Compact ultrathin asphalt overlay and preparation method thereof

Abstract

The invention discloses a compact ultra-thin asphalt overlay and a preparation method thereof. The compact ultra-thin asphalt overlay comprises mineral aggregate, SBS modified asphalt, modified rubber filler, fly ash, a water reducer, basalt fibers and an antifreeze agent. Wherein the modified rubber filler is a rubber mixture wrapped by polydimethylsiloxane. The preparation method comprises the following steps: uniformly mixing the mineral aggregate, the SBS modified asphalt, the modified rubber filler, the fly ash and the antifreeze agent, mixing according to a water-cement ratio, adding the water reducer, stirring, adding the basalt fiber, mixing to obtain a mixture, and finally paving the mixture to form the compact ultrathin asphalt overlay. According to the compact ultrathin asphalt overlay, on the basis that mineral aggregate gaps are filled with the rubber powder to improve the compactness, the rubber powder is wrapped with the polydimethylsiloxane, and separation and layering of the rubber powder and asphalt are effectively avoided; key performance indexes such as the freeze-thaw splitting strength ratio, the immersion Marshall residual stability, the dynamic stability and the crack resistance of the asphalt mixture are remarkably improved, and the mechanical property is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ultra-thin asphalt surface layer, and particularly relates to a dense type of ultra-thin asphalt cover surface layer and a preparation method thereof. BACKGROUND

[0002] The ultra-thin cover surface has the advantages of excellent material performance and extremely thin thickness, and has been proved to be a fast, economical and durable preventive maintenance, which can not only fully improve the driving comfort of the road surface, but also reduce the maintenance cost and improve the road service performance.

[0003] However, in the existing engineering practice, although the dense graded mineral aggregate is used to prepare the ultra-thin pavement, the mixture is difficult to compact due to the thin thickness of the ultra-thin cover surface, which leads to poor compaction effect, poor water stability and poor crack resistance. Based on this, the prior art improves the water stability by doping rubber waste to fill the gaps between the mineral aggregates. However, because the surface tension of rubber and asphalt does not match, the compatibility of the two is very poor, which may cause segregation, and thus the adhesion of the entire pavement system is poor, which reduces the compaction effect and crack resistance.

[0004] Therefore, the present research is to provide a new dense type of ultra-thin asphalt cover surface layer and a preparation method thereof, which can improve the compatibility of rubber powder and asphalt, avoid segregation, and improve the adhesion of the pavement system on the basis of filling the gaps between the mineral aggregates with rubber powder to improve the compaction degree, so as to achieve the technical goal of improving the water stability and crack resistance. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a new dense type of ultra-thin asphalt cover surface layer and a preparation method thereof, which can improve the compatibility of rubber powder and asphalt, avoid segregation, and improve the adhesion of the pavement system on the basis of filling the gaps between the mineral aggregates with rubber powder to improve the compaction degree.

[0006] The technical scheme of the present application is that the dense type of ultra-thin asphalt cover surface layer comprises the following raw materials in weight fraction: 100-120 parts of mineral aggregate, 5-8 parts of SBS modified asphalt, 8-15 parts of modified rubber filler, 1-3 parts of fly ash, 0.8-1.5 parts of water reducing agent, and 0.3-0.5 parts of anti-freezing agent; wherein the modified rubber filler is a rubber mixture wrapped with polydimethylsiloxane.

[0007] The application is based on the preparation of an ultra-thin asphalt overlay layer by using a polydimethylsiloxane-coated rubber mixture as a filler to fill the voids of the mineral aggregate to improve the density, and using polydimethylsiloxane to coat the rubber powder, on the one hand, the high active silicon-oxygen bond of polydimethylsiloxane can form hydrogen bonds or chemical bonds with the polar components in the asphalt, thereby improving the interfacial bonding ability of the rubber powder and the asphalt, improving the cohesion of the overall asphalt concrete, and avoiding the segregation of the filler and the asphalt, which leads to cracking. On the other hand, the methyl group of polydimethylsiloxane makes it hydrophobic, thereby effectively blocking the further penetration of water into the thin layer pavement, improving the water stability.

[0008] Further, the overlay layer further comprises 0.5-1.0 parts by weight of basalt fibers with a length of 6-12 mm.

[0009] Further, the modified rubber filler used in the ultra-thin asphalt overlay layer is prepared by the following steps: dissolving polydimethylsiloxane in an aromatic hydrocarbon solvent to prepare a solution, placing waste rubber powder in the solution, and evaporating and drying to obtain a polydimethylsiloxane-coated rubber mixture; wherein the addition amount of polydimethylsiloxane is 3-10% of the mass of the waste rubber powder.

