Concrete is a unique product that begins its life as a semi-solid, can be manipulated and worked to assume most any shape, and then hardens to assume that shape. This ability to fill voids and assume shapes is what makes concrete the most-used building material on the planet. None of this would be possible without concrete forms.
In simple terms, concrete forms are nothing more than a solid barrier that holds concrete in place or forces concrete to assume a certain shape. However, many newer forming systems serve other purposes as well, such as providing insulation or imparting special decorative effects
A square foot of conventional concrete weighs about 150 pounds, and a typical concrete project may require hundreds to thousands of square feet of concrete to be placed at one time. All that weight needs to be held back by concrete forms, which is why most forms are made from rigid wood or metal. In recent years, there have seen some advancements in concrete forms made of plastic, fiber glass and resins, but the cost and strength of these materials are slow to overcome the proven performance of metal and wood.
TYPES OF CONCRETE FORMS