Replacing hard subgrade with another material like engineered backfill material
Replacing hard subgrade with another material like engineered backfill material
(OP)
I am working for the asphalt contractor and we have this argument with the owners representative about sub grade layer (layer A). The owners representative insist we must follow the design and disregard the actual site condition.
Below is the Asphalt Cross section as per design. The actual site condition, layer A and B is limestone.
Asphalt Road Cross Section Design:
F. 50mm thick - Bituminous Wear Course
E. RC2
D. 100mm thick - Bituminous Base Course
C. MC1
B. 200mm thick - Aggregate Base Course
A. 300mm thick - Sub Grade, CBR>80, MDD>95%
We agree on him to remove the limestone layers on Layer B to accommodate the 200mm Aggregate Base Course, however, we argue that the limestone at Layer A is sufficient enough as base for aggregate base course. The owners rep insist to remove and replace limestone with granular base course.
We find it unnecessary because limestone is a limestone. The properties has more than it requires. Its a hard rock. In fact it took us 3 weeks to remove the limestone at layer B. The road is 500m x 7m wide.
My question is, is it necessary to remove the limestone and replace it with 300mm - Engineered Backfill Material.
Below is the Asphalt Cross section as per design. The actual site condition, layer A and B is limestone.
Asphalt Road Cross Section Design:
F. 50mm thick - Bituminous Wear Course
E. RC2
D. 100mm thick - Bituminous Base Course
C. MC1
B. 200mm thick - Aggregate Base Course
A. 300mm thick - Sub Grade, CBR>80, MDD>95%
We agree on him to remove the limestone layers on Layer B to accommodate the 200mm Aggregate Base Course, however, we argue that the limestone at Layer A is sufficient enough as base for aggregate base course. The owners rep insist to remove and replace limestone with granular base course.
We find it unnecessary because limestone is a limestone. The properties has more than it requires. Its a hard rock. In fact it took us 3 weeks to remove the limestone at layer B. The road is 500m x 7m wide.
My question is, is it necessary to remove the limestone and replace it with 300mm - Engineered Backfill Material.





RE: Replacing hard subgrade with another material like engineered backfill material
RE: Replacing hard subgrade with another material like engineered backfill material
Did the owner clarify what part of the design you are not following? Seems to me if the limestone meets the subgrade requirements listed above then you have met the design.
RE: Replacing hard subgrade with another material like engineered backfill material
Or maybe the owners rep is the contractors buddy and is just helping the contractor get the full worth of work
RE: Replacing hard subgrade with another material like engineered backfill material