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D4013-09 – Standard Test Method Technical Guide
ASTM D4013-09 defines a standardized practice for preparing 4-in. (101.6 mm) diameter cylindrical specimens of bituminous mixtures using a Gyratory Shear Compactor. The method is intended for mixtures containing aggregate up to −7⁄8-in. (−22.4 mm). The compaction process simulates the density, aggregate degradation, and structural characteristics achieved during proper road construction.
📐 Scope and Specimen Geometry
This practice specifically covers the preparation of 4-in. (101.6 mm) diameter test specimens of bituminous mixtures containing aggregate that passes the −7⁄8-in. (−22.4 mm) sieve. The resulting specimens mimic the density and structural properties of the actual road surface when proper construction procedures are followed. These specimens are suitable for subsequent testing to determine stability, density, strength, and water susceptibility.
⚠️ Unit Precedence and Safety: Values are stated in inch-pound units as the standard. SI equivalents in parentheses are mathematical conversions provided for information only. This practice does not purport to address all safety concerns; it is the responsibility of the user to establish appropriate safety and health practices.
⚙️ Compaction Parameters and Procedure
The procedure employs a gyratory-shearing action at low initial pressures to orient aggregate particles, followed by a high-pressure nongyratory compression phase for final consolidation. The following stresses are critical to the procedure:
- Pregyration Stress: 31.8 psi (219 kPa) / 400 lbf (1779 N) – applied while the tilt mechanism cocks the mold 6°.
- End Point Stress: 95.3 psi (657 kPa) / 1200 lbf (5338 N) – monitored by the low-pressure gauge.
- Consolidation Stress: 1590 psi (11.0 MPa) / 20,000 lbf (89 kN) – monitored by the high-pressure gauge.
The gyration mechanism moves the mold through a 12° total angle at approximately 1 second per cycle. The count mechanism shuts the gyration motor off after exactly three complete cycles and stops it in the loading position using an electric brake.
💡 Hydraulic Control: The hydraulic hand pump must meter precise ram movements (minimum of 0.020-in. (0.508 mm) per stroke). The low-pressure gauge is equipped with an automatic valve to protect against accidental high-pressure damage during the transition to the consolidation phase.
📊 Key Apparatus Specifications
The GSC apparatus relies on precisely machined components to ensure uniform compaction.
| 🟦 Phase | 📏 Pressure (inch-pound
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