1. Review of the research and application of colored asphalt concrete pavement

The research and application of colored asphalt concrete pavement can be traced back to the 1950s, starting from European and American countries. This kind of pavement can not only better coordinate with the architectural art around the road, but also play a role in beautifying the city and inducing traffic. It can also reflect the characteristics and style of a country or a city and enhance the image and function of the entire city. , showing the style and charm of a modern city. Discussions in this area began in our country in the early 1980s, but there are still few applications on roads. In recent years, as a new paving technology, it is increasingly used on highways, roads or squares in order to create a contemporary atmosphere for transportation.

II. Overview of Colored Asphalt Concrete Pavement

1. Definition of Colored Asphalt Concrete Pavement:

The so-called colored asphalt concrete pavement refers to decolored asphalt and various Materials such as colored stones, pigments and additives are mixed at a specific temperature to form various colored asphalt mixtures, which are then paved and rolled to form colored asphalt concrete pavements with certain strength and road performance. .

2. Technical indicators of colored asphalt mixture:

(1) The main technical indicators of the binder (colored asphalt) should reach GB 50092-96 heavy traffic asphalt AH-50 ( Non-motorized lanes can also use AH-90) standards. That is, penetration (25℃): 40~60, ductility (15℃) 80, softening point (ring and ball method): 45~55.

(2) The Marshall stability of fine-grained colored asphalt mixture is 7.5kN, and the flow value is 20~40. The fine-grained AC10 colored asphalt mixture has a Marshall stability of 11.9kN and a flow value of 30.

3. The main performance characteristics of colored asphalt concrete pavement:

(1) It has good road performance, and its high temperature stability and resistance to different temperatures and external environments. The water damage resistance and durability are very good, and there is no deformation, asphalt film peeling, etc., and the adhesion to the base layer is good.

(2) It has bright and long-lasting color, does not fade, can withstand high temperatures of 77°C and low temperatures of -23°C, and is easy to maintain.

(3) It has strong sound-absorbing function. When car tires roll at high speed on the road, they will not produce strong noise due to air compression, and they can also absorb other noise from the outside world.

(4) It has good elasticity and flexibility, good foot feel, is most suitable for the elderly to walk, and is anti-slip in winter. In addition, the color mainly comes from the color of the stone itself, and will not cause any damage to the surrounding environment. Big harm.

3. Introduction to the mixing of colored asphalt concrete and its pavement construction

1. When mixing the mixture, you should pay attention to the following different matters from the mixing of ordinary asphalt mixture:

(1) Before mixing, the mixing tank of the mixing station, asphalt transportation pipelines, transport vehicles, construction machinery and equipment, etc. should be cleaned.

(2) In order to make the production target mix ratio as close as possible to the design mix ratio, the performance of the raw materials should be stable.

(3) When adding toner, its impact on the environment must be considered, because toner has a large specific proportion and has the functions of coloring, dispersing, adsorbing, stabilizing, and thickening in the mixture.

(4) The mixing temperature should be controlled at 160℃~170℃, and the mixing time should be 10 seconds longer than the normal time. After discharging, check whether the pellets and color are uniform.

2. Mixed material paving:

First of all, check whether the base layer is solid, flat and clean, and also check whether the paving and compaction machinery are in good working condition; < /p>

Then, clean the base layer and spray 0.3-0.5kgm2 of emulsified asphalt. Improve the interface adhesion and reduce the penetration of rainwater into the pavement structure;

Then, use pads to pad the screed in strict accordance with the loose paving elevation to ensure that the initial paving thickness meets the requirements; strictly control the paver The working speed (speed range: 2.0~2.5mmin) ensures continuous paving;

Finally, the entire width is paved, formed at one time without interruption, and rolled in time. Achieve consistent color, uniform pellets and beautiful appearance.

3. Mixed material compaction and forming:

(1) Road machinery selection: According to the size of the project and the complexity of the construction site, the model, power and number of rollers are selected . It is not advisable to use a tire roller because it will pollute and stick to the road surface.

(2) Pressure combination method: It is also divided into three stages: initial pressure, re-pressure and final pressure. The initial pressing temperature should be controlled between 130°C and 145°C, and the final pressing temperature should not be lower than 70°C. Rolling should be carried out according to the principles of tight follow-up, slow pressing, high frequency and low amplitude.

First, determine the rolling combination method based on the paving results of the test section;

Then, after the road surface is statically pressed once by a heavy-duty roller, it is rolled with light vibration for 1 time. One pass, that is, the initial compaction is completed;

Then, the light roller will complete the main work of re-compaction, and the number of rolling passes will be determined according to the on-site conditions until compaction;

Finally, Start final pressing when the road surface temperature drops to 80°C, and use a heavy-duty roller to press statically 1-2 times until the wheel marks are completely eliminated.

