Q: How thick should my sidwalk or driveway be?

A: That depends on the weight that will be applied. Sidewalks 4 inches and driveways 4-5 inches. If the use of heavy equipment is frequent, I recommend 6-8 inches. 

Q: How much rebar is required? And why is it needed? 

A: Reinforcing Bar (rebar) is the backbone of your concrete. Concrete is strong under compression but has a weak tensile strength. There is no general rule of thumb as to how to space rebar in a slab.