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Concrete Pier for LXD55 & Atlas Mounts, The Build

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#1 Project Galileo

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Posted 23 April 2009 - 06:47 PM

Today I dug a hole 42" deep and 9 inches wide. I intend to build a permanent concrete pier for my LXD55 mount and future Orion/CGEM. I plan on adding to my arsenal of mounts someday and am ensuring compatibility when I do.

For now the moist ground made for an easy half hour on the end of the post hole digger. I made the hole wider around at the bottom by a couple inches. It is well below code/frost line to prevent heave.

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#2 Doug76

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Posted 23 April 2009 - 06:53 PM

I have to do the same thing come June. What are you going to use for a form? And how high off the ground are you going with it?

#3 Project Galileo

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Posted 23 April 2009 - 06:59 PM

I intend on having power and cable/internet in the pier. In the first picture you can see how the boxes were fitted to make the conduit bend down the pier.

A clear seal around the outside of the boxes will ensure no concrete seeps out during the pour. The boxes fit very tight so I am not too worried. I cut them to pretty exact size using a drywall saw. This step is probably mostly because I had the sealer stuff laying around and can use it someway now. I will run a couple laps of duct tape around the boxes and tube/form before pouring to hold them in. I am sure the pressure of wet concrete will require some tape strapping.

In the third picture you can see the boxes and elbows from bottom inside of the tube. Once concrete is poured they will be more flush mounted now.

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#4 Project Galileo

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Posted 23 April 2009 - 07:04 PM

I have to do the same thing come June. What are you going to use for a form? And how high off the ground are you going with it?


I am using a Quik-tube type form I picked up at the local hardware store. As far as height I am not as concerned. Every inch I can get I will use in the form. I suspect it will finish at 52" to the top of the mounting plate. I am very tall and use refractors so the taller the better. I also use an adjustable chair giving me a cushion that way.

#5 Project Galileo

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Posted 23 April 2009 - 07:10 PM

Here is a picture looking down the hole with the rebar cage and conduit tubes. Notice how the conduits turn 90 degrees and then continue towards the house.

The terminal ends of the horizontal conduit at the bottom were about 12 inches long. I covered the ends with duct tape (love it) and jammed them back into the earth at the bottom of the hole. Then I covered them with dirt partially to prevent concrete from soaking/seeping into the end, rendering them plugged.

After the pier is complete, at another time, I will dig the trench back from the house that will carry power and cable. When I get to the base of the pier I will excavate these taped ends and tie into the pier that way.

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#6 Project Galileo

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Posted 23 April 2009 - 07:14 PM

I slammed together some scrap 1"x2" to make a frame to hold the tube low. Here you can also see how the conduit comes up to meet the boxes and the rebar extends up. The rebar terminates just below the L bolts at the top of the pier.


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#7 Project Galileo

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Posted 23 April 2009 - 07:19 PM

The same scrap 1"x2" and some screws helped with the upper support and frame. Again I was precise with leveling before staking and screwing the form into place.

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#8 Project Galileo

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Posted 23 April 2009 - 07:22 PM

Staked and ready for the pour. I plan on doing that in two days on Saturday morning. Stay tuned.

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#9 Project Galileo

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Posted 23 April 2009 - 07:25 PM

A spring thunderstorm squall came in fast and I was without a tarp. I improvised and used the barbecue cover quick. I can't wait for the upcoming pour.

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#10 EricJD

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Posted 24 April 2009 - 06:12 AM

Great post, I love this stuff. Good luck on your pour.

#11 Project Galileo

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Posted 24 April 2009 - 04:19 PM

Today I woke to the weatherman telling me there is 3 days of rain in the forecast coming a day sooner than previously thought. I bumped the pour up until today so it will have a gentle rain keeping it moist during the cure. I will post pictures of the pour later tonight when I get home again.

I was able to get the pour done this morning before 11 a.m. and the afternoon thunder storms. Everything went without a hitch until about a half hour after I cleaned up. The thunderclap was...well...thunderous.

Can anyone tell me what happens to wet concrete after it is hit by lightning? I believe the bolt passed down the stainless steel L bolts and hopefully down the rebar into the ground. The concrete was wet enough to perhaps disipate the charge throughout the pier however.

So now I sit and wait until I can take off the form and see what happened if anything. What do you all think? Is it going to mess with my concrete's chemistry? How long do you think I should wait until I take off the form?

#12 SkyArcher

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Posted 24 April 2009 - 07:19 PM

I've seen lightning struck concrete and it is usually exploded.

But lightning damage is unpredictable. So if you see any visible signs of damage, take pictures, I'd like to see it.

Good luck and let us know how it turns out.

#13 Calvin Sereda

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Posted 25 April 2009 - 12:30 AM

Maybe the lightning hitting the pier will be a good thing, maybe it acted as a super concrete de-airator.

#14 Project Galileo

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Posted 25 April 2009 - 01:23 AM

I will go out in the morning and get some pictures of it. I didn't take any today since the rain and fear of another strike kept me mostly away from the pier then I had to head to work.

At first I didn't even think it was hit until I saw the top of the cardboard of the tube smoldering. I did head out after a bit to check out what happened. The concrete was still wet enough to allow my finger to go all the way in and still allow me to smooth it out. However, around the bolts and in some chunks I could feel hard spots in the concrete. It wasn't aggregate. These felt like they were larger and sharper hard, cured, concrete spots. Some were immovable. That is what got me to worrying. Had something happened to the concrete that would effect its curing or strength?

