Acidic aggregate asphalt mixture and preparation method thereof

Abstract

The present invention provides an acid aggregate asphalt mixture and a preparation method thereof, the main application field of which is road engineering. The mixture includes the following components: stone, asphalt, rock asphalt, asphalt anti-stripping agent, polylactic acid / polycaprolactone blend, and an oil-stone ratio of 4-7%. The stone contains 90-97wt% of acid aggregate and 3-10wt% of carbide slag. First, the asphalt anti-stripping agent and the polylactic acid / polycaprolactone blend are added to the asphalt to prepare modified asphalt. Then, the acid aggregate, rock asphalt and carbide slag are mixed. The modified asphalt prepared according to the set oil-stone ratio is added and mixed to obtain the acid aggregate asphalt mixture. The present invention solves the water damage resistance and fatigue resistance of the acid aggregate asphalt mixture by adjusting the void ratio, asphalt film thickness, bonding force between asphalt and adhesion between asphalt aggregates.

Description

Technical Field

[0001] The present invention relates to the field of road engineering, and in particular to an acidic aggregate asphalt mixture and a preparation method thereof. Background Art

[0002] Common building blocks for asphalt concrete pavements include alkaline limestone and neutral basalt, which are widely used due to their good adhesion to asphalt. However, acidic aggregates have poor adhesion to asphalt. Under the combined effects of repeated loads and water erosion, asphalt pavements can prematurely develop defects such as potholes, impacting driving comfort and pavement durability.

[0003] To address the poor adhesion of acidic aggregates to asphalt, anti-stripping agents such as amine surfactants, cement, lime, and alkaline materials like steel slag are often added to asphalt or asphalt mixtures. However, prolonged heating of asphalt causes the amine surfactants to decompose in the asphalt, affecting the adhesion between the asphalt and the aggregate. Furthermore, materials like lime and cement can be mixed unevenly during the asphalt mixture process, reducing the bond between the asphalt mortar and the aggregate and affecting the mixture's resistance to water damage. Therefore, developing a method for preparing acidic aggregate asphalt mixtures and improving the durability of acidic aggregate asphalt pavements has become an urgent need. Summary of the Invention

[0004] In order to overcome the defects of the prior art, the present invention provides an acid aggregate asphalt mixture and a preparation method thereof, which realizes the large-scale application of the acid aggregate asphalt mixture while ensuring the road performance.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides an acid aggregate asphalt mixture, comprising the following components: stone, asphalt, rock asphalt, asphalt anti-stripping agent, polylactic acid / polycaprolactone blend, and an oil-to-stone ratio of 4-7%;

[0007] The stone material contains 90-97 wt% of acidic aggregate and 3-10 wt% of carbide slag.

[0008] The asphalt-to-stone ratio is the mass ratio of asphalt to stone.

[0009] Preferably, the asphalt is SBS polymer modified asphalt.

[0010] Preferably, the mass of the rock asphalt is 0.6-1% of the mass of the stone; the mass of the asphalt anti-stripping agent is 0.4-1% of the mass of the asphalt; and the mass of the polylactic acid / polycaprolactone blend is 1-1.5% of the mass of the asphalt.

[0011] The acidic aggregate is an aggregate with a silicon dioxide content exceeding 65%, and is selected from granite or quartzite.

[0012] Preferably, the crushing value of the acidic aggregate base material is not greater than 22%, and the polishing value is not less than 40%.

[0013] Preferably, the effective calcium content of the carbide slag is not less than 40%, and the 0.075mm pass rate is not less than 90%.

[0014] Preferably, the rock asphalt has an ash content of ≤20%, a 200-mesh pass rate of not less than 99%, and a softening point of not more than 165°C.

[0015] Preferably, the asphalt anti-stripping agent is a blend of a silane coupling agent and polyamide wax, the mass ratio of the two is 1:9 to 3:7, and the acid value of the polyamide wax is 8-10.

[0016] Preferably, the mass ratio of the polylactic acid / polycaprolactone blend is 1:9 to 5:5. The number average molecular weight of the polylactic acid is 8,000-15,000, and the number average molecular weight of the polycaprolactone is 15,000-20,000.

