What are the quality requirements for the selection of coarse aggregate and sand aggregate for asphalt concrete bases?
September 14 07:13:01, 2025
I. Asphalt Concrete Base: Quality Requirements for Coarse Aggregates
For the asphalt concrete base course, the quality requirements of the coarse aggregate used in the selected asphalt concrete should comply with the standards set for urban road projects, as outlined in Table 1.4.6.
**Coarse Aggregate Quality Requirements for Asphalt Concrete Base**
| **Index** | **Asphalt Concrete Base** |
|------------------------------------|---------------------------|
| Stone Crush Value (not more than %) | 30 |
| Los Angeles Abrasion Loss (not more than %) | 40 |
| Apparent Density (not less than t/m³) | 2.45 |
| Water Absorption (not more than %) | 2.0 |
| Adhesion to Asphalt (not less than) | Level 3 |
| Durability (not more than %) | 12 |
| Flaky and Elongated Particles (not more than %) | 20 |
| Particle Content by Washing Method (not more than %) | 1 |
| Soft Stone Content (not more than %) | 5 |
| Polishing Value (not less than BPN) | 42 |
| Impact Value (not more than %) | 28 |
| Crushed Stone Content (for upper, middle, and lower layers, not less than %) | 40 |
*Note: Ruggedness tests may be conducted as needed. The stone polishing value, impact value, and other parameters should be referenced according to the "Asphalt Pavement Construction and Acceptance Specifications."*
II. Quality Requirements for Sand Aggregate in Asphalt Concrete Base
For the asphalt concrete base course, the quality requirements for sand used in the selected asphalt concrete should also follow the specifications for urban road projects, as shown in Table 1.4.7.
**Natural Sand Specifications for Asphalt Concrete**
| **Square Hole Sieve (mm)** | **Round Hole Sieve (mm)** | **Percentage Passing (Coarse Sand)** | **Percentage Passing (Medium Sand)** | **Percentage Passing (Fine Sand)** |
|----------------------------|---------------------------|--------------------------------------|--------------------------------------|-------------------------------------|
| 9.5 | 10.0 | 100 | 100 | 100 |
| 4.75 | 5.0 | 90–100 | 90–100 | 90–100 |
| 2.36 | 2.5 | 65–95 | 75–100 | 85–100 |
| 1.18 | 1.2 | 35–65 | 50–90 | 75–100 |
| 0.6 | – | 15–29 | 30–59 | 60–84 |
| 0.3 | – | 5–20 | 8–30 | 15–45 |
| 0.15 | – | 0–10 | 0–10 | 0–10 |
| 0.075 | – | 0–5 | 0–5 | 0–5 |
| **Fineness Modulus (Mx)** | – | 3.7–3.1 | 3.0–2.3 | 2.2–1.6 |
*Note: This table is based on the "Asphalt Pavement Construction and Acceptance Specifications."*
In addition to these specifications, it's important to ensure that the aggregates are clean, free from organic impurities, and properly graded to meet the performance requirements of the asphalt pavement. Proper testing and documentation are essential to maintain quality control throughout the construction process.