Any tips for setting a 3" cap in concrete at a specific coordinate to be used for control?
So far I'm thinking I will dig my hole about 2 feet deep with post hole diggers if I can't get an auger.
I'll drive rebar in the hole, pour the concrete in, then use string lines to get set the center of the cap close to the deaired coordinate. Come back the next day stamp it and dimple it.
Is there a better way? This is in West Texas.
Maybe a section of PVC or a milk jug would make things easier or more stable?
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Arctan,
First thing I would do is stakeout the point and place rough straddle marks. Then dig out the hole with a bell shape at the bottom. I always try to use a bit of Sonotube at the top 6 inches for a nice finish. Fill with concrete and place a disc at the straddle intersection. I'm not sure why you would place an iron but you could drive the iron and set a cap on it as well. I always try to finish the concrete so the monument sits a little proud of the outer rim of the concrete so water sheds. The NGS has some good info on installing monuments. Once the concrete is cured you can set the dimple on the monument as you please.
On a side note, I'm not sure why you would set control at a specific coordinate unless you are actually talking about some kind of grid line.
Thanks, John! I'm essentially re-establishing old control points that got taken out during construction. The client would really like for me to be able to get it to within a hundredth on XY and Z of where they used to be. I don't think it's possible but I'm going to try [emoji3].
The rebar was just for adding stability to the concrete.
Now I need to look at tools for getting the concrete job done.
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Anybody have a video?
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Forget about the rebar, it will just rust out if it isn't all in the concrete. Deeper the hole the better (up to 5ft) with a bell shape at the bottom adds stability. NGS has specifications for setting concrete caps. See page 15.
I would suggest that set the monument in the original location but establish new adjusted coordinates. As for the rebar, I don't think that is a big issue since you are not putting any structural forces on it. I have never placed or seen rebar in a concrete monument.
As for videos, check the Bernsten Site.
I've been known to throw some scrap iron (chunks of rebar, pipe, bolts, etc.) in the concrete to help a magnetic locator scream better.
arctan(x), post: 448221, member: 6795 wrote: Any tips for setting a 3" cap in concrete at a specific coordinate to be used for control?
So far I'm thinking I will dig my hole about 2 feet deep with post hole diggers if I can't get an auger.
I'll drive rebar in the hole, pour the concrete in, then use string lines to get set the center of the cap close to the deaired coordinate. Come back the next day stamp it and dimple it.Is there a better way? This is in West Texas.
Maybe a section of PVC or a milk jug would make things easier or more stable?Sent from my SAMSUNG-SM-N920A using Tapatalk
Got hired to set a big cemetery once. Hundreds of caps, pre stamped with centers. They wanted them set with concrete. Staked and pre augered the holes about 8 inches deep each, set the rebars and caps flush to grade in each hole, putting masking tape over each cap. Hired a contractor friend to fill the holes to flush with concrete then came back and took the tape off before the concrete fully cured. Looked good and met requirements. Not what I'd do if those were geodetic control monuments, of course.
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John Putnam, post: 448232, member: 1188 wrote: NGS has some good info on installing monuments
arctan(x), post: 448239, member: 6795 wrote: Anybody have a video?
RADAR, post: 448269, member: 413 wrote: I found a PDF...
And the PDF has links to videos!
http://www.sonotube.com/sonotubeconcreteforms/round.aspx
Just google "Sono tube" and you can buy them at any friendly, big box store.
John Putnam, post: 448245, member: 1188 wrote: I I have never placed or seen rebar in a concrete monument.
I have set plenty of "rebar in concrete". One may not refer to them as monuments, but they are substantial, cheap, and easy to install.
I would not try to set them or any other monumented point to a specific elevation. In my part of the world monuments tend to settle. I let them cure a few days before observation.
Having said that, I have had less settling using the Berntsen pipe monuments with caps attached. The ones with the flared ends work best for me.
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John Putnam, post: 448245, member: 1188 wrote: ... I have never placed or seen rebar in a concrete monument ....
Putting rebar in the concrete does 2 things. It makes the pin finder sing, and it makes the concrete more resistant to freeze/thaw.
+1 for using Sonotube
If you want it to sing. Place a magnet in the concrete.