[0017] The present invention also provides a method for preparing an acidic aggregate asphalt mixture, comprising the following steps:

[0018] (1) heating asphalt, adding an asphalt anti-stripping agent and a polylactic acid / polycaprolactone blend to the asphalt, and shearing and stirring to obtain a modified asphalt;

[0019] (2) The acidic aggregate is heated and mixed with rock asphalt and carbide slag, and the prepared modified asphalt is added according to the set oil-to-stone ratio to obtain an acidic aggregate asphalt mixture.

[0020] Preferably, the asphalt heating temperature in step (1) is 175-185° C., and the shear stirring time is 10-15 minutes.

[0021] Preferably, the heating temperature of the acidic aggregate in step (2) is 180-195° C., the mixing time of the acidic aggregate with rock asphalt and carbide slag is 5-10 seconds, and the mixing time after adding the modified asphalt is 35-45 seconds.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention provides an acidic aggregate asphalt mixture, comprising acidic aggregate, carbide slag, rock asphalt, an asphalt anti-stripping agent, and a polylactic acid / polycaprolactone blend. In the present invention, the water damage resistance and fatigue resistance of the acidic aggregate asphalt mixture are achieved by achieving "quadruple protection". First, the asphalt anti-stripping agent contains polar groups and non-polar groups. The polar groups have strong adhesion to the aggregate, and the non-polar groups have good compatibility with the asphalt, which can improve the adhesion between the asphalt and the aggregate. Secondly, adding a polylactic acid / polycaprolactone copolymer to the asphalt can improve the adhesion between the asphalt and the asphalt. The present invention also provides a method for preparing the acidic aggregate asphalt mixture. A higher oil-to-stone ratio can be used to increase the thickness of the asphalt film on the aggregate surface. The heated acidic aggregate is mixed with the rock asphalt, and the rock asphalt is bonded to the hot aggregate, which can reduce the porosity of the asphalt mixture and prevent external water from penetrating into the gaps in the mixture. The main components of carbide slag are calcium oxide and calcium hydroxide. Carbide slag is used instead of mineral powder to form mortar with asphalt. The mortar is filled between acidic aggregates, which improves the overall bonding and adhesion of the mixture. DETAILED DESCRIPTION

[0024] The technical solutions of the present invention are described in detail below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0025] In this specific embodiment, the silane coupling agent, model KH-550, was purchased from Shandong Huachen New Materials Co., Ltd.; polyamide wax was purchased from Shandong Yousuo Chemical Technology Co., Ltd.; polylactic acid, with a number average molecular weight of 8,000-15,000, was purchased from Shandong Suihua Biotechnology Co., Ltd.; and polycaprolactone, with a number average molecular weight of 15,000-20,000, was purchased from Shandong Jiaying Chemical Technology Co., Ltd. The asphalt is SBS polymer-modified asphalt purchased from Shandong Qilu Petrochemical Co., Ltd., and its technical specifications meet the requirements of JTGF40-2004 Technical Specification for Highway Asphalt Pavement Construction.

[0026] Example 1

[0027] This embodiment provides an acid aggregate asphalt mixture, comprising the following components: stone, asphalt, an oil-to-stone ratio of 7%, rock asphalt, an asphalt anti-stripping agent, and a polylactic acid / polycaprolactone blend. The stone comprises 90 wt% of acid aggregate and 10 wt% of carbide slag.

[0028] The mass of the rock asphalt is 1% of the mass of the stone; the mass of the asphalt anti-stripping agent is 0.4% of the mass of the asphalt; and the mass of the polylactic acid / polycaprolactone blend is 1% of the mass of the asphalt.

[0029] Among them, the acidic aggregate is granite, the parent material crushing value is 20%, and the polishing value is 45%; the effective calcium content of carbide slag is 50%, and the pass rate of 0.075mm is 90%; the ash content of rock asphalt is 18%, the pass rate of 200 mesh is 99%, and the softening point is 165℃; the asphalt anti-stripping agent is a blend of silane coupling agent and polyamide wax, the ratio of the two is 1:9, and the acid value of polyamide wax is 8; the ratio of the two in the polylactic acid / polycaprolactone blend is 5:5.

