Color 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:

Before mixing, the mixing tank of the mixing station, asphalt conveying pipeline, transport vehicles, construction machinery and equipment, etc., should be cleaned thoroughly.

② Raw material properties should be stable to ensure that the production target mix can approach the design mix as closely as possible.

③ Due to the high specific gravity of the color powder, it serves as a coloring, dispersing, adsorbing, stabilizing, and thickening agent in the mixture. When adding it, the environmental impact must be considered. Before production, the amount of color powder per batch of the mixture should be calculated based on the target proportion, packed in polyethylene plastic bags, and manually assisted in the blending process.

④ The blending temperature should be maintained between 150℃ and 170℃，with a blending time 10 seconds longer than that of regular asphalt mixture. Immediately after discharge, the particle size and color uniformity should be checked promptly.

3.2 Mixed Material Spreading

3.2.1 Prior to laying colored asphalt mix, carefully inspect the subgrade quality to ensure it is firm, level, and clean. Additionally, check the working condition of the spreading and compaction machinery to prevent work stoppages during construction due to inadequate preparation.

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

3.2.3 Upon starting the laying process, ensure the leveling plate is properly supported with blocks according to the specified elevation, to guarantee the initial laying thickness meets requirements.

Based on the project timeline, considering the production, transportation, spreading, and compaction capabilities of the mixture, 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 to full width, formed in one continuous pass, to ensure consistent color, even granular distribution, and aesthetics.碾压 promptly after spreading.

3.3 Compacted Molding of Blended Material

3.3.1 Compactor Selection: Select the model, power, and number of compactors 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 adhesive material on the colored asphalt surface during compaction, it is not suitable for 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.

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".

  Generally, under normal circumstances, the碾压 combination method is determined based on the results of the test section paving. 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, marking the end of the initial compaction.

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

③After 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 static compaction 1-2 passes until the 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 operation, you can add laundry detergent (0.15kg/m3) to the water tank of the roller to provide appropriate lubrication for the steel wheels, thus avoiding sticking issues with the steel wheel roller.

3.4.2 To ensure civil construction and prevent damage to curb stones caused by excessive edge碾压 during compaction, the distance between the steel wheels of the heavy roller and the curb stone should not be less than 15 cm during compaction. The remaining area will be compacted by a light roller under the guidance of a dedicated supervisor.

3.4.3 To prevent contamination of the colored asphalt surface, it is mandatory to wash off any debris and sand adhering to the steel wheels of the roller before compaction. The roller equipment must be confirmed clean before compaction is permitted. Additionally, traffic may only be reopened after the temperature has cooled to ambient and the compaction process is complete.