fndn:
Good link, very interesting info. Here is another resource for slab on grade floor designs:
"Designing Floor Slabs on Grade, Step-by-Step Proceedures, Sample Solutions and Commentary", 2nd Edition, by Boyd C. Ringo and Rober B. Anderson, published by The Aberdeen Group, 426 South Westgate, Addison, IL 60101, ISBN 0-924659-75-0