Retaining Wall Cap

[lzicc]

I have a retaining wall that I want to cap. It is a concrete block wall and instead of buying a cap, I am going to form the top of the blocks for the cap and pour it right on the top of the wall. In the past I have used sand mix to pour the cap but someone suggested to me to try mortar mix. I think mortar mix would smooth out nicer but will it be as durable as concrete. My concern is cracking. I would use re-bar either way. Any suggestions?

 

[Steevo]

Re: Reatining Wall Cap

I poured caps on my columns (16"x16" columns) using swimming pool coping forms and a mix of standard bagged concrete mix with added mortar mix. The trick was to vibrate/settle the mix very well to eliminate any voids along the forms.
I had rebar coming up from inside the block columns which also tied it together.

 

[shannonw]

Re: Reatining Wall Cap

that pergola is awesome!

Not to hijack the thread but i'm just curious what are the columns made of?

 

[VANAMAL]

Re: Reatining Wall Cap

Grout the wall and after its set go back and cap it. You can buy a capping tool thatruns along the top to shape it. You can use a pre mix mortar mix or mix your own. Its a four to one ratio of plastic cement and plaster sand. To make sure the cap sticks to the top we use a bonder thats brushed or rolled on. This is a must because they tend to pop off. Weldcrete,therobond or something similar will work.

 

[ConCretin]

Re: Reatining Wall Cap

Use concrete. Course aggregate helps control shrinkage. A grout/mortar lacks stone and is more likely to crack.

I'd form something at least 4" thick with a couple #4 bars running longitudinally. If the concrete quantity doesn't justify ready mix, use a commercial bagged concrete mix (4000 psi). Constructed this way, the cap will add a lot of strength the the wall.

 

[Real McCoy]

Re: Reatining Wall Cap

I capped a block retaining wall using concret flat walking blocks. Looks nice, was easy and has held up about 10 yrs so far.

 

[Steevo]

Re: Reatining Wall Cap

that pergola is awesome!

Not to hijack the thread but i'm just curious what are the columns made of?

Those columns are made of these, laid in pairs in alternating directions:

3x3x18" footings, rebar inside 2 of the 4 vertical voids, filled with concrete.

We now return you to the original thread . . .

 

[lilredex]

Re: Reatining Wall Cap

Here's a couple of examples, done with simple forming and DIY concrete.

That block wall was filled with grout leaving a space (about 2") at the top. The form was two 2X4's laid together (staggered) so the outside one was up about 2 1/2", defining the cap's thickness, and the inside one was at the wall's top. The forms were pinched to the wall with shop made clamps....

Like these.

The concrete mix was something like: 1:2:3 (sand), no rebar or mesh, still there in fine shape after thirty years.

 

[lilredex]

Re: Reatining Wall Cap

Here is a shot of those clamps in action. Looking at those forms again, it looks more like a 1X6 nailed to a 2X4, rather than two 2X4 as earlier suggested.

 

[Jagmandave]

Re: Reatining Wall Cap

I capped a block retaining wall using concret flat walking blocks. Looks nice, was easy and has held up about 10 yrs so far.

I did this a well on my low retaining wall (it was only 3 blocks high) then I stucco'd the whole thing, still looks great and hasn't moved or cracked and it's been about 22 years now.

I don't own the house anymore, but this recent Google maps pic shows the wall is still there, plus you can see where I built around a transformer, and simply rounded the concrete mix on top of the blocks - that's stil there too.

 

[NUTTSGT]

Re: Reatining Wall Cap

If I was capping a wall with concrete, it'd probably be minimum of 4" thick, with rebar running the length tied to a piece stuck in every few blocks. I think I would fill the holes in every block maybe every other block 2 deep.

It might be overkill, but that's what I like to do.