[0030] The preparation method of the above-mentioned acid aggregate asphalt mixture comprises the following steps: (1) adding an asphalt anti-stripping agent and a polylactic acid / polycaprolactone blend to asphalt in the above-mentioned proportion to prepare a modified asphalt, wherein the asphalt is heated at a temperature of 185°C and the shear stirring time is 15 minutes. (2) mixing the acid aggregate, rock asphalt and carbide slag, and adding the prepared modified asphalt according to a set oil-to-stone ratio to obtain an acid aggregate asphalt mixture. The acid aggregate is heated at a temperature of 195°C, the acid aggregate is stirred with the rock asphalt and carbide slag for 10 seconds, and the stirring time after the addition of asphalt is 45 seconds to obtain an acid aggregate asphalt mixture. Sample preparation and testing are carried out in accordance with the standards of the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". The test results are shown in Table 1.

[0031] Example 2

[0032] This embodiment provides an acid aggregate asphalt mixture, comprising the following components: stone, asphalt, rock asphalt, asphalt anti-stripping agent, polylactic acid / polycaprolactone blend, and an oil-to-stone ratio of 4%; the stone comprises 97 wt% of acid aggregate and 3 wt% of carbide slag;

[0033] The mass of the rock asphalt is 0.6% of the mass of the stone; the mass of the asphalt anti-stripping agent is 1% of the mass of the asphalt; and the mass of the polylactic acid / polycaprolactone blend is 1.5% of the mass of the asphalt.

[0034] Among them, the acidic aggregate is quartzite, the parent material crushing value is 20%, and the polishing value is 47%; the effective calcium content of carbide slag is 55%, and the pass rate of 0.075mm is 95%; the ash content of rock asphalt is 20%, the pass rate of 200 mesh is 100%, and the softening point is 160℃; the asphalt anti-stripping agent is a blend of silane coupling agent and polyamide wax, the ratio of the two is 3:7, and the acid value of polyamide wax is 10; the ratio of the two in the polylactic acid / polycaprolactone blend is 1:9.

[0035] A method for preparing an acidic aggregate asphalt mixture comprises the following steps: (1) adding an asphalt anti-stripping agent and a polylactic acid / polycaprolactone blend to asphalt in the above-mentioned proportions to prepare a modified asphalt, wherein the asphalt is heated at a temperature of 175°C and the shear stirring time is 10 minutes. (2) mixing the acidic aggregate, rock asphalt and carbide slag, and adding the prepared modified asphalt according to a set oil-to-stone ratio to obtain an acidic aggregate asphalt mixture. The acidic aggregate is heated at a temperature of 180°C, the acidic aggregate is stirred with the rock asphalt and carbide slag for 5 seconds, and the stirring time after the addition of the asphalt is 35 seconds to obtain the acidic aggregate asphalt mixture. Sample preparation and testing are carried out in accordance with the standards of the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". The test results are shown in Table 1.

[0036] Example 3

[0037] This embodiment provides an acidic aggregate asphalt mixture, which is composed of the following components: stone, asphalt, rock asphalt, asphalt anti-stripping agent, polylactic acid / polycaprolactone blend, and an oil-to-stone ratio of 5.0%.

[0038] The stone material is composed of 95wt% acidic aggregate and 5wt% carbide slag. The mass of the rock asphalt is 0.8% of the stone material mass; the mass of the asphalt anti-stripping agent is 0.7% of the asphalt mass; and the mass of the polylactic acid / polycaprolactone blend is 1.2% of the asphalt mass.

[0039] Among them, the acidic aggregate is granite, the parent material crushing value is 18%, and the polishing value is 46%; the effective calcium content of carbide slag is 55%, and the pass rate of 0.075mm is 92%; the ash content of rock asphalt is 15%, the pass rate of 200 mesh is 100%, and the softening point is 162°C; the asphalt anti-stripping agent is a blend of silane coupling agent and polyamide wax, the ratio of the two is 2:8, and the acid value of polyamide wax is 9; the ratio of the two in the polylactic acid / polycaprolactone blend is 4:6.

