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Concrete Mix Ratio's

Mixing Concrete

Date created

Wednesday, 27 April, 2016 - 10:41

Last updated

Wednesday, 27 April, 2016 - 10:41

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Concrete is made up of a ratio of mixed cement, sand, and aggregates or gravel. When mixed with water cement becomes a paste that chemically sets hard. However cement alone is not strong enough and so sand and gravel are mixed in for strength and bulk or volume.
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Concrete Mix Ratio

Concrete is made up of a ratio of mixed cement, sand, and aggregates or gravel. When mixed with water cement becomes a paste that chemically sets hard. However cement alone is not strong enough and so sand and gravel are mixed in for strength and bulk or volume.

Concrete mixing Ratio

There are many different types of concrete and uses but the most common are high strength and water tight, general use and foundations.

High Strength Concrete Mix Ratio

  • Cement = 1 part.
  • Sand = 2 parts.
  • Stone or gravel = 3 parts.

This concrete mix ratio will give you high strength concrete plus water tight properties making it great for ponds, and structural uses such as concrete panels and building slabs.

General Use Concrete Mix Ratio

  • Cement = 1 part.
  • Sand = 2.5 parts.
  • Stone or gravel = 3 parts.

This concrete mix ratio will give you concrete that is great for paths, floors, general land scraping, and driveways.

Foundations and large volume Concrete Mix Ratio

  • Cement = 1 part.
  • Sand = 3 parts.
  • concreting aggregate or gravel

  • Stone or gravel = 5 parts.

Foundations are the main use for this concrete mix ratio where a large amount of concrete is used to fill up strip footings trenches. This concrete mix is used in house foundations, to make solid and stable, when filling from bed rock to ground level.

Mortar Mix Ratio

Mortar is a mix of sand, cement, lime and water. When mixed properly it forms a bond between masonry surfaces such as bricks and concrete blocks of all different sizes.

  • Cement (using General purpose cement) = 1 part.
  • Sand = 6 parts.
  • Lime = 1 part.

Cement and Concrete Tips

Types of cement

All of the concrete mix ratios above use type GP or General Purpose Portland cement. However type GP and Type GB are the most common types.

  • Type GP - General Purpose Portland cement.
  • Type GB – General Purpose Blended cement.
  • Type HE – high Early Strength Cement – or rapid set.
  • Type LH – low heat cement – used on large structure such as building and dams.
  • Type SR – Sulphate Resisting cement – use in salty areas.
  • Type SL – Shrinkage Limited cement.

All of these types have different properties and have a different purpose and are made to have different end results.

Some of the types above all contain additives such as: fly ash, silica fume, and ground slag that change the workability of the cement and the end result.

When laying a path or slab it is best practise to compact the concrete by removing the air from the concrete. This is done by placing a vibrator pole into the concrete at the time of laying to release the air bubbles which in turn increases the density and strength of the concrete.