06-04-2011, 11:46 AM
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GEOSYNTHETICS IN PAVEMENT DESIGN
INTRODUCTION
Pavements are civil engineering structures used for the purpose of operating wheeled vehicles safely and economically.
The development of geosynthetics in the past three decades has provided the strategies for enhancing the overall performance of the paved roadways.
Commonly a paved road becomes a candidate for maintenance when its surface shows significant cracks and pot holes.
GEOSYNTHETICS
Geosynthetics is defined as “a planar product manufactured from polymeric material used with soil, rock, earth, or other geotechnical engineering related material”.
Geosynthetic usage has steadily increased in both public and private construction projects.
Geosynthetics is likely to increase in the future with stricter environmental regulations enforcement.
GEOSYNTHETICS
PRODUCTS OF GEOSYNTHETICS
Geotextiles
Geogrids
Geocells
Geonets
Geomembranes
Geocomposites
PROPERTIES OF GEOSYNTHETICS
Thickness
Tensile strength
Tear strength
Apparent opening size
Puncture resistance
Permittivity
Transmissivity
Ultraviolet resistance
GEOSYNTHETICS IN PAVEMENT
The primary purpose of incorporating the use of geosynthetics in the pavement design process is to reduce reflective cracking
Geosynthetics resist moisture intrusion into the underlying pavement structure, stabilize roadways and their edges.
It improve road quality, particularly when roads were built on unstable soil.
GEOSYNTHETICS IN PAVEMENT
METHODS OF INSTALLATION
POST CONSTRUCTION
FUNCTIONS
SEPARATION
Geosynthetics is sandwiched between aggregate base course and subgrade material.
It prevents mixing of the two layers, aggregate loss and pumping.
FILTRATION
Geosynthetic acts as a filter by preventing material from washing out while allowing the water to flow through.
Allowing an increase in subgrade strength.
DRAINAGE
Drainage applications refer to situations where the water flows within the plane of the geosynthetic product .
Prevents water logging in the pavement structure.
REINFORCEMENT
It helps in maintaining the pavement integrity and uniformity.
It reduces the differential settlement in roadways.
ADVANTAGES
Reduces the intensity of stress on the subgrade.
Prevents the base aggregate from penetrating into the subgrade.
Prevents subgrade fines from pumping.
Reduces the thickness of aggregate required to stabilize the subgrade.
Reduces the differential settlement of the roadway.
Reduces maintenance and extending the life of the pavement.
CONCLUSION
Geosynthetics reinforce the structural section through: lateral restraint and tensile membrane support.
The addition of a geosynthetic to a structural section increases the friction between the aggregate layer and the geosynthetic.
Geosynthetics increase the overall bearing capacity of the pavement.
The filtration-drainage function is vital to the performance of geosynthetics in road construction as any pore water pressure developed in the subgrade must be dissipated.