What would be a drawback of using recycled (crushed concrete/asphalt) 3/4" minus material for back filling foundations I would think it would self compact decently enough- better than topsoil not quite as good as sand, it drains well, and it has plenty of voids in it so freezing water wont move it around so much, and it's inexpensive- $7.50 yd around here for recycled. Much cheaper than sand or any other aggregate.
in my opinion, it would be good over pipes for the first lift maybe, but it not large enough for the complete backfill. Here we use #57 which is 1.5" minus I think as a start then go to screened #3 rock. It really lets the water thru.
I have always been of the mind set that you put #57 (2b limestone) about a foot over the French drain then backfill with dirt. Was never a big fan of putting surface water in a footer drain system. Only takes one hiccup in the drain and you start putting all that water against the foundation.
I should have mentioned that I would have the top 12" of grade be topsoil so surface water can be pitched away. Then my theory of having the gravel under it is that any water that does percolate through the surface will "free fall" easily down to the drain tile. Whereas back filling completely with topsoil (except around the drain tile) can keep and hold water against the foundation wall, bad for freeze /thaw cycles stressing the foundation wall, not to mention potential water intrusion.
I've mentioned it a time or two in other thread's, that recycled concrete breaks down very fast ( rots).. but nobody else ever mention this aspect of the recycled concrete. Maybe its just in my area .:beatsme If you could put the natural stone in there you'd be better off..
Hey stump. how is the hand? Chum.
Why not use the excavated material to backfill? Of course use washed stone for the foundation drains but why truck in backfill, just curious.
I've used both recycled concrete and #57 rock also, the#57 rock always worked better for me, and where we were using it. Seems that we have to use more of the Reclaim than virgin rock. We did a large backfill project a couple of years where we were required to backfill with pea gravel and build it with the gravel separated by geofabric and placed in a sloped fashion the entire depth of the wall (which was 23 vertical feet at the deepest point), the cap the final 2 feet with a heavy PI clay in order to prevent infiltration of surface water. The Engineer's explanation of the sloped aggregate was not for water bearing but compressive bearing near the wall. apparently the nesting value of the polished gravel is far less than the surcharge weight of a select material backfill in that amount of fill. There was also waterproofing, subsurface drain and lightning arrest system that was contained in that 9 foot overcut. Made for a crowded day! Also the soil bolts and gunite walls made it fun also.
In The State of Illinois the DOT allows using recycled concrete to be used under highway pavement. I have pushed thousands of yards of it into undercuts.
I am a concrete recycler in NC . we recommend using recycled our #5 stone("11/2 to"1 clean stone)for backfilling walls,voids,foundations ect.it's cheaper than backfilling with dirt because you don't have to compact it(no labor) just dump it in . just hauled 120 tons thurs to backfill a porch .the plumbers do not like the rock against there PVC pipes so we make a "1/2 minus fines for backfilling slab houses but it must be compacted. As far as it (ROTTING) never heard that one I Guess his house does not have concrete foottings under it or concrete sidewalks ,curbs,roads or buildings in his area
I have heard of recycled concrete material not rotting, but dissolving over time from moisture passing over it. But like in NC, recycled concrete is commonly used here (MN) in road base material, so I don't see how that can be true?
My term rotting is referring to dissolving over time. I've witnessed yellow streams of water running out of the crushed concrete... can't imagine the epa allowing this for much longer,,, but then again they allow millions of tons of salt to be dumped around so what the H.
Is limestone aggregate used to make concrete in your area?