What kind of gravel is used for asphalt pavement? ——Comprehensive analysis of gravel selection and construction points
In road construction, the quality of asphalt pavement is directly related to service life and driving safety, and gravel, as the key aggregate for asphalt mixture, is crucial to its choice. This article will combine industry hotspots in the past 10 days to analyze the types of gravel, technical indicators, application scenarios, etc., and provide structured data for reference.
1. Comparison of commonly used gravel types on asphalt pavement
| Gravel type | Material Features | Compressive strength (MPa) | Applicable tiers | Market price (yuan/ton) |
|---|---|---|---|---|
| Basalt | High hardness and strong wear resistance | ≥200 | The upper layer | 80-120 |
| granite | Clear edges and good adhesion | 150-200 | Middle and lower layer | 60-90 |
| Limestone | Easy to process, low cost | 80-150 | Base layer/cushion layer | 40-70 |
| Diamondite | Excellent durability | ≥180 | Special sections | 100-150 |
2. The latest industry hot spot correlation analysis
1.Upgraded environmental protection requirements: Many places have introduced policies to restrict mining, promoting the recycling and utilization technology of gravel (RAP) to become a hot topic, and the proportion of recycled materials can reach up to 30%.
2.High temperature construction dispute: Recently, the use of limestone gravel with excessive mud content in a certain place has caused early damage to the road surface, which has caused extensive discussion on the standard of gravel mud content ≤1%.
3.Intelligent detection application: The AI-based gravel grading automatic identification system has been piloted in the Yangtze River Delta region, with detection efficiency increased by 300%.
3. Key technical indicators and requirements for gravel
| Indicator items | The upper layer requirements | Middle and lower levels requirements | Testing standards |
|---|---|---|---|
| Crush value | ≤20% | ≤25% | JTG E42-2005 |
| Needle sheet content | ≤15% | ≤18% | T0312-2005 |
| Water absorption rate | ≤2% | ≤3% | T0307-2005 |
| Los Angeles wear value | ≤28% | ≤30% | T0317-2005 |
4. Material selection suggestions under different climatic conditions
1.Alpine area: Basalt is preferred, and its low-temperature crack resistance is more than 20% better than granite.
2.Rainy areas: Acid stone (such as granite) should be used and anti-flaking agents should be added, and the water stability index should be ≥95%.
3.Heavy traffic section: It is recommended to use diaquat, the dynamic stability should be ≥6000 times/mm.
5. Key points of construction quality control
1.Grading control: The key screen hole pass rate of AC-13 type asphalt mixture should comply with: 35-50% of 4.75mm screen holes, 23-37% of 2.36mm screen holes.
2.Temperature management: The heating temperature of gravel should be controlled in the range of 160-180℃, and the temperature difference from asphalt is ≤15℃.
3.New technology: The recent popular warm-mixed asphalt technology can reduce the construction temperature by 30℃ and reduce thermal damage to gravel.
Conclusion: With the implementation of the "Outline for Building a Strong Transportation Country", the standardization and greening of gravel materials have become the industry development trend. It is recommended that the construction unit establish a full-process quality traceability system, and record the entire process data of gravel from mining to laying through blockchain technology to ensure the quality of pavement projects.
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