Colored asphalt concrete mixing and pavement construction technology

3.1 Mixing of Blends. The mixing of colored asphalt with regular asphalt is generally similar, but the following points should be emphasized:

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

② The properties of raw materials should be stable, allowing the production target blend ratio to approach the design blend ratio as closely as possible.

③ Due to the high specific gravity of the color powder, which imparts coloring, dispersion, adsorption, stabilization, and thickening properties to 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 proportion, 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 mixing time 10 seconds longer than that of regular asphalt mixtures. After discharging, it is essential to promptly inspect the granular material and color for uniformity.

3.2 Mixed Material Spreading

3.2.1 Before laying colored asphalt mixture, the quality of the subgrade should be carefully inspected to ensure it is firm, level, and clean. Additionally, the working condition of the laying and compaction machinery should be checked to avoid stoppage during construction due to insufficient preparation.

3.2.2 To enhance the adhesion of the surface and reduce water infiltration into the road structure, the subgrade should be cleaned thoroughly before paving. An emulsified asphalt should be sprayed, with a dosage of 0.3-0.5 kg/m2.

At the beginning of the laying process, strictly adhere to the loose laying elevation and use spacers to properly elevate the smoothing plate, ensuring the initial laying thickness meets the requirements.

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

3.2.4 The mixed material should be spread in full width, forming a continuous layer in one go to ensure uniform color, even granules, and aesthetics.碾压 should be done 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 tire rollers causing severe contamination and adhesion on colored asphalt surfaces during compaction, their use is not permissible.

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.

Initial temperature should be controlled between 130℃ and 145℃, final temperature should not be lower than 70℃, and the rolling process should be carried out according to the principle of "close follow-up, slow pressing, high frequency, and low amplitude".

Under normal circumstances, the碾压 combination method is determined based on the results of the trial section laying. The conventional approach is:

① The initial compaction is completed by passing a heavy roller over the road surface once in static mode, followed by one pass with light vibration compaction; the initial compaction is then finished.

② The main compaction work is performed by a light roller, with the number of passes depending on the site conditions until full compaction is achieved.

③Once the edge treatment of the lightweight roller is completed and the road temperature drops to 80°C, the final compaction begins. The heavy roller performs a static pass 1-2 times until the wheel tracks are completely eliminated, at which point the compaction process is finished.

3.4 Details to Note During the Crushing Process:

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

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

3.4.3 To prevent contamination of the colored asphalt surface, it is necessary to rinse off debris and sand adhering to the roller's steel wheels with water prior to rolling. Only after confirming the cleanliness of the rolling equipment should compaction be permitted. Additionally, traffic can only be opened once the temperature has cooled to ambient after rolling is completed.