Moving, going to need to build a garage

Congrats on being able to build your own garage. Hopefully my post isn't too late for your concrete pour. Being in the concrete supply industry I would strongly suggest you look into Vapor Lock Enhanced Concrete, VLEC. We try to put Vapor Lock in 100% of our projects here in Michigan. If cost is a concern, i'll do the math for you. Based on 24x32 @4"= 9.48 cyd's of concrete x ~$35/cyd (probably less) for the admixture =$350 extra. However, VL technology has been around since 1975 and it prevents all moisture vapor emission. It also eliminates (or virtually eliminates in some applications), plastic cracking, efflorescence, delayed ettrignite (?sp), slab curl and ASR. VLEC completely shuts down the bleed channels and capillaries. Very early psi strengths, 3 day breaks ~87% of target and 28 day breaks almost double. You pay for 3,500 or 4,000 psi concrete and Vapor Lock will give you about 8,000. Also, if you want to epoxy it later or two weeks later, your contractor will waste his/your money on a calcium chloride test, save it and tape a clear lunch zipbag down and you will see zero moisture. Assuming your Batch Plant puts the VL in the truck. I have the driest garage floor in all of Michigan. Even under the anti-fatigue matts. Good Luck.