Pouring new concrete shop floor and thinking about power hammer

[Smith Studio]

I have just recently relocated my ironwork and fabrication business back to my family ranch in Wyoming, where I grew up. I am re-setting up the entire shop and enterprise. I am planning to purchase my first power hammer for the business. Along with sculpture, I produce ironwork from furniture to architectural elements, gates, and rails. I am currently renovating a huge steel barn into my new shop (built from salvaged power plant tank steel, built by my father a welder/boiler-maker). The floor is currently gravel, so I am in the process of excavating the interior floor and planning to pour a concrete pad floor. Since I will be pouring a completely new floor are there any suggestions or recommendations on laying out the concrete pad that will be under the new power hammer? Any input would be greatly appreciated! thank you.

[arftist]

I have just recently relocated my ironwork and fabrication business back to my family ranch in Wyoming, where I grew up. I am re-setting up the entire shop and enterprise. I am planning to purchase my first power hammer for the business. Along with sculpture, I produce ironwork from furniture to architectural elements, gates, and rails. I am currently renovating a huge steel barn into my new shop (built from salvaged power plant tank steel, built by my father a welder/boiler-maker). The floor is currently gravel, so I am in the process of excavating the interior floor and planning to pour a concrete pad floor. Since I will be pouring a completely new floor are there any suggestions or recommendations on laying out the concrete pad that will be under the new power hammer? Any input would be greatly appreciated! thank you.

What size powerhammer? What type? In your shoes, I would be pouring a heavily reinforced (re-rod) block just for the powerhammer. It should be isolated from the rest of the slab. This can be acomplished by leaving a space between the block and the slab. This site has foundation plans; http://www.littlegianthammer.com/plans.html

[Dillon Sculpture]

I found it just as easy to cut the hole after, give yourself time to figure where you want stuff, especially if you don't have the hammer yet.

[thecelticforge]

I agree with just cutting the hole after the fact. I just got my Fairbanks hammer in my shop today and the specs call for an 18 inch slab with 10 inches of lumber underneath it. The wood under the anvil should be dense (oak or persimmon) set as end grain.

[ironstein]

Being a union ironworker (rodbuster), if i were to build a floor for a shop, i would reinforce with 5/8 or larger rebar, and in the area where i knew power tools would be, thicken the slab and use a double mat of rebar with a tighter spacing. I have worked on slabs which were to be used for heavy equipment and power equipment which were reinforced with 5/8 rebar at 12" on center, and they held up very well. Depending on your budget, a post tension cable reinforced slab is very expensive, but the cables keep the concrete in compression so cracking is kept to a minimum. A reinforced slab with 1/2 inch rebar at twelve inches on center is probably overkill for most shops, but if you are planning on driving forklifts and such , i would go with as large as you can. Like previously stated, you can always saw cut the spot where your hammer will be located, excavate a footing, and install what is recommended.
I am envious of your adventure, wyoming is beautiful, i would love to be able to live somewhere where i could do the same! Good luck. If you have any specific questions, feel free to pm me.
Brian

[Bryce Masuk]

you probley wont need to worry too much about a slab with the size of hammer you are planning to get

it might be nice but if it were me I would probley just build a quality floor for the whole building and go with that.

people have ran much bigger hammers without a slab under the hammer obviously with larger hammers you can notice the increase in hitting power quite abit

but with a 60kg hammer or less you wont notice much if the foundation is good

it would still be nice to have but obviously if your building a shop you have bigger things to worry about

[ianinsa]

I believe that if you take the general area where heavy equipment will be located and your 'driveway'(internal route for forklift etc.)and put down hardcore(crushed bricks, clean rubble etc.) and compact it well(95%mod ahsto)(very, very firm), i.e. rent a whacker rammer for a day it will be money well spent. Then put mesh in your slab to prevent cracking.
With a well compacted sub base a 3" 25mpa slab should be suficient for most purposes. Don't be tempted to add 'extra' cement into your concrete mix 'to strengthen' it as it also makes it more likely to crack with vibration. When your shop is sut up you can always cut free a 'raft' section providing that you have a well compacted sub base.
Ian

[kevan]

I am definitely with Michael on this one. Cut the hole later. Where you think you will place the hammer now may not be where you will place it when you actually have it in the shop.

Kevan

[aquamanlr]

In my view, make sure you get the sub grade compaction in first. most of the trouble I have seen with poured floors is the sub grade settles under the weight of the floor and traffic on it. Good compaction and a good mixture of concrete with reinforcement is the ticket.

LeeRoy

[Frosty]

Make sure your base is fully compacted, do NOT over wet it in the process.

I have a 6" slab with #5 rebar 5/8" and it's a bit thicker with the rebar on 12" centers where I'd planned on the power hammer going. I also laid 3/4" Pex in floor hydronic heat tubing because I LIKE warm feet. I also put a grid of 2" sq reciever tubing on 48" centers as gozintas and interconnected them all to a sub floor exhaust system. The gozintas allow me to use the entire shop floor as a jig table and I can use them as anchors for straightening or bending steel members with hydraulics. They're welded into the rebar too so I can ground anywhere in the shop through the gozinta grid. The exhaust is downdraft so my cutting/welding tables are bar grate on a sheet metal plenum. This keeps smoke from getting loose in the shop so I don't have to use a big exhaust fan under the eaves that has to exchange ALL the warm air in the shop for cold Alaskan winter air a couple times to get rid of smoke.

