Office of Roadway Materials Testing
CALTRANS MOVES TO SUPERPAVE
The California Department of Transportation (Caltrans) is transitioning to Superior Performing Asphalt Pavement technology, or Superpave, for asphalt concrete mix design. With the increase in traffic loadings and volumes, change in axle configurations, depleting aggregate sources, and the inability to obtain, repair or calibrate current outdated equipment. Caltrans recognizes the need to change.
Superpave is a performance based standard of test procedures for asphalt concrete (AC) that was developed under the AASHTO Strategic Highway Research Program (SHRP). It is a comprehensive method of designing asphalt mixes tailored to specific unique performance requirements governed by the traffic, environment (climate), and layer location. It also facilitates selecting and combining asphalt binder, aggregate, and any necessary modifier to achieve the required level of pavement performance.
Superpave utilizes the Superpave Gyratory Compactor (SGC) as a method of compacting test specimens during the mix design process and for Quality Control and Quality Acceptance testing during production.
The Superpave gyratory compactor has the ability to produce asphalt mix specimens to densities achieved under actual environmental and traffic loading conditions. Utilizing a 150 mm (5.90 inch) diameter mold, the SGC can accommodate large aggregate mixtures.
The SGC consists of a rigid reaction frame, loading system, and specimen height measurement. Depending on the model used it has the ability to compact asphalt mixture specimens at a variety of pressures. The mixture is compacted by a gyratory kneading action using a compaction angle of 1.25 degrees external and 1.16 degrees internal. The SGC typically gyrates at 30 RPM.
|Superpave Gyratory Compactor (SGC) Model AFG2A, Distributed by Pine Instrument Co.||Troxler Gyratory Compactor Model 4140, Distributed by Troxler|
In addition to the SGC, Caltrans will be utilizing the Hamburg Wheel Tracker (HWT). The HWT measures the rutting and surface moisture susceptibility of an asphalt paving mixture by rolling a steel wheel across the surface of an asphalt concrete slab that is immersed in 50°C (122°F) water. The HWT measures the combined effects of rutting and moisture damage by rolling a steel wheel across the surface of an HMA specimen that is immersed in 50°C (122°F) water. It measures the rutting rate (creep slope) of depth of rut verses number of passes of the steel wheel.
|Hamburg Wheel Tracker (HWT)|
|Hamburg Wheel Tracker (HWT)
Moisture susceptibility is measured as the intersection of the creep slope and the striping slope (Inflection point). The stripping slope is nothing more than the creep slope changes rutting rate.
TEST PROCEDURESGo to Top
As part of the transition to Superpave, Caltrans will use a combination of California Test Methods and AASHTO/ASTM national test methods. The AASHTO/ASTM test procedures are internationally recognized and widely used by other state DOTs and industry. Test methods include:
|AASHTO/ASTM Standard Test Method Designations|
|AASHTO T 11||Materials Finer Than 75-µm (No. 200) Sieve in Mineral Aggregates by Washing|
|AASHTO T 27||Sieve Analysis of Fine and Coarse Aggregates|
|AASHTO T 84||Specific Gravity and Absorption of Fine Aggregate|
|AASHTO T 85||Specific Gravity and Absorption of Coarse Aggregate|
|AASHTO T 176||Plastic Fines in Graded Aggregates and Soils by Use of the San Equivalent Test|
|AASHTO T 209||Theoretical Maximum Specific Gravity and Density of Hot Mix Asphalt (HMA)|
|AASHTO T 269||Percent Air Voids in Compacted Dense and Open Asphalt Mixtures|
|AASHTO T 275||Bulk Specific Gravity of Compacted Hot Mix Asphalt (HMA) Using Paraffin‑Coated Specimens|
|AASHTO T 283||Resistance of Compacted Hot Mix Asphalt (HMA) to Moisture-Induced Damage|
|AASHTO T 308||Determining the Asphalt Binder content of Hot Mix Asphalt (HMA) by the Ignition Method|
|AASHTO T 312||Preparing and Determining the Density of Hot Mix Asphalt (HMA) Specimens by Means of the Superpave Gyratory Compactor|
|AASHTO T 324||Hamburg Wheel-Track Testing of Compacted Hot Mix Asphalt (HMA)|
|AASHTO T 329||Moisture Content of Hot Mix Asphalt (HMA) by Oven Method|
|AASHTO T 335||Determining the Percentage of Fracture in Coarse Aggregate|
|ASTM D2172||Quantitative Extraction of bitumen from Bituminous Paving Mixtures|
SPECIFICATIONSGo to Top
Pilot Specifications have been developed for Superpave. They include a new Superpave Section 39, nonStandard Special Provision and support specifications.
- Section 39_2010_09-24-12
- SN-0XX_E_D02-22-12 Superpave
FORMS*Go to Top
- CEM-3511SP Contractor Job Mix Formula (JMF) Proposal
- CEM-3512SP Contractor Hot Mix Asphalt Design Data
- CEM-3513SP Caltrans Hot Mix Asphalt Verification
- CEM-3703SP Hot Mix Asphalt Production Start-up Evaluation
TOOLSGo to Top
PILOT PROJECTSGo to Top
|04||CC-580||0.0/5.8||40,000 RHMA; 500 HMA|
|04||Sol-80||11.3/12.9||12,530 RHMA; 33,920 HMA|
|04||CC-4||31.1/32.4||3,490 RHMA; 10,480 HMA|
|04||CC-680||10.5/15.1||3,160 RHMA; 22,000 HMA|
|04||CC-80||3.8/5.3||1265 RHMA; 19025 HMA|
|05||Mon-101||50,000 HMA Type A|
|05||Mon-101||61.0/69-4||18,800 HMA Type A|
|06||Tul-216||1.9/2.9||14,000 HMA Type A|
|06||Tul-190||0.00/4.4||5800/9200 HMA Type A|
|07||LA-110||20.1/30.5||5,200 RHMA-G WMA LSM|
|10||Tul-99||30.9/38.7||31,247 HMA Type A|
IMPLEMENTATION TIMELINE FOR SUPERPAVEGo to Top
|2012||Implement approximately 6 pilot projects|
|Nov 2012||Revise Superpave specification|
|2013||Implement approximately 6 to 12 pilot projects|
|Nov 2013||Revise Superpave specification|
|Jul 2014||Full Implementation|
RELATED DOCUMENTSGo to Top
- Caltrans Issue Memo Superpave Transition 09-19-11
- Amended Caltrans issue Memo Superpave Transition 05-21-12
FOR MORE INFORMATIONGo to Top
Office of Roadway Materials Testing