Cement for tee pads

[Bultx1215]

4" is what most municipalities require for minimum thickness of flatwork, which teepads are. So, if its in the city limits, or ETJ of a city, you probably couldn't get away with less. All cities vary as to ordinances, so YMMV. In some places, counties can get that specific. If it must be permitted, you can pretty much be assured they will want 4" and some sort of treatment underneath, whether that is gravel, compacted base, sand, etc.

If no permits of gov't entities are involved, you can go thinner, but it really won't help you that much with cost vs. longevity. 3-3.5" would be acceptable for the most part, but below that, you are looking at a very short lifespan. Thin sections like to crack into jigsaw puzzles and fail a lot faster than thick sections. For the sake of discussion, I am saying this is less than 3". Just the heat/cool cycle of the summer sun is enough to play havoc on them. Freeze/thaw cycle can be even worse depending on your location. Here, where it actually gets hot and stays hot, the heat is worse. Up north the cold is worse.

Also, with teepad sized chunks of rigid concrete, the ground movement will affect them. Again, the "how much" part depends on location and ground stability. High soil plasticity index (PI) along with thin concrete will mean quick failure while low PI and stable ground is the opposite. That is where the 4" thickness was developed. It is the nominal thickness that seems to withstand pretty much all conditions with relative ease.

How do you mean bond with boulders? Are you using them as an edging? Concrete will bond to rocks easily enough mainly due to the irregular surface. It won't be full strength, but it will stick pretty good.

 

[Mando]

How do you mean bond with boulders? Are you using them as an edging? Concrete will bond to rocks easily enough mainly due to the irregular surface. It won't be full strength, but it will stick pretty good.

Thanks for the info, I'll have to look into the PI up here in NC mountains.
Many of the tee pads are on shallow soil with huge boulders underneath (think slickrock with a few inches of topsoil). After removing topsoil,should I pour concrete directly on rock, or put gravel between rock and concrete ? Due to the terrain, this will have to be done with bags or pre-made squares, so the less thickness, the better without running the risk of cracking.

 

[knettles]

What kind of course is it? A Rec/Int course can get by with 4' x 8' tee pads. If you are looking at an Int/Adv or Pro course, you should make them 5' x 12' and don't go less than 5' x 10'. Mixing bagged concrete on site is labor and dollar intensive and you only want to do it if you have to (due to site location, terrain or other restrictions). Redimix from a truck is the way to go. About $100 per cubic yard. Add in some polyfiber mix (forget the rebar or wire mesh) and it might go to $110 / cu. yd.

4' x 8' tee pads, for 18 is 7.11 cu. yds. (x 1.05% for waste/error = 7.46 cu. yds., order 7.5)

If you are mixing your own, on site, have a reliable crew that is willing to work some long hours, over several days. If you do the redimix off the truck, have a crew of 4-6 guys who are willing to work hard, and quickly. The truck will be sitting there waiting. Anything more than 2 hrs and they will likely bill you for it. Don't forge,t how you are going to get that concrete out to all those (pre-dug, pre-framed and crushed stone base prepared) tee-pads. (I just got 10 tons of recycled, crushed concrete for $5.50 per ton. It makes a great base.)

This is very crucial. It'd be a shame to get some nice new concrete teepads and have them being the one thing that really holds the course back because they don't allow half of disc golfers to get their runup.

 

[Bultx1215]

Thanks for the info, I'll have to look into the PI up here in NC mountains.
Many of the tee pads are on shallow soil with huge boulders underneath (think slickrock with a few inches of topsoil). After removing topsoil,should I pour concrete directly on rock, or put gravel between rock and concrete ? Due to the terrain, this will have to be done with bags or pre-made squares, so the less thickness, the better without running the risk of cracking.

Do you have red clay soil? If so, PI will be up there. Black gumbo...even worse. Sandy soil is very low PI, if not the lowest. Depends what is in it along with the sand.

Loose boulders or locked in and stable? Stable could maybe go directly on top, but any movement will split your 'crete. Putting a buffer between the concrete and boulder would be ideal. That way, everyone can move and no risk to losing the concrete. I would not go less than 3" with 3 1/2" being ideal and would put 6 gauge wire mesh in it, not 10 gauge. If the access is as bad as you make it sound....do it right the first time and they will last decades...skimp and your final product will have a short lifespan and you will be back at it soon. Concrete work is not something that takes cutting corners well.

