Equipment pad over existing pad

[Idigguns]

I have an existing 5' X 10' X 4" pad that is too small. I don't want to have to chip it up to pour the new pad. The new pad will be about 6' X 20'. I plan on stippling the top of the old pad with a chipping hammer and coating it with an epoxy bonding agent. I need the finished pad to be at least 6" thick. Is 2" of concrete on top of the old pad going to be enough? Or should I make it thicker? Any other suggestions? The equipment going on the pad will weigh about 2,500 pounds.

 

[cvg]

This is a good source for the information you are looking for.

Publication Number: EM 1110-2-2002
Title: Engineering and Design - Evaluation and Repair of Concrete Structures

http://140.194.76.129/publications/eng-manuals/em1110-2-2002/toc.htm

 

[kslee1000]

If there is any bending, the new pad will crack around the perimeter of old pad. Also, is the pad placed over soil, or structural slab?

 

[csd72]

Definately not.

No shortcuts, remove the existing and create a new pad.

 

[hokie66]

Agree with csd72. How hard can it be to remove the thing? Hire a concrete saw for the morning, cut it up into little chunks, cart it away.

 

[chicopee]

When adding new concrete to existing concrete, we had to drill holes on the sides of the existing slab and expoxy dowel pins in order to tie the new material rebar to the old material; then overlay with 2" of new material.

 

[kslee1000]

I would at least increase the 6' to 6.5' so there is enough room on each side (of the existing 5' width) to make a concrete beam with pair of L bars, drill & grout into slab, acting as shear reinforcement, and support for at least two longitudinal bars in the 20' direction. Install the L bars at the 6.5' edges as well. You can then use WWF for the top face to tie everything together.

Roughen the existing pad and applied bonding agent will help the performance. You can make it (6.5'x20') one placement, or leave the area over the existing pad for later using stronger/finer grout fill.