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Slide 1

Project Team

• Pine Instrument
• Texas A&M
• Texas DOT

Slide 2

Need:

• Aggregate shape properties have been shown to be related to the structural integrity and performance of pavement systems.
• Existing tests for aggregate shape properties are time consuming and subjective in nature.

Anticipated Advantages:

• Enhanced information on the aggregate material shape properties will help improve pavement performance and augment predictive models.
• AIMS provides objective, repeatable, and rapid measurement of aggregate shape properties.

Slide 3

Highways for LIFE Aggregate Imaging Measurement System Project Outline

• Phase I
  • Develop implementation ready equipment
    • Tool for design and production QC/QA
  • Establish standard test protocols
    • Use for aggregate consensus properties
• Phase II
  • Assess relationship between aggregate shape & performance
    • Correlate with HMA field performance
  • Identify methods for implementation
    • Quarry, plant, pavement surface

Slide 4

The Aggregate Imaging Measurement System (AIMS) characterizes aggregate shape properties related to pavement performance including Two and 3-D form, Coarse Aggregate Angularity, Fine Aggregate Angularity, and Texture properties.

Slide 5

Coarse Aggregate Form Characterization

Current techniques for evaluating flat and elongated aggregates (2-D form) include ASTM D4791 Standard Test Method for Flat Particles, Elongated Particles, or Flat and Elongated Particles in Coarse Aggregate.

This technique measures the length to width ratio of a material sample of coarse aggregates. Each particle is categorized by a length to width ratio individually

Slide 6

The AIMS characterizes a sample tray of coarse or fine aggregates providing a graphical output of the sample form distribution. Each sieve size is characterized separately.

Slide 7

This graph represents the AIMS 2D form distribution for several coarse aggregate samples.

Slide 8

This graph represents the AIMS 2D form distribution for several fine aggregate samples

Slide 9

The AIMS measures the 3-D shape of coarse aggregate samples. This shape information is reported as a sphericity index and plotted as a distribution.

Slide 10

This graph represents the AIMS Sphericity distribution for several coarse aggregate samples.

Slide 11

Coarse Aggregate Angularity

Current techniques for evaluating coarse aggregate angularity include ASTM D5821 Standard Test Method for Determining the Percentage of Fractured Particles in Coarse Aggregate.

This technique requires each particle to be viewed and the number of fractured faces per particle be counted

Slide 12

The AIMS characterizes a sample tray of coarse or fine aggregates providing a graphical output of the angularity distribution of the sample. Each sieve size is characterized separately.

Slide 13

The AIMS characterizes aggregate angularity using an angularity index value. Below is the AIMS angularity index values compared with the Krumbein images.

Slide 14

This graph represents the AIMS Angularity Index distribution for a #8 natural sand versus a #8 manufactured sand sample.

Slide 15

This graph represents the AIMS Angularity Index distribution for several coarse aggregate samples.

Slide 16

AIMS also characterizes the surface texture of coarse aggregate samples. Texture has been linked to pavement structural performance as well as pavement frictional properties.

Slide 17

The AIMS characterizes coarse aggregate texture with a Texture Index value.

Slide 18

This graph represents the AIMS Texture Index distribution for two coarse aggregate material samples.

Slide 19

• Research at the Texas Department of Transportation has also shown promise for using the AIMS system to objectively characterize an aggregate sample's resistance to polishing.
• An aggregate's resistance to polishing is related to HMA pavement surface skid resistance. Further research on polishing characterization is planned.