How to Construct Asphalt Pavement? A Comprehensive Guide to Standardized Processes, Technical Key Points, and Quality Control FAQs

 Asphalt pavement is the cornerstone of modern road construction. Its quality directly determines the service life and traffic safety of the road. To help industry professionals master standardized construction processes, this article provides a deep analysis of core links, technical parameters, and common quality control issues, aiming to ensure that the pavement reaches its 15-20 year design life.

I. Pre-construction Preparation: What are the Hard Indicators for Base Acceptance and Material Selection?

The foundation work before construction is critical to the smoothness and stability of the pavement.

1.Base Acceptance Standards:

1.Smoothness: When tested with a 3m straightedge, the gap must be controlled at ≤5mm.

2.Degree of Compaction: Under heavy compaction standards, it must reach ≥98%.

3.Deflection Value: It must be controlled within the design limit (the conventional standard is usually ≤200μm).

2.Material Quality Control:

1.Asphalt: Use AH70/AH90 heavy-duty asphalt with a penetration of ≥60 and a softening point of ≥45°C.

2.Coarse Aggregate: The crushing value should be ≤26%, and the maximum particle size should not exceed 31.5mm.

3.Fine Aggregate: The mud content should be controlled within 3%, and the sand equivalent should be ≥60%.

4.Mineral Filler: The hydrophilic coefficient should be ≤1.0 to ensure strong adhesion with the asphalt.

3.Equipment Calibration:

The screed of the paver must be preheated to above 100°C. The aggregate measurement error of the mixing plant should be within ±2%, and the asphalt error should be controlled within ±0.5%.

II. Asphalt Mixture Production: How to Ensure Proper Mix Ratio and Temperature?

1.Mix Design:

Determine the optimum asphalt content through the Marshall Test (usually between 4.5% and 5.5%), ensuring that the air void ratio is maintained at 3%-5% and the stability is not less than 8kN.

2.Production Temperature Control:

1.Aggregate Temperature: 190-220°C.

2.Asphalt Temperature: 150-170°C.

3.Mixture Discharge Temperature: 140-165°C.

4.Mixing Time: 5-10 seconds for dry mixing and 30-60 seconds for wet mixing. "White spots" (uncoated aggregate) are strictly prohibited.

III. Paving Operations: How to Achieve Continuous and Uniform Construction?

1.Interlayer Treatment:

1.Prime Coat: The dosage is 0.8-1.2kg/m², and the penetration depth must be ≥5mm.

2.Tack Coat: Use PC3 modified emulsified asphalt with a dosage of 0.3-0.6kg/m².

2.Core Paving Parameters:

1.Loose-fill Coefficient: Controlled between 1.05 and 1.10.

2.Paving Speed: Maintain a constant speed of 2-4m/min.

3.Arrival and Paving Temperature: The arrival temperature should be ≥130°C, and the paving temperature should not be lower than 120°C.

IV. Compaction Operations: What are the Requirements for Initial, Intermediate, and Final Compaction?

Compaction is the final stage in forming the strength of the asphalt pavement. It must be executed in stages and follow the rolling principle of "sides first, then middle; low first, then high."

1.Initial Compaction (Breakdown Rolling):

Initial compaction follows immediately after the paver to stabilize the mixture. Use a tandem steel drum roller for 1-2 static passes. The rolling temperature should be maintained above 110°C, and the speed should be controlled within 3km/h. The goal is to stabilize the mix while minimizing heat loss.

2.Intermediate Compaction (Secondary Rolling):

This is the core stage for achieving the required density. Usually, a vibratory roller is used for 4-6 passes with an amplitude of 0.3-0.5mm. The temperature during intermediate compaction should not be lower than 90°C, and the speed should be kept within 4km/h. High-frequency, low-amplitude vibration helps the aggregate particles rearrange into a dense state.

3.Final Compaction (Finish Rolling):

The main purpose of final compaction is to eliminate roller marks and smooth the surface. Typically, a pneumatic tire roller is used for 1-2 passes. The pavement temperature should not be lower than 70°C, and the speed can be slightly increased up to 5km/h.

Throughout the rolling process, the overlap of adjacent rolling strips should be maintained at 200mm or more to ensure uniform compaction without any missed areas.

V. Joint Treatment: How to Avoid Early Pavement Cracking?

1.Longitudinal Joints:

1.Hot Joints: Leave a 30-40cm strip uncompacted until the adjacent lane is paved, then roll across the joint.

2.Cold Joints: Cut the edges straight, apply a tack coat, and overlap by 10cm before rolling.

2.Transverse Joints: These are handled using a joint cutter. The cutting depth should be 1/2 of the layer thickness. After cleaning, roll across the joint 3-5 times to ensure smoothness and density.

VI. Quality Control: Core Detection Indicators and Common Defect Handling

1.Core Detection Indicators:

1.Compaction Degree: Tested by core drilling or nuclear density gauge, it must be ≥96%.

2.Smoothness: Tested by a continuous profilometer, the standard is ≤3mm/3m.

3.Permeability: Tested by a water permeability meter, it must be ≤120mL/min.

4.Skid Resistance: The texture depth measured by the sand patch method must be ≥0.5mm.

2.Emergency Handling of Defects:

1.Shoving and Corrugation: Check the screed temperature and appropriately reduce the paving speed.

2.Bleeding/Flushing: Appropriately reduce the asphalt content and increase the mineral filler ratio.

3.Cracking: The stability of the base course must be reinforced before repaving the surface layer.

VII. Maintenance and Traffic Opening: How Long After Construction Can the Road be Used?

·Closure Time: The road should be closed to traffic for 24-48 hours after final compaction.

·Traffic Opening Conditions: Traffic can be opened only when the pavement temperature drops below 50°C.

·Post-maintenance: Regular preventive maintenance such as micro-surfacing or slurry seal can effectively extend the pavement's life.

VIII. Environmental Protection and Safety: How to Achieve Green Construction?

·Dust Suppression: Equip the site with water trucks and mist cannons.

·Fume Treatment: Asphalt fumes must be treated through WESP or RTO systems before discharge.

·Personal Protection: Warning signs should be set up in high-temperature work areas, and workers must be equipped with professional heat-resistant protective gear.