Concrete sawmill pad --- 14 x 4 x 6" --- what not to do

[OffGrid973]

I have a guy quoting me a price to frame and pour my slab and I was curious if any good threads exist on this. (My searches are failing to find em)

Any "do nots" that I should be aware of like one full slab vs expansion joints.  Is 6" too deep and 4" will do for a Woodmizer LT-10.

Laid the gravel end of last year,  now just need to pour and a truck can drive right up as it's right off the driveway.

[ChugiakTinkerer]

Considering you could probably operate just fine on packed gravel, I reckon your concerns are more aesthetic than structural.  The concrete will crack, so you should put in some contraction joints every 4'.  Well, make it 4.67' and you'll have three panels that will be almost square.  I don't think an expansion joint is warranted on a slab that short.  And you certainly can get away 4" thick unless you plan on some insanely large logs.  Just my thoughts, from a guy with no particular expertise.

[DPatton]

Cwimer, CT is correct about the contraction joints. I would also add some wire mesh or small diameter reinforcing bar to keep this long narrow pad in one piece.
Two thing are absolute about concrete. 1, its going to get hard. 2, its going to crack. Properly placed and sized contraction joints will control where it cracks. Properly installed mesh or reinforcing will keep the cracks from shifting or moving around.
As far as thickenss is concerned it depends on how heavy your mill and logs are. Or if your will ever be driving up on it with a loader or tractor. I would suggest a 5" thickness if you want something a little heavier than 4".

[Ljohnsaw]

And don't forget you can opt for stronger concrete mix.  The standard is "4 sack" (I forget the compression strength numbers) and I will often pay the extra $10 or so per yard to make it "5 sack".  Remember that you want the concrete mix a stiff as possible.  Extra water makes it easy to work, but also greatly weakens it.  +1 on the remesh.  I did several 12' x 24' slabs with remesh and NO expansion joints.  Only one small hairline crack in a 4" thick slab with 5 sack.  Also, in this barn, three 5' wide x 48' long slabs for the isle (sunken middle for rubber mats).  Remesh and NO expansion joints and no cracks.

How wide will your slab be?  Just enough for the wheel base (or feet)?  Will you have dirt or gravel next to the slab or will it be a step up from the ground?  You need to think how the slab will affect your working height.  Would it be better to pour a wider slab so you have something smooth (and not muddy?) to walk on when working?

[dustyhat]

Lots of metal, i think you can get it mixed with some type of fiber but i have never used it ,it may be higher than using metal though.

[4x4American]

From what little knowledge I have on concrete, I seen a few sawmills have trashed sides where the loader drives up onto the concrete so I would suggest digging a haunch around the perimeter to make it extra more strong

[YellowHammer]

What everybody else says, form it well, metal mesh to keep parts of it from walking off, make it bigger than you need, and mainly, control the edges as they can become a real tripping hazard (which isn't good around a mill) by fairing them into the grade, or sloping the concrete to the grade, as well as a thicker edge footing to keep it from cracking at the interface from dirt to slab.

[Larry]

That's such a small slab no cutting required and may be detrimental.  #4, that's 1/2" rebar should be placed on 12" grid using chairs to hold it off the gravel.  Tie the rebar with wires.  The rebar will keep the slab from moving if it does crack.  Forget about fiber reinforcement, that's to control shrinkage cracking only.  4" thick will be fine.

The slab is so small even beginners could finish without much problem.

[ChugiakTinkerer]

Cwimer,

I looked in your gallery and I think this is probably how your workspace is currently set up.



If you keep the slab narrow enough then you will be walking on the driveway and not the slab.  Tripping shouldn't be an issue while operating the mill but you still want to keep that transition from slab to driveway smooth.  Minimize stubbed toes and all that.  I'd want to have a little crown on the slab so that rain sheds easily and doesn't pool.  If you end up with standing water during freeze-thaw cycles your concrete will spall much more quickly.

[Sixacresand]

After the concrete set up, you hammer drill holes to add anchor bolts

[OffGrid973]

Thanks guys...I priced things out and may give it go myself, just afraid of not being able to mix and pour fast enough.  Having a truck stop over requires a big # and getting leftovers from a big job is tough to coordinate. 

You guys suggest any kind of plastic to hold liquid in like making concrete countertops or just right onto the 1x6's is ok on top of the rock?

[Ljohnsaw]

You don't need plastic.  That is just used for a slab where you don't want moisture coming up - like a basement.  Just right on the rock is fine.  Also, 1x6 won't be good unless you use a LOT of stakes.  2x6 would be much better.  Also, place a wooden stake at an angle so that it touches the top of the form boards in addition to the normal vertical stakes.  Screw this in to provide a brace to keep the forms from tipping out when the concrete pushes on it.  Also, when you pour the concrete, bang the boards to get it to settle well with no air pockets against the boards.