[0010] Further, the mineral aggregate used in the ultra-thin asphalt overlay layer is one of basalt or limestone aggregate, and the gradation type is stc-5, under which the proportion of each grade of coarse aggregate is 62-67% for 3-5mm, 18-23% for 0-3mm, and 10-20% for mineral powder.

[0011] Further, the type of SBS modified asphalt used in the ultra-thin asphalt overlay layer is I-A, I-B, I-C or I-D.

[0012] Further, the content of SiO2 in the fly ash used in the ultra-thin asphalt overlay layer is 42-61%, the content of Al2O3 is 20-30%, and the content of CaO is 5-18%.

[0013] Further, the water reducing agent used in the ultra-thin asphalt overlay layer is one of polycarboxylic acid water reducing agent, sulfonate type water reducing agent or fatty acid salt type water reducing agent.

[0014] Further, the anti-freezing agent used in the ultra-thin asphalt overlay layer is a mixture of sodium acetate and ethylene glycol in a weight ratio of 1:(1-3).

[0015] The method for preparing the dense type ultra-thin asphalt cover layer comprises the following steps: mixing the mineral aggregate, SBS modified asphalt, modified rubber filler, fly ash and anti-freezing agent, adding water according to the water-cement ratio of 0.18-0.22, mixing, adding water reducing agent, stirring for 3-5 min, and then preparing the mixture.

[0016] Further, the method for preparing the dense type ultra-thin asphalt cover layer comprises the following steps: mixing the mineral aggregate, SBS modified asphalt, modified rubber filler, fly ash and anti-freezing agent, adding water according to the water-cement ratio of 0.18-0.22, mixing, adding water reducing agent, stirring for 3-5 min, adding basalt fiber and mixing for 10-15 min, and then preparing the mixture.

[0017] Further, the thickness of the dense type ultra-thin asphalt cover layer is 0.8-1.5 cm.

[0018] Beneficial effects: Compared with the prior art, the significant advantages of the dense type ultra-thin asphalt cover layer are as follows: based on the filling of the mineral aggregate gap by the rubber powder to improve the compactness, the polydimethylsiloxane is used to wrap the rubber powder, which effectively avoids the segregation and delamination of the rubber powder and the asphalt, significantly improves the key performance indicators such as the freeze-thaw splitting strength ratio, the immersion Marshall residual stability, the dynamic stability and the crack resistance of the asphalt mixture, and improves the mechanical properties. DETAILED DESCRIPTION

[0019] The technical solutions of the present application will be further described in detail below in combination with the embodiments.

[0020] It should be noted that the raw materials used in the present application can be purchased from the market.

[0021] The mineral aggregate used in the following examples and comparative examples of the present application is basalt aggregate, and the gradation type is stc-5. As shown in Table 1 below. The gradation proportion of each grade used in the following examples is shown in Table 2 below.

[0022] Table 1: Mineral aggregate gradation range of stc-5

[0023]

[0024] Table 2: Proportion of each grade of mineral aggregate gradation of stc-5

[0025]

[0026] The type of SBS modified asphalt used in the following examples and comparative examples is type I-A. The component content of the fly ash is shown in Table 3 below. The anti-freezing agent is a mixture of sodium acetate and ethylene glycol in a weight ratio of 1:1. The basalt fiber has a particle size of 6-12 mm. The waste rubber powder used in the present application has a particle size of about 100 mesh.

[0027] Table 3 Main component content of fly ash

[0028] Component SiO2 CaO <![CDATA[Al2O3]]> SO3 Content / % 43.5 9.92 25.5 2.5

[0029] The modified rubber filler used in the following examples of the present application is prepared by the following steps:

[0030] (1) Dissolve polydimethylsiloxane in toluene to prepare a solution, the concentration of which is 15 wt.%;

[0031] (2) Put the waste rubber powder into the solution, stir at a speed of 300 rpm for 1 h, and then evaporate and vacuum dry to obtain a polydimethylsiloxane-coated rubber mixture; wherein the amount of polydimethylsiloxane added is 8% of the mass of the waste rubber powder.

[0032] Example 1

[0033] The compact type ultra-thin asphalt cover layer of this example 1 uses the raw materials shown in Table 4 below.

