Crush Exisiting Concrete and Use as Granular Base for Slab 1

[ajk1]

Does anyone have experience with using the crushed up exisiting concrete as the granular base for a new stacker warehouse slab-on-grade? It would have to be processed somehow to get the right aggregate size and gradation I suppose. Does anyone know where I can find a specification covering the whole process?

 

[JAE]

Check with your local department of transportation - the highway folks do this all the time.

 

[ajk1]

Thanks for the lead, JAE. I will follow up.

 

[Ron]

ajk1...done a lot around here. There are a couple of companies that specialize in crushing concrete for base material. Commonly called "Crushcrete" in this area.

As for layer coefficients and mechanical properties, it will vary. In testing I've done using a falling weight deflectometer, I've found the layer coefficient to be typically better than crushed limerock base or crusher-run granite.

 

[ajk1]

Ron - thanks for this information. Very much appreciated. Is there a master specification for crushcrete that I can get anyhwere that we can include in the project specifications for a stacker warehouse slab-on-grade project we are designing?

Currently we have specified 200 mm of crusher run limestone compacted to 98% Proctor density, but our client has asked us to include crushed concrete (crushed from the existing slab-on-grade that is too thin to support the proposed new stacker shelving loads) as an option. Is there a specification that would cover all aspects from crushing, dust control and any health issues (is it crushed on site; how is it crushed; can it be crushed within the confines of the exisiting empty building; waht equipment is used), quality and gradation of materials, compaction of materials when it is placed, wetting pof materials, pre-construction testing, test procedures and methods, etc., etc.

I am in the Toronto, Ontario, Canada area. Do you mind if I ask if you are in this area as well?

 

[civeng80]

Im from australia and I used it and its a great material.

 

[Ron]

ajk1..I'm in the US (Florida). I'll see if I have a spec with those details. Mostly done off site by separate producers, but can be done on site.

About 5 years ago a large earthmoving equipment dealer here moved and their complex (thousands of cy of concrete) was demolished and crushed on site. Very noisy, very dusty but they seemed to get it all done without being shut down by the tree huggers.

The odd part was that they did not use any of the recycled material on that site for the construction of a new Lowe's Home Improvement Center! I suppose the crushing contractor sold it for use elsewhere.

I ran into a situation about 20 years ago where a crusher contaminated a lot of concrete base by crushing some construction materials that contained asbestos. That created a bit of a problem when it was used for base material!

 

[ajk1]

Ron - thanks so much. Our client is also based in Florida! Maybe that's where he got the idea from. If you do eventually find a spec, that would be really helpful to us.