THE FORM TIE DETAIL
Corbusier was the first architect to use cast-in-place concrete as exterior (and interior) cladding, probably in the Unité d’habitation (1946-62) in Marseilles. The Unité was actually hybrid construction, consisting of cast-in place and precast concrete as well as a steel frame. By the time he built the Shodhan house (1956) in Ahmedabad, he was using exposed cast-in-place concrete throughout. Concrete formwork must be designed to resist the pressure of the heavy concrete until it sets. The cheapest way to do this is to use form ties—wire ties that hold the two pieces of formwork together;