the asphalt dosages of 3.9%, 4.2%, 4.5%, 4.8% and 5.1% are mixed, a Marshall compaction instrument is used for molding test pieces, the compaction times are two-sided 25 times, the molded test pieces are put into a los Angeles abrasion machine to rotate for 300 circles at the rotating speed of 33r/min, the ratio of the loss mass to the original mass of the test pieces is taken as the scattering loss, the scattering and leakage test results of different asphalt mixtures are shown in table 2, and the optimum asphalt dosage volume parameter table of the asphalt mixture is shown in table 3.
TABLE 2 asphalt mixture optimum asphalt dosage range table
When the asphalt dosage is in the range of 4.4-4.6%, the change rate of leakage loss and scattering loss is greatly different, and because the leakage loss and scattering loss of the asphalt mixture meet the specification requirements, the asphalt dosage of 4.5% is the optimal asphalt dosage of the asphalt mixture.
TABLE 3 volume parameters of bituminous mixtures
Experimental example 1
In this experimental example, according to the preparation method of the rut-resistant drainage ultrathin overlay asphalt mixture described in example 1, the drainage ultrathin overlay asphalt mixture is obtained by using the optimal asphalt dosage, and the pavement performance of the drainage ultrathin overlay asphalt mixture is verified through a rutting dynamic stability test, a low-temperature trabecular bending test, a water immersion marshall test, a freeze-thaw splitting test and a construction depth test.
1. Rut dynamic stability test
According to the requirements of the test procedure (JTGF20-2011) T0719 of asphalt and asphalt mixtures, three rutting tests (all of which are asphalt mixtures prepared in the same batch and are repeatability tests) are carried out under the conditions of 60 +/-1 ℃ and 0.7 +/-0.05 MPa, and the test results are shown in Table 4.
TABLE 4 Rut dynamic stability test results
The test results in table 4 show that the drainage ultrathin overlay asphalt mixture of example 1 of the invention meets the specification requirements and has good high temperature stability.
2. Low temperature trabecular bending test
The test results are shown in Table 5, and the test results are obtained by performing a low-temperature bending test (the test pieces in the following 4 groups are asphalt mixtures prepared in the same batch, and are repeatability tests) according to the requirements of the asphalt and asphalt mixture test procedure (JTGF20-2011) T0715 under the conditions that the temperature is-10 ℃ and the loading rate is 50 mm/min.
TABLE 5 results of the Low temperature trabecular bending test
The results in table 5 show that the drainage ultra-thin overlay asphalt mixture of example 1 of the present invention has a low temperature bending failure strain of greater than 2500, meeting the specification requirements.
3. Water stability test
The water stability of the asphalt mixture was tested by conducting a water immersion marshall test and a freeze-thaw splitting test according to the designed optimum asphalt amount and gradation, and the following 4 sets of test pieces were asphalt mixtures prepared in the same batch, and the test results are shown in tables 6 and 7 for the repeatability tests, respectively.
TABLE 6 immersion Marshall test results
TABLE 7 Freeze-thaw cleavage test results
The test results in tables 6 and 7 show that the water damage resistance and low temperature crack resistance of the drainage ultrathin overlay asphalt mixture of the embodiment 1 of the invention meet the standard requirements.
4. Test of depth of formation
The surface texture depth of the asphalt mixture was determined by a sand-spreading method, and the following 3 sets of test pieces were prepared in the same batch, and the test results are shown in table 8 for the repeatability test.
TABLE 8 results of texture depth test
The road performance test and verification of the drainage ultrathin overlay asphalt mixture in the experimental example 1 show that the high-temperature stability, the low-temperature crack resistance, the water damage resistance and the skid resistance of the prepared anti-rutting drainage ultrathin overlay asphalt mixture meet the standard requirements, and because the drainage performance and the anti-rutting capability are good, the pavement is not easy to generate cracks, ruts, pits and other diseases, and the drainage ultrathin overlay asphalt mixture can be applied to the pavement to improve the driving comfort and the safety.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the protection scope of the present invention, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.