MSE Wall Leveling Pads: Concrete vs. Gravel
MSE Wall Leveling Pads: Concrete vs. Gravel
(OP)
Here in Colorado we have a proposed MSE retaining wall (Allan Block) with heights varying from ~6'-4" to ~24'-9". The wall is surcharged with highway vehicle loads (250 psf) and it has a toe-slope of 2H:1V. I have the wall embedded to H/7, plus I have 4' of horizontal soil cover per AASHTO recommendations. In addtion, much of the toe is to be paved over with 4" of concrete for slope protection. My question is regarding the advantages of a concrete vs a gravel leveling pad. It appears that CDOT specifies only concrete leveling pads. Why would CDOT do that? Is a concrete leveling pad the way to go?





RE: MSE Wall Leveling Pads: Concrete vs. Gravel
I suggest contacting Allan Block to get to the bottom of the situation since I know this has come up in many provincial areas and they constantly work with DOTs on numerous industry projects for similar products also.
Dick.
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: MSE Wall Leveling Pads: Concrete vs. Gravel
EIT
RE: MSE Wall Leveling Pads: Concrete vs. Gravel
Because they are CDOT and all it takes is a single problem and a master solution is imagined. Cynical, I know. But fits what I have personally seen in over 40 years. The trully frightening result is that CDOT specs are adopted by most county and city govs and the foolishness is magnified.
RE: MSE Wall Leveling Pads: Concrete vs. Gravel
CDOT may have some unique and provincial situations due to the rock and lack of geo-grid length possible for development of the soil strength in some mountainous locations. Then, an application not recognizing the feature of a flexible wall may be used if engineered without the developers support.
In Spain, there is a mountainous stretch of road curving through rock cuts for several miles and the curved wall segment heights vary between 5' and 40' engineered without concrete "pads".
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: MSE Wall Leveling Pads: Concrete vs. Gravel
RE: MSE Wall Leveling Pads: Concrete vs. Gravel
Concrete causes a constructability issue too. An uneven concrete surface can cause leveling issues when setting the blocks.
NCMA allows the use of a concrete leveling pad, but not sure why you would want to use it. What is the benefit of concrete?
RE: MSE Wall Leveling Pads: Concrete vs. Gravel