OT Cinder block construction

I have a couple projects in mind involving cinder block. The only time I have ever used it was when I built the core for my field stone bbq where I made a block perimeter but filled the inside with more block and mortar to support the firebricks...

So the first project involves a short retaining wall at the east end of my barn. It will be about 5 block high. There is an existing footing there but no re-bar. I have been doing some research and it sounds like the wall wants re-bar in the corners and then every 16" in between. Also sounds like I need to put a bond beam every third row. Lastly, and I did not know this, they put pea gravel concrete in the voids?

So what is my best plan for drilling holes for rebar in an existing footing? And...do I have the rest of the above right? Anything else I should do to reinforce the wall? It would have sand behind it and eventually (if I do it right and it doesn't fall over!), a concrete slab extension of the barn floor would come out over it making a loading and unloading spot for the truck. Any help, guidance, tips, etc very much appreciated!

you can lay the first course,then drill for the uprite r rods with a hammer drill,.drill the hole,and pound the rods in about 2 to three inches,the pea gravel concrete is a good idea,not sure if you need a bond beam with only 5 courses high,you could put durawall,a wire that goes in the bed joint too if you have it

I've seen many block buildings demoed and few had concrete in more than a few cores for doors and cornors. For a retainer wall I'd only fill holes that have rebar.

If you want bars running horizontal in the wall you can just lay 3/8" bar in the mortar line. Then the verticals can be put in the holes.

I would think you should use concrete blocks, cinder blocks are not very strong and not used below grade.

I'd use 2 by 2 by 6 concrete blocks. They are heavy enough the dirt behind them won't blow them out. And they will shrug off 45,000 pounds. Some feed lots use them for bunker walls, back the belt trailer up onto the blocks and run the feed out.

When I lift my tag axle and back up to the pit I've got about 23,000 sitting on top of that block and another 23,000 about to back onto it.

Use bondbeam 1/3 of a pallet is bond beam. Fill all cells with concrete ( grout ) that have upright rebar and fill every cell on the top corse and I would lay a bar of rebar in this course as well. Here is a trick stuff all of your concrete bags in the cells that did not get grout. crumble them up shove them down past the top of the 2nd corse from the top and grout the top corse of the wall.

There are some details to consider being its a retaining wall and it may serve as a loading dock.

Cinder block is a term that many use to refer to a common material known as concrete masonry units, (CMU) or concrete block.

To dowel into the existing footing you need to drill oversize holes at an appropriate depth, then epoxy the rebar, (deformed metal bar/rebar) into the footing. There is a bagged material you can use and is commonly available. You can set your first course so you have the layout, like Larry said. #4 bar is most common in masonry. Clean that footing off well so the mortar bed achieves a good bond. I like to moisten the area before placing the mortar, so the footing, slab, or what have you does not dry out the mortar to rapidly. With all cementitious materials including concrete a slow hydration/cure process is always best.

Below is a link to a supplier of masonry accessories. You can reinforce same with ladder mesh every course, look at the products, they cover everything you could ever need in masonry construction or just about.

CMU comes in various compressive strengths, with up to 75% filled cells, which is high strength CMU upwards to 5000 PSI. The MFR can certify this.

You can reinforce and completely fill the cells and make a substantial wall if you like, given it could be a loading dock, I would do so myself if using CMU construction. The grout you use to fill the cells should be 3000 psi or better or match the CMU compressive strength, but just filling the cells with decent material will strengthen it significantly. That and the vertical bars, every cell, every other or depending on what you want in strength. Its commonly set at wider spacing, but every wall is different.

Retaining walls need to be tied back into the backfill or what is behind it. You also need to have drainage, say just over the top of the footing. Weep holes, pipe, the below site has smaller weep materials for masonry.

Straight up sand may not achieve good compaction under the slab, its all one sieve size, so a good crusher run or bank run gravel, or what have you, with optimum moisture and composite sieve size aggregate will compact properly. Gravel will also drain well too, just like sand.

This sounds like something I would want to form and use cast in place concrete, not CMU, but if you do decide on CMU, make it strong, or you will be disappointed after all the hard work.
Hohmann & Barnard

Embedment length for a #4 rebar, grade 60, is about 15 inches which I doubt your footing is that deep, however at only 5 blocks high, 40 inches , you will not need the full strength. I doubt if your footing is wide enough to prevent overturning of the whole wall structure so Billy's suggestion of tying the wall back into the soil is a very good one

Do they even make actual cinder blocks any more. I remember them from back in the 50's and 60's. But haven't seen them for yrs.

I remember them being called waylights. I think at one time some of the ash (cinders) from the boiler at the paper mill I retired from went to a facility that made lightweight blocks, but that mill has been torn down and cut up for scrap. I would think that the supply of usable ash has kind of gone away.

I would advise completely against filling that block with pea gravel. It will draw and hold moisture making the block soft. Grandpa built a block wall around his entire feedlot and they filed it with pea gravel....most of it is now crumbling. If anything, slush it with concrete

I deliver for a masonry manufacture/supplier. There are different weights of block in the different sizes. The most commonly used weight around here is what they call "medium" weight. They are sometimes used below grade, but are always grouted when used below grade. Around here they use Bond-Beam block every 3rd layer, and put a horizontal rebar in that layer. A true masonry supplier will have the answers as to what is practice and code in your area. Have fun with your Project.
Tim in OR