Difference between revisions of "Jar test"

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[[file: Jar_test.jpg|thumb|Steps in conducting a jar test to detect fines in construction materials]]
 
Specifying that [[aggregates]] for the construction of LID practices must be free from fines is important.  
 
Specifying that [[aggregates]] for the construction of LID practices must be free from fines is important.  
 
But checking that the delivered materials meet specification is essential to reduce problems with construction and longer term performance.   
 
But checking that the delivered materials meet specification is essential to reduce problems with construction and longer term performance.   

Revision as of 19:04, 12 June 2018

Steps in conducting a jar test to detect fines in construction materials

Specifying that aggregates for the construction of LID practices must be free from fines is important. But checking that the delivered materials meet specification is essential to reduce problems with construction and longer term performance. When possible, Construction Managers should observe the offloading of materials to watch for dust clouds. Aggregates or sand for LID construction should not give rise to clouds of dust when dumped.

A simple jar test can be used to gauge the proportion of fines in an aggregate product before acceptance. Apparatus:

  • A large wide-mouthed jar - glass or clear plastic are both fine.
  • Tap water, and
  • The aggregate to be tested.

Method:

  1. Collect approximately 5 cm of material in the jar (or at least two complete layers of 40 mm clear stone),
  2. Add water to around 3/4 full,
  3. Secure cap and shake,
  4. Leave for at least 30 minutes until the water is clear - longer is better, so overnight when possible.
  5. Examine the layer of sediment - if > 3 mm has been washed from 5 cm of product, reject the material.