# Forum Home Renovation Retaining Walls  Core filling

## barney118

I am about to plan the retaining wall. It specifies clean out blocks for first course. What about if you core fill as you go rather than hire a pump and fill the lot in one go. Given the wall will be 1.8m high in some sections would there be a possibility of having air pockets? This would mean I could put a course up at a time. Would this be advisable?  
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## Gaza

Yep it's called bucket filling 
Often done usual have one guy filling with one guy laying   
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## barney118

> Yep it's called bucket filling 
> Often done usual have one guy filling with one guy laying   
> Sent from my iPhone using Tapatalk

  This way no need for clean out bricks just use h blocks?  
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## Blocklayer

How long is the wall? 
If you've never core filled a wall before (especially H blocks) you'll be amazed just how much concrete it takes.
Have you worked out the total volume of core fill? Just find how many blocks (H blocks ?) per m3 (from the manufacturer) and divide into total blocks. 
If you core fill each course (or 2) as you go, you'll need the vertical bars full height (1800) from the start. Not such a big deal with H blocks (no ends), but for normal stretchers you'd need to lift every block right up and over the vertical steels and (gently) lower into place. A real pain.  
And if you lay your own, you'll most likely drop a lot of mortar on top of each layer of core fill.
I'd much rather use clean out blocks and lay the whole wall first, then clean out the bases (clean out blocks) and block cores, then core fill all at once (with a pump)

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## barney118

> How long is the wall? 
> If you've never core filled a wall before (especially H blocks) you'll be amazed just how much concrete it takes.
> Have you worked out the total volume of core fill? Just find how many blocks (H blocks ?) per m3 (from the manufacturer) and divide into total blocks. 
> If you core fill each course (or 2) as you go, you'll need the vertical bars full height (1800) from the start. Not such a big deal with H blocks (no ends), but for normal stretchers you'd need to lift every block right up and over the vertical steels and (gently) lower into place. A real pain.  
> And if you lay your own, you'll most likely drop a lot of mortar on top of each layer of core fill.
> I'd much rather use clean out blocks and lay the whole wall first, then clean out the bases (clean out blocks) and block cores, then core fill all at once (with a pump)

  The perimeter is 24lm , I was planning on laying 1 or 2 courses and filling then another 2 etc. so it works out .48 m3 per course so it is a fair bit, I will be going min 4 courses before it steps in places so 2 m3. In the long run looking at saving some coin on the pump vs bucket. Looks like it's not going to save that much given the time I will save.  
The overlap is 600 min for vertical bars. Why would you need to go 1800 from the start?
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## barney118

I have downloaded the 200 series blocks, I take it pays to buy a few stretcher (double H) incase of verticals not lining up.

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## shauck

I'm working on a difficult site at the moment and talked to a local guy about using a line pump as it's the only real option. I was surprised to find his price really reasonable. minimum 2 hours at 140 bucks an hour plus 6 bucks per m3 plus GST. Not sure what it would cost where you are but anyway, I thought that was cheap.

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## barney118

> I'm working on a difficult site at the moment and talked to a local guy about using a line pump as it's the only real option. I was surprised to find his price really reasonable. minimum 2 hours at 140 bucks an hour plus 6 bucks per m3 plus GST. Not sure what it would cost where you are but anyway, I thought that was cheap.

  Su it costs a min 4 hrs up here $600-650 min, you lucky I wouldn't worry too much if I had your prices. They do the job in 2 hrs and get payed for 4.  
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## shauck

I think they'd probably do the job in 1 hour and go to the pub for three.

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## Marc

I built a shed that way, after giving up on finding a brick (block) layer willing to do it. After digging and filling and levelling the footings with steel rods in them at the appropriate spacing, I started laying the blocks, and every second row, I would clean out the mortar that inevitably spills in the cavity, by hand. Mix the concrete with a cement mixer and fill the core with a bucket. No big deal. As far as the steel rods, I had them only half way to save my back. Once the blocks where close to the edge, I would take another half length and tie them together with wire, overlapping 6" or so. Every 2 rows I had a run of reo horizontally tied to the vertical rods as well.  I am sure my shed wall will not stop a tank shell but they have certainly not cracked nor moved. For a retaining wall you can have more vertical reo, say every block if you want and horizontal every row as well. Will resist one hour of heavy shelling guaranteed.

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