When mixing
concrete make a little well in the middle of the dry cement.
 Always use clean tap water that is free of salt and
contamination. Add a little water at a time until you have
achieved a firm consistency. A sloppy mix will result in weak
concrete because excess water will have taken the place of dry
cement. Even a firm mixture of concrete will flow into shape when
tapped or vibrated because the water moves to the top. For this
reason the best way to remove air bubbles from the form work side
that will be visible when the job is finished is to tap the board
firmly with a hammer.
Always protect new concrete from rain until it has hardened.
Never lay concrete on extremely hot days because the evaporation
during mixing and curing will give a poor result. When the slab
has hardened, lightly spray with water for the first day and/or
cover with wet hessian bags so it can cure slowly.
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