For most do-it-yourselves, the best material for building a concrete slab is a ready-mix crack-resistant concrete product. The wet mix is poured into a prepared wood form, then left to cure. After the concrete has hardened, the sides of the form are knocked off and the slab is ready to use.
Ready-mix concrete is a blend of gravel, sand, cement, and other additives. Bagged and available in most home centres, ready-mix concrete contains all of the materials to make concrete, except for the water.
To avoid setting a reinforcing bar (rebar) for strength, buy crack-resistant ready-mix. Its synthetic fibres eliminate the need for rebar on small-scale concrete slabs.
Working concrete by hand in a wheelbarrow requires strength, organization, and speed. For this 91,44cm 91,44cm slab, you will need two assistants. Two people will mix the concrete in the wheelbarrow, while the third person spreads out the mixed concrete in the form.
Wait for dry, warm conditions to pour your concrete slab. For most ready-mixes, the temperature should be 22 °C or higher for five days after pouring. You can pour the slab in colder temperatures but the curing time will be extended to seven days.
Always use breathing protection when working with dry concrete mix since it is an irritant to breathing passages and lungs.1 Eighty-pound bags of concrete are very heavy, so have help when moving them to protect your back.