IC Specifications

Since intelligent compaction (IC) is equipment-based technology, new specifications must be developed in order to take full advantage of IC’s benefits.

These specifications must also be flexible enough to handle the varied capabilities of IC rollers and properties of compacted materials. Additionally, an IC roller is just one type of roller needed to compact road materials—this must also be addressed by compaction specifications.

Specification guides for onsite training:

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Asphalt IC Specifications

Current state DOT compaction specifications generally focus on the following objectives:

  • Construction operations: Lift thickness, roller specifications, rolling pattern, temperature range, visual observations, etc. May be based on data collected from test beds.
  • Finished properties: Density or voids (based on a nuclear gauge or pavement cores), and strength or stiffness (based on cores or other field tests).

Asphalt IC Specification

IC concepts and capabilities for asphalt materials were developed later than those for soils and aggregates. Asphalt compaction is complex: in addition to requiring a different roller configuration, asphalt is temperature-dependent and the possibility of damaging the material is greater. Developing specifications for asphalt pavement materials involves considering the varied approaches of several roller manufacturers. At the moment, different manufacturers’ versions of IC technology vary greatly in availability and sophistication. For example, some IC rollers track only asphalt mat temperatures and the number of roller passes—however, the benefits from just these features alone can significantly improve asphalt compaction.

Specifications for IC of this material type should be flexible enough to utilize the benefits of all available rollers. The capabilities of dual-drum IC rollers are expected to evolve over the next few years, so specifications must be able to evolve as well.

United States National Guidelines

  • FHWA Generic Asphalt IC Specification
  • AASHTO PP81-14 IC specification (for both soils and asphalt)

Soils IC Specifications

Current state DOT compaction specifications often follow one or more of the following approaches:

  • Ordinary Compaction: A specified roller makes a specified number of passes, or makes continuous passes until no further compaction can be observed.
  • Stiffness Control: Each lift is compacted to reach a target stiffness value, which is often measured with a Dynamic Cone Penetrometer (DCP), Light Weight Deflectometer (LWD), or GeoGauge (Soil Stiffness Gauge). In Europe, a Plate Load Test (PLT) is sometimes used.
  • Density Control: Each lift is compacted until a target density value is met through direct or indirect measurements; often accompanied by an acceptable range in moisture content. Field QC/QA options usually include a direct measurement of density/moisture content or an indirect measurement using a nuclear density gage. This is the most common specification currently in use.

Current specifications also commonly dictate size and weight characteristics, allowable roller patterns, and allowable lift thicknesses in either a loose or compacted state.

Soils IC Specifications

The first intelligent compaction specifications were established in Europe in the early 1990s, and the US first adopted IC specifications in the mid-2000s.

Current IC specifications for these material types generally follow one of the following two approaches:

  • Field calibration of IC roller measurements to either stiffness or moisture/density test data using test beds.
  • Identification of weak areas for assessment with conventional QC/QA methods (e.g. moisture/density or stiffness).

The following is a timeline of specification development for IC of soils. They are also applicable to aggregate subbase.

United States National Guidelines

  • FHWA Generic Soils IC Specification
  • AASHTO PP81-14 IC specification (for both soils and asphalt)

Current IC specifications in the US:

AgenciesAsphalt IC SpecsSoils IC Specs
FHWA

Asphalt

Soils

AASHTO

Asphalt-Soils combined (PP 81-14)

Asphalt-Soils combined (PP 81-14)

Central Federal Land HD

Asphalt

Eastern Federal Land HD

Asphalt

Alabama DOT

HMA

Alaska DOT

HMA

Arizona DOT

HMA)

California DOT

HMA , CIR

Connecticut DOT

HMA

DC DOT

HMA

Georgia DOT

Asphalt

Soils

Indiana DOT

Soils

Iowa DOT

Asphalt

Soils

Kentucky Transportation Cabinet

Asphalt

Soils

Michigan DOT

Soils

Massachusetts DOT

HMA

Minnesota DOT

Asphalt-Soils combined, Thermal profiles

Asphalt-Soils combined

Nevada DOT

Asphalt

New Jersey DOT

Asphalt 1 (draft) , Asphalt 2 (draft)

New Mexico DOT

Asphalt (draft)

North Carolina DOT

Asphalt (draft)

Soils (draft)

North Dakota DOT

Asphalt (draft)

Oklahoma DOT

Asphalt

Oregon DOT

Asphalt and thermal profiles

Pennsylvania DOT

Asphalt, RCC, embankment, subbase

Rhode Island DOT

HMA

Tennessee DOT

HMA

Texas DOT

Soils, , Approved IC rollers

Utah DOT

Asphalt

Vermont Agency of Transportation

Asphalt

Subbase

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