Slurry seal and micro-surfacing technologies play a crucial role in road construction. These two technologies not only effectively extend the service life of pavements but also significantly improve road safety. By understanding the principles and applications of these technologies, we can better grasp the key aspects of pavement maintenance and contribute to road safety and smooth traffic flow.
1. Construction Standards
1.1 > Material Standards
In the field of road construction, slurry seal and micro-surfacing technologies are widely used in pavement maintenance to extend pavement service life and improve road safety. Slurry seal typically uses unmodified emulsified asphalt, such as BC-1 and BA-1 types, with a residue content of no less than 60%. Micro-surfacing uses cationic polymer-modified emulsified asphalt, model CQS-1h fast-setting type, with a residue content of no less than 62% and a modifier dosage of no less than 3%. The aggregate sand equivalent used in slurry seal should be no less than 45%, and the abrasion loss should not exceed 35%. Microsurfacing requires an aggregate sand equivalent of over 65% and an abrasion loss of no more than 30% to ensure the material is clean, hard, and wear-resistant.
1.2 > Performance Standards Slurry seal is often used as a surface overlay for road surfaces; if used as a sub-seal, it has no special requirements for skid resistance. Microsurfacing, however, requires good skid resistance to handle high traffic volumes and provides a rough, skid-resistant surface. Both should bond firmly to the existing pavement to ensure good water sealing and prevent water damage. Under suitable temperature (24℃) and humidity (less than 50%), a 12.7mm thick microsurfacing can be opened to traffic within one hour after application. In contrast, slurry seal takes longer to open to traffic; fast-opening types typically require several hours, while slow-opening types can take up to 12 hours. The surface should be smooth, straight, without any slippage, and dense and firm, free from scratches, wheel tracks, cracks, or areas with excessive or insufficient coverage. Longitudinal and transverse joints should be smooth, tight, and uniform in color. The mixture must not overflow the road surface, and waste materials should be cleaned up promptly to keep the road clean.
2. Detailed Construction Process
2.1 > Construction Preparation
Before formal construction, a test section should be paved to determine the optimal construction process and mix proportions. Simultaneously, prepare equipment including a slurry sealer, road roller, air compressor, and water truck, and calibrate them to ensure normal operation and accurate mix proportions. In addition, prepare auxiliary tools such as shovels and rubber mops.
2.2 > Existing Road Surface Treatment and Paving Construction
Conduct a comprehensive inspection of the existing road surface, repairing cracks, potholes, and other defects. Cracks wider than 5mm require grouting; ruts with a depth between 15 and 40mm require milling. Simultaneously, use high-pressure water to clean the road surface to ensure it is clean and free of standing water. Adjust the paving equipment to ensure close contact with the road surface. Start the auger distributor in the paving box to begin mixing and paving the mixture.
2.3 > Joint Treatment and Repair
Transverse joints are butt-jointed, with tar paper covering the end of the previous section for 1 to 3 meters, ensuring the tar paper edge is flush with the edge of the slurry seal material. After paving, remove the tar paper and the mixture over it at the joint. Longitudinal joints are lapped, with an overlap width controlled between 30 and 70 mm, and the overlap not exceeding 6 mm. Immediately after paving, manual leveling is performed, focusing on the starting and ending points, longitudinal joints, and areas that are too thick or too thin.
2.4 > Early Curing and Opening to Traffic
During paving, material usage must be closely monitored. If any material is running low, the conveyor switch should be immediately shut off to ensure paving continuity. Traffic can be opened when the mixture has completely solidified, the surface no longer scatters, and it has good water tightness. For slurry seal applications in areas such as hard shoulders or parking lots, it is recommended to use a 6t to 10t pneumatic tire roller to compact the pre-formed mixture after demulsification, thereby further improving the water sealing effect and density.