Cement Dry Mix - Ready Reckoner

Boral Cement

Mix Design & Calculation Chart

Mortar Sand-Cement Concrete

Mortar

  • Laying BRICKS and BLOCKS
  • Building STONE walls
  • POINTING existing brickwork
  • RENDERINGM
  • REPAIRING concrete

Sand-Cement

  • RENDERING walls
  • TOPPING or CAPPING on walls
  • Brickwork BELOW GROUND level
  • REPAIRING concrete
  • SCREED for ceramic tiles

Concrete

  • Laying PATHS
  • Setting POSTS
  • Creating MOWING STRIPS
  • Light-duty FOUNDATIONS

Mix Design & Calculation Chart

Ready Reckoner - Concrete

For slabs, paths and driveways

1. First calculate the area:
Area square metres(m²) = length x width (metres)

2. Then use the following table:

Area
(m²)
Cubic metres(m³) needed. Slab thickness in mm.
50 75 100 125 150
5 0.4 0.4 0.6 0.8 0.8
10 0.6 0.8 1.0 1.4 1.6
15 0.8 1.2 1.6 2.0 2.4
20 1.0 1.6 2.0 2.6 3.0
25 1.4 2.0 2.6 3.2 3.8
30 1.6 2.4 3.0 3.8 4.6
35 1.8 2.6 3.6 4.4 5.4
40 2.0 3.0 4.0 5.0 6.0
45 2.4 3.4 4.6 5.8 6.8
50 2.6 3.8 5.0 6.4 7.6

Yellow area: When using premixed bagged concrete as a guide 1 cubic metre (m³) requires 108 x 20kg bags

Blue area: 1 cubic metre (m³) of concrete contains roughly 2.5 tonnes of raw material. Non-trades customers with jobs that fall into the shaded area might wish to consider ordering premixed concrete from a ready-mixed supplier



Mixing Raw Materials

Suggested mix proportions by volume

Materials High Strength & water tight General use, paths, floors etc Foundations & large masses
cement 1 1 1
sand 2 2.5 3
stone or gravel 3 4 5

Estimating How Much to Oder To fill 1 cubic metre (m³)

Mix (as per concrete use) No. 20kg bags
of cement
cubic metres
(m³) of sand
cubic metres
(m³) of stones
Cement Sand Stone
1 2 3 16 0.5 0.8
1 2.5 4 13 0.5 0.8
1 3 5 11 0.5 0.9



Buying Premix Bags: Concrete

Estimating the number of bags of concrete Mix by job size

Cubic metres (m³) .02 .04 .06 .08 0.10
No.20kg bags 2 4 6 8 10*

* 108 x 20kg bags of Boral Concrete Mix will fill 1 cubic metre



For fence posts and other round excavations

Calculate for each hole as:

Depth of hole (mm) Cubic metres(m³) needed. Hole diameter (mm).
300mm 400mm 500mm 600mm 700mm
200 0.01 0.03 0.04 0.06 0.08
400 0.03 0.05 0.08 0.11 0.15
600 0.04 0.08 0.12 0.17 0.23
800 0.06 0.10 0.16 0.23 0.31
1000 (1m) 0.07 0.13 0.20 0.28 0.38



Post Calculations

Step1.

Calculate entire hole volume.
Post Calculation
Formula:
TT r² h
= 3.14 x (0.15m x 0.15m) x 0.5m
= 3.14 x 0.0225
x 0.5
Volume = 0.0353m³

Step2.

Calculate Post Area
Formula:
TT r² h
= 3.14 x (0.075 x 0.075) x 0.5m
= 3.14 x 0.00563 x 0.5
Volume = 0.00884m³

Step3.

= Volume Step 1 – Volume Step 2
= 0.353m³ – 0.0088m³
= 0.02646m³

Step4.

= Multiply by number of 20 kg bags
per m³ (108 bags)
= 0.02646m³ x 108
Therefore = 2.86 bags of 20 kg
Concrete Mix, required to fix post in hole.
Ready Reckoner - Mortar

Mixing Raw Materials

Suggested mix proportions by volume

Materials External Brick & Block Construction Exposed to sea air or spray (within 1km of coast) Internal rendering above damp course Internal rendering below damp course
cement 1 1 1 1
sand 6 4 6 3
hydrated lime 1 0.5 1 -



Buying Premix Bags: Mortar

Using Brickies Mortar to lay bricks Estimating bags by brick number

No. bricks 200 400 600 800 1000
No. 20kg bags 12 24 36 48 60

Laying bricks - Estimating how Much to order

For every 1000 bricks Bricks without frog
cement sand hydrated lime No. 20kg bags of cement cubic metres (m3) of sand No. 20kg bags of hydrated lime
1 6 1 8 0.65 3
1 4 0.5 12 0.65 2
1 3 - 16 0.65 -



Which cement for what conditions?

Condition
General Purpose Cement Builders Cement Pozzoment Off-White Cement High Early Strength Cement Special Purpose Cement

General - No specific requirements

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In Service - Exposure to weak acids

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Exposure to soft water (low in dissolved salts)
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Expose to sulphates (SO4)

           
<600mg/litre
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600-3000mg/litre
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>3000mg/litre
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Marine Environment - Permanently submerged in seawater

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Tidal or splash zone
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Marine atmosphere
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During Construction - Cold weather

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Early strength required for stripping of formwork
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Hot weather
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Mass concrete where rapid heat evolution is to be avoided
           
Coloured concrete specified
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