You should look at getting a trailer cart of concrete - you will not like mixing all that concrete!

[OffGrid973]

Is a trailer cart a smaller version of the truck with a hose?  Thx for advice on 2x6, having a flood would not be optimal.

[DDW_OR]

here is a link to my Central Boiler install, it has info on how i did the pad
https://forestryforum.com/board/index.php/topic,92218.0/all.html#top



 

[Ljohnsaw]

Is a trailer cart a smaller version of the truck with a hose?  Thx for advice on 2x6, having a flood would not be optimal.

No.  Check out "redi mix" type suppliers in your area.  They will have one of two types of trailers.  They will be tandem axle (4 tires) and equipped with surge brakes on a 2" ball hitch.  They may limit you on how much they will load based on your tow vehicle.  I've had some places say they will only do 1/2 yard with a 1/2 ton pickup.  One type is a open top box with a sort of spout and a manual hydraulic jack to help you dump it into wheel barrows or directly into your forms if you can back up to them.  The other is a rotary drum (like a mini cement mixer truck) that is run by a gas engine connected to a hydraulic pump.  There are controls to adjust the speed of the drum and to dump the load.  I prefer the mixer type - especially if you have to drive a bit.  Concrete in a plain dump trailer tends to get pretty stiff from the vibration during the trip.  Never add more water to the mix unless it is really dry.

[paul case]

Most redi mix trucks would have no problem putting the mud in your forms as quick or as slowly as you want to go. They may have a minimum, 2 yards here. but by my calculations you only need 1 yard. I would dig a little footing around the inside of your form to give it a thik edge and then fix up a form for extra to make sidewalk or???? so that you waste nothing. Redimix concrete for flooring here is about $90/yard delivered.

If you plan to do this yourself it would be invaluable to you to go watch someone else finish concrete before you do it. You can make a fine sawmill pad by screeting off the forms and floating it and when it is almost set trowling it or a soft broom finish.

PC

[fishfighter]

If it was me, which I am planning to do a slab, I would go wider then 4'. My plan is to go as wide as 8'. Reason, a place to walk along both sides of the mill and easy to clean up saw dust off concrete.


As others pointed out, a 4' slab has tripping in your future unless you grade up to the edge of the slab. Putting down rocks has a very good chance of getting rocks in your logs. Rocks and saw blades don't mix well.

[highleadtimber16]

I would suggest making the slab wider. You want to walk on the concrete, not in mud and wet sawdust. Mine is 18x40' and still, never enough room. I didn't use any metal and it hasn't cracked, but it's not a bad idea to use some in yours.

[Bruno of NH]

Do you have one of the trucks in your area that comes to the site with the dry mix and then mixes only what you need?
They tend to be less money than the ready mix companies.

[jmouton]

i have been doin concrete for almost 30 years now ,,,,  make the pad bigger  10 x 20 youll need it,,,  mesh has its drawbacks and advantages ,, its a 50/50 ,,  4 inch its alright ,,,   just place it in when you pour it ,,  no chairs ,waste of money,,, if you go with 6 inch ,,,better  in my opinion ,,  just run some  rebar lengh ways  num 4 ,,,,half inch ,,just place it in,,,,dont try to mix it with redi mix ,,,, way too much work and you wont keep up and not as good as standard 6 bag mix with a compression strength of over 4000 psi at 4 in thick ,,4 bag is not standard for flatwork,,,, 2500 psi is for footings ,,   just my 2 cents worth of 30 yrs of knowledge ,,,,

[jmouton]

oh and the only guarantee that we have is , that concrete will crack ,,even with wire or bar in it ,,

[Jemclimber]

Jmounton,

When you say mesh, are you referring to fiber mesh?  Can you tell me the drawbacks besides increase in price.   

I've busted up my share of concrete and without chairs the rebar was always on the bottom.  I know most guys say they pull it up, but from what I've seen when removing it, it doesn't happen.

[fishfighter]

Jmounton,

When you say mesh, are you referring to fiber mesh?  Can you tell me the drawbacks besides increase in price.   

I've busted up my share of concrete and without chairs the rebar was always on the bottom.  I know most guys say they pull it up, but from what I've seen when removing it, it doesn't happen.

I always wire tie in bricks under the wire to lift it off the ground. ;D

[bandmiller2]

Seeing as your next to your drive I would consider attaching it to your drive with a lead in, then if the mill is removed you can park on it. Would pay to make it wide enough to park a car or truck on. Frank C.

[Ljohnsaw]

I always wire tie in bricks under the wire to lift it off the ground. ;D

I visited a construction site and the boss said I could have whatever was in this big pile.  I got 250+ doobie blocks (little concrete blocks with some bailing wire sticking out) to lift my rebar, FOR FREE! 8)  HD wants 42 cents a piece for them   That still wasn't quite enough so I had some broken bricks in a few places.