I like it and will shoot you the pics if you want details.

Frosty the Lucky.

[Fosterob]

Frosty, I like your idea of gozintas. I am not clear on their function though. It sounds like the exhaust sucks through them?
Also anyone pouring a concrete slab of just about any kind should seriously consider the pex tubing in the pour. It is very cheap ansd easy to insulate the slab and put the tube in at the time and very expensive and difficult to do later. The only thing is that you can not start cutting out large raft sections and have radiant floor heating so plan ahead. The heat source can come later.
Rob

[ianinsa]

Frosty,
Are you fixing up junked tanks for Sadam's boys as a sideline?
Please post pictures it sounds interesting, I would consider coming over there just to have a decco! Long swim though.

Joshua,
I can't overemphasise the importance of a good sub base as all load is transfered to it. If you live in a cold climate pex tubing in the floor is a must. With a bit of inventiveness you could rig up a burner using the principals op a propane/used oil burner under a donkey tank thus little opperating cost.
If your sub base is well done(think of well compacted sub base as '85%extra concrete at 20%the cost) and you must use load bearing insulation, (and you don't intend fixing tanks)3" with ref 193 mesh should be plenty.

[Smith Studio]

Thank you for all of the insight and comments! All of which are very helpful. I do understand the benefit of planning the shop floor space with all equipment in the shop and cutting a hole later, however, I am planning to install in-floor hydronic radiant heat for the shop. So I do need to plan ahead where not to lay water tubing.

Frosty, I would love to see a little more about your gozinta grid system and its exhaust capabilities, and would love to see some images! Any quick tips on installing the in-floor heat? do you use water or anti-freez?

So I am planning to pour separate a 15' x 15' or so concrete slab that is a little thicker (5"-6") than the rest and with out in-floor tubing. This separate (unheated) slab will be designated for forging and is where I will set the hammer and other anvils. By the way, I am planning to get an Iron Kiss 100. According to the Iron Kiss maker, John Larson, the Iron Kiss has such a heavy anvil weight that extra concrete in the floor is not usually necessary. This will be the only power hammer in the shop.

Thanks again for all of the input. I will make certain to pay close attention to compacting the sub-base!

[Fosterob]

Smith, I am putting radiant in my house right now and did a lot of homework on it. The shop will be next. Two good websites that have a lot of good info are www.radiantdesigninstitute.com, www.radiantec.com. I chose to use radiant design institute, really helpful and super knowledgeable. I would still put the heating tubes in your forging floor, you do not have to hook them up but if you decide later you should have .... ooops, was the $19 savings on that tube worth it? Those sites talk about everything you need to know. If you want more details send me a PM.
Rob

[Frosty]

Sorry I'm slow getting back, we had a club meeting at my place Saturday and I got a little busy.

The pic with me and the red Pex is while I was stringing the infloo hydronic heat tubing. The other shows some of the gozintas and rebar along the north end of the floor by the footing.

I don't seem to have a pic showing the ABS pipe under the finish base course making the downdraft exhaust but each gozinta connects to the 3" ABS which forms an interconnected grid for the exhaust.

The gozintas are welded to the rebar to make a shopwide welding/etc. ground system so I don't have so many cables laying around to trip over.

Frosty the Lucky.

[ianinsa]

Well Frosty,
I am impressed! that's a lotta input for that floor.
Looking at the surrounding 'soil' you seem to have a seriously sucksessfull 'rock farm' as well .
your gazinta system looks useful
How come no insulation and no damp proof membrane?
Ian

[Frosty]

Well Frosty,
I am impressed! that's a lotta input for that floor.
Looking at the surrounding 'soil' you seem to have a seriously sucksessfull 'rock farm' as well .
your gazinta system looks useful
How come no insulation and no damp proof membrane?
Ian

We're on "glacial till" which is the densest unconsolidated soil type on the planet. Till is laid down by glaciers and then compacted when a mile or two of moving ice compacts it. I did the finish grading with D1 and the till has decent drainage so I didn't bother with a vapor barrier.

I didn't put insulation under it because that'd reduce the thermal mass under the shop and once soil freezes it becomes frost susceptible and nothing will wrack a building like frost heaves under it.

Oh yeah, till is a near perfect soil gradation from car or house sized dornics down to silt so boulder farm is a fitting name I just wish it was easier to pull the things and sell em.

Frosty the Lucky.

[ianinsa]

Hi Frosty,
It just goes to show! coming from a warm climate, you don't know nuthin about cold climate construction. We were in Abu Dhabi 2 years ago on a 'chilly' day 20deg C on the beach my wife felt the need to put on a jersey! When it gets to 12deg C here out come the heaters.
Thanks for the info.
Ian

[Ross_FL]

Coming from a construction engineering background, I would just pour a 12" - 18" thick monolithic 5k @ 28 days mix with a super plasticizer additive.

I don't know how big you want your building though.

I don't know what a power hammer calls for but I do know what I've seen done on the above slab 24 hours after it was poured. You should be fine.

You could always bump up to a 7k, but just make sure you tell them super-p. This is the mix we've used to support $50 million dollar GE gas turbine generators.