[0034] Table 4 Raw material components of example 1

[0035] No. Raw material Content / parts 1 Mineral aggregate 110 2 SBS modified asphalt 6 3 Modified rubber filler 10 4 Fly ash 2 5 Polycarboxylic acid water reducer 1 6 Basalt fiber 0.8 7 Anti-freezing agent 0.4

[0036] The compact type ultra-thin asphalt cover layer of this example 1 is prepared by the following steps: mix the mineral aggregate, SBS modified asphalt, modified rubber filler, fly ash, and anti-freezing agent, then add water according to a water-cement ratio of 0.2, mix, add polycarboxylic acid water reducer, stir for 4 min, add basalt fiber, mix for 12 min, to obtain the mixture, and then pave the mixture to a thickness of 1 cm to form the compact type ultra-thin asphalt cover layer.

[0037] Example 2

[0038] The compact type ultra-thin asphalt cover layer of this example 2 uses the raw materials shown in Table 5 below.

[0039] Table 5 Raw material components of example 2

[0040]

[0041]

[0042] The dense type ultra-thin asphalt cover layer of this embodiment 2 is prepared by the following steps: after mixing the mineral aggregate, SBS modified asphalt, modified rubber filler, fly ash and anti-freezing agent, water is added according to the water-cement ratio of 0.2 and mixed, at the same time, polycarboxylic acid water reducing agent is added, after stirring for 4 min, basalt fiber is added and mixed for 12 min, the mixture is prepared, the mixture is paved to 1.2 cm to form the dense type ultra-thin asphalt cover layer.

[0043] Embodiment 3

[0044] The dense type ultra-thin asphalt cover layer of this embodiment 3 uses the raw materials shown in Table 6.

[0045] Table 6 Raw material components of embodiment 3

[0046] No. Raw material Content / parts 1 Mineral aggregate 100 2 SBS modified asphalt 5 3 Modified rubber filler 8 4 Fly ash 1 5 Polycarboxylic acid water reducer 0.8 6 Basalt fiber 0.5 7 Anti-freezing agent 0.3

[0047] The dense type ultra-thin asphalt cover layer of this embodiment 3 is prepared by the following steps: after mixing the mineral aggregate, SBS modified asphalt, modified rubber filler, fly ash and anti-freezing agent, water is added according to the water-cement ratio of 0.18 and mixed, at the same time, polycarboxylic acid water reducing agent is added, after stirring for 3 min, basalt fiber is added and mixed for 10 min, the mixture is prepared, the mixture is paved to 0.8 cm to form the dense type ultra-thin asphalt cover layer.

[0048] Embodiment 4

[0049] The dense type ultra-thin asphalt cover layer of this embodiment 4 uses the raw materials shown in Table 7.

[0050] Table 7 Raw material components of embodiment 4

[0051]

[0052]

[0053] The dense type ultra-thin asphalt cover layer of this embodiment 4 is prepared by the following steps: after mixing the mineral aggregate, SBS modified asphalt, modified rubber filler, fly ash and anti-freezing agent, water is added according to the water-cement ratio of 0.22 and mixed, at the same time, polycarboxylic acid water reducing agent is added, after stirring for 5 min, basalt fiber is added and mixed for 15 min, the mixture is prepared, the mixture is paved to 1.5 cm to form the dense type ultra-thin asphalt cover layer.

[0054] Comparative example 1

[0055] The comparative example 1 is basically the same as the embodiment 1, except that the waste rubber powder is directly used in the raw materials of the ultra-thin asphalt cover layer.

[0056] Comparative example 2

[0057] The comparative example 2 is basically the same as the example 2, except that the waste rubber powder is directly used in the raw material of the ultra-thin asphalt cover layer.

[0058] Performance detection

[0059] The thin layer pavement layer prepared in the above examples 1 to 4 and the comparative example 1 is respectively subjected to the dynamic capacity splitting strength test, the immersion Marshall residual stability test, the high temperature durability and the anti-cracking performance detection, and the obtained results are shown in the following table 6.

[0060] Among them, the freeze-thaw splitting strength test: according to the “Highway Engineering Asphalt and Asphalt Mixture Test Regulation” JTGE20-2011, the strength ratio in the freeze-thaw splitting test is used as the evaluation means. The experimental conditions are that the temperature is 25℃±0.5℃, and the freeze-thaw splitting test is carried out at a loading rate of 50mm / min.

[0061] The immersion Marshall residual stability test: according to the method in the “Highway Asphalt Pavement Construction Technical Specification” (JTGF40-2004), the immersion Marshall residual stability test is carried out. The higher the freeze-thaw splitting strength and the immersion Marshall residual stability, the higher the water stability of the micro-surfacing asphalt mixture.

