Particle Index
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Description
The particle index test provides a combined shape-texture characterization. This test requires that an aggregate sample be divided up into specific size fraction. Each size fraction is placed into a container in three layers. This is done twice; the first time, each layer is compacted with 10 blows of a tamping rod, and the second time, each layer is compacted with 50 blows of a tamping rod. The particle index is computed from the following equation:
Calculations
where:
- = particle index
- = voids in aggregate compacted at 10 drops per layer
- = voids in aggregate compacted at 50 drops per layer
The overall sample particle index is computed as a weighted average of the individual size fraction particles indexes based on the size fraction weights. Aggregates composed of rounded, smooth particles may have a low particle index of around 6 or 7, while aggregates composed of angular, rough particles may have a high particle index of between 15 and 20 or more.
Test Procedures
- ASTM D 3398: Index of Aggregate Particle Shape and Texture
Teaching this? Figures and worked examples are free to use with credit. Course reading lists
Cite this page
APA
Pavement Interactive. (2018, September 5). Particle index. HeadLight. Retrieved [the date you read it], from https://pavementinteractive.org/reference-desk/testing/aggregate-tests/particle-index/
ASCE
Pavement Interactive. (2018). “Particle Index.” HeadLight, <https://pavementinteractive.org/reference-desk/testing/aggregate-tests/particle-index/> ([the date you read it]).
BibTeX
@misc{pavint-particle-index,
author = {{Pavement Interactive}},
title = {Particle Index},
year = {2018},
publisher = {HeadLight},
howpublished = {\url{https://pavementinteractive.org/reference-desk/testing/aggregate-tests/particle-index/}},
note = {Accessed [date]}
}