Chemical Anchor Studs & Sleeves

Chemical anchor bolts and studs

A chemical anchor holds a threaded stud, or an internally threaded anchor, in a drilled hole with resin instead of expansion. Hobson describes its chemical anchor studs as non-expansion fasteners set in a pre-drilled hole with a curing resin from a glass capsule or an injection system. Because nothing expands, Hobson lists them for fixing to concrete or masonry, holding down machinery and jobs that need a non-expansion fastener, and lists the flat top studs for closer edge distance and spacing.

Common jobs include resin-set hold-down studs for posts, plant and handrails. The holding capacity comes from the resin, the embedment and the base material, so it is in the resin's ETA or data sheet, not on these parts: for any structural or safety-critical fixing, the stud, resin, embedment and spacing come from the engineer's or designer's specification.

Stud, internal thread anchor or sleeve?

• •Chemical anchor stud kit: a threaded stud with a nut and washer, for fixing through a base plate or bracket. Hex drive studs have an external hex on top and a chisel point; a 1/4 inch hex drive bit comes in each pack, so they can be spun into glass capsules with a hammer drill. Flat top studs have an angle (bevelled) point. Each stud has an embedment mark so you can see the depth once it is in.
• •Internal thread anchor: a short, internally threaded stud with a chisel tip that sets flush in resin, so the bolt or threaded rod can be removed and refitted. Hobson lists it for temporary or removable fixings and close edge distances, with no expansion forces on the concrete.
• •Sleeves for hollow masonry: Mungo nylon sleeves (MIT-SH) and 1m metal sleeves (MIT-SH-S0) hold the resin in hollow block or brick so it bonds around the stud instead of running into the voids. MIT-IGH is a zinc plated internal thread sleeve with an external knurl and a centering ring.
• •Resin, capsules, guns and nozzles are on the chemical anchor resin and accessory pages. Long hot dip galvanised rod kits (up to 500mm) have their own page.

Chemical anchor stud sizes

Every stud comes as a kit with a nut and washer, at a fixed length per size. The length sets the embedment and the thickest fixture you can clamp. On the hex drive studs the drive hex on top takes up some of the thread, so the maximum fixture thickness is less than on a flat top stud of the same size: an M12 hex drive stud clamps up to 24mm, an M12 flat top up to 32mm.

Stud embedment, edge distance and spacing

From the installation parameters on Hobson's chemical stud anchor data sheet, for every stud range above, with the maximum fixture thickness for each head type taken from the sheet's dimension tables. Hobson gives the minimum base material depth as the embedment plus 30mm (and at least 100mm) for M8 to M12, and the embedment plus twice the drill size for M16 to M24; the figures below are that arithmetic. Hobson's sheet gives one value for minimum spacing and minimum edge distance. These are minimums for installing the stud; the loads the fixing can carry, and any reduction close to an edge or another anchor, come from the resin's ETA or data sheet.

Internal thread anchor sizes and installation values

Zinc plated (Class 5.8) and 316 stainless (A4-50) internal thread anchors, from Hobson's data sheets. The anchor length is its embedment, set flush with the surface.

Internal thread anchor edge distance and spacing

The zinc plated and 316 sheets give the same installation values. As with the studs, Hobson gives one value for minimum spacing and minimum edge distance, and the holding capacity comes from the resin's data.

How to set a chemical anchor stud

From the installation guides on Hobson's stud and internal thread anchor data sheets. Always follow the resin maker's instructions as well.

1. Drill the hole at the drill size and embedment depth for the stud or anchor (see the tables). Do not use a diamond drill bit where the resin maker says not to.
2. Clean the hole. As a minimum, Hobson calls for the AEFAC certified installer method: from the bottom of the hole, blow it out 3 times with a hand pump (holes up to 20mm) or compressed air at 6 bar or more; brush it 3 times with the right wire brush (at least the hole diameter), rotating as you pull out; then blow it out 3 times again.
3. Prepare the resin (polyester, vinylester, epoxy) as its maker directs. For injection resin, fill from the bottom of the hole, drawing the nozzle back slowly to avoid air pockets; for internal thread anchors, fill at least two thirds of the hole.
4. Push the stud in, rotating it slowly to spread the resin. With a glass capsule, a hex drive stud can be driven in with a hammer drill and the hex drive bit from the pack. Fit a bolt into an internal thread anchor before you push it in.
5. The stud or anchor should sit at the bottom of the hole with resin showing at the top. Clean off the excess.
6. Leave it undisturbed for the resin's gel time and do not load it until its full cure time; gel and cure times by temperature are on the chemical anchor resin page and printed on the cartridge. Then fit the fixture and tighten.

Chemical anchor sleeves for hollow block and brick

In hollow block or perforated brick, injected resin would run away into the voids. A sleeve keeps it around the stud. Hobson's Mungo range lists MIT-SH-K0 and K1 nylon sleeves for hollow base materials, and MIT-SH-K2 sleeves (with over-fill protection and a stud centering cap) for Mungo MIT-SE Plus and MIT-SP resin. The MIT-SH-S0 metal sleeve comes in 1m lengths. For XCHEM resins, Hobson also lists nylon perforated sleeves and bright steel mesh sleeves (12, 16 and 22mm x 1m); those are with the guns and nozzles on our chemical anchor accessories page, which gives their installation limits.

MIT-SH-K2 sleeve installation values with MIT-SP resin

Mungo's MIT-SP sheet gives these values for threaded rod in solid and hollow masonry with an MIT-SH-K2 sleeve. It gives the minimum wall thickness; the edge distance and spacing in masonry are in the masonry assessment it refers to (ETA-13/0033), which is not among the documents we hold, so this page gives none: they come from that assessment, through the designer. No values are published here for the K0, K1, S0 or IGH sleeves, or the 12 x 50mm K2 sleeve.

Looking for jet plugs?

Mungo MFJ and MJP jet plugs are screw-in plugs for plasterboard, not resin anchors: they are on the hollow wall anchors page.

Which finish for where?

• •Hot dip galvanised (Class 5.8 and 8.8 studs): Hobson rates hot dip galvanising high corrosion resistance and recommends it for long-term outdoor use. Hobson's corrosion guide lists hot dip galvanising or stainless for exposed work outside the sea spray zone.
• •Zinc yellow (Class 5.8 studs) and zinc plated (internal thread anchors, MIT-IGH): low corrosion resistance, for dry, indoor or low-corrosion fixings and temporary work.
• •316 stainless studs and internal thread anchors: for coastal and sea spray zones and within 2m of a pool, where Hobson's corrosion guide calls for stainless. 316 is not made to sit in seawater.
• •Class 8.8 is the higher strength stud: Hobson's sheet gives 800MPa minimum tensile strength (830MPa for M20 and M24) against 520MPa for Class 5.8, 700MPa for A4-70 and 500MPa for A4-50. Which class a fixing needs comes from the design.

Chemical anchor bolts in Adelaide

Allmat supplies chemical anchor studs, internal thread anchors, sleeves, resin and injection guns to builders, steel fixers, fabricators and trade across Adelaide and South Australia. Add the studs to a quote with the resin, nozzles and hole cleaning brushes, and we will price the lot.

Questions