You are building your first house, and are pouring your foundation, which is a 4" concrete slab (assume for simplicity this is equal to 10cm ). It has a moisture content of 75% dry basis and needs to be dried throughout to a moisture content of 25% in order for the forms to be removed. The top of the slab is exposed to air at an equilibrium moisture content of 15% dry basis, leading to an average mass transfer coefficient of 0.1m/s. How long should you wait until you remove the forms? Assume water molecules to be spheres, with a diameter of 0.282nm, the outside temperature is 75F(24C), and the viscosity of the cement is 2.755105kg/ms. You will need to determine the diffusion coefficient of water in concrete - recall that the friction factor of a sphere is 6R (20 points out of the 50 points total). If you are unable to calculate a diffusion coefficient (or simply do not have the time), use 6108m2/s