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Community and Q&A

How to grout concrete block wall?

etting | Posted in General Questions on

My foundation stem wall for a raised-floor house is four courses high, made of 8x8x16 concrete blocks with #4 vertical rebars every 4 feet and a #5 rebar in the bond beam top course. I’ve installed grout stop over the unreinforced vertical cells. After two days of searching, I haven’t found any step-by-step instructions on how to grout the reinforced cores and the bond beam, but I have gleaned a few tips to supplement what seems fairly obvious about the procedure. Does the following overlook anything important?

The local concrete supplier will send a truck with a pump, and their pump operator will direct grout into my bond beam and reinforced cells. (They do that here.)

I will poke a length of rebar up and down in each vertical cell to make sure the grout consolidates.

After the pump operator has gone around the wall perimeter once, he will make another pass to top off the grout where it has settled.

I will use a float or some other straightedge to smooth out the top of the grout where needed.

I will insert anchor bolts for the sill plate.


Will the grout be thick enough to keep the anchor bolts from sinking or leaning? If not, how can they be secured?

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  1. Expert Member

    That's a fairly good description. Grouting cores is usually down with a higher slump mix than pouring whole walls so you probably won't have much work to do with your rebar poker. I doubt you will need a second go round if you slow down a bit on the first pass.

    The mix should support the anchor bolts without needing other support. The key is placing them as the mix sets up, but not waiting so long that they create voids around them as they go in. That's probably a job you want to have someone dedicated to so you don't miss the sweet spot while doing other work.

  2. etting | | #2

    Thank you very much, Malcolm. I'm sure the time window for placing the anchor bolts depends on the weather. Roughly speaking, how long after the grout is poured would you expect the sweet spot to start and end on a dry 85-degree day?

  3. Expert Member

    It depends on both the weather and the mix. I have had walls that were almost too dry to get the anchor bolts in by the time I had finished levelling. others had a half hour or so. Once you start you should have a good window to work because not all the concrete was poured at the same time.

    Have whoever is placing the bolts work behind you as you compact and level the grout. They may well be able to keep up with you.

  4. etting | | #4

    Thanks again, Malcolm. It sounds as if placing each bolt may take more time than I imagined, and I don't know whether I'll have a helper who knows more than I do. Is there more to it than pushing them in to the correct depth?

  5. Expert Member

    No - you just sink them into the mix, give them a small shake to make sure the concrete is adhering to them, and you are done. I've made this seem like a bigger deal than it is. It all should tie less than ten minutes, it's just with concrete pours everything tends to happen at once, so it's good to have someone else dealing with the anchor bolts.

  6. etting | | #6

    Thank you, Malcolm. It does seem wise to have ample help for such a brief and critical process.

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