There are two basic types, cast in place and precast.
Cast in place concrete countertops are done right on the cabinets. The forms are built on the cabinets and the concrete poured in the forms. The surface is then troweled until smooth and free of pinholes. Countertops can then be embedded with almost anything including glass chips, marbles, or metals, imprinted, custom colored, and polished to a smooth matte or glossy finish for high-end, handcrafted appearance. Retrowel after embedding. Many coloring effects are possible, including integral colors and acid stains, and you can do amazing things with stencils or other techniques. Achieving a fine finish with cast in place countertops requires a some skill with a trowel, and cast in place countertops often have more of a handmade or rough look.
A concrete countertop mix includes sand, stone, and cement along with other ingredients such as glass fibers, that are unique to the mix you desire. If the countertop has to extend out over the cabinet, for example, it has to be extra strong. Dyes can be added to penetrate the concrete completely for colors that won’t fade over time.
Concrete tops are usually cast in thicknesses from 1½ inches to about 2 inches. If they are too shallow they can curl while curing, but concrete forms are often reinforced with rebar or wire mesh for strength and stability. Dyes penetrate the concrete completely for integral colors that won’t fade over time and sculptural properties allow for any edge profile.
Mild detergent and water is recommended for regular cleanup. Even if there are no spills on the counter, take a damp towel and wipe the counter occasionally. Regular waxings are also recommended. You can tell if the countertop needs waxinb by throwing a little water on the counter. If it beads up, then it’s OK, If it doesn't bead, then it’s probably time to wax again.