Using recycled concrete and asphalt
Using recycled concrete and asphalt
(OP)
I am currently working on a project where the client wants to use recycled concrete from previously demoed floor slabs and foundations as fill material and recycled asphalt as a base course.
For recycled concrete, they know to remove all metal and construction debris. They say their crusher can crush the pieces into 6 inch pieces. My thoughts are that this would be fine provided there were enough fines in the material and treat it like a shot rock fill.
For the recycled asphalt, the asphalt is about 2 to 3 inches thick with fatigue cracking everywhere (very poor condition) Boring logs indicate two or less inches of crushed stone base. Our client want to mill the asphalt and use it as the base. My concern is contamination of the underlying soil subgrade into the milled asphalt. In addition several people at our firm have had negative experiences using milled asphalt as a base material.
Would appreciate any comments, concerns, or literature that could help. Thanks
For recycled concrete, they know to remove all metal and construction debris. They say their crusher can crush the pieces into 6 inch pieces. My thoughts are that this would be fine provided there were enough fines in the material and treat it like a shot rock fill.
For the recycled asphalt, the asphalt is about 2 to 3 inches thick with fatigue cracking everywhere (very poor condition) Boring logs indicate two or less inches of crushed stone base. Our client want to mill the asphalt and use it as the base. My concern is contamination of the underlying soil subgrade into the milled asphalt. In addition several people at our firm have had negative experiences using milled asphalt as a base material.
Would appreciate any comments, concerns, or literature that could help. Thanks





RE: Using recycled concrete and asphalt
try the PCA site. they have some free publications and very inexpensive publications that have great info in them on the subject.
http://www.cement.org/
also check ASTM and your DOT sites for additional info.
RE: Using recycled concrete and asphalt
I've used both recycled concrete and asphalt for roadways. Recycled asphalt can be tricky to test for compaction. A nuclear densiometer tests for dry density and moisture. The problem with the asphalt is that there is hydrogen in the oil, which counts for moisture, which makes your dry densities low, making your compaction measurements read as low (even though they're not).
I've seen recycled concrete used in the 1 1/2" size and it tested well. I wouldn't use that ashpalt/crushed/soil for base/top course unless you had to. Maybe for fill in case the recycled concrete runs out. Crushed rock is always the best.
RE: Using recycled concrete and asphalt
RE: Using recycled concrete and asphalt
For the asphalt, there is currently existing asphalt in place, they would like to just mill up the existing 2 to 3 inches of asphalt and immediately compact it behind the milling process and consider that the base material without any additional base. Once the asphalt is milled, then they would put 3 to 4 inches of asphalt on top. My calculations for 100,000 ESAL's indicates approx. 4 inches of asphalt and 6 inches of crushed stone base.
My opinion is that the recycled asphalt will not work without the addition of more crushed stone and if the milled asphalt becomes "contaminated" with soil then structural capacity becomes less. From talking with some more experienced engineers, they seem to have had negative experiences with using recycled asphalt as base material.
Any comments still appreciated. Thanks
RE: Using recycled concrete and asphalt
If you are after structural fill that's where it goes wrong. It's the knowing AND the doing that matters. Actually performing the task of debris removal is time consuming and labor intensive. The owner should be advised of the nearly constant inspection/observation/oversight that will be required to verify this.
RE: Using recycled concrete and asphalt
it is not cheap to reclaim material as i describe so your project may not be big enough to be cost effective. i suggest you avoid a "billy bob" type reclaiming contractor since they could easily screw up the entire process for a whole lot of money.
go to this site to see if it helps. the basic asphalt recycling manual is very good. http://www.arra.org/
good luck
RE: Using recycled concrete and asphalt
f-d
¡papá gordo ain’t no madre flaca!
RE: Using recycled concrete and asphalt