Architecture Puzzler #102

Acrylics and polyurethanes are two main types of sealant. Which is generally cheaper and can be painted sooner? Typically, a knowledgeable specifier would use the polyurethane on the exterior and the acrylic for the interior. Why?

You direct a contractor to excavate a 3-foot by 3-foot area, 3 feet deep (one cubic yard of earth, or about 3/4 of a cubic meter). Yet when loaded into a pick-up truck that holds exactly one cubic yard, the earth spills over the edges. In dry earth, what is the swell (percent of expansion of undisturbed medium-density soil when excavated) that should have been planned for? Would clay or gravel have a lesser swell?