Cement pavement "white to black" long-life epoxy asphalt thin layer cover and its construction method

Abstract

The application discloses a cement pavement "white to black" long-life epoxy asphalt thin-layer overlay and a construction method thereof. The epoxy asphalt thin-layer overlay structure is sequentially composed of a modified emulsified asphalt bonding layer, a 2cm AC-5 rich-oil modified asphalt mixture stress absorption layer and a 4cm AC-13 high-toughness plastic epoxy asphalt mixture surface layer from bottom to top. The core lies in that high-toughness plastic epoxy modified asphalt is used as a binder, which has excellent flexibility and strength. The structure can effectively reduce more than 50% of reflection cracks, and the road performance of the surface mixture is improved by more than 50% compared with ordinary asphalt mixture. The application realizes a total overlay thickness of only 6cm, reduces initial investment and material consumption, improves the durability of the pavement, prolongs the design service life by more than 50%, and solves the technical problems of thick overlay, easy damage and short service life in traditional "white to black" technology.

Description

Technical Field

[0001] This invention relates to the field of road construction materials technology, and in particular to a long-life epoxy asphalt thin-layer overlay for cement pavement "white-to-black" conversion and its construction method. Background Technology

[0002] Cement concrete pavements have been rapidly adopted due to their advantages such as high strength, mature technology, and relatively low investment, especially in areas with complex geological conditions and climates. Currently, under the dual pressure of heavy traffic flow and heavy loads, most of these cement pavements have developed varying degrees of damage. These damages significantly affect the quality of road traffic, pose serious safety hazards, and hinder economic development.

[0003] To meet the increasing travel needs and environmental protection requirements, since 2011, ordinary national and provincial highways have undergone annual "white-to-black" road surface renovation, primarily employing a scheme of treating existing road defects and then overlaying a 12cm or 18cm asphalt mixture. However, this thick overlay results in high initial investment, and the thinner layer is prone to rapid aging, cracking, and water damage under harsh service conditions such as high temperatures and heavy rainfall, leading to frequent and difficult maintenance. Due to insufficient performance of modified asphalt and unreasonable structural design, the service life of both "white-to-black" road surfaces and newly constructed asphalt pavements often fails to meet design life requirements, resulting in significant resource waste and economic losses. With the continuous advancement of my country's transportation development plans and policies, especially regarding extending road surface service life and improving environmental sustainability, developing durable, long-life pavements has become the recognized fundamental solution to this problem. The development and structural design of novel high-toughness and plastic epoxy-modified asphalt pavement materials are key issues that urgently need to be addressed to solve the technical dilemmas of "white-to-black" transformation of cement pavement and the durability of asphalt pavement, and to achieve long-life asphalt pavement. Summary of the Invention

[0004] Objective: To address the above problems, this invention provides a long-life epoxy asphalt thin-layer overlay for cement pavement "white-to-black" conversion and its construction method.

[0005] Technical solution: A long-life epoxy asphalt thin-layer overlay for "white-to-black" conversion of cement pavement, wherein the epoxy asphalt thin-layer overlay comprises, from bottom to top:

[0006] Modified emulsified asphalt bonding layer;

[0007] The stress-absorbing layer of oil-rich modified asphalt mixture is paved with AC-5 graded oil-rich asphalt mixture and has a thickness of 2cm.

[0008] A high-toughness, plastic epoxy asphalt surface layer, wherein the surface layer is laid with AC-13 graded high-toughness, plastic epoxy asphalt mixture, and the thickness is 4cm;

[0009] The high-toughness plastic epoxy asphalt binder of the high-toughness plastic epoxy asphalt surface layer is composed of the following components in parts by weight: 100 parts of 70# or 90# road petroleum asphalt; 20-30 parts of epoxy component system; 5-10 parts of toughening agent; 0.5-2 parts of anti-aging agent; and 0.5-1.5 parts of coupling agent. The epoxy component system is composed of bisphenol A type epoxy resin and modified amine curing agent, wherein the bisphenol A type epoxy resin accounts for 60%-70% of the total mass of the epoxy component system, and the modified amine curing agent accounts for 30%-40% of the total mass of the epoxy resin component system.

[0010] Preferably, the material of the modified emulsified asphalt binder is a high-permeability modified emulsified asphalt binder, and its application rate is 0.8~1.2 L / m2.

