How to make a concrete slab?

[coinmaster32]

I have a c band pole from a radio shack dish that does not go into the ground, j hooks in a concrete pad are used to secure it to the pad.

Made a cube in the ground 22x22x27. Should be more then plenty to hold the dish.

However, when you make a concrete pad, do you use regular cement, pure?, or do you mix with pea gravel?

 

[rv1pop]

If you want a concrete foundation block -- pure raw cement will not do. Concrete = cement + gravel + sand + water. Mix well in proper proportions and allow to cure. Put the J bolts in before it starts to set up. Since you are not telling us where you are, we can not say if that will be good enough. At my location it would not be enough.

 

[Paradox-SJ]

I have a c band pole from a radio shack dish that does not go into the ground, j hooks in a concrete pad are used to secure it to the pad.

Made a cube in the ground 22x22x27. Should be more then plenty to hold the dish.

However, when you make a concrete pad, do you use regular cement, pure?, or do you mix with pea gravel?

What leads you to believe that it SHOULD BE plenty to hold the dish?

What size/weight is your dish, pole, wind conditions in your area

 

[Magic Static]

I'm planning a block 3'X3'X6'deep

 

[dfergie]

You can buy ready mixed known as Sacrete and other like names where you just add water, mix & pour.

 

[AcWxRadar]

Coinmaster,

You can mix it (your concrete and substrates) how you like. Best to use fine sand and small grain gavel for a tight finish to the pad. The finer your sand and gravel is, the better it will lock your J- bolts in. You don't want the very coarse gravel or anything large in diameter in your concrete mix. You want the mix to flow tightly around your bolts and/or your pole and lock it into place securely for many years to come.

If you are just planting a 2-4 inch pipe or mast in the concrete, the grain or size of the concrete fillers (the gravel) is not very important. But, if you want to set anchors in the wet cement or drill holes in the cement later (after curing) to install red-head anchors then you want the size of the fillers to be small grained. This will provide a very smooth finish and a tight adherence of the concrete to your anchor bolts. This is good policy especially if you plan to drill holes in the concrete to set anchor bolts after the concrete has been cured.

The greatest concern that you need to address is dependant upon your winter temperature. In Nebraska, you do NOT want to just pour a simple concrete pad 6 inches deep on the surface of the ground. The frost line goes deeper than that and if you put such a pad atop the soil, in the top 6 inches, the ground will do what we call "heaving" when the frost goes out. This may cause your mast base to become unlevel. That will throw off your dish alingment every spring. So, in northern climes, you want to pour your concrete base or pad deeper than the frost line so that it will remain stable and be permanent anchor in the ground, below the frost line. If the base is below the frost line, it won't move on you when the thaw comes in spring.

Ground heaving during the spring thaw will cause you headaches every year if you live in a northern area and you don't set it up correctly in the beginning. You can reduce the dimensions of the surface area of the pad if you pour the concrete deeper. The depth of the concrete base should be one foot deeper than the normal or average frost line in your area.

RADAR

 

[Anole]

In addition to all the good advice above...
... shouldn't the j-bolts be attached to something inside the concrete?
Should there be a wire or metal structure holding onto them?
Maybe weld them to a simple rebar X or O ?
There sure as #$%^ would be if I built it! -

 

[FaT Air]

My "slab" is approx 5x8 and weighs around 1.5 ton. My 10 ft'r is happy above it.

 

[zamar23]

One can learn a lot from this concrete story. Are there any (possibly older) published guidelines from a former major C-band signal provider & dish installer on how to properly install a C-band dish depending on its size and geo location & weather pattern?

Also, its easy to see from the pic above, the bigger the distance between dish bolts, the smaller concrete area is required to hold the dish stably. Of course sufficient concrete depth would additionally prevent seasonal dish misalignment as Radar pointed.

 

[dfergie]

My first Bud was planted in the early 80's 3" pipe 4' deep with concrete around it in the hole... hole probably 1' in diameter, my 2nd Bud about 30' away I was only able to go about 2.5' till I hit rock so I poured a 8" x 2.5' slab then added a 12" x 1' pipe casing full of concrete on top of that... original Bud is down now from wind fatigue on the mount (10' fiberglass) the 2nd 8' mesh is still going strong.

 

[coinmaster32]

The current hole is going to take at least 10 60lb bags. That's 600 pounds, the dish and mount is 150 pounds, the pole is 50, that's 800 pounds. If I get a strong enough wind to move 800 pounds out of the ground, then I will need a change of drawers.

