The rapid advancement of expressways today has led to the widespread use of asphalt concrete pavements, which have seen the development of comprehensive equipment and technology focusing on pavement structure, raw materials, construction techniques, and inspection. This has significantly enhanced the technical proficiency of construction projects. Some asphalt concrete pavements now match or nearly reach international excellence in terms of technique and quality. However, the quality of these pavements is affected by numerous factors including personnel, raw materials, machinery, technical processes, environmental conditions, and the complexity and interconnectedness of the construction procedures. Thus, an essential supervision system is crucial. Engineering supervisors and construction companies should strictly adhere to approved plans and guidelines to execute orderly and appropriate construction activities.
Every step in the pavement construction process directly impacts the overall quality. Therefore, meticulous oversight of each phase is vital to ensure the production of high-quality asphalt concrete pavement.
1. Mixing Asphalt Mixture
During the asphalt concrete mixing process, quality inconsistencies may arise due to various factors such as temperature imbalances, inconsistent aggregate sizes, or improper screening. These issues can alter the flow value and porosity, negatively affecting pavement quality. To address this, daily extraction and screening tests are conducted, with results analyzed to guide production adjustments. Cold hopper proportions are frequently adjusted, and oscillating screens in the mixing plant are calibrated accordingly. Practical experience shows that using circular hole screens with specified dimensions is effective. For instance, a 33mm, 16mm, 6mm, and 3mm setup has yielded favorable outcomes. Professional inspectors continuously monitor the mix's formation to immediately rectify any issues.
2. Rolling Processing Technology
Compaction is pivotal for creating asphalt surfaces, ensuring physical and mechanical properties align with design standards. Supervisors implement strict oversight at all levels, correcting deviations promptly. Key considerations include:
- Ensuring proper rolling temperatures to prevent edge voids.
- Avoiding sudden braking or acceleration on freshly laid surfaces.
- Regulating water application to the vibrating roller to prevent excessive cooling and cracking.
- Checking tire pressures and conditions before using the tire method to maintain surface evenness.
3. Penetration Macadam Surface Layer Construction
Follow these steps for constructing a penetration macadam surface layer:
- Prepare the sub-base and construct curbs.
- Apply a permeable oil layer to the prepared surface.
- Lay the primary layer of gravel, ensuring consistent particle size distribution and proper loose-laying thickness.
- Compact the gravel using a 6-8 ton vibrating roller at 2 km/h, overlapping wheel tracks by 30 cm.
- Adjust the road arch and correct any deviations after initial compaction.
- Use a 10-12 ton roller for further compaction, overlapping wheel tracks by more than half, rolling 4-6 times until the surface stabilizes.
4. Asphalt Concrete Mixing Guidelines
Adhere to the following rules:
- Precisely control mineral and asphalt usage according to the gradation chart.
- Monitor raw material and asphalt heating temperatures.
- Ensure uniform mixing without segregation or clumping.
- Regularly sample asphalt concrete for characteristic analysis and grading composition.
5. Sampling and Testing
Construction site tests must yield reliable results. Samples are taken statistically to measure asphalt mix proportions. Test pieces are extracted from compacted pavement for density checks. If discrepancies arise, immediate corrective actions are taken.
6. Paving Quality
Paving quality directly affects overall pavement performance. Key concerns include:
- Maintaining consistent asphalt thickness to achieve uniform compaction.
- Addressing uneven screed temperatures to ensure flatness.
- Matching the paver’s feeder and paving rates to prevent material accumulation.
- Ensuring a steady paving speed of 3-4 meters per minute to minimize shutdowns.
- Using ground leveling beams to enhance surface smoothness and thickness.
7. Joint Inspection
Address joints through:
- Cutting cross-sections to create positive drooping surfaces.
- Removing crushed sections and maintaining continuous tamping until paving ends.
- Gradual compaction with coarse materials to achieve standard cutoffs.
- Leveling structural connections with proper filling and rolling.
By implementing these measures, we can enhance pavement quality and longevity, ensuring compliance with rigorous standards.
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