I did some googling and found out a bit. There seems to be some info available from reports of lightning strikes to roadwork as it is being done. I found reports of exloding/fractured spots mostly. Also reported were areas of heat damage. I couldn't find what they meant by heat damage. The reports spoke as if heat damage was common knowledge among concrete workers. Additionally discovered, visual strikes sometimes left no damage at all and other times required complete reworking. Basically it was unpredictable as to what happens.

I have no idea what to expect when I unveil the pier. Before leaving to work, about an hour after the strike, I went back out and the concrete was still real soft and the pier had some wobble to it. It hadn't set much yet. I had been stressing a bit about this until I came home tonight and checked it again. Now the pier seems very stout and unshakable when I pound on it or give it a hard shove. I am more optimistic now.

On a side note my wife tells me tonight the neighbors house was also struck by the same bolt. There was only one close strike in the squall. They had damage to part of their roof and down a wall. I haven't talked to them about what else may be damaged. Inside our house we lost my old 19 tube TV upstairs that was in a guest bedroom and several light bulbs. The TV just won't turn on now. However, I can't find anywhere on the house where it may have been struck so think it may be a factor of EMP or something.

Here are the pictures from this morning before the strike.

#15 Project Galileo

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Posted 25 April 2009 - 02:05 AM

Everything assembled and ready. Nothing to add but some sweat.

The mixer works like a wheel barrow and I was able to pour it directly into the hole or a 5 gallon bucket to hoist to the top of the pier.

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#16 Project Galileo

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Posted 25 April 2009 - 02:16 AM

A few laps of duct tape held in the boxes nicely.

I dug a spout at the top of the pier to pour into.

A concrete buddy of mine gave me this water reducer additive. Two ounces per bag of concrete made the slump go from a 2-3 to a 12-14. It works like a charm. The concrete was dry and crumbly in the mixer then you add this and bam, it gets all sloshy without having the aggregate separate. Less water means more strength too. I recommend this stuff highly. Lets see if it makes for a cleaner finished surface too. I have no idea what brand or even what is in this bottle. He uses it to make concrete counter tops in his trade and gets it from a large barrel at his shop. This mystery sauce works.

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#17 Project Galileo

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Posted 25 April 2009 - 02:29 AM

A bare sander helped with bubble control. Again, my concrete buddy recommended this trick. I did the pour alone so am a bit lacking on some pictures. I would mix the concrete in the mixer, refill the water measuring pitcher while it turned, dump the load into the hole or tube via a bucket, reload the mixer and water pitcher, then go vibrate a while. I also rapped on the side of the tube at the same time with the other hand and a rubber mallet. I would then just repeat each step until the top was reached.

The second picture shows how I intended to install the pier plate. I wanted to nurse the tube for as many inches as I could.

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#18 Project Galileo

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Posted 25 April 2009 - 02:33 AM

After the top was reached I pushed the L bolts and pier plate into the concrete, inserted the 2x4s, then shimmed and leveled the plate. Last night I went out spotted Polaris' direction and marked it on the pier for correct positioning. I think I am within 3-4 degrees eyeballing it. The plate allows for 20 degrees of adjustablily so I am golden.

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#19 Project Galileo

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Posted 25 April 2009 - 02:38 AM

The tube was filled to within an inch of the top. Add the 3 1/2" of the 2x4 and the plate will sit about 4 1/2" from the concrete. This should give me enough room to reach under to loosen and tighten the mount's bolts.

Once the hole was filled I covered it with dirt and built a smallish mound around the base. I was figuring it might help keep the concrete from blowing out of the bottom of the form. You can see it covers the frame I built.

Now we wait.

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#20 Project Galileo

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Posted 25 April 2009 - 02:41 AM

Right now it looks better from far off. I really, really, really hope the reveal brings good news and a strong, pretty pier.

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#21 Project Galileo

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Posted 25 April 2009 - 10:59 AM

Okay gang. I awoke today fully committed to not taking the form off too soon. Sleep had cured my worries. Letting it cure inside the form may help with keeping moisture in it. I was gonna not think about what may have happened.

Thankfully, my oldest son woke today and couldn't wait himself. He and I were chatting about the pier last night and when he woke he went out and took the cardboard off himself. I'm not wiped out since it is now drizzling and going to rain for three days or so. I am sure it will stay plenty moist.

It came off in one piece my son said and was laying next to the trash can. I snapped this pic of the tube's damage.

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#22 Project Galileo

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Posted 25 April 2009 - 11:24 AM

Ta da! The cool part was I got to have my son do all the clean up. He really got into helping.

So, here it is. There wasn't a bubble anywhere and I attest this to the additive and vibrator/sander. Thanks Jeff. There is a separation between bags of concrete midway. The firmness of the concrete seems strong everywhere so far. Whew.

The concrete finished at 45" above ground making the top of the pier plate 51 1/2" tall. The stock LXD55 tripod (rest it's miserable soul) was 41". A gain of 10 1/2" rocks.

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#23 Project Galileo

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Posted 25 April 2009 - 11:27 AM

Up close the separation point doesn't seem structurally weak. It just looks like the edge of top pour had more liquid at the bottom and the bottom pour a bit more aggregate. I can live with this especially after I finish the surface of the pier.

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#24 Project Galileo

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Posted 25 April 2009 - 11:29 AM

The top looks great.

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#25 Project Galileo

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Posted 25 April 2009 - 11:35 AM

I used 3/4" bolts I ordered from Dan's Pier Plates. I had them from a couple years ago when I had been planning a 10" SCT pier. Time brought different scopes so I used the ones I had for this pier. When I ordered the 8" pier plate from Dan's they machined one special for me so I could use the 3/4" bolts I already had. Thanks Dan's! It took about 12 weeks for them to make my plate. I had the time so didn't mind.

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