California Department of Transportation
 

CALTRANS MOVES TO SUPERPAVE Updated 07-09-13

Looking at 2 lane highway.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change in axle configurations, depleting aggregate sources, and the inability to obtain, repair or calibrate current outdated equipment.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).Asphalt Concrete (AC) sample 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.

 

 

EQUIPMENT

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.

Model AFG2A Superpave Gyratory Compactor   Model 4140 Troxler Gyratory Compactor
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 50C (122F) 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 50C (122F) 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)
Hamburg Wheel Tracker (HWT)
Inside View
  Hamburg Wheel Tracker (HWT) Inside View

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.

Rutting Stripping Slope Graph

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_07-08-13

FORMS*Go to Top

*Interactive PDF forms will be available in the future.

TOOLSGo to Top

PILOT PROJECTSGo to Top

District
County/Route
Tons/Type
01
Lak-20
50,000-60,000 HMA
02
Sha-299
35,000 HMA/Pulv
03
Col-20
6300 HMA
04
CC-580
40,000 RHMA; 500 HMA
04
Sol-80
12,530 RHMA; 33,920 HMA
04
CC-4
3,490 RHMA; 10,480 HMA
04
CC-680
3,160 RHMA; 22,000 HMA
04
CC-80
1265 RHMA; 19025 HMA
05
Mon-101
50,000 HMA Type A
05
Mon-101
18,800 HMA Type A
06
Ker 33
11,000 HMA Type A
06
Tul-216
14,000 HMA Type A
07
LA-405
9,280 RHMA-G
07
LA-405
5,200 RHMA-G WMA LSM
07
LA-110
25,200 RHMA-G
07
LA-107
6,970 RHMA-GWMA
07
Ven-101
08
SBd-10
9,940 RHMA-G
08
SBd-10
36,000 RHMA-G
09
INY-395
20000 HMA/CIR
09
Mno-395
10
Tul-99
31,247 HMA Type A
10
Imp-8
3700 HMA Type C
11
Imp-8
2900 HMA Type C
11
Imp-98
17,500 RHMA-G

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

FOR MORE INFORMATIONGo to Top

Contact: Joe Peterson
Office of Roadway Materials Testing
Phone: 916-227-7303
Cellular: 916-813-3677
Facsimile: 916-227-5295
E-mail: Joe_Peterson@dot.ca.gov