Start with the actual quantity
Measure the removal area and record the thickness when it is known. Distinguish a floor slab from thickened edges, footings, steps and walls. Unknown thickness should be identified as an estimate, not converted into a precise truck quantity.
Describe reinforcement and access
Steel reinforcement, restricted access and the distance to the loading area can change how pieces are broken and handled. Photographs of the route through the property can be as useful as photographs of the concrete itself.
Separate the stages of the price
Ask whether the proposal includes saw cutting, breaking, loading, trucking, disposal, excavation, base preparation and new concrete. A lower removal price may exclude work another quote includes.
Ask how unknowns will be handled
Agree how additional thickness, buried material or unsuitable soil will be documented and priced. A clear change process is more useful than a low initial number built on unexplained assumptions.