how much cement/sand for cement block laying

[penfold74]

Hi all,
I am going to attempt to lay a retaining wall using Tarmac 100 concrete blocks.I will lay them back down to give better strength. It is 9 m long by 1m high so I've calculated 200 blocks. I bought 1 ton of sand and 10 bags of cement, but now i'm wondering if I have under ordered. I don't want to get so far and find I've run out as I plan to do it over the weekend.
Any help would be grand
Cheers

 

[Porque223]

'It is 9 m long by 1m high so I've calculated 200 blocks'

What is the calculated concrete volume necessary for this? By converting to densities this should be reasonably easy to solve.

 

[kingandy2nd]

I find this website useful for rough estimations. If you're a diy er you need to anticipate more wastage than a professional.

http://www.source4me.co.uk/calculate_brick_block_mortar.php

 

[tony1851]

Porky is right; you'd better get some extra blocks in for the weekend.

You are probably in the right area for your sand/cement but why not overbuy - you can always take stuff back. Don't make the mix too strong or you may get a crack in the wall, 1;4 1/2or 5 should be OK.

 

[limerockconstruction]

9 blocks high which should gauge 990mm, by 20 long for 9m = 180 Blocks.

1 ton sand and 8 cement should do the job nicely.

 

[pred]

Porky is right; you'd better get some extra blocks in for the weekend.

You are probably in the right area for your sand/cement but why not overbuy - you can always take stuff back. Don't make the mix too strong or you may get a crack in the wall, 1;4 1/2or 5 should be OK.

Also add a decent plasticiser, http://www.toolstation.com/shop/p53...ogleshopping&gclid=COf1i-uNzrcCFZIPtAod-X4AhA about an M/T can full per bucket.

 

[Skimmers]

your laying solids on there side you your laying 225mm with 10mm full bed
i make that just titch under a tone of sand 11 bags of OPC 2 lime and 200 blocks are you having pairs in the wall?? this will need more materials
and extra footing

 

[^woody^]

Laying blocks on their side does not give extra strength, and actually increases the risk of vertical cracking.

If doing this, you really need to lay 2 course of straight joints and then bond the alternate two course

 

[Skimmers]

No your wrong WOODY you can lay solids on there side one course at a time no need to double up as it gives you more load bearing.
for side pressure id lay raking pairs on 9" pairs you can use 215mm Hollow Concrete Blocks 7N with rebar tied into footing then twist tied if over 1.8m then full fill with lean mix concrete thats first year NVQ stuff