Adhesive systems tend to be the most expensive concrete
anchors, but they have advantages that make them ideal for some
applications. They can be spaced closer to each other and to
the edge of a slab than comparable mechanical anchors, so when
the foundation sub leaves out or misplaces an anchor bolt,
adhesive fasteners may be the only alternative. Adhesive
systems also tend to be more resilient than comparable
mechanical anchors, so they perform better against impact and
Adhesive systems are available in two forms —
dispensing systems and glass capsules. Dispensing systems use a
gun (similar to a caulk gun) to premix the adhesive and inject
it into the hole. This system tends to be the most economical,
but not the most convenient. Obviously, you have to use up an
open cartridge fairly quickly, and you have to pay close
attention to the "nozzle time" — how quickly the adhesive
sets up in the gun nozzle. Also, non-acrylic adhesives can be
tough to inject in below-freezing temperatures, not so much
because the bond reaction is affected, but because the adhesive
becomes so stiff.
Glass capsules come in two types, spin-in (such as Hilti
HVA, Powers/Rawl Chem-Stud, and Ramset/Redhead
Maxim), and hammer-in (Powers/Rawl Hammer Capsule
and Ramset/Redhead Impact). Spin-in systems require a
specialized chuck to drive the anchor in and mix the chemicals.
With a hammer-in-capsule, all you need is a small sledgehammer.
The chemicals mix when you pound a rebar dowel or threaded
anchor into a hole containing a capsule. Typically sold in
boxes of ten, capsules have a long shelf life, so you can keep
them on the truck for use when needed.
Glass capsules.The simplest, but
most expensive adhesive anchors come in glass capsules.
Two types are available — spin-in capsules, which
require a special chuck for a hammer drill to drive in
the anchor and mix the chemicals, and hammer-ins, which
only require a hammer to drive in a rebar dowel or
Adhesive anchors are generally available in three
formulations — epoxies, vinylesters/polyesters, and
Epoxy-based adhesives cure strong and
aren’t effected by water, so they can be used in damp or
water-filled holes. (Redhead’s Ceramic 6 is even
recommended for use under water.) But the mixing and
proportions must be exact, so you usually find true epoxies
only in dispenser systems with high-quality (and more
expensive) mixing guns.
epoxy-based adhesives are unaffected by water, making
them a good choice for damp locations, such as
foundation pins in water-bearing granite.
Vinylesters and polyesters cure by a chain
reaction, so they don’t need thorough mixing, which is
why most of the glass capsules use this formulation. The
drawback is that these adhesives shrink more than other
formulations when cured.
Acrylics have the fastest curing times with
little shrinkage. They also perform better in cold weather (for
example, Ramset/Redhead’s Epcon 7 stays workable
and bonds down to 0°F).
With all adhesive systems, you need to be careful to clear
the hole of dust or slurry to ensure a good bond to the base
material. This involves using compressed air (a squeeze bulb
will work if a compressor is not available), and a wire brush
to roughen the sides of the hole.
Between the World Wide Web and a vast network of local
contractor suppliers, the answer to your specific fastening
needs is out there.
Literature. One of the best resources
available is the Powers/Rawl Fastening Systems Design
Manual. This is the concrete-fastener equivalent of
USG’s Drywall Handbook or the Simpson Strong-Tie
catalogs. Once you’ve plowed through this one, the
performance specs in other references will make a whole lot
CD-ROM. ITW Ramset/Redhead offers an
interesting CD — Concrete Fastening Solutions
— complete with performance data and animated
Web. Several manufacturers, including
Ankr-Tite, Ramset/Redhead, Star Fasteners, and Simpson
Strong-Tie, have Web sites with product listings and
performance data. More useful, however, are a few sites that
offer an extensive listing of distributors by state for a wide
range of concrete fasteners (as well as other construction
Blue Book of Construction:
Sources of Supply
Ankr-Tite Fastening Systems
2415 E. 13th Place
P.O. Box 21148
Tulsa, OK 74104
P.O. Box 1740
1300 N. Michael Dr.
Ridgeland, MS 39158
Wood Dale, IL 60191
Star Anchors and Fasteners
P.O. Box 641
P.O. Box 1
New Rochelle, NY 10802
Mountainville, NY 10953
U.S. Anchor Corp.
4637 Chabot Dr. Suite 200
450 E. Copans Rd.
Pleasanton, CA 94588
Pompano Beach, FL 33064
Clayton DeKorne is a senior editor at the Journal
of Light Construction.