 

[MacDaddy]

I'm all for reinforcing the concrete with something, but I prefer polyfiber over wire or rebar, here's why. Polyfiber is just that. Hundreds of thousands of short poly fibers that are completely randomly oriented. This prevents micro crack propagation. And stopping micro cracks, means stopping big cracks. The fibers are everywhere in the concrete. The wire or rebar are not. And once cracks get to their metal surfaces, water gets to them. And water has salts and minerals that help oxidize the wire or rebar. Once they are rusted out, the voids and cracks allow the water freeze-thaw cycle to work on breaking up the concrete. On top of that, it is inexpensive and easy to use. Just ask for it on your redimix order, or add it in your batches as you mix them.

 

[Bultx1215]

Fiber is fine, but it was never designed as a stand alone reinforcement. Its used all the time that way, but its not what its designed for. Its an admixture, not reinforcement...used to fill the voids between the steel reinforcement to limit or prevent random cracking. Steel fiber with rebar makes an incredibly tough floor. Steel fiber by itself, not so much. Polyfiber isn't as strong as the steel fiber.

I did work for a general contractor that got on the poly only bandwagon in the early and mid 90's. I have done close to 500,000sf of 4" polyfiber only parking lots for them. Every one of the lots had a major failure within a year and all had to be replaced within 15 years. All of my steel or mesh parking lots from that same time period are still in service with no repairs. That GC stopped using fiber only by '96 or '97, IIRC. It cost them a fortune to replace all that warrantied concrete. I will never use fiber by itself. If I use it, it will be with steel of one sort or another only, as it was intended.

 

[davetherocketguy]

You do not need reinforcement for something that is only going to support people. 4" ready mix no reinforcement on a good sand base and your set. If you're unsure about your mixing abilities with the bags then steel mesh is just fine.

One question though...If you can't get ready mix back to each location then how are you going to get the water needed to mix all those bags? How are you going to get all those bags to each location? My back is sore just thinking about that....

 

[davetherocketguy]

Also, I don't know if this has been discussed but finish of the concrete is incredibly important. If you have the $$$ to hire a pro just tell them to finish it like your typical city sidewalk with a broom finish. If they're any good they will know exactly what your are talking about. If you need to use volunteers see if you can find someone who knows how to do a broom finish which IMHO is just right for disc golf.

Also, to go along with finishing something that people seem to forget is to make sure your concrete is sloped one way or another to get the water off. If you make it perfectly flat it is going to suck rocks every time it rains. I'd say 1% (1" fall for every 100" run) by a skilled finisher should be no problem. 2% if you want to be absolutely sure. Even at 2% slope I doubt most disc golfers are even going to notice the tilt however, don't go much more than 2%.

 

[Mando]

Thanks for all the comments. Soil is loamy and ranges from a few inches to 2 feet in depth. Boulders are huge-vary from 100 feet to 600 feet long. Most pads can be accessed with farm roads,but not suitable for a concrete truck.
I currently have 6 gravel pads and 19 framed carpet pads that have PT 2x4 frames with a combo of mulch and gravel underneath. They work great but insects are starting to eat the frames after 4 years and small animals are using the pads for condos,burrowing and making them unlevel. The carpet is in great shape after 4 years, and is easy on the knees.

The gravel pads are going to concrete,but the carpet pads could be a mix of materials.

Thinking about pouring a thin layer of concrete at the bottoms of the pads to keep out the varmits, and then framing a band inside the existing frame and pouring concrete,which will give me a perimeter band when the wood rots. Then refilling the rest of the pad with filtered gravel (like sand) and a layer of mulch on top and cover with carpet (like they are now).

 

[davetherocketguy]

Thanks for all the comments. Soil is loamy and ranges from a few inches to 2 feet in depth. Boulders are huge-vary from 100 feet to 600 feet long. Most pads can be accessed with farm roads,but not suitable for a concrete truck.
I currently have 6 gravel pads and 19 framed carpet pads that have PT 2x4 frames with a combo of mulch and gravel underneath. They work great but insects are starting to eat the frames after 4 years and small animals are using the pads for condos,burrowing and making them unlevel. The carpet is in great shape after 4 years, and is easy on the knees.

