Recycling Reinforced Concrete Pavement

[canman]

I have a project in Southern California where some large existing steel reinforced portland cement concrete tennis courts need to be replaced in kind. It would be nice to recycle the concrete as base material for use under the new tennis court concrete surface. Since the existing courts have rebar in them pulverization in place is probably not an option. When concrete is reinforced what is the process in which the reinforcement is removed and the concrete recycled.

 

[cvg]

cut using a torch and haul away to a recycler. The recycler removes the steel and crushes the concrete. Unless you run the concrete through a crusher, I would not advise using it for your base.

 

[canman]

There's going to be about 1,600 cubic yards of recycled concrete generated that I wanted to pulverize and use as misc. base meeting the Greenbook standard 200-2.8 provisions. The soils report calls for new 6" agg. base under 4" sand under 4" new reinforced concrete tennis court. I would use the pulverized base material as the agg. base which the soils engineer has agreed to. What are your concerns with using it as base?

I am curious what the price difference would be from hauling off to be crushed and brought back as new base as compared to hauling off to waste yard and then importing new base. I can do an alternate bid to get 2 different costs from Contractors.

 

[cvg]

nothing wrong with using it as base, if it is processed properly. However, I'm not sure how you will do that on site, meet specs and still be economical. Leave the recycling up to the pros and just bring in recycled concrete miscellaneous base material meeting the specs.

 

[concretemasonry]

Cut and haul out the old concrete slabs and bring in other recyled materials from the same recycler.

It helps the schedule/progress, is cheaper and more reliable since the material can be tested before placement. This also limits the problems when the quantities in and out do not agree and uses less fuel and trucking.

Fortunately, recyclers can bridge the time and practicality gap and still satify the requirements (LEED, etc.), which makes recycling more possible at the present time.

Job by job/site by site recycling is a noble cause, but can cause a stumbling block that sets things back. Sometimes, you have to look at the bigger picture - recycle what is possible and use the recycled materials where they work the best.

 

[Ron]

Many recyclers have portable crushers that they will bring to the site and do the work. Assuming you have no restrictions for noise at the site, you might consider this.

No problem using it as a base material, just keep in mind that after you compact the material, it will harden and develop shrinkage cracks with time. (this is due to unhydrated cement that exists in the concrete, as well as leaching calcium compounds that will hydrate after exposure to moisture during compaction) Since you are putting a sand buffer over the base (questionable practice), then reflective cracking is not really an issue.

I question the need for a base material at all. If you are trying to mitigate an expansive soil condition below, there are better ways to do so.

Typically, you can just place the concrete on compacted sand. The vertical loads are minimal and drainage shouldn't be a big deal.