This is an epoxy vs. lead anchor discussion. Considering the effects of weather on epoxy, should we consider using lead anchors to secure aluminum concrete survey markers?
Epoxy is used to secure anchors in all types in construction, so I consider it permanent enough for monuments. Epoxy is plastic, and UV light is the enemy of most plastics. As long as the UV can't get to it I expect the epoxy to last as long as the metal monument and the concrete it is in.
I find my epoxied disks in place after 25 years, and Tucson gets a lot of sun.
Epoxy and lead aren't your only choices. I prefer anchor cement over both -- it's cheap, readily available (any hardware store or home improvement center), easy to carry in the truck (dry powder), requires only water to mix and clean up, is non-toxic, and is as permanent as the concrete that it bonds with.
jhframe++
Grout them in, some of mine are 35 years on and still in great shape. I'm not using epoxy or lead for that task.
@ jhframe
I had to do a little research on anchoring cement. Research indicates that it's a more cost-effective method, which the county would like. We currently use a two-part epoxy, which we mix from two different containers. It's a bit of pain to apply, and we have to mix the black and white parts together in a paper bowl using a plastic spoon.
I use an epoxy putty I get on the plumbing aisle, which greatly reduces the mixing hassle.
@ Norman_Oklahoma
At our last crew meeting, someone mentioned that the epoxy ring around the outside of a marker was coming off. We smear the excess epoxy, that rises out of the drill hole when the marker is being set, around the exposed part of the marker to ensure a tighter bond with the concrete. Apparently, the UV light, like you mentioned, is causing the epoxy to become brittle and come off.
@ Bruce Small
Here, in Orange County, FL, we're using 3.50 in. (split shank) markers, but we're switching to 3.25 in. (hexagonal shank) markers to save money. The 3.50 in. markers cost about $21 each vs. about $7 each for the 3.25 in. markers.
I would have some reservations about using the 3-1/4 cap vs the 3-1/2 disk. First, you will need to modify the cap's smooth stem to allow for any method of bounding. The stem needs something for the bonding agent to form around. That is why discs have split or notched stems.
Secondly, you're going to need a core drill to make a hole big enough for the caps stem and bounding agent.
Given the additional cost to install the 3-1/4, the $14 savings probably is not worth it. You can get 2" discs from Berntsen for around the $8 mark.
P.s. I'm with Jim on the anchoring cement. It works like a charm, is cheep, easy to use and cleans up nicely.
I use a wood stake as a base and a craft stick to mix the two (white and black) components, and disposable gloves. Clean up is easy (wipe the stick and toss the gloves in the trunk).
@ john-putnam
The county used 2.25 in. brass markers in the past but has been using 3.50 in. aluminum markers for at least the past 7 years. I realize that the 3.25 in. markers are caps. I had to research what a core drill is. Thanks for mentioning it. I agree with your reservations about using a 3.25 in. cap vs. a 3.50 in. disc.
The 3-1/4" caps shown are constructed to fit over a 3/4" aluminum power grip rod. I've probably set 3-4 thousand of them for sectional/boundary markers but they aren't appropriate as a concrete grouted monument, unless you plan to drill through the concrete for the 3/4" rod. If you use them core out a hole for the entire diameter, pound the rod down, pour in some grout, then tap on the cap till flush.
The flared or ribbed caps are what you want. Faster means savings also.
@ MightyMoe
Using a 0.75 in. rod will raise the cost of setting BM's. There was a discussion about drilling a small vent hole in each cap stem to prevent an air pocket from forming when the cap is pressed down into a hole filled with epoxy. A better solution, some think, would be to fill the stem with epoxy. Additional epoxy will raise the cost. I think we should stick with the discs we've been using and use anchor cement as jhframe prefers. Besides, we like the Orange County orange that's on our discs.
"There was a discussion about drilling a small vent hole in each cap stem to prevent an air pocket from forming when the cap is pressed down into a hole filled with epoxy."
Years ago USC&GS experimented with vent holes, and concluded that they don't add much (if anything) to the installation, but they do cause a lot of confusion: surveyors mistaking the vent hole for the mark. Early in my career I made this mistake a time or two.
