Question on pouring a slab

Flatwork finishers often want to water down the mix to make it easier. That decreases the cured strength. The worst is adding a large amount of sodium chloride to make a high slump mix (almost self-leveling) set up quickly. You won't see any used on a gov't pour- for good reason. I once allowed it used for a private pour. Bad decision. Weak concrete that cracked badly. Last time I used that highly-recommended finisher too. I didn't know that non-chloride accelerators were available. Chloride has a tendency to eat any steel present.

An alternative to the sealer is to place sheet plastic over the fresh slab to slow down evaporation.

The American Concrete Institute has a good inexpensive booklet. All they want is for everyone to have a successful experience.

You don't need a cone or measurements, but the guy in charge of the pour should be able to talk knowledgeably with the ready-mix company. Here, the driver notes on the ticket if there is a test cylinder used. That's to lab-test the strength of the concrete. They also note if water was added, which voids the strength request.

I quit bothering when I found out from a lab employee that the strength was always more than specified. The salesman told me that was the case but I didn't believe him. Covering their posteriors and accounting for our relatively high concrete costs. Your experience may vary. But if you ask for 4000# it won't make any practical difference, even if you add quite a bit of water.

The guy in charge really does have responsibility.

Before you start to far, you might pick out a local heavy equiptment repair shop and then visit the county planning and zoning deptartment. Pull the building plans for that building and see what the engineer spec'd for that floor. That will save you alot of guess work and money. The plans will give what base is required for your area.

Since your goal is to work on a Dozer, consider making only one area of the shop floor for the Dozer work. That might save you some dollars on the rest of the floor.

T_Bone

I can't imagine you needing 8" of concrete, but your ready-mix supplier will love you. And if you're not insulating it I guess you don't plan to heat the barn.