Concrete Adhesive Anchoring
Concrete Adhesive Anchoring
(OP)
For anchoring rebar or threaded rod to concrete most manufacturers offer both a 1:1 two part epoxy and ~10:1 acrylic epoxy. Both offering relatively similar capacities.
I'm interested in what others feel is the better product or for what situations one may be better over the other.
I'm interested in what others feel is the better product or for what situations one may be better over the other.






RE: Concrete Adhesive Anchoring
RE: Concrete Adhesive Anchoring
I like these anchors for columns anymore. I do not have to work with having to burn base plates because the "J" anchors were misplaced or shifted during concrete placement. They can use the base plate as template to drill and place the anchor bolts.
RE: Concrete Adhesive Anchoring
RE: Concrete Adhesive Anchoring
The quantity of each component is premeasured and the glass capsule breaks (chemicals are mixed) at the precise moment that installation of the rebar / threaded rod begins. I have used this type product (successfully) for over 15 years for many heavy industrial applications, such as both building & machinery anchor bolts, rebar dowels, and even overhead anchors for supporting piping & electrical conduit.
The bulk versions (concentric & side-by-side tube applicators) work just as well but are more dependent on the skill of the installer to apply the proper quantity AND do so in a timely manner.
Hilti has extensive test data on glass capsule adhesive anchor performance. Since each capsule is essentially identical, the data should be reliable.
As stated the adhesives are affected by temperature. Hilti shows bond strength dropping linearly from 100% at 70 deg F. to 63% at 212 deg F.
RE: Concrete Adhesive Anchoring
RE: Concrete Adhesive Anchoring
RE: Concrete Adhesive Anchoring
RE: Concrete Adhesive Anchoring
I wouldn't use a polyester- or acrylic-based adhesive to carry any significant, permanent loads. These materials can cure quick and can have published load capacities comparable to epoxies, but I have heard that they are also somewhat more susceptible to poor performance resulting from jobsite errors, and also that the capacity of the adhesive can degrade significantly over time.
Epoxies also require care when placing, but they've been around longer and I believe there is a fair amount of data out there showing that epoxies keep their strength over time (Unless as noted by others they are heated).
I don't have a lot of experience yet with the new Hilti methacylate adhesives but did use it recently for an anchor bolt fix. Did not see it installed so can't comment further.
RE: Concrete Adhesive Anchoring
The injection systems are more flexible than capsual systems in that they can be used for different hole sizes and depths. I don't like glass capsuals because they are too easy to break before you get them in the hole!
RE: Concrete Adhesive Anchoring
What code and where only allows half the capacity for non-inspected holes?
thanks
RE: Concrete Adhesive Anchoring
RE: Concrete Adhesive Anchoring
Do you know if the rated capacities of the epoxies are rated for immediate use such as the 4000 psi number you quoted or do they consider future devaluation and rate per the 3000 psi value considering the effects of time?
RE: Concrete Adhesive Anchoring
I'm not an engineer, but as I understand it when a joint is specified the engineer typically applies a large "safety factor" to the design--in other words, if a joint strength of, say, 1000psi is required, the spec may call for a minimum of 3000psi, yielding a "safety factor" of 3:1. The adhesive thus needs to be chosen that will maintain that 3000psi strength throughout the intended lifespan of the joint. In the example I cited above, and epoxy meets the requirements; the polyester or acrylic would not.
RE: Concrete Adhesive Anchoring
RE: Concrete Adhesive Anchoring
Please don't quote me but my understanding is that the methacrylates marketed by Hilti (Such as HIT 150) are a second generation type of acrylic that is different from the vinyl esters and polyester adhesives available in the '80s and 90's. (SIKA also markets a modern methacrylate adhesive.)
The new methacrylate compounds are supposedly more more resilient. I'm not aware of any data on how well they keep their capacity over a long time though.
RE: Concrete Adhesive Anchoring
RE: Concrete Adhesive Anchoring
RE: Concrete Adhesive Anchoring
RE: Concrete Adhesive Anchoring
That was the Standard Building Code (1999 edition, at least the one I had). We used SBC in Florida before we came up with Florida Building Code.
The rational behind that is that if the hole is not inspected (i.e. done prepared properly in accordance with the manufacture’s recommendations) the published value may not be achieved.
Regards,