[0011] Preferably, the binder used in the oil-rich modified asphalt mixture is modified asphalt, which is composed of base asphalt, fillers, toughening agents and other modifiers, and has an elongation at break of not less than 300% and a tensile strength of not less than 4.5 MPa at 25°C.

[0012] Preferably, the total amount of the epoxy resin system is 25%–30% of the total mass of the asphalt binder, and the mass ratio of bisphenol A epoxy resin to modified amine curing agent is 1.5–2.0:1.

[0013] Preferably, the penetration index (PI) of the high-toughness plastic epoxy modified asphalt is not less than +1.0, and the adhesion grade with aggregate is not less than level 5.

[0014] Preferably, the stress-absorbing layer uses AC-5 graded oil-rich modified asphalt mixture, and its key sieve passing rates must meet the following requirements: 90-100% passing rate for 4.75mm sieves, 60-80% passing rate for 2.36mm sieves, 6-10% passing rate for 0.075mm sieves, a designed asphalt-aggregate ratio of 7.0-8.5%, and a designed porosity of 3.5-4.5%.

[0015] Preferably, the surface layer uses AC-13 graded high-toughness plastic epoxy asphalt mixture, and its key sieve passing rates must meet the following requirements: 13.2mm sieve passing rate of 95~100%, 4.75mm sieve passing rate of 50~65%, 2.36mm sieve passing rate of 30~45%, 0.075mm sieve passing rate of 4~7%, designed asphalt-aggregate ratio of 5.5~6.5%, and designed porosity of 3.0~4.0%.

[0016] Preferably, the high-toughness plastic epoxy asphalt mixture used in the ultra-thin overlay layer has a dynamic stability of not less than 10,000 cycles / mm, a low-temperature flexural strain of not less than 4,500 με, and a freeze-thaw splitting strength ratio of not less than 95%.

[0017] This solution also provides a construction method for long-life epoxy asphalt thin-layer overlay on cement pavement for "white-to-black" conversion, including the following steps:

[0018] Treatment and cleaning of old cement concrete pavement;

[0019] Modified emulsified asphalt bonding material is sprayed onto the treated road surface to form the modified emulsified asphalt bonding layer.

[0020] An AC-5 graded oil-rich modified asphalt mixture is spread and compacted on the modified emulsified asphalt bonding layer to form a stress-absorbing layer with a thickness of 2 cm.

[0021] A high-toughness, plastic epoxy asphalt mixture of AC-13 gradation is spread and compacted on the stress-absorbing layer to form the surface layer with a thickness of 4 cm.

[0022] Preferably, the mixing and discharge temperature of the high-toughness and plastic epoxy asphalt mixture is 150~160℃, and the paving temperature is not lower than 150℃; the compaction process includes: initial compaction at above 135℃, secondary compaction at 100~120℃, and final compaction at above 95℃, and adopts a compaction process combining vibration compaction and tire compaction.

[0023] Beneficial effects: This invention, through a composite epoxy asphalt overlay structure only 6cm thick, effectively suppresses reflective cracks by more than 50% while saving materials and costs; this solution improves key pavement performance by more than 50%, extends design life by more than 50%, and combines excellent durability with economic efficiency throughout the entire life cycle. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the epoxy asphalt thin-layer overlay of the present invention.

[0025] Figure 2 This is a flowchart of the construction method for epoxy asphalt thin-layer overlay of the present invention. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present invention.

[0027] Taking the "white-to-black" renovation project of a national highway cement concrete pavement as an example, this invention is specifically implemented.

[0028] Old road surface treatment

[0029] The old cement concrete pavement was inspected and treated. Cracks wider than 3mm were filled with epoxy resin; locally broken slabs were replaced and repaired. Subsequently, shot blasting was used to treat the entire pavement to thoroughly remove surface laitance and contaminants, exposing a clean, rough surface. Testing showed that residual dust on the surface was less than 0.1 g / m2.

[0030] Material preparation

[0031] Preparation of high-toughness, plastic, epoxy-modified asphalt: 70# road petroleum asphalt was heated to 140℃, and a pre-mixed epoxy resin system (component A to component B mass ratio of 3:1) was added at a ratio of 30% of the total asphalt mass. Simultaneously, a plasticizer (such as carboxyl-terminated liquid nitrile rubber) was added at 5% of the total asphalt mass. The mixture was then sheared and blended at 150℃ and 4000 r / min for 15 minutes to obtain the finished product. Its elongation at break at 25℃ was 320%, and its tensile strength was 4.8 MPa.

