68th Canadian Geotechnical Conference and 7th Canadian Permafrost Conference

DESIGN AND CONSTRUCTION OF A GEOSYNTHETIC REINFORCED PAVEMENT ON WEAK SUBGRADE

Session: Transportation and Linear Infrastructure III / Transports et infrastructures linéaires III

Sam Bhat, Titan environmental Containment Ltd (Canada)
Venkat Lakkavalli, Pavement Engineer- Materials Research Construction Roads - City of Calgary (Canada)
Dr. Jimmy Thomas, Sr. Design Consultant - Titan Environmental Containment Ltd (India)

This paper describes the salient features of the design and construction of a geosynthetic reinforced pavement and presents initial assessment of the performance. The project involved rehabilitation of old and damaged roads in the City of Calgary in Canada. At many locations the existing pavement was a full-depth asphalt pavement which was up to 20 years old and was in a distressed state. Poor sub-grade conditions were indicated to be one of the major causes for the distress in the pavement. As part of the city roads rehabilitation program, it was required to reconstruct the pavement as a pilot project. The proposed solution required replacement of the existing distressed pavement with a design comprising asphaltic concrete, granular base and granular sub-base. This required excavations to accommodate the designed pavement thickness. To minimize the disruptions and inconvenience to the road users, it was desirable to minimize the depth of excavation. Therefore it was necessary to minimize the pavement thickness as far as possible. It is known that reinforcement of the pavement with geosynthetics enhances the strength and stiffness of the pavement and also contributes to the fatigue life of the overlay and hence a reinforced pavement of lower thickness can give the same level of performance as an unreinforced pavement. Alternatives with different types and combinations of geosynthetics were evaluated. A design in which a bitumen coated fiberglass grid was incorporated at the center of the asphalt concrete layer and a biaxial geogrid composite comprising of a stiff polypropylene biaxial geogrid bonded to a nonwoven geotextile was incorporated at the bottom of granular sub-base was finally adopted for one section and only bitumen coated fiberglass grid was incorporated for the other section. The pavement was constructed without any significant issues and the initial assessment of the performance seems to be quite encouraging. The paper describes the site conditions and constraints, evaluation of alternative designs, design of the geosynthetic reinforced pavement, construction and the initial assessment of performance.