The gravel pads are going to concrete,but the carpet pads could be a mix of materials.

Thinking about pouring a thin layer of concrete at the bottoms of the pads to keep out the varmits, and then framing a band inside the existing frame and pouring concrete,which will give me a perimeter band when the wood rots. Then refilling the rest of the pad with filtered gravel (like sand) and a layer of mulch on top and cover with carpet (like they are now).

If you can get farm equipment down the roadway you can get a bobcat or backhoe down it. Park the concrete truck as close as possible then bucket the concrete in with a loader of some sort. Bobcats are great for this sort of thing. You need to go quick though because that sort of thing can be time consuming and concrete can only sit for so long in the truck.

-Dave

 

[Gblambert]

Has anyone made tee pads using cement mixed with soil? It would seem to be easier, quicker, and definitely less expensive than using bags of concrete mix. I wouldn't expect soil mixed with cementy to be as durable as concrete, but is it durable enough for a tee pad?

http://garages.about.com/od/buildingagarage/a/Soil-Cement-Paving-For-Driveways-Sidewalks-Patios-And-Garage-Floors.htm

 

[joecoin]

Just dig down to the boulder and use it for the pad.

 

[Mando]

Just dig down to the boulder and use it for the pad.

Nowhere near level. I'm wondering why patio concrete squares can be 2" thick, but not
t-pads. Would it make any difference if the pad was subdivided into 4 or 5 segments and poured separately ?

 

[MiketheGoalie]

Came into this thread to point out that cement is not concrete. Subtle but important difference. Nobody talks about baking flour, they discuss baking cakes.

That said...

You do not need reinforcement for something that is only going to support people. 4" ready mix no reinforcement on a good sand base and your set. ...

I've designed thousands of square feet of slab that only hold people and put steel rebar or mesh in nearly all of them. It has nothing to do with load and everything to do with how the concrete behaves as it dries. As the concrete hardens it's going through a chemical process that burns off water in the mix. It actually exudes heat. As it does this, it shrinks. The reinforcing is to control random shrinkage cracking. Add in the variable of how much restraint is provided by the base (soil/sand/rock underneath) and how freely the concrete can shrink and you have even more reason to want to control cracking. Severe temperature swings, freeze-thaw cycles, erosion, etc. are all other examples that can cause uneven tension stresses and therefore cracking. Wire mesh is cheap insurance for most of this.

Poly or organic fiber work great when you can control the aspect ratio (1:1 or 1:1.5) but once you get rectangular the shrinkage rates differ enough in the two directions and you'll likely need something to control/limit the shrinkage cracking. An unreinforced 5x10 or 5x12 pad as some have suggested will develop a crack. And using my incredible powers of prediction, it'll be exaclty where mother nature wants it to be: right in the middle, splitting the two slabs into approximately equal pieces unless something else causes it to relieve tension stress somewhere else (uneven base, differing materials, etc.).

One thing nobody else has mentioned is that for any concrete that you want to last a good long time in an exterior environment that undergoes freeze/thaw cycles, you need to consider air-entrained admixtures. They will drastically improve the durability of the pads.

 

[MiketheGoalie]

Nowhere near level. I'm wondering why patio concrete squares can be 2" thick, but not
t-pads. Would it make any difference if the pad was subdivided into 4 or 5 segments and poured separately ?

The patio squares are typically plant-cast with better concrete and better QC meaning a tighter, more durable product. 2x2 squares also have the 1:1 aspect ratio I discussed above and therefore uniform, unbound shrinkage. Once you get past the shrinkage phase all you have to worry about is tension stresses induced by outside forces like uneven support caused by poor construction, erosion, active soils that shrink/swell, abuse by dropping during construction, etc.

Subdividing the pour will minimize random shrinkage cracking and likely reduce the demand for crack control measures (reinforcing or fibers) however as the concrete breathes during the shrinkage cycles, the joints will grow. Will the joints present any issues?

 

[MiketheGoalie]

Has anyone made tee pads using cement mixed with soil? It would seem to be easier, quicker, and definitely less expensive than using bags of concrete mix. I wouldn't expect soil mixed with cementy to be as durable as concrete, but is it durable enough for a tee pad?

