Chapter 4, Problem 4.58PP

Insulated concrete forms (ICFs) are becoming more and more common for a variety of reasons including the desire to build more energy efficient "green" structures. Instead of using temporary forms like lumber to hold poured concrete in place until it has cured, an ICF is essentially a rigid lightweight foam container for a poured wall that is left in place permanently, providing an added layer of insulation. See the basic layout of the system in Fig. 4.56. The form, of course, needs to provide adequate strength to contain the wet concrete (sg = $2.4$ ) until it cures. A leak or blowout at the bottom of the form would have a catastrophic effect on construction. What is the maximum pressure that the form needs withstand if the wall is to be $4.5$ in thick, $35$ ft wide, and $14$ ft tall?