[0040] The preparation method of the above-mentioned acid aggregate asphalt mixture comprises the following steps: (1) adding an asphalt anti-stripping agent and a polylactic acid / polycaprolactone blend to asphalt in the above-mentioned proportion to prepare a modified asphalt, wherein the asphalt is heated at a temperature of 180°C and the shear stirring time is 12 minutes. (2) mixing the acid aggregate, rock asphalt and carbide slag, and adding the prepared modified asphalt according to a set oil-to-stone ratio to obtain an acid aggregate asphalt mixture. The acid aggregate is heated at a temperature of 190°C, the acid aggregate is stirred with the rock asphalt and carbide slag for 7 seconds, and the stirring time after the addition of asphalt is 40 seconds to obtain an acid aggregate asphalt mixture. Sample preparation and testing are carried out in accordance with the standards of the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". The test results are shown in Table 1.

[0041] Comparative Example 1

[0042] The amount of rock asphalt in Example 1 was changed to 0 parts, and the other components remained unchanged. The test was prepared and tested according to the process in Example 1, and the results are recorded in Table 1.

[0043] Comparative Example 2

[0044] The amount of the anti-stripping agent in Example 1 was changed to 0 parts, and the other components remained unchanged. The test was prepared and tested according to the process in Example 1, and the results are recorded in Table 1.

[0045] Comparative Example 3

[0046] The mineral powder in Example 1 completely replaced the carbide slag, and the other components remained unchanged. The test was prepared and tested according to the process in Example 1, and the results are recorded in Table 1.

[0047] Comparative Example 4

[0048] The amount of polylactic acid / polycaprolactone in Example 1 was changed to 0 parts, and the other components remained unchanged. The test preparation and testing were carried out according to the process in Example 1. The results are recorded in Table 1.

[0049] Comparative Example 5

[0050] The amount of rock asphalt in Example 1 was changed to 0 parts, the amount of anti-stripping agent was changed to 0 parts, the mineral powder completely replaced the carbide slag, the amount of polylactic acid / polycaprolactone was 0 parts, and the other components remained unchanged. The test was prepared and tested according to the process in Example 1, and the results are recorded in Table 1.

[0051] Comparative Example 6

[0052] The ratio of the silane coupling agent to the polyamide wax in the anti-stripping agent in Example 1 was changed to 5:5, and the other components remained unchanged. The test preparation and testing were carried out according to the process in Example 1, and the results are recorded in Table 1.

[0053] Comparative Example 7

[0054] The oil-stone ratio in Example 1 was changed to 3.8%, and the other components remained unchanged. The test was prepared and tested according to the process in Example 1. The results are recorded in Table 1.

[0055] Table 1 Comparison of road performance of acid aggregate asphalt mixture

[0056]

[0057]

[0058] As can be seen from the above examples, the present invention provides an acidic aggregate asphalt mixture and its preparation method. By combining various components, the mixture's water damage resistance and durability can be effectively improved. Under the dual coupling of a 60°C water bath and a cyclic load (0.7 MPa), the rutting depth was only 3.5 mm, the dynamic stability reached 5510 times / mm, the Marshall residual stability reached 95.7%, and the freeze-thaw splitting residual strength ratio reached 116.5%, meeting the JTGF40-2004 Technical Specification for Highway Asphalt Pavement Construction. Test results demonstrate significant improvements in the water damage resistance and durability of the acidic aggregate asphalt mixture. Comparative Example 1 shows that without the addition of rock asphalt, the dynamic stability and Marshall residual stability of the mixture decreased significantly. In Comparative Example 2, where no anti-stripping agent was added, the Marshall residual stability and freeze-thaw splitting residual strength ratio of the mixture decreased significantly. In Comparative Example 3, mineral powder was used instead of carbide slag, and the mixture's water damage resistance decreased significantly. In Comparative Example 4, no polylactic acid / polycaprolactone was added to the asphalt, and the mixture's rutting resistance decreased significantly. In Comparative Example 5, the anti-stripping agent was added at zero dosage, resulting in reduced adhesion between the asphalt and aggregate. The use of mineral powder instead of carbide slag reduced the adhesion between the asphalt mortar and aggregate, leading to significant decreases in the mixture's residual stability and freeze-thaw splitting strength ratio, and significantly reduced the mixture's water damage resistance. The zero polylactic acid / polycaprolactone addition reduced the adhesion between the asphalt and the aggregate, and due to the dual effect of poor adhesion to the aggregate, the mixture's rutting resistance decreased significantly. Comparative Example 6 adjusted the proportion of anti-stripping material. While the mixture's rutting resistance remained unchanged, its residual stability decreased significantly, indicating a reduction in water damage resistance. Comparative Example 7 reduced the asphalt-to-stone ratio, resulting in a reduced asphalt film thickness and a decrease in overall performance. These comparative results demonstrate that the various components of the acidic aggregate asphalt mixture complement each other, providing multiple protections and ensuring the overall road performance of the acidic aggregate asphalt mixture.

