Tower Building

[Devo]

I have kind of a stupid??

I am using 66lb bags of sakrete for cement , when I mix this with water does it increase the weight or when it hardens does the water evaporate?  

The reason I ask is I wanted 6 foot deep 12 inch around holes (as I told the people at Home Depot) but the machine I rented only went 4 feet deep... I was looking for 800 lbs give or take per hole but I could only get 7 bags in a hole 460 lbs....

I am going to try to set my furling point at the max wind speed without pulling the anchors out.

Also does the fact that it is not a dead straight lift add weight? As the cement would have to twist in the ground to pull out?

I have a 40 foot tower with a maximum 11 foot blade diameter.The Tower is 3 " thick at the bottom 15 feet & 2 1/2" thick the rest of the way.

The guys are anchored 20 Feet from the tower, at this point I could still drop it to 30 or 35 feet. The highest thing on the property is a 30 foot silo 100 feet away & a 25 foot barn 40 feet away.

all other trees etc. at least 200 feet away.

The center hole also has 4 feet/7 bags of Sakrete & 2 3" U Beams in the Ground with a 1" Solid Shaft to pivot on , I can also drill another 1" shaft through the tower 4 feet from the ground  as the Beams are that high so far.

Sorry for the Novel, all input welcome

Devin

[wdyasq]

"I am using 66lb bags of sakrete for cement , when I mix this with water does it increase the weight or when it hardens does the water evaporate?"

Yes.

As far as pulling out, one needs to analyze exactly what all happens. Smart design can beat brute force or shear weight but, is harder to design.

Ron

[dbcollen]

Concrete does not dry, it cures, when you add 3 quarts of water to the 66 pounds of redimix the water has a chemical reaction with the hydrated lime in the portland cement and turns back into limestone with all the aggregate (sand and gravel) to form concrete. the water weight stays, because the water stays.

Dustin

P.S. the 3 quarts of water weighs aprox 6 lb

[Mary B]

Guy anchors shouldn't be installed in a vertical position. The forces on the tower can pull the anchor sideways. The last large tower I helped a friend put used trenches that were inline with the guy wires. The anchors went in to the concrete at an angle that pointed towards the tower. That type of guy was relying on the weight of the concrete plus the forces it would take to pull it through the ground.

[wooferhound]

Yes tall Guy Anchors need to point toward the guy wires

The ground on the side toward the tower should be undisturbed

The bottom of the anchor hole needs to be larger at the bottom than at the surface

  before the concrete is poured

use plenty of metal reinforcement in the concrete

[phil b]

I agree that the holes with the anchors need to be angled. If you are using a machine that can do that.

My  solution is to dig a vertical hole as deep and wide as needed. Then drive an iron T post into it at the correct guy angle. The bottom of the T post should end up in the bottom of the hole. Drive at least one piece of 1/2" rebar vertically into the bottom of the hole that goes all the way to the top. Allow enough room to pour at least 3 inches of concrete around the post and fill the hole up with one concrete pour.

I have 30 and 40 ft. towers that have been up at least 5 years in strong winds with no problems at all with the anchors.

I have heavy clay soil with thin layers of soft rock in my area. Of course, your soil type will determine how large the hole has to be as well as the weight of tower and turbine.

                     T post

                   

           I       /

         ( I )    

         ( I )  

         ( I )  

         ( I )

         ( I )

         ( I )

         ( I/)

         (/I )

          hole        

[phil b]

I see my diagram didn't turn out so well. The T post should bisect the hole.

[TomW]

Phil;

Great idea! I think I will steal it.

Cheers.

TomW

[coldspot]

Wow,

I'd planed on making my anchors by fence post hole digging down 2 1/2' placing heavy cardboard 2' tubes, (saved from shrink-wrap rolls about 1/2" walled 5" OD), into holes with golf ball sized rocks lining hole bottom for concrete to be able to flow out and mushroom the bottom side. these would also be ree-bar with Eye-bolts welded on in them to hook to.

 I might have to plan on digging them leaning AWAY from the tower not towards it.

 I've checked out some huge radio n other towers around and see that some have all guy lines from that side tied at one anchor spot, while others use spots closer and farther out for them.

 I'll be only around 50' if lucky and 30' if not using 7'-9' fiberglass blades.

 I have an old sat-dish mount that will make a nice pre-built tip-up type starting with 6" at bottom and 4" top with pipe I now have. This base has a couple foot ring that I'll have to set in some serious concrete for the base.

 Was wondering about welding it to 55 drum top dropped into a hole

maybe then filling the drum with water for weight. Being a bit more temp than forever type.

:|

$0.02

 

[Devo]

Thanks fella's , I should have posted first before starting-lol. I have one post in vertical but I can put the other 3 angled toward the tower, the more I think of it this would make the anchor twist the cement more making harder to pull out(I think)

Phil , are you saying put a piece of rebar through the vertical anchor post to act like a hook?

I have clay in 2 holes & a mix in the other 2.

Just my luck I bought the cement yesterday & it is suppossed to rain today but the wife & I where at the hospital with our boy until 1 am waiting for a Doctor (hurt wrist at hockey)home by 1:30 am & back up at 6:30 am for X-rays , had about 4 hours sleep last night so slept most the day away today, hope if it rains the unused cement will survive under a tarp outside(wrist is fine)

Devo

[SparWeb]

Devo,

You bring back memories of my tower-planting this spring.  I had poured the concrete not 2 hours before, when it started raining.  The rain didn't let up for another 3 days!

It sounds like Phil has your answer.  If I could have put in my 2 cents earlier, I would have suggested large earth anchors, but now you've already bought the concrete.  There are screw-in anchors and burial-plate anchors.  Since you have the holes dug, you can put a burial-plate anchor in at the slanted angle, and then pour some cement over the bottom end with the plate.

The other advantage of these anchors is that they are forged with loops that perfectly fit the shackles to connect the cables.

[phil b]

Too late Tom...

I published it here for all to see and freely copy!

[phil b]

"Phil , are you saying put a piece of rebar through the vertical anchor post to act like a hook?"

Yes, sort of. The spade on the T post usually has a notch on it's top. I drive the rebar into that notch. It probably is not needed, but it's there and can't hurt.

Also, If you leave the top of the rebar exposed above the concrete, you can bend the rebar or weld some type of a circle in place to put your saftey line for your turnbuckles and cables.