[0032] (2) Mixture design:

[0033] Stress-absorbing layer (AC-5): The modified asphalt is used as the binder, with an asphalt-aggregate ratio of 7.8%. The key sieve passing rates of the synthetic gradation are controlled as follows: 4.75 mm (95%), 2.36 mm (70%), and 0.075 mm (8%). The Marshall test determined the design porosity to be 4.0%.

[0034] Surface layer (AC-13): Uses the same epoxy-modified asphalt, with an asphalt-aggregate ratio of 6.0%. The key sieve passing rates of the synthetic gradation are controlled as follows: 13.2mm (98%), 4.75mm (58%), 2.36mm (38%), and 0.075mm (5.5%). The designed porosity is 3.5%.

[0035] Construction process

[0036] (1) Spraying modified emulsified asphalt binder: On the cleaned road surface, use an intelligent sprayer to evenly spray high-penetration epoxy asphalt binder, with the dosage controlled at 1.0 L / m. 2 Let it sit for 25 minutes until it is slightly sticky to the touch.

[0037] (2) Construction of stress-absorbing layer: The mixed AC-5 oil-rich modified asphalt mixture (discharge temperature 130℃) is transported to the site and laid immediately. The loose paving coefficient is 1.18, and the paving temperature is controlled to be no less than 122℃. The double-drum roller is used for static compaction once (initial compaction, temperature 115℃), the pneumatic tire roller is used for tumbling five times (secondary compaction, temperature 100℃), and the steel-drum roller is used for finishing twice (final compaction, temperature 95℃). The compacted thickness is 2.0cm.

[0038] (3) Paving the surface layer: After the stress-absorbing layer is compacted, continuous operation is carried out to pave AC-13 epoxy asphalt mixture (discharge temperature 155℃). The initial compaction is carried out with a vibratory roller (138℃), the secondary compaction is carried out with a pneumatic tire roller (5 passes, 105℃), and the final compaction is carried out with a steel wheel roller (98℃), with a compaction thickness of 4cm. The total thickness of the entire composite overlay is 6.0cm.

[0039] (4) Curing: After construction is completed, the road will be closed and allowed to cure naturally for 24 hours. The road will be opened after the road is fully cured.

[0040] 4. Effect Verification

[0041] Core samples were drilled from the completed road section and subjected to indoor testing. Performance was compared with an adjacent section using a conventional 6cm thick SBS modified asphalt AC-16 overlay. The results are as follows:

[0042] Interlayer bond strength: The average interlayer bond strength of the cover layer of the present invention is 1.72 MPa, which is more than twice that of the comparative section (0.85 MPa).

[0043] Anti-reflective cracking capability: Through three-point bending fatigue test simulation, the stress-absorbing layer of this invention increased the number of cycles required for crack propagation to reach completion by 2.3 times. After 18 months of operation, the comparison section showed 8 reflective cracks per kilometer, while the section with this invention showed only 3 cracks per kilometer, a reduction of 62.5%.

[0044] Road performance: The dynamic stability of the core sample of the cover of the present invention reaches 12,500 times / mm, the low temperature bending strain reaches 4,800με, and the freeze-thaw splitting strength ratio is 96.5%. All indicators are better than the comparative section (4,800 times / mm, 2,650με, and 86%, respectively), with an improvement of 50% to 160%.

[0045] Expected lifespan: Based on fatigue damage model calculations, under the same traffic load, the fatigue life of the canopy structure of the present invention can reach 19 years, which is about 73% longer than the expected fatigue life of the comparative section (about 11 years).

[0046] This embodiment fully demonstrates that the thin-layer overlay solution provided by the present invention, through innovative material and structural design, achieves a comprehensive improvement in interlayer bonding, crack resistance and overall road performance while significantly reducing the thickness, thus achieving the core goal of extending the service life of the pavement.

