Concrete Overlay Under Rail Track
Concrete Overlay Under Rail Track
(OP)
Dear All,
Around 10,000 sqm of tansfer pit area contains 9000 meters of rails laid to carry ships lifted over trolley wheels in a Naval Dock Yard. After 30 years of service life without any maintenance the area is left deteriorated and subject to refurbishment. The specs call for chipping 150mm out of a 300mm concrete base slab, dowelling, replacing the top rebars and filling self levelling concrete. The rails will be removed during these works and the embedded U bolts (depth = 250mm inside concrete) to be kept undisturbed. Upon relaying the new concrete the rails will be re-installed and ships to move again.
Now, is it structurally ok to chip half concrete and replace with a more good quality concrete than the base concrete. sounds like we are building a new storey above a weak foundation. Your expert comments please...
Around 10,000 sqm of tansfer pit area contains 9000 meters of rails laid to carry ships lifted over trolley wheels in a Naval Dock Yard. After 30 years of service life without any maintenance the area is left deteriorated and subject to refurbishment. The specs call for chipping 150mm out of a 300mm concrete base slab, dowelling, replacing the top rebars and filling self levelling concrete. The rails will be removed during these works and the embedded U bolts (depth = 250mm inside concrete) to be kept undisturbed. Upon relaying the new concrete the rails will be re-installed and ships to move again.
Now, is it structurally ok to chip half concrete and replace with a more good quality concrete than the base concrete. sounds like we are building a new storey above a weak foundation. Your expert comments please...





RE: Concrete Overlay Under Rail Track
RE: Concrete Overlay Under Rail Track
cntw's suggestion for a checklist is a good one.
RE: Concrete Overlay Under Rail Track
Thanks for your kind comments. I guess it is more likely casused by long term exposure to moist/humid environment. One area he might want to pay close attention to is the levelness of the rail tracks and concrete surface, looking for indication of area with potentially weakened subgrade due to water penetration.
RE: Concrete Overlay Under Rail Track
RE: Concrete Overlay Under Rail Track
You probably don't need a base course (actually called a subbase under concrete), unless you have a subgrade drainage issue that needs correction. In that case I would use a free draining coarse sand or combination of sand/gravel.
RE: Concrete Overlay Under Rail Track
RE: Concrete Overlay Under Rail Track
RE: Concrete Overlay Under Rail Track
Check the water level (and variations) and make sure it is similar to what was assumed in the original plans. Coastal areas have experienced settlement.
After 30 years of service with no maintenance, the project is probably near the end of its life and anything near the surface is just a temporary repair.
RE: Concrete Overlay Under Rail Track
Richard A. Cornelius, P.E.
WWW.amlinereast.com