The most commonly used compaction methodologies for specimen preparation for the assessment of porous asphalt (PA) mix properties are gyratory and Marshall. Even though several individual blocks prepared by one of these test methods are usually considered to be replicates, the heating and handling histories are never identical as these are individual specimens prepared at different times. In contrast, the Shear Box Compaction (SBC) technique allows fabrication of a single slab, at a given time, which is then used to extract multiple specimens that can be considered as true replicates. The SBC can offer significant advantages in preparation of PA specimens for various tests typically performed on gyratory or Marshall specimens. ASTM D7981-15 Test Method on SBC of Asphalt Mixes standard is written around compaction of dense-graded (DG) mixes, as well as porous asphalt (PA) mixes.
Standard: ASTM D7981-15 Standard practice for compaction of prismatic asphalt specimens by means of the Shear Box Compactor.
The ASC is being used in FHWA Contract “Deployment of Performance-Based Technologies for Mechanistic-Empirical Pavement Design and Resource Responsible Materials Design” to fabricate specimens for Level 1 analyses using the AASHTOWare Pavement ME Design software.
It is the only compactor capable of fabricating specimens for all of the following mechanistic-empirical performance tests:
Dynamic Modulus, AASHTO PP 61
Repeated Load Permanent Deformation, AASHTO TP 79
Flexural Fatigue, AASHTO T321
Low Temperature Creep and Strength, AASHTO T322
Main Features
- Extremely sturdy fabricated frame combined with precision machined components.
- Servo hydraulic vertical ram with integral hydraulic power supply.
- Precision electro-mechanical shearing motion (user programmable).
- Integral specimen extruder.
- Electronic control unit with touch screen color display (no need for PC).
- Unlimited memory storage with: 2 USB ports, 1 SD card slot , RS232/485 serial port.
- The compaction cycle can be programmed by specifying vertical stress/load and test termination conditions; Number of cycles, Specimen height and/or density.
- Precision load cell(s) for vertical and shear stress measurement.
- Optional built-in mould heater.
Technical Specification
Vertical force: Up to 100kN
Shearing force: Up to 50kN
Shear angle: 4° ± 0.1°
Shearing cycle rate: 3 ± 0.1 cycles per minute
Mould width: 150mm ± 0.1 mm
Mould length: 450mm ± 0.1 mm
Mould surface finish (inside): Smoother than 0.4μm rms
Mould surface hardness: More than 48 Rockwell C
Mould capacity: Approx. 20 litres
Loading platen width: 149 mm ± 0.2 mm
Loading platen length: 449 mm ± 0.2 mm
Loading platen smoothness: Smoother than 0.4μm rms
Loading platen surface hardness: More than 48 Rockwell C
Number of cycles: Up to 100
Vertical stress: 0.1 to 1.5MPa ± 0.01MPa
Compaction height: 0 mm to 200 mm ± 0.1mm
Power supply: 230V 1ph 50-60Hz
Dimensions: 788x1360x1314 mm
Weight: 1200 kg approx.