IMO, No. The soil/cement mix is used for base courses and modifying soils that will then typically be protected from the weather. That's where they really make sense. That doesn't sound like a tee pad to me.

Here's the key phrase that they blow past in your link:
Soil cement may not work well in soils that have a high clay content or a lot of organic content, but it is suitable for most soil types.
Good luck finding that. The kind of soil they are discussing is engineered fill or something approaching gravel/sand. (BTW: Once you've mixed sand and cement and water, you have a product familiar to us all: concrete.) Are you willing to truck in good soil to your site because chances are the soil AT YOUR SITE won't be organic free or low in clay.

 

[Gblambert]

IMO, No. The soil/cement mix is used for base courses and modifying soils that will then typically be protected from the weather. That's where they really make sense. That doesn't sound like a tee pad to me.

Here's the key phrase that they blow past in your link:
Soil cement may not work well in soils that have a high clay content or a lot of organic content, but it is suitable for most soil types.
Good luck finding that. The kind of soil they are discussing is engineered fill or something approaching gravel/sand. (BTW: Once you've mixed sand and cement and water, you have a product familiar to us all: concrete.) Are you willing to truck in good soil to your site because chances are the soil AT YOUR SITE won't be organic free or low in clay.

Yea, I missed the "may not work well in soils that have a high clay content" disclaimer. My soil is mostly clay, which would probably bust up the slab after the first rain. Trucking in soil would be expensive so I'll stick with concrete. Thanks for the warning, Mike.

 

[davetherocketguy]

Came into this thread to point out that cement is not concrete. Subtle but important difference. Nobody talks about baking flour, they discuss baking cakes.

That said...



I've designed thousands of square feet of slab that only hold people and put steel rebar or mesh in nearly all of them. It has nothing to do with load and everything to do with how the concrete behaves as it dries. As the concrete hardens it's going through a chemical process that burns off water in the mix. It actually exudes heat. As it does this, it shrinks. The reinforcing is to control random shrinkage cracking. Add in the variable of how much restraint is provided by the base (soil/sand/rock underneath) and how freely the concrete can shrink and you have even more reason to want to control cracking. Severe temperature swings, freeze-thaw cycles, erosion, etc. are all other examples that can cause uneven tension stresses and therefore cracking. Wire mesh is cheap insurance for most of this.

Poly or organic fiber work great when you can control the aspect ratio (1:1 or 1:1.5) but once you get rectangular the shrinkage rates differ enough in the two directions and you'll likely need something to control/limit the shrinkage cracking. An unreinforced 5x10 or 5x12 pad as some have suggested will develop a crack. And using my incredible powers of prediction, it'll be exaclty where mother nature wants it to be: right in the middle, splitting the two slabs into approximately equal pieces unless something else causes it to relieve tension stress somewhere else (uneven base, differing materials, etc.).

One thing nobody else has mentioned is that for any concrete that you want to last a good long time in an exterior environment that undergoes freeze/thaw cycles, you need to consider air-entrained admixtures. They will drastically improve the durability of the pads.

Oh ok...Well, I'm not smart enough to be a designer but I merely test concrete and can only speak from my experience so maybe you can answer this...I've been a construction inspector/tester for 15 years and have probably tested 10s of thousands of yards of concrete and of all the concrete sidewalk I've seen put in none of it had any reinforcing steel of any kind. Grade it off 4", dump, screed and finish. Every location where I've had it put in seems to be holding up just fine unless it's been abused by a rouge car or heavy equipment. Just plain old 5.5 sack 3500 psi mix. Why do you need steel in your designs and every single one of the engineers around here don't? Heck, we don't even put reinforcement in the drive approaches we do on the road reconstruct jobs - 6" unreinforced MDOT S2 mix. Just drove down my project from 2004 and all those approaches are looking pretty dang good.

And what about saw cutting a joint right down the middle of the slab if you are worried about cracking? I've only seen that done a few thousand times. In fact, using a saw rather then tooling in a joint and even the DG'er with the most robust run up isn't even going to notice it.

 

[Mando]

Will the joints present any issues?

That's a loaded question.

 

[Mando]

So if 1:1 is important and the pad is 5x10,are we talking 2 squares or 8 squares ?
Again, my question is how to build a pad with 2" of concrete ?