[0047] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A long-life epoxy asphalt thin-layer overlay for "white-to-black" cement pavement conversion, characterized in that, The epoxy asphalt thin-layer overlay, from bottom to top, includes: Modified emulsified asphalt bonding layer; The stress-absorbing layer of oil-rich modified asphalt mixture is paved with AC-5 graded oil-rich asphalt mixture and has a thickness of 2cm. A high-toughness, plastic epoxy asphalt surface layer, wherein the surface layer is laid with AC-13 graded high-toughness, plastic epoxy asphalt mixture, and the thickness is 4cm; The high-toughness plastic epoxy asphalt binder of the high-toughness plastic epoxy asphalt surface layer is composed of the following components in parts by weight: 100 parts of 70# or 90# road petroleum asphalt; 20-30 parts of epoxy component system; 5-10 parts of toughening agent; 0.5-2 parts of anti-aging agent; and 0.5-1.5 parts of coupling agent. The epoxy component system is composed of bisphenol A type epoxy resin and modified amine curing agent, wherein the bisphenol A type epoxy resin accounts for 60%-70% of the total mass of the epoxy component system, and the modified amine curing agent accounts for 30%-40% of the total mass of the epoxy system.

2. The epoxy asphalt thin-layer overlay according to claim 1, characterized in that, The modified emulsified asphalt binder is made of a high-permeability modified emulsified asphalt binder, with a spreading rate of 0.8~1.2 L / m2.

3. The epoxy asphalt thin-layer overlay according to claim 1, characterized in that, The binder used in the oil-rich modified asphalt mixture is modified asphalt, which is composed of base asphalt, fillers, toughening agents and other modifiers. Its elongation at break at 25℃ is not less than 300%, and its tensile strength is not less than 4.5 MPa.

4. The epoxy asphalt thin-layer overlay according to claim 3, characterized in that, The total dosage of the epoxy resin system is 25%–30% of the total mass of the asphalt binder, and the mass ratio of bisphenol A epoxy resin to modified amine curing agent is 1.5–2.0:

1.

5. The epoxy asphalt thin-layer overlay according to claim 1, characterized in that, The penetration index (PI) of the high-toughness and plasticity epoxy-modified asphalt is not less than +1.0, and its adhesion grade with aggregate is not less than level 5.

6. The epoxy asphalt thin-layer overlay according to claim 1, characterized in that, The stress-absorbing layer uses AC-5 graded oil-rich modified asphalt mixture, and its key sieve passing rates must meet the following requirements: 90-100% passing rate for 4.75mm sieves, 60-80% passing rate for 2.36mm sieves, and 6-10% passing rate for 0.075mm sieves. The designed asphalt-aggregate ratio is 7.0-8.5%, and the designed porosity is 3.5-4.5%.

7. The epoxy asphalt thin-layer overlay according to claim 1, characterized in that, The surface layer uses AC-13 graded high-toughness plastic epoxy asphalt mixture, and its key sieve passing rates must meet the following requirements: 13.2mm sieve passing rate 95~100%, 4.75mm sieve passing rate 50~65%, 2.36mm sieve passing rate 30~45%, 0.075mm sieve passing rate 4~7%, the designed asphalt-aggregate ratio is 5.5~6.5%, and the designed porosity is 3.0~4.0%.

8. The epoxy asphalt thin-layer overlay according to any one of claims 1-7, characterized in that, The high-toughness, plastic epoxy asphalt mixture used in the ultra-thin overlay layer has a dynamic stability of not less than 10,000 cycles / mm, a low-temperature flexural strain of not less than 4,500 με, and a freeze-thaw splitting strength ratio of not less than 95%.

9. A construction method for a long-life epoxy asphalt thin-layer overlay for cement pavement "white-to-black" conversion as described in any one of claims 1-8, characterized in that, Includes the following steps: Treatment and cleaning of old cement concrete pavement; Modified emulsified asphalt bonding material is sprayed onto the treated road surface to form the modified emulsified asphalt bonding layer. An AC-5 graded oil-rich modified asphalt mixture is spread and compacted on the modified emulsified asphalt bonding layer to form a stress-absorbing layer with a thickness of 2 cm. A high-toughness, plastic epoxy asphalt mixture of AC-13 gradation is spread and compacted on the stress-absorbing layer to form the surface layer with a thickness of 4 cm.

10. The construction method according to claim 9, characterized in that, The mixing and discharge temperature of the high-toughness and plastic epoxy asphalt mixture is 150~160℃, and the paving temperature is not lower than 150℃. The compaction process includes: initial compaction at 135℃ or above, secondary compaction at 100~120℃, and final compaction at 95℃ or above, and adopts a compaction process combining vibration compaction and tire compaction.

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