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View Full Version : The firing line and FROST . . .



Joe Haller
03-19-2010, 02:20 AM
At our club's annual meeting tonight we "finally" decided to redo our 96 foot long firing line. It has cracked and heaved due to frost over the years since the cement was laid, in back 1976. A couple of our Engineer types suggested we get some expert advice from a Civil Engineering Firm on a design that will not move and crack again because of frost.

Any of you guys that live up here in the snow belt have experience with protecting a firing line from frosts?

Joe Haller
Sault Sainte Marie, Michigan

Pete Wass
03-19-2010, 09:02 AM
Water expands when it freezes. If there is little or no water, well you see where I am going here. Also the parimiter of one's foundation can be protectd by laying a blanket foam board that does not absorb water burried down a foot or 18" and sloping slightly outward to shed the water. I have been told that frost penetrates more or less straight down.

I am not an authority but there is a local talk radio show on every Saturday Morning in Bangor, Maine that I listen to often when I am home. The show is called Hot & Cold and is hosted by Prof. RIchard Hill of UMO and a former student, Tom Gosie (sp?) and these kind of issues are discussed there. Tom is a big advocate of using Foam to keep out the cold from wherever. He is also very big on drainage; who isn't. Tom is in the business of retro-fitting older homes to be energy efficient and to consult on frost problems. He also is involved in Solar and Wind Power for the Homeowner.

mooner
03-19-2010, 09:11 AM
Talk with your local concrete supplier and or a reputable concrete contractor, they can guide as to what concrete will stand up to the elements in your area. I would think that you need concrete that has air and protected from water intrusion that will freeze and expand and crack or lift the concrete.

Boyd Allen
03-19-2010, 09:25 AM
If you excavate below the frost line and fill under the slab with crushed rock, cover that with a membrane and then sand, wouldn't that solve the problem?

Dennis Sorensen
03-19-2010, 09:31 AM
Footings with drainage - 8 feet down.

TomD
03-19-2010, 10:05 AM
I believe that Francis Bes (don't ask me to spell his name) is a contractor up there. Ask him what steps the locals take to protect non-load bearing slab on grade concrete. Call your local concrete plant, they have salesmen who are well versed in local methods and people. I suspect a gravel sub base with a moisture barrier but all of my experience is in the South East, so what do I know?

Dave Coots
03-19-2010, 10:25 AM
Lots of good ideas above. Most concrete will crack and heave from the frost sooner or later. The key is to put drainage tile in. This is done on all State highways here in Iowa nowdays. They put in 4" drainage tile, 42" deep and fill with washed limestone. This goes to a collector line and flows downhill and helps keep the water from under the concrete. Another thing to do is to put a good base of clean drainable rock under the slab. Use lots of re-rod in the concrete.

Alinwa should have some good advice on this if he see's the post, as he is a concrete contractor, i believe.

Later
Dave

40EZXS
03-19-2010, 10:54 AM
You need what we called "heaters".
When we built freezers for our food service ware house .
To off set that or your problem. We have plastic pipe under the floor with it raising a few feet on both ends.This let air flow under and away from the frost build up under your floor.Make sure the ends have a downward U so rain and snow don't get in to your heater pipes.
They are called "Heaters".:)

alinwa
03-19-2010, 12:07 PM
Others have covered it in prior posts....... You either dig down and set your footings below the frost line or dig down to below the frost line and fill back up with a compacted free-draining fill material. Something like "drain rock" or "Con-Ag" or Inch-and-a-quarter "Gabian" or "Ballast" or "crushed" or even "Pea Gravel"...... Terminology varies acros't the country but it ain't Rocket Science. IF you cut and fill then the material used must be capable of taking the loading without settling over time yet porous to allow water to get to the drainage system. IF you set your footings below the frost you must still provide some sort of drainage so that water doesn't get trapped in the ditch and permeate the ground to cause settling.

The key is this ELIMINATE the water using drainage and EXCAVATE to below the frost line. Implementing either of these items alone is throwing money away.

