Color asphalt concrete mixing and pavement construction technology

3.1 Mixing of blends. The mixing process for colored asphalt and regular asphalt blends is generally similar; however, special attention should be given to the following points:

Prior to mixing, the mixing tank of the mixing station, asphalt conveying pipes, transport vehicles, construction machinery and equipment should be thoroughly cleaned.

② Raw material properties should be stable, allowing the production target mix ratio to approach the design mix ratio as closely as possible.

③ Due to the high specific gravity of the color powder, which provides coloring, dispersion, adsorption, stabilization, and thickening effects in the mixture, its environmental impact must be considered during addition. Before production, the amount of color powder per batch of mixture should be calculated based on the target mixing ratio, packed in polyethylene plastic bags, and manually assisted in during the mixing process.

④ The mixing temperature should be maintained between 150℃ and 170℃, with a longer mixing time of 10 seconds compared to ordinary asphalt mixture. After discharging, it is essential to promptly check for uniformity of the granular material and color.

3.2 Mixed Material Spread

3.2.1 Prior to laying colored asphalt mixture, the quality of the subgrade should be meticulously inspected to ensure it is firm, level, and clean. Additionally, the working condition of the spreading and compaction machinery should be checked to prevent any downtime during construction due to inadequate preparation.

3.2.2 To enhance the interface bonding and reduce water penetration into the pavement structure, the subgrade should be cleaned thoroughly before laying, and emulsified asphalt should be sprayed, with a dosage of 0.3-0.5 kg/m2.

At the start of laying, strictly adhere to the loose laying elevation and properly pad the leveling plate with blocks to ensure the initial laying thickness meets the requirements.

Based on the project schedule, considering the production, transportation, spreading, and compaction capabilities of the mix, ensure continuous spreading and strictly control the paver's working speed between 2.0 to 2.5 m/min.

3.2.4 The width of the mixed material should be adjusted for full-width spreading, formed in one continuous pass to ensure uniform color, even particle distribution, and aesthetics.碾压 should be performed promptly after spreading.

3.3 Compacted Molding of Blended Material

3.3.1 Compaction Equipment Selection: Select the model, power, and number of rollers based on the scale of the project and the complexity of the construction site.

Due to the black rubber tires of the tire roller causing severe contamination and sticking to the colored asphalt surface during compaction, it is not advisable to use.

3.3.2 Compaction Combination Method: The compaction of colored asphalt mixture is also carried out in three stages: initial compaction, secondary compaction, and final compaction.

The initial pressing temperature should be controlled between 130℃ and 145℃, with the final pressing temperature not less than 70℃. The rolling process should be carried out according to the principle of "quickly follow, slowly press, high frequency, and low amplitude."

Generally, under normal circumstances, the rolling combination method is determined based on the results of the test section laying. The conventional approach is:

① The initial compaction is completed by passing a heavy roller over the road surface once statically, followed by one pass with light vibration compaction, at which point the initial compaction is finished.

② The primary compaction work is carried out by a light roller, with the number of passes depending on the site until full compaction is achieved.

③Upon completion of the edge treatment by the light compactor, and when the road temperature drops to 80°C, the final compaction begins. It is carried out by a heavy compactor performing 1-2 passes of static compaction until all wheel marks are completely eliminated, at which point the rolling is finished.

3.4 Details to Note During the Crushing Process:

3.4.1 To prevent the sticking phenomenon during the roller compaction process, you can add laundry detergent (0.15kg/m3) to the roller's water tank for proper lubrication of the steel wheels, thereby avoiding sticking issues with the steel wheel roller.

3.4.2 To ensure civil construction, prevent damage to curb stones due to excessive edge碾压 by heavy roller compactor, during the compacting process, the distance between the steel wheels of the heavy roller compactor and the curb stones should not be less than 15 cm. The remaining area will be compacted by a light roller compactor under the guidance of a designated person.

3.4.3 To prevent contamination of the colored asphalt surface, prior to rolling, it is mandatory to rinse off debris and sand adhering to the steel wheels of the roller with water. The rolling equipment must be confirmed clean before rolling is permitted to commence. Additionally, traffic can only be reopened after the temperature has cooled down to ambient, following the completion of rolling.