Construction Condition Assessment
Base Layer Moisture Control
1. The base layer surface must be completely dry, without standing water or water accumulation.
After rain, the base layer must be drained to ensure no standing water.
The moisture content of the base layer must be controlled below 5%. Drying can be accelerated using a blower or natural air drying.
Low-lying areas with standing water must be filled to prevent the mixture from coming into contact with water and causing delamination.
Ambient Temperature Requirements
1. The ambient temperature for construction must meet the specifications.
The construction temperature for expressways and Class I highways must not be lower than 10℃.
The construction temperature for other highway grades must not be lower than 5℃. Paving should not be carried out during cold seasons or when rapid compaction cannot be guaranteed due to strong winds and temperature drops.
Weather Condition Assessment
1. Ensure there is no rainfall during construction.
Closely monitor the weather forecast before construction and schedule construction during periods without rain.
Construction should not be carried out within 24 hours after rain; wait until the base surface is completely dry.
Special measures must be taken when the relative humidity is higher than 80%.
Key Points for Construction Preparation
Material Selection and Treatment
1. Select water-resistant materials
Preferably use modified emulsified asphalt-based cold mix
Cement (1%–2%) can be added to improve water stability
Aggregates must be clean, dry, and have a moisture content ≤3%
2. Material Storage Requirements
Cold mixes should be stored in sealed containers to prevent moisture absorption and clumping. Emulsified asphalt in drums must be protected from rainwater infiltration. Sufficient rainproof materials such as plastic sheeting and rain shelters should be stocked. Equipment Commissioning and Preparation
1. Construction Equipment Inspection
Pre-commission asphalt mixing plants, pavers, road rollers, etc.
Ensure the normal operation of equipment during rainy season construction. Provide sufficient drainage equipment such as water pumps and drainage pipes.
2. Emergency Equipment Preparation
Prepare generators, lighting equipment, and other emergency equipment. Ensure proper equipment maintenance to improve reliability. Construction Process Control
Paving Operation Requirements
1. Paving Temperature Control
The paving temperature of hot mix asphalt mixtures must meet the specifications. The paving temperature should ideally be 130℃–160℃. Construction on urban expressways and main roads should not be carried out when the air temperature is below 10℃.
2. Paving Process Control
Mechanical paving should be used, maintaining uniformity and continuous operation.
The paving speed should be 2–6 meters per minute.
The auger feeder should rotate continuously to prevent segregation of the mixture.
Compaction Process Control
1. Compaction Temperature Requirements
The initial compaction temperature must meet the specifications, ensuring the mixture is stable. The final compaction temperature must meet the specifications; a double-drum steel roller is recommended. The rollers should be kept clean during compaction; brushing with diesel fuel is strictly prohibited.
2. Key Points of Compaction Process
Compaction should be carried out in three stages: initial compaction, intermediate compaction, and final compaction. The roller should compact at a slow and uniform speed. The overlap width of adjacent compaction strips should be 10–20 cm.
Joint Treatment Requirements
1. Joint Quality Control
Construction joints should be tight and smooth. Longitudinal hot joints of upper and lower layers should be staggered by 15 cm. Cold joints should be staggered by 30–40 cm.
2. Joint Construction Process
Surface layer joints should be straight.
Before applying cold joints, a small amount of asphalt should be applied to the joint surface and preheated.
Anti-reflective cracking measures should be taken at the joints.
Quality Inspection and Maintenance
Quality Inspection Requirements
1. On-site Testing Items
Strictly control compaction, thickness, aggregate gradation, and asphalt content.
Test the factory temperature and on-site temperature of the asphalt mixture.
Conduct Marshall tests to check aggregate proportions and asphalt content.
2. Special Testing Items
Adhesion Test: Pull-out test 24 hours after construction.
Water Stability Verification: Immersion Marshall test.
Drainage Performance: On-site permeability coefficient test.
Maintenance Management Requirements
1. Curing Time Control
Hot-mix asphalt pavement should be allowed to cool naturally until the surface temperature is below 50℃ before opening to traffic.
Extend the molding time to 48-72 hours in humid environments.
Vehicle traffic is prohibited within 24 hours after compaction.
2. Maintenance Measures
Systematic inspection is required after construction.
Mark repaired areas for later tracking.
Establish a record of crack width changes to predict expansion trends.