Can we talk about Concrete?

[/pine]

FWIW...
A few factoids about concrete...(things I can remember from classroom hours learning about concrete to pass the Class A GC test...)

There are likely thousands of different concrete admixtures that do a plethora of different things either during a pour or for the final product...this includes coloring agents...

The most common admixtures (minor ingredients) are an air entraining agent (prevents freeze/thaw cycle damage) retardants (used in hot climates to prevent curing too fast) and accelerators (used in cold temps to induce curing) FWIW regular sugar is an old time retardant and is still used in some cases...

A simple to remember formula of 1 / 2 / 3 will yield an mix that is roughly 2000 psi in compressive strength... where Portland cement is the first ingredient, fine aggregate (sand) the second and large aggregate (gravel) is the third...using just enough water to make a malleable mix...if crusher run is used a 1 / 5 ratio of Portland and c.r....

There is a device known as a "Swiss Hammer" or Schmidt Hammer that can test the compressive strength of an existing pour regardless of age...

Portland Cement is ground so fine it will pass through a sieve that will hold water...

One of the best waterproofing mixes for masonry surfaces is a mix of very fine sand, Portland cement and liquid bonding agent...no water required but a moist surface will help with cohesion...apply with a masonry brush and float with a moist, small cell float/sponge as it cures...it lasts forever...works much better than bitumen/tar based products...

 

[ericm979]

Lifts have requirements for proximity of rebar and joints to where the lift is bolted down.

 

[Cord]

Rebar installed. (The fiber stuff does not replace rebar)

Actually, I've been doing some really neat stuff with fiber and it can replace rebar. FORTA-FERRO(R) - FORTA Corporation What's so cool about this stuff is that the joint spacing can be opened up. If you have the slab thickness, I've had projects where the joints are spaced 80' apart!

Back to the OP. If he's got drains, he'll want to specify the floor be pitched to the drain without ponding. He'll also want to designate the area which is to be pitched to the drain and if he wants the drain to have a gravel trap. I'd recommend have the trap in the open bay. If the drain will rarely see water, a trap primer might be a good idea. I'd also recommend the use of a vapor barrier. Because this will be a wood shop, I'd suggest upgrading to Stego product. Stego Wrap | 15 Mil Below Slab Vapor Barrier For Foundation Protection This product is much tougher than 6mil poly and will resist punctures. If he does go with rebar (typically these slabs would not be reinforced), then the bars must be on standoffs. You can't "pull the reinforcement up" when pouring. It simply doesn't work.

 

[skipperbrown]

I learned a lot by going to the Portland cement website and reading up on how to have a successful pour.

 

[Fuddy1952]

Since you haven't poured yet I'm curious what others think about a grease pit. If I had it to do over I'd consider one. That I'd have a drain, and bury plastic PVC or conduit over to it, a few feet from bottom for outlets, lights.
To me safer than a lift.

 

[Streetcar]

Grease pit is a big hole you need to secure when not in use. You need to build foundation and walls . You may get ground water in pit

 

[Jstpssng]

^^^^
They can be a trap in the unfortunate event of a fire... especially since that's where any fumes would be collecting.
Also a thread topic a few years ago. https://www.tractorbynet.com/forums/rural-living/328873-new-garage-grease-pit.html

 

[Gary Fowler]

I would much rather have a shop slab lightly sloped to the outside doors than have a central drain. Shops accumulate a lot of trash that will completely clog a floor drain (especially a woodworking shop). I would sure hate the job of keeping them opened. I can just pressure wash my shop floor and push the water out the open garage doors. The floor dries fairly quickly after such treatment.

 

[PILOON]

Grease pit is a big hole you need to secure when not in use. You need to build foundation and walls . You may get ground water in pit

I believe that grease pits have been banned in many areas. Many people have sustain very bad burns that resulted from fires/explosions in them.
The pits retain fumes and vapors.
Insurance might also be a problem if they are aware that you have a pit.

 

[cycle_gator]

I had a pro,40 years in concrete pour a similar slab. Mixture was 6 1/2 sack mix (about 4500 psi) 5”slump, 1/2 shot of air and he used Super P which is really something to see. The slab is very smooth and very, very dense. 2 months old and already had 30000 # machine on it (raising trusses). Was saw cut with no panel more than 12x 12. So far looks fantastic. Slab has three perimeter #4 bars, otherwise not reinforced and is 5.5” thick.