Case Study _ BXC Geogrid_ Mine Haul Roads_Final_Sept 2018

CASE STUDY

Mine Haul Road Application

TE-BXC40 COMPOSITE GEOGRID

WHAT: Mine haul road construction project – Northern Ontario, Canada. APPLICATION: This application involves the construction of mine haul roads built on compacted clay with blast rock/granite. These haul roads extend into a mine pit providing passage for rock dump trucks weighing several hundred tonnes. CHALLENGE: The compacted clay with blast rock/granite base course meant that the roads would be unreinforced at the interface of the sub-base and the subgrade, giving rise to lateral movement of particles. This would cause upward movement of the subgrade fines by pumping action resulting in sub-base failure. Repetitive heavy dump truck traffic also meant that heavy dynamic loads would be concentrated over the weak subgrade resulting in higher differential settlement. CONVENTIONAL SOLUTION: The conventional solution for this challenge would consist of using 1.0m of compacted crushed rock backfill (aggregate base) over the compacted clay subgrade.

TITAN SOLUTION: Considering the characteristics of the subgrade soil in this scenario, both reinforcement and separation functions were important for optimal road performance. To ensure this, Titan proposed a solution which consisted of our TE-BXC40 composite geogrid installed at the bottom of the aggregate base layer. TE-BXC40 is a biaxial geogrid bonded to a 200 gsm continuous filament nonwoven geotextile by a precision heat bonding process. The geogrid acts as reinforcement, whereas the geotextile works as a soil separator and filter to prevent contamination of the aggregate base by fines from the subgrade. This allows for better drainage of the sub-base which helps maintain stability of the soil structure. In addition to its effective soil reinforcement, drainage and filtration functions; TE-BXC40 allows for thinner aggregate base and makes it easier to place and compact aggregate base. Furthermore, it minimizes the loss of aggregate into the soft subgrade during construction and prevents penetration of individual aggregate particles into the soft subgrade under repeated traffic loads. This solution provided our client with significant cost savings by allowing them to use far less aggregate base (0.7 mm thick vs. 1.0 mm) while helping to reduce impact on environment.

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