8,255
edits
Changes
Jump to navigation
Jump to search
m
no edit summary
Line 1:
Line 1:
−*Maximum wash loss of 0.5%
For advice on decorative surface aggregates see [[Stone]]<br>
+<poem>
−Gravel for underdrains and underground infiltration structures should be 20 - 50 mm, uniformly-graded, clean, crushed angular stone that has a void ratio of 0.4 (40%)<ref>Porosity of Structural Backfill, Tech Sheet #1, Stormtech, Nov 2012, http://www.stormtech.com/download_files/pdf/techsheet1.pdf accessed 16 October 2017 </ref>.
+For advice on decorative surface aggregates see [[Stone]]
+Gravel for underdrains and underground infiltration structures should be 20 - 50 mm, uniformly-graded, clean (maximum wash loss of 0.5%), crushed angular stone that has a void ratio of 0.4 (40%)<ref>Porosity of Structural Backfill, Tech Sheet #1, Stormtech, Nov 2012, http://www.stormtech.com/download_files/pdf/techsheet1.pdf accessed 16 October 2017 </ref>.
+The uniform grading and the angularity are important to maintain pore throats and clear voids between particles. (i.e. achieve the void ratio).
+The clean wash is to prevent rapid accumulation of fines in the base of the reservoir.
Gravel with structural requirements should also meet the following criteria:
Gravel with structural requirements should also meet the following criteria:
−*Minimum durability index of 35
*Minimum durability index of 35
*Maximum abrasion of 10% for 100 revolutions and maximum of 50% for 500 revolutions
*Maximum abrasion of 10% for 100 revolutions and maximum of 50% for 500 revolutions
+</poem>
----
----
[[category:materials]]
[[category:materials]]