Geosynthetics June/July 2020 - 28

Enhanced moisture
management of
pavement systems
through capillary suction
By René B. Laprade and John M. Lostumbo

M

René B. Laprade, P. Eng., is technical
marketing manager for TenCate
Geosynthetics Americas in Aurora,
Ont., Canada.
John M. Lostumbo, P.E., is director
of technical marketing for TenCate
Geosynthetics Americas in East
Amherst, N.Y.
All figures courtesy of the authors.

28

oisture within pavement layers is a principal cause of pavement deterioration
(Cedergren 1994, Christopher and McGuffey 1997, Henry and Holtz 2001). Specific
problems associated with moisture include (1) reduction in pavement strength caused by
excess water in the base course layers and/or the subgrade soils, (2) shrinking and swelling of
subgrade materials caused by moisture content changes, (3) frost heave and thaw weakening
caused by capillary moisture flow beneath pavements, (4) stripping of asphalt pavements and
(5) joint displacement in concrete pavements. Moisture-related problems are responsible for
decreased pavement life, increased maintenance costs and increased pavement roughness,
and they occur throughout all regions and climates around the world. The detrimental effects
of moisture in pavements are tremendous. According to Cedergren (1987), a pavement's
service life can be reduced by half if the pavement approaches saturation just 10% of the time.
Geosynthetics have been effectively incorporated into roadways for several decades to
improve the performance and longevity of these and other civil structures. The principal
functions to which geosynthetics contribute in these applications include separation, filtration, confinement, reinforcement and drainage. Drainage is one of the most important
functions to maintain pavement performance and, historically, has been addressed with
passive systems in roadway applications. These passive systems rely on gravitational flow
in order to provide drainage. This can provide limited benefit because most water flow in
pavement systems is unsaturated through capillary movement. This unsaturated flow cannot
be drained effectively by conventional geotextiles if a capillary barrier is formed. When two
porous materials with differing hydraulic conductivities are in contact with one another, a
capillary barrier develops; the capillary barriers increase the moisture storage around the
contact area by forming a temporary barrier at the interface of the two materials (Zornberg
et al. 2010).
The development of an enhanced lateral drainage geosynthetic (ELDG) has provided
an important tool toward the management of moisture in roadways. The ELDG's unique

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Geosynthetics June/July 2020

Table of Contents for the Digital Edition of Geosynthetics June/July 2020

Geosynthetics June/July 2020 - Cover1
Geosynthetics June/July 2020 - Cover2
Geosynthetics June/July 2020 - 1
Geosynthetics June/July 2020 - 2
Geosynthetics June/July 2020 - 3
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