Mixing small quantities by mechanical mixer
Concrete can be mixed in one of two ways for household projects: in a mechanical mixer, or by hand on a board or in a wheelbarrow. Mechanical mixing is less strenuous and much more reliable than hand mixing. The latter should therefore be used only for very small quantities. Mixers should not be overfilled and revolve at speeds recommended by the maker.
For small quantities of concrete (around the house an garden for instance) the materials should be batched using a suitable gauge box or bucket – not larger than 10 litres or it will be difficult to handle. The materials should not be batched by shovelful, as a shovelful of sand is not the same volume as a shovelful of cement or aggregate.
Using a mechanical mixer
Step 1 Turn the mixer on and prime the bowl with approximately 2/3 of the required water.
Step 2 Add the coarse aggregate followed by the sand and then the cement.
Step 3 Blend together until a uniform colour is achieved.
Step 4 Add rest of water slowly and sparingly until a workable mix is achieved.
Step 5 Continue mixing for at least 2 minutes.
Step 6 Discharge mixer.
Repeat the process until the required amount of concrete has been produced.
IMPORTANT SAFETY INFORMATION
Never add just water to the concrete to make it more workable, always add cement. Also when handling and using cement or fresh concrete, avoid skin contact.