[0059] The above specific implementation manner cannot be used as a limitation on the protection scope of the present invention. For those skilled in the art, any replacement, improvement or transformation made to the implementation manner of the present invention falls within the protection scope of the present invention.

[0060] Anything not described in detail in the present invention is well known to those skilled in the art.

Claims

1. An acidic aggregate asphalt mixture, characterized in that: The acid aggregate asphalt mixture comprises the following components: stone, asphalt, rock asphalt, asphalt anti-stripping agent, polylactic acid / polycaprolactone blend, and an oil-to-stone ratio of 4-7%; The stone material contains 90-97 wt% of acidic aggregate and 3-10 wt% of carbide slag; The asphalt anti-stripping agent is a blend of a silane coupling agent and polyamide wax, the mass ratio of the two is 1:9 to 3:7, and the acid value of the polyamide wax is 8-10.

2. The acidic aggregate asphalt mixture according to claim 1, characterized in that: The asphalt is SBS polymer modified asphalt.

3. The acidic aggregate asphalt mixture according to claim 1, characterized in that: The mass of the rock asphalt is 0.6-1% of the mass of the stone; the mass of the asphalt anti-stripping agent is 0.4-1% of the mass of the asphalt; and the mass of the polylactic acid / polycaprolactone blend is 1-1.5% of the mass of the asphalt.

4. The acidic aggregate asphalt mixture according to claim 1, characterized in that: The crushing value of the acidic aggregate base material is not greater than 22%, and the polishing value is not less than 40%.

5. The acidic aggregate asphalt mixture according to claim 1, characterized in that: The effective calcium content of the carbide slag is not less than 40%, and the 0.075mm pass rate is not less than 90%.

6. The acidic aggregate asphalt mixture according to claim 1, characterized in that: The rock asphalt has an ash content of ≤20%, a 200-mesh pass rate of not less than 99%, and a softening point of not more than 165°C.

7. The acidic aggregate asphalt mixture according to claim 1, characterized in that: The mass ratio of the polylactic acid / polycaprolactone blend is 1:9-5:5; the number average molecular weight of the polylactic acid is 8000-15000; and the number average molecular weight of the polycaprolactone is 15000-20000.

8. The method for preparing the acidic aggregate asphalt mixture according to any one of claims 1 to 7, characterized in that: The steps include: (1) heating the asphalt, adding the asphalt anti-stripping agent and the polylactic acid / polycaprolactone blend into the asphalt, shearing and stirring, and obtaining the modified asphalt; (2) The acidic aggregate is heated and mixed with rock asphalt and carbide slag, and the prepared modified asphalt is added according to the set oil-to-stone ratio to obtain an acidic aggregate asphalt mixture.

9. The method for preparing an acidic aggregate asphalt mixture according to claim 8, characterized in that: The asphalt heating temperature in step (1) is 175-185°C, and the shear stirring time is 10-15 minutes.

10. The method for preparing an acidic aggregate asphalt mixture according to claim 8, wherein: The heating temperature of the acidic aggregate described in step (2) is 180-195°C, the mixing time of the acidic aggregate with rock asphalt and carbide slag is 5-10 seconds, and the mixing time after adding the modified asphalt is 35-45 seconds.

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