Is it acceptable to use large chunks of the old patio as a base for a new concrete patio? I need an answer as soon as possible. The contractor is pouring in the morning.
Good evening. My name's Kel. You can certainly use old chunks of concrete as apart of a base. A rule of thumb is the larger the hole the larger the chunk. The problem is making sure the chunk is solidly in place. Really large chunks -- say 12" across are hard to tamp down. The base needs to be solid and stable. Use large chunks to fill in large holes then complete with crushed stone or sand. Are you using the chunks to fill large irregularities or to build up low spots?
The chuncks are about 6-8" , they are piled on top of each other. They are flush with the rebarb which is 3" from final grade
If it's been tamped either by hand or with a mechanical wacker packer you're good to go. The rebar will suppress cracking and resist any heaving.
Licensed Building Contractor & Certified Building Designer