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Highways for LIFE

Arrow Aggregate Imaging Measurement System (AIMS) long presentation

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Slide 1

image is a conceptual computerized representation of the AIMS system placed on a bench

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.

image is a representation of an aggregate  particle outline indicating the shape properties of 2D-Form, angularity and surface texture which the AIMS characterizes


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

 image represents the outline of an aggregate particle with an ellipse circumscribing the particle which represents the form property characterized by the AIMS.

image is a photograph of an instrument known as an aggregate proportional caliper used for ASTM D4791


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.

image is a conceptual computerized representation of the AIMS system placed on a bench


Slide 7

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

The image is a sample AIMS output graph of the 2D-form showing the percentage of 8 coarse aggregate samples fitting into 4 different form categories: Circular, Semi-circular, Semi-elongated, Elongated


Slide 8

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

The image is a sample AIMS output graph of the 2D form showing the percentage of 4 fine aggregate samples fitting into 4 different 2D-form categories: Circular, Semi-circular, Semi-elongated, Elongated.


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.

The photo shows an aggregate particle and arrows representing the physical 3-D measurements the AIMS system makes.

The image shows a representation of the physical 3-D shape measurements the AIMS system makes on an egg shaped particle.


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

image represents the outline of an aggregate particle with an circle highlighting the angularity characteristic as measured by the AIMS.

image represents the outline of an aggregate particle with arrows pointing to two fractured faces on the particle.


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.

image is a conceptual computerized representation of the AIMS system placed on a bench


Slide 13

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

The image shows 9 sample shapes for each of four angularity categories: Angular, sub-angular, sub-rounded, rounded.

Four photos of aggregates falling into 4 angularity categories: Angular, sub-angular, sub-rounded, rounded


Slide 14

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

The image is a sample AIMS output graph of the angularity index for a natural and manufactured #8.  The curve indicates the percentage of aggregate particles in the sample which fall into each of 4 angularity categories: Round, Sub-round, Sub-angular, and Angular


Slide 15

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

The image is a sample AIMS output graph of the angularity index for four coarse aggregate samples.  The curve indicates the percentage of aggregate particles in each sample which fall into each of 4 angularity categories: Round, Sub-round, Sub-angular, and Angular


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.

image represents the outline of an aggregate particle with a circle showing the texture characteristic as a small area of the overall particle as characterized by the

AIMS.

Slide 17

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

The image shows 5 sample texture images captured by the AIMS and the texture classification of each: High Roughness, Moderate Roughness, Low Roughness, Smooth, and Polished.  Four aggregate particles are shown at the bottom representing rough to polished surface textures.


Slide 18

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

The image is a sample AIMS output graph of the angularity index for 2 coarse aggregate samples. At the top of the graph are 5 images captured by the AIMS representing the 5 texture surface textures. The graph curve indicates the percentage of aggregate particles in the sample which fall into each category: Polished, Smooth, Low Roughness, Moderate Roughness, High Roughness


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.
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Contact

Julie Zirlin
Highways for LIFE
202-366-9105
julie.zirlin@dot.gov

Updated: 04/04/2011
 

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United States Department of Transportation - Federal Highway Administration