[0062] High temperature durability: the rutting test is carried out according to the method of “JTGE20-2011”, and the dynamic stability of the asphalt mixture is tested.

[0063] Anti-cracking performance: the semi-circular bending (SCB) test is used, the semi-cylindrical test piece with a diameter of 150mm and a thickness of 50mm is pre-cut on the bottom of the test piece to form a crack as the starting point of the crack, and the crack is guaranteed to expand and fracture along the cutting direction. The span of the semi-circular bending test is 120mm, and the fracture toughness is measured.

[0064] Table 6 Performance test

[0065]

[0066] As can be seen from table 6, the dense type ultra-thin asphalt cover layer of the application improves the compactness based on the filling of the mineral aggregate voids by the rubber powder, and effectively avoids the segregation and delamination of the rubber powder and the asphalt by wrapping the rubber powder with polydimethylsiloxane, which significantly improves the key performance indicators of the asphalt mixture, such as the freeze-thaw splitting strength ratio, the immersion Marshall residual stability, the dynamic stability and the anti-cracking strength, and improves the mechanical properties.

[0067] In addition to the above examples, the components and processes defined in the application can achieve the technical effects claimed by the application, and therefore no further experimental evidence is provided.

Claims

1. A dense ultra-thin asphalt overlay layer, characterized in that: The overlay layer comprises the following raw materials by weight: 100-120 parts of mineral material, 5-8 parts of SBS modified asphalt, 8-15 parts of modified rubber filler, 1-3 parts of fly ash, 0.8-1.5 parts of water reducer and 0.3-0.5 parts of antifreeze agent; wherein the modified rubber filler is a rubber mixture wrapped in polydimethylsiloxane.

2. The dense ultra-thin asphalt overlay layer according to claim 1 is characterized in that: The cover layer further comprises 0.5-1.0 parts by weight of basalt fibers with a length of 6-12 mm.

3. The dense ultra-thin asphalt overlay layer according to claim 1 is characterized in that: The modified rubber filler is prepared by the following steps: dissolving polydimethylsiloxane in an aromatic hydrocarbon solvent to prepare a solution, placing waste rubber powder in the solution, and preparing a rubber mixture coated with polydimethylsiloxane through evaporation and drying; wherein the amount of polydimethylsiloxane added is 3-10% of the mass of the waste rubber powder.

4. The dense ultra-thin asphalt overlay layer according to claim 1 is characterized in that: The mineral material is one of basalt or limestone aggregates, and its gradation type is stc-5. Under the gradation, the proportion of each grade of coarse aggregate is 3-5mm 62-67%, 0-3mm 18-23%, and mineral powder is 10-20%.

5. The dense ultra-thin asphalt overlay layer according to claim 1 is characterized in that: The fly ash contains SiO2 at a content of 42-61%, Al2O3 at a content of 20-30%, and CaO at a content of 5-18%.

6. The dense ultra-thin asphalt overlay layer according to claim 1, characterized in that: The water reducer is one of polycarboxylate water reducer, sulfonate water reducer or fatty acid salt water reducer; the type of SBS modified asphalt is type IA, type IB, type IC or type ID.

7. The dense ultra-thin asphalt overlay layer according to claim 1 is characterized in that: The antifreeze agent is a mixture of sodium acetate and ethylene glycol in a weight ratio of 1:(1-3).

8. A method for preparing the dense ultra-thin asphalt overlay layer according to claim 1, characterized in that: The method comprises the following steps: uniformly mixing mineral material, SBS modified asphalt, modified rubber filler, fly ash and antifreeze agent, adding water according to a water-cement ratio of 0.18-0.22, adding a water reducer at the same time, stirring for 3-5 minutes to obtain the mixture, and paving the mixture to form a dense ultra-thin asphalt overlay layer.

9. A method for preparing the dense ultra-thin asphalt overlay layer according to claim 2, characterized in that: The method comprises the following steps: uniformly mixing mineral material, SBS modified asphalt, modified rubber filler, fly ash and antifreeze agent, adding water according to a water-cement ratio of 0.18-0.22, adding a water reducer at the same time, stirring for 3-5 minutes, adding basalt fiber and stirring for 10-15 minutes to obtain the mixture, and paving the mixture to form a dense ultra-thin asphalt overlay layer.

10. The method for preparing a dense ultra-thin asphalt overlay layer according to claim 8 or 9, characterized in that: The thickness of the dense ultra-thin asphalt overlay layer is 0.8-1.5 cm.

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