Concrete @ your Fingertips


Batching by volume - DIY

When concrete is to be mixed on site rather than ordered from a ready-mixed concrete supplier, an estimate of the materials needed is necessary. Materials can be purchased as individual constituents with either the fine and coarse aggregate pre-blended (ballast/all-in aggregate) or separately.The quantities of cement, sand and coarse aggregate or cement and ´all-in aggregate´ for various concrete volumes are estimated in the Table below. The bags of cement are assumed to be 25 kg and the largest size aggregate is assumed to be of nominal size 20 mm.

Mix Materials 0.2 m3 concrete 0.5 m3 concrete 1 m3 concrete
A1 cement (no. 25 kg bags) 2.5 6 12
  sand (volume in m3) 0.1 0.25 0.5
  coarse aggregate (volume in m3) 0.2 0.5 1
  water (volume in litres) 32 80 160
B1 cement (no. 25 kg bags) 3.5 7 14
  sand (volume in m3) 0.1 0.25 0.5
  coarse aggregate (volume in m3) 0.2 0.5 1
  water (volume in litres) 34 85 170
A2 cement (no. 25 kg bags) 2.5 6 12
  all-in aggregate (volume in m3) 0.25 0.65 1.3
  water (volume in litres) 32 80 160
B2 cement (no. 25 kg bags) 3.5 7 14
  all-in aggregate (volume in m3) 0.25 0.65 1.3
  water (volume in litres) 34 85 170

The table is for batching by volume. A suitable gauge box or similar is therefore needed. The figures assume a general bulking factor for the materials and does not take into account any water in the sand or aggregate. Water should be added to obtain a workable but non-segregating mix, the total free water being roughly 170 litres per cubic metre of concrete.

Mix A is suitable for general-purpose projects, such as paths, patios and general slabs. Mix B is suitable for concrete subject to wear or heavier-duty applications, e.g. driveways. Designation 1 is for separate sand and coarse aggregate mixes and 2, all-in aggregate.


Acknowledgement: The Concrete Society