The total gradation of the stone is important in determining if water will percolate through the material. There must also be someplace for the water to go once it reaches the bottom of the layer or you will have created a bath tub. You need interconnected voids in the stone and sub-drains to provide a working system.
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DeWayne Heintz EI, A.M.ASCE
Project Manager
L.L. Pelling Company
North Liberty IA
(319)626-4600
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Original Message:
Sent: 01-02-2019 10:16
From: Ejaz Khan
Subject: Drainage or Permeable Layer?
Sub-base course main function is drainage in a flexible pavement combination, but it has fines passing Seive no 200 up to 15 percent of the sample size. Would it still be a drainage or permeable layer?
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Ejaz Khan S.M.ASCE
Director
Pakhtunkhawa Highways Authority
Islamabad
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