00933635

Monograph

http://onlinepubs.trb.org.../NCHRP068_Final_Report.pdf

This Innovations Deserving Exploratory Analysis (IDEA) project determined the effectiveness of a geocomposite capillary barrier drain (GCBD) system in preventing pavement damage by controlling moisture movement in pavement subgrade and base course. A number of geotextiles were evaluated for their suitability as a transport layer, and a multifilament, woven fiberglass geotextile, denoted as TGLASS, was identified as the most suitable material. At typical field infiltration rates, the GCBD drained water from overlying base material that was not saturated. Furthermore, the GCBD prevented the moistening of the subgrade at many of the filtration rates tested. This allows the design of unsaturated soil drainage to help extend pavement life by limiting the time the bases are saturated and by diverting large volumes of water to a drainage system before it reaches the subgrade. In the specific GCBD tested, water drained from overlying base soil when subjected to suction head of 100 mm and greater. Furthermore, at long term infiltration rates of .1 to .15 mm/hr, the GCBD prevented infiltrating water from reaching the subgrade. Finally, the GCBD recovered its function and protected the subgrade in a test in which a small amount of water had broken through the GCBD into the subgrade. Further development is needed before the technology can be implemented and a more economical transport layer than the one tested in this project would make GCBD more affordable and implementable.

This NCHRP-IDEA investigation was conducted by the U.S. Army Cold Regions Research and Engineering Laboratory, Hanover, New Hampshire. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

NCHRP-IDEA Project 68

NCHRP-68

English

27 p.

2002-10

NCHRP-IDEA Program Project Final Report

9908-0204

Figures (24) ; Photos (5) ; References (11) ; Tables (6)

Base course (Pavements); Drains; Geotextiles; Performance; Subgrade (Pavements); Subsurface drainage; Technological innovations

Geocomposite capillary barrier drain

Design; Geotechnology; Highways; Pavements; I22: Design of Pavements, Railways and Guideways; I23: Properties of Road Surfaces

TRIS, TRB

Nov 6 2002 12:00AM