Concrete chunks in place of cinderblock?

[crokett]

I have a lot of concrete chunks from what I jackhammered up. Since I am a bit on the cheap side, is there any reason I can't use the busted pieces in place of cinderblocks to build my retaining wall? Would they be any weaker? Obviously they'd be harder to mortar and keep straight but the one side would be backfilled with dirt. The other would be faced with brick for steps.

I am guesstimating I'd save about 60 bucks on the block. Do you think the extra mortar and time worth it?

[TheRic]

I am guesstimating I'd save about 60 bucks on the block. Do you think the extra mortar and time worth it?

NOPE!!!!!!

[newbie2wood]

How will you stabilize the cinder blocks vertically?

The blocks sold for retaining walls have a lip on the back edge that locks or press against the blocks below them.

Edit: Just re-read your post about using mortar. However, I still don't its worthwhile in terms of time, labor, or savings.
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[crokett]

I don't think it worth it either. However my next thought is forms, a mix n pour and add the smaller concrete chunks to take up space. I am thinking about that - I think I can do the intial wall for cheaper and quicker than laying block.

[kramer katt]

Actually Crokett if you are talking pieces from a broken up slab it is pretty common around here to see low walls built that way when some one is a little low-budget but also just for the effect of a very rustic wall. if you lay the pieces flat with the broken edges visible it give a look almost like stone. That way also they are a little more uniform in thickness.
To allow better advice just how high are you planning to build and how much retainging? Anything of 4 ft or more needs a permit and inspection typically. Wall under that are considered landscaping and not as critical. Footings and stable soil in your trench are also important.
if you are leaning to the concrete pour, keep in mind that building forms is quite a bit of work, (wet concrete can be very strong in bursting out the sides) Small chunks as aggregate are ok unless you overdo it by amount or size. The wall should still stand up but will not be as strong.
If you've got enough concrete chunks you might be able to build a mortarless wall using a plastic fabric back into the soil in each course. Post back if you want more info on this.
kk

[crokett]

If you've got enough concrete chunks you might be able to build a mortarless wall using a plastic fabric back into the soil in each course. Post back if you want more info on this.
kk

I would love more info on this. I have plenty of concrete chunks. The application in question is a 2' high wall that will run 13' long between two existing red brick walls. It will be backfilled with dirt and the ground slopes up fom the base of the wall to ground level approx 20' away.

If I did a form n pour I'd make the forms out of 2x6s I have - they will be strong enough. I can tie them together across the top to keep them from blowing out.

[kramer katt]

Sure,
The idea for these walls is taken from several proprietary systems for large retaining walls. The basic idea is to tie the wall masonry back into the dirt backfill and use the weight of the dirt itself as a "deadman" to stablize the wall from toppling over from the retained dirt wanting to slide down. Each course is done the same. Lay one course (layer) of stone or block or concrete then fill in the dirt backfill but only up level to the top of the wall. The dirt needs to be compacted well. On top of the dirt and also over the stone lay the fabric course. Lay the next course of stone and dirt and fabric and again until you reach the top. Of course the last stone course has no fabric.
On some large walls the fabric may lay back into the dirt 6-10 ft. In your case you might only need 2-3 feet. The depth and width of the fabric and dirt determing how much the wall can retain. Equally as important is the "bite" the stone wall holds on to the fabric. If your wall is not too wide and the fabric could pull out you might hold it with added mortar. Another idea is to "sew" a rebar in the edge of the fabric which is between stones. If your wall was a mix of large and small concrete chunks and maybe 18 inches deep that would likely grab the fabric enough.
The material used for the fabric must be strong but of a very course weave. Burlap may work but not last long enough. I was going to use the orange plastic temporary fence material now used for construction fences. The designed systems use nylon or fiberglass I think.
You might also want to use a slight back slope to the wall called "battered" an old masons trick.
Good luck
kk

[crokett]

Thanks for the info. My wall is only 24" tall so not sure it will have enough courses for this application. I am still thinking it will be a form and pour since the wall will be turned into brick and mortar steps at some point. I don't think I can do that with a stacked wall