A formwork carpenter creates the shuttering and falsework used in concrete construction. These systems consist of prefabricated timber, steel or aluminum beams and formwork modules. Modern builders use plywood and/or steel to build formwork. The reinforced concrete can be cast by conventional formwork or sliding formwork. Wet concrete also applies hydrostatic pressure to formwork. Once the concrete formwork was removed, the cantilever developed a noticeable sag. Fabric formwork is a small niche in concrete technology. Someone who builds custom concrete formwork is a "form carpenter". Although previous technology limited formwork to , this technology permitted the pumping of concrete high. The core was constructed using a climbing formwork. It had a 12-meter diameter, 6-meter height, and was lifted using Bini's patented pneumatic formwork. The main shaft was built using climbing formwork. The International Society of Fabric Forming conducts research on fabric formwork. Investigators subsequently determined that the wooden formwork did not meet industry standards. After a wall is complete, it is sufficiently strong to immediately remove the formwork.