Volume Batching

Volume batching is the most suitable method used on small projects or for smaller quantities of concrete where mixing might be carried out by hand or by using a manually loaded concrete mixer.

The accuracy of this method relies on the use of a standard unit of volume for gauging the quantity of each material. A simple example is a bucket that can be filled to the top with
each material and emptied into the mixer the relevant number of times as determined by the mix proportions. A quicker method is to use a ‘gauge box’, designed to the required size. It is a bottomless box into which the individual dry materials are placed before being ruled off with a timber straight-edge at the top in order to get equal proportions.

The dimensions of the box in Fig 9 equate to four 25-kg bags of cement but smaller boxes for smaller projects are available, or could easily be made out of plywood for smaller mix requirements.

Подпись: Volume Shrinkage When volume batching for concrete, account must be made for ‘volume shrinkage’ on mixing. For example, 1m3 of cement, 3m3 of fine aggregate and 6m3 of coarse aggregate

The gauge box is placed on a clean, firm base (wooden board or steel sheet) and filled in proportion to the design of the mix. When full, the box is lifted and removed, and the contents can be shovelled into a mechanical mixer or on to an appropriate hard surface for mixing by hand.

Volume Batching

Fig. 9 A typical example of a gauge box.