A local PTA purchased 8 cast concrete tables, and 24 concrete benches to go with them for a local High School student use. The Co manufacturing them said to use Liquid Nails to hold the tops on the bases, and the bases in place. The school custodian did so- but did not believe they would "hold up". We are now 1 month later, and at least 2 benches have come "unglued".
My wife is wanting me to check into alternatives to the Liquid Nails while others are checking back with the manufacturer. My first thought was some sort of epoxy grout (machine mounting connection to forum!), but I have no experience with these. Any suggestions?
The tables and benches are out in the weather in Central MO. My guess is the Liquid Nails was specifed for its gap filling properties and not being brittle.
I have seen (in poor lighting) the legs of the benches. One one pair I see no evidence of Liquid Nails, and on the other I see some, and at areas some evidence of adherance to another surface, but large sections that look like they never touched anything. My wife says no cleaning of any kind was done to the surfaces before the liquid nails was applied- nor was surface prep specified by the maker. I believe the maker "screwed up" by not specifying a surface prep- and the custodian by not using enough liquid nails to span the gap in the joints- or putting on adhesive and letting it "skin over" before assembly. I also believe where it did touch it was to a surface contaminated by dust, dirt, and form release compound and so had poor adhearance. What do you think?
I have had good luck with liquid nails on concrete. You do have to make sure the surface is clean and dry. I have used it to attach all kinds of items to concrete including wood, sheetrock, fiberglass and epoxy based items. You need to make sure that there is enough of the liquid nail to fill the gap. I would think that on concrete to concrete you should fill the gap completely so that it also acts as a seal to keep moisture out of the joint.
Another item that I have used is silicone based adhesives. They are clear in color and work very well on epoxy based items like imitation marble counter tops and sinks. It acts as an adheasive and sealer. I think the liquid nails has a stronger bond.
Hope this helps.
There is another product called gorilla glue that I have used in gluing concrete.It foams when it expands so it gets into any cracks or depressions.
Just a thought, but maybe if the products were recently poured before you got them, the concrete didnt have enough time to cure, so some of the lime or whatever it is leached out and weakend the bond. Cleaning is important - how about using TSP (tri-sodium phosphate, or a good driveway cleaner, with plenty of rinsing and drying time?
There are several Liquid Nails formulations availabe. Maybe they are all the same stuff with different labels.
The instructions tell you to apply the glue, separate the parts, let the stuff dry for the instructed time, and then reassembke the product. I recently installed a shower stall and attached the plastic liner with Liquid Nails as instructed. The glue worked well and really holds. Maybe the installer did not read the instructions.
In addition to your own thoughts, and those above, the "standard" liquid nails isn't rated for exterior use.
The local grave monument emporium can guide you to a good adhesive to use. I had a project to glue together some time ago and used an adhesive that I got from the monument fellow. I'd offer the name, but alas, I've slept since then.