(3) Details that should be paid attention to during the compaction process:

① Properly lubricate the steel wheel to avoid material sticking in the steel wheel roller. It is recommended to add an appropriate amount of washing powder (0.15kgm3) to the water tank of the road roller.

② Combined compaction by light and heavy rollers. In order to avoid the heavy roller's steel wheels from damaging the curbs, the light rollers will roll the area 15CM close to the curbs.

③ Make sure that the rolling equipment is clean before rolling is allowed to proceed, in order to prevent the colored asphalt surface layer from being contaminated.

IV. Advantages, applications and development of colored asphalt concrete pavement technology

1. Colored asphalt concrete pavement technology has two major advantages:

(1) It has the effect of beautifying the city, improving the road environment, and displaying urban style. It is specifically used in urban streets, squares, scenic spots, parks, tourist attractions, etc.

(2) It has the function of inducing traffic flow and making traffic management intuitive. It is specifically used to distinguish road sections and lanes with different functions to improve driver recognition and increase road traffic capacity and traffic safety.

The most typical applications of colored asphalt concrete pavements abroad are: Japan’s National Highway 199 (street section) in Kyushu City, the lanes on both sides of the road are paved with iron red pavement; France’s Northeast Road in Paris, a long section The road surface of about 30km is blue; cities such as Amsterdam, The Hague and Rotterdam in the Netherlands have 1.5~2.0m iron-red asphalt bicycle lanes on the sidewalks; the boulevards in front of Buckingham Palace in London, UK are all paved with iron. Red pavement and so on.

The most typical applications of colored asphalt concrete pavements in China include: non-motorized lanes on both sides of Xiamen City Avenue about 4km and Huandao Road Tourist Scenic Road; Beijing Chang'an Street Extension and Xin Dacheng Color Basketball Court and Shijingshan Playground; Shenyang Botanical Garden Color Tour Road, Botanical Garden Color Tour Road (Phase II), Luda Color Roof, Huaxing Middle School Color Playground and Shenyang Beijing Street and Beiling Street Color Landscape Road; Shanghai Zhaojiabang Road and Taiyuan Road Slow lane, hundreds of meters of Admiral Street in Chengdu, 8m wide motor vehicle lanes will be built on the river beach in Wuhan, color scenic road of Binhai Middle Road in Yantai City, Royal Blue from the intersection of Huangpu Avenue and Chebei Road in Guangzhou to Guangyuan East Expressway overpass sidewalk, Liaoning Building Colorful Plaza and Nanjing Shengzhou Road sidewalk, etc.

At present, my country's colored asphalt concrete pavements have been successfully laid in more than 20 cities such as Xiamen, Guangzhou, Ningbo, Guilin, Yantai, and Beijing. The results are quite good and have been well received by the world.

2. Development of colored concrete pavement technology: At present, the focus abroad is on the research on the series and varieties of colored asphalt and its concrete pavement technology products, specifically in the following aspects:

(1 ) The production method of cementing material (colored asphalt) has evolved from the traditional decompression and dequality to using modern industrial petrochemical products to prepare polymer light-colored cementing material (colored asphalt) with properties equivalent to asphalt, and developed a red and yellow A series of colored asphalts mainly composed of , blue, green and camel (natural color), which have better color, performance and longer life.

(2) The production and construction technology of colored asphalt concrete has also been continuously improved and great achievements have been made. More than 10 kinds of colored asphalt such as red, yellow, blue and green have been laid and developed. Concrete pavement and production technology and the process flow of pavement construction form a complete set of colored asphalt concrete pavement application technology.

(3) Incorporate night-luminous materials such as glass beads into colored asphalt concrete materials. The luminous effect is better, making the road more eye-catching at night. It has high practical value in view of the complex highway network and numerous vehicles in my country.

(4) Another technology is colored slow cracking and fast setting emulsified asphalt slurry sealing layer. It is a colored slurry seal layer that combines colored asphalt and slurry seal technology. Due to the thin layer of overlay, there is no need for pre-processing such as milling of the original road surface, so it is easy to construct and reduces the cost of colored asphalt pavement. . This technology fills the domestic gap, is suitable for urban construction, and has high development value.

In short, colored asphalt concrete pavement has great advantages in beautifying the environment, adding urban style, guiding traffic, and reducing traffic accidents. Its highway performance is not inferior to ordinary asphalt highways. Although in terms of materials, There are disadvantages in terms of cost compared to ordinary asphalt roads. But it can be seen that after several years of research, the technical performance of my country's colored asphalt concrete pavement has basically synchronized with the international advanced level. Therefore, it can be believed that as the research on colored asphalt concrete pavement technology further develops and the construction method system is further developed, the disadvantages in this area will gradually disappear. Our country is moving towards becoming a world power. In the future, colored asphalt concrete pavement technology will be increasingly used in urban road construction. According to the current development trend of highway construction in my country, some experts have analyzed that colored asphalt concrete pavement is another hot spot in highway construction.