The chemical anchor is the high-load, edge-tolerant, vibration-resistant alternative to mechanical concrete anchors. A two-part resin is injected into a clean borehole, a threaded stud is set into the resin while it's still fluid, and the resin cures to bond stud to concrete with a load capacity that typically exceeds what wedge, sleeve or drop-in anchors can achieve at equivalent stud size. Used correctly with the right resin chemistry, the right embedment depth, and the right concrete preparation, chemical anchors carry loads that mechanical anchors physically cannot match — and they do it close to edges and in cracked concrete where mechanical anchors fail.
Used incorrectly, they fail spectacularly. Dust contamination in the borehole reduces bond by 60%+ across published research. Wrong resin chemistry in a wet hole causes 100% bond failure within days. Diamond-cored boreholes void most manufacturer approvals. Polyester resin in a cracked-concrete seismic application is a code violation. The difference between a 25-year structural anchor and a six-month failure is process discipline.
This guide covers chemical anchor resin chemistries (polyester vs vinyl ester vs pure epoxy), capsule vs injection cartridge systems, AS 5216:2018 compliance including ETA options, cracked vs uncracked concrete categories with C1/C2 seismic requirements, embedment depth and edge distance design rules, the AU brand reality (Ramset Chemset, Hilti HIT, Würth Wit), installation procedures including the borehole cleaning protocol that determines pass-or-fail, and the AIMS supply story.
Trademark note: "Chemset" is a registered trademark of Ramset Australia. AIMS does not sell Ramset Chemset products. We stock Hobson chemical anchor stud kits and Epirez structural epoxy products