 

[dfergie]

My 10' Bud as described before is layed over facing the West where our prevailing & strong winds come from and the pole has survived (in the desert so no frost line )...

 

[rv1pop]

The current hole is going to take at least 10 60lb bags. That's 600 pounds, the dish and mount is 150 pounds, the pole is 50, that's 800 pounds. If I get a strong enough wind to move 800 pounds out of the ground, then I will need a change of drawers.

Yeah, That is what I thought! The dish is over about 18 feet. Notice the 1/2 inch stainless steel bolts are missing. The post is pulled over, the top of the concrete is almost up to the ground and it was down about 2.5 feet... That bracket is 1/4 inch steel that WAS fastened to the mount, the bend is from the bolt, before it broke.......

 

[Auric]

In SW Missouri where I am, 3' is deep enough for a 10' Mesh dish.
When I mix cement I always buy Portlan & mix 30 shovel scoops of creek gravel with fines in, & 4 or 5 scoops of sand.
If you don't have access to creek gravel get clean 1/2" chat.
1 scoop Portlan
2 scoops chat
3 scoops sand

You can mix it in a wheel barrow, but if you are going to pour 1/3 of a cubic yard I would rent a mixer.

It takes 6 bags of Portlan to make a yard, so your talking at least 20 #60 bags of ready mix, or 15 #80 bags ready mix. You can probably narrow the hole & go deeper & save yourself a lot of work

 

[coinmaster32]

Got the base made. I cheated and use about 4 bricks and one big rock to use as fill in the inside.

Took 9 60 pound bags. The only 80 pound bags they had was commercial grade at $4 a bag.

Between everything, there is about 650-700 pounds. I also countersunk the pad so I can put more dirt over it, which will make it hold better.

 

[PopcornNMore]

I poured a concrete slab for my 8' dish last July which resulted in a rotator cuff injury to my left arm and to date I'm unable to lift that arm above my head. Hire a professional.

 

[coinmaster32]

Gotta be tough. I can squat 290 pounds. The cashier lady thought I was he-man moving a 600 pound cart of concrete bags with one hand.

 

[Candid]

Got the base made. I cheated and use about 4 bricks and one big rock to use as fill in the inside.

Took 9 60 pound bags. The only 80 pound bags they had was commercial grade at $4 a bag.

Between everything, there is about 650-700 pounds. I also countersunk the pad so I can put more dirt over it, which will make it hold better.

The countersunk will cause moisture if you keep dirt around it when rain fall and will cause the pole to rust and weaken at the base, leave it free of dirt to keep away any m0isture.

Candid

 

[coinmaster32]

It's only counter sunk around the pole. The area where the pole goes on will be kept a bit above ground. The other areas will be covered in dirt.

 

[AcWxRadar]

It's only counter sunk around the pole. The area where the pole goes on will be kept a bit above ground. The other areas will be covered in dirt.

That's not good Coinmaster. As Candid stated, you don't want to have the pad below ground so that water is retained there. If the water cannot drain away it will rust out your pole as well as it will accumulate around the pole and seep down around it, freeze and break the concrete apart. You might get away with this if you live very far south where it only freezes once every two years. Here in Nebraska, it freezes and thaws repeatedly all through late fall, winter and early spring. Especially in spring! It thaws during the day and freezes at night for many days. I think you can imagine what that will do to concrete over just one year or even one season.

If your pad is countersunk around the mast, you are doing the wrong thing. It should be the reverse and built up around the mast (higher and then sloping away).

Many people from the south don't think of this situation because their climate is so much different. Maybe even folks from the far north don't consider this because the ground may only freeze and thaw once a year. It is a very different situation here in the middle. Even the ground heaving is something to behold. One section of concrete road near our family cabin heaves about 30 inches vertically over the seasons. It has been doing that for about 30 years now. Amazingly, the concrete has not broken up. But, can you imagine what that might do to your dish alignment?

Coinmaster, ensure that you set your pad properly now, while the concrete is still "green". If you think that you need to add some more crete to what you have already poured, now is the time to do so. The new concrete will adhere better to the existing concrete now better than it will a year from now. Just ensure that water drains downhill away from your mast. I don't wish to be preaching or lecturing to you, but I'd rather do that then have you find your pad all broken and disintegrating into sand and gravel two or three years from now and your mast rusted away at the base.

RADAR