The Whats and Hows of Chemical Anchors
Fasteners used to attach different fixtures to concrete, brick and stone are referred to as masonry anchors. There are dozens of different types. They differ in how they attach to masonry, the materials they’re made of, designs and sizes, as well as the items they can hold. A dividing line is that between mechanical and chemical anchors.
Mechanical anchors like wedge and sleeve anchors are a type of expansion anchors that expands into the substrate when set. This ensures high holding force, and they are generally used in medium to heavy-duty applications. Other mechanical anchors have threading that bites into the masonry to secure the load. This is not always possible with different materials, like hollow blocks or cracked concrete, nor in every location.
Chemical anchors are preferred here as they don’t exert outward stress on the masonry. Instead, they rely on adhesives as well as fasteners to create that strong bond and positively impact the substrate by filling any cracks or fissures. They work considerably better than mechanical anchors under heavier loads and extreme environmental conditions.
In addition, chemical anchors work better in substrates with questionable compressive strength, as well as in edge anchoring applications, often with heavier loads. On the Australian market, Ramset and its chemset ramset chemical anchoring products are widely recognised as the best in the industry. They offer a variety of chemical resins and threaded anchoring studs, as well as sleeves and retaining collars, and capsules used in edge anchoring. Besides this, Ramset has all the application tools and accessories required for the job.
Resins Used in Chemical Anchoring
Ramset produces a range of chemical adhesives that bond the fastener and substrate in differing loads and at varying depths. Polyester resins, like the Chemset 101 Plus, can be used for light to medium anchoring applications for anchoring threaded studs and reinforcing bars, into solid concrete, stone, hollow masonry, and brickwork.
The resin also works well in lighter applications like fixturing handrails, balustrades, rails, and facade pins. It can be applied in dry, wet, or flooded holes that are carbide drilled and once applied has fast curing times (60 minutes at 20 degrees). Additional benefits are the low VOC levels, meaning safety, the non-drip formula making it good for overhead applications and the long holding life.
Another polyester-based adhesive is the chemset ramset UltraFix Plus, ideal for small jobs or around the home, including steel fencing, gates, brackets, hinges, guard rails, and handrails. It’s also used in medium-duty anchoring of studs and bars into solid concrete, stone and hollow, and solid brick applications. Like the 101 Plus, it has quick curing times and can be applied with a standard caulking gun, and in dry or wet holes.
Heavy-duty applications are carried out with pure epoxy resins, like the Chemset™ Reo 502™ PLUS. This is good for post-installed reinforcing bars and for anchoring structural steel columns and beams. It works well in all masonry types, especially in cracked concrete, ahs a seismic and fire rating. Versatility is on par with the best resins, as this can be used in dry damp, and wet holes that are carbide or diamond drilled, in both cold and temperate climates. Curing times for dry and wet concrete are around 8 hours at 20 degrees, with a gelling time of 25 minutes.
For extreme conditions and anchoring, loads look to Epcon™ C8 XTREMTM, a pure epoxy resin with the highest bond strength on the market. This is used for thicker diameter starter bars, reinforcing bars for columns and beams, and threaded bars and studs for structural steel elements. It too can be used in cracked concrete, is seismic and fire rated, is all-purpose, all-weather resin, and has a 100-year working life. Similar properties are exhibited by the Chemset vinyl ester resin 801 XTREM™ XC², the company’s most recent chemical anchoring solution.
Anchor Studs, Threaded Inserts, and Anchoring Accessories
Attaching fixtures into solid concrete and brick is best done with threaded anchoring studs sourced in high-strength carbon steel (grade 5.8 or above). This can be treated with zinc plating or hot-dip galvanised to avoid corrosion and adverse effects of temperature extremes. Overall thread pitch and diameters in addition to lengths are available for different anchoring jobs. Thread size ranges from 8 to 24mm, with holes being drilled to 10 and 30mm respectively. When anchoring into hollow brick or concrete block cavities, it is advised to use anchoring plugs and metal mesh sleeves. For a flush fit of different bolts anchored into concrete, use carbon steel threaded inserts. All products are produced by Chemset.
Capsules contain a prepared mix of resin, meaning no wasted adhesive, no need for applicator guns, and save time from unnecessary mixing. They are used in solid concrete and brick and can accommodate a range of fasteners. They can also be used in a range of environments due to the non-drip formula, including overhead applications, as well as underwater installations. Curing is especially fast, within 20 minutes
Ramset offers a range of applicator guns that work with all Chemset resins mentioned above. There are also mixing nozzles to get the right concentration of resin. Other accessories in the same product line include different hole cleaning items, like brushes and blowers to ensure clean holes for maximum bonding. All products can be bought separately, but it makes more sense to purchase application kits that contain all the required goodies for your type of resin and application.