Difference between revisions of "Gravel"
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| − | <li>Granular material for underdrains should be clear crushed 50 mm diameter stone graded in accordance with [https://www.astm.org/Standards/D2940.htm | + | <li>Granite is generally recommended over limestone for all drainage applications. Granite is both more chemically stable, and more resistant to crushing over time. </li> |
| + | <li>Granular material for underdrains should be clear crushed 20 or 50 mm diameter stone graded in accordance with [https://www.astm.org/Standards/D2940.htm ASTM D 2940].</li> | ||
| + | <li>The 20 mm clear crushed aggregate permits the use of an overlaid layer of high performance bedding (HPB) as a choker layer.</li> | ||
<li>The void space ratio should be > 0.35 (or > 35%)</li> | <li>The void space ratio should be > 0.35 (or > 35%)</li> | ||
</ul> | </ul> | ||
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<li>Maximum abrasion of 10% for 100 revolutions and maximum of 50% for 500 revolutions</li> | <li>Maximum abrasion of 10% for 100 revolutions and maximum of 50% for 500 revolutions</li> | ||
</ul> | </ul> | ||
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[[Category:materials]] | [[Category:materials]] | ||
Revision as of 11:06, 8 August 2017
- Granite is generally recommended over limestone for all drainage applications. Granite is both more chemically stable, and more resistant to crushing over time.
- Granular material for underdrains should be clear crushed 20 or 50 mm diameter stone graded in accordance with ASTM D 2940.
- The 20 mm clear crushed aggregate permits the use of an overlaid layer of high performance bedding (HPB) as a choker layer.
- The void space ratio should be > 0.35 (or > 35%)
All gravel should meet the following criteria:
- Maximum wash loss of 0.5%
- Minimum durability index of 35
- Maximum abrasion of 10% for 100 revolutions and maximum of 50% for 500 revolutions