Basic concrete composition requires cement, water and sand. Some concrete also has granite or aggregate stone added to lower the overall cost and add additional texture. Standard concrete has 1 part cement, 2 to 3 parts sand, 2 parts gravel and 1/2 part water.
Smoother, thin pour concrete often leaves out granite and aggregate. Thinner concrete recipes also use more water. A basic thin concrete recipe includes 1 1/2 parts cement, 1 part water and 2 parts sand. The finished product has a consistency like pancake batter, whereas a regular concrete recipe has a consistency like a thick brownie batter.
As with any concrete recipe, you should add the water a little at a time to form the desired consistency. Too much water will make the finished product weaker, and extremely thin recipes will often produce concrete that is not suitable for load-bearing purposes. Additionally, using damp sand instead of dry sand reduces the amount of air holes in the finished concrete.