You cannot "seal" or "waterproof" anything to keep water out nor can you "insulate" to "keep heat in" when there's no heat present except ambient ground temp. And adding heat to keep the thing from freezing???? Well, I guess if your budget allows you to just essentially make a direct short and pour power into the ground then heating the firing line "would" be an option.... HUGELY expensive but possible. We in the industry see this sort of option used only on public funded or "green" projects like schools and govt buildings.

The concrete material itself will easily withstand the freeze-thaw cycle. The concrete supplier will provide an air entrained mix at no charge.

hth


al

CYanchycki
03-19-2010, 05:55 PM
knows how to build some nice benches and line in the Northern parts of the US it is AL.....

Right, if memory serves me right you have a pretty nice bench set up.......

Oh........ That's right you live on the OCEAN.................. Frost and FREEZING................ Hah I think NOT:p:p:p

Come to Manitoba if you want to see how to use concrete for cold weather......:eek::eek:

Calvin

danbnimble
03-19-2010, 10:07 PM
I think what you may be looking for we call a floating slab. We dig 24 inch footing then fill and tamp river wash sand. Tie in 3/4 inch rebar on 1 foot centers, form it up oil the forms and call the cement trucks. If you elect to put drain tile in, better if it is sleeved. Broom it the last thing you do...makes a non-slip surface and reduces porocity.

alinwa
03-20-2010, 02:55 PM
Yeahh I've done a few....

Some of these are on beds of gravel, one is fully isolated with the table on piers and the slab floating, and some of the others I've done are dug in. I've also done individual benches.

Calvin, I growed up in Minnesota, frost line is 8ft (nearly 3M) down. I'm well aware of frost code issues.

al

Bill Wynne
03-20-2010, 06:14 PM
I think what you may be looking for we call a floating slab. We dig 24 inch footing then fill and tamp river wash sand. Tie in 3/4 inch rebar on 1 foot centers, form it up oil the forms and call the cement trucks. If you elect to put drain tile in, better if it is sleeved. Broom it the last thing you do...makes a non-slip surface and reduces porosity.

:)Dan, one thing you said makes my skin crawl. I have literally spent a lifetime working in construction. I even worked for a concrete company for a while. For whatever good it has done me, I even have a university degree in construction management but that was back in the days of slide rules. Now here is my problem with what you have said. Cement is an ingredient in concrete just as sand and gravel. As one of my old crusty estimating instructors said, "Cement comes in bags and concrete comes in trucks".

All that being said, I am climbing off my high horse. Our frost line in West Texas is less than eight inches and there is never much moisture in our soil to freeze. Dan, It sounds like you have a handle on the solution and I meant no harm. Al is our concrete expert on BRC and as a bonus, he has lived in some cold wet areas. I would trust his advice.

Concho Bill

LHSmith
03-21-2010, 09:39 AM
Ask two different construction engineers what is the best design for a project and you'll get two different answers. The only absolute in dealing with concrete is the old adage "there is two types of concrete....concrete that has cracked and concrete that will."

Bill Wynne
03-21-2010, 01:44 PM
I like that Smith.

I am of the opinion that there are only two schools of engineering in the world.

Engineers from the first school built the pyramids and engineers from the second school built the Golden Gate Bridge.:)

One depends on the most material for the longest time and the other the most strength with the least material. If I am paying for it, I want to see what the engineers of the latter school can come up with. If I want it to last forever and the cost is no factor and I don't have to move any of the rocks, I would go with the first.

Concho Bill

alinwa
03-22-2010, 12:18 AM
Ask two different construction engineers what is the best design for a project and you'll get two different answers. The only absolute in dealing with concrete is the old adage "there is two types of concrete....concrete that has cracked and concrete that will."

True, but irrelevant IMO. :)

"Cracked" doesn't necessarily mean bent, displaced or misaligned in any way. Concrete shrinks on curing, then expands and contracts throughout its life just like steel or most anything else. You WILL get shrinkage cracks or stress cracks over time but this doesn't cause displacement provided other issues are in order. The reinforcing steel in the concrete matrix gives the necessary stability, all the concrete does is hold the steel in place.

Cracking couple with displacement indicates a real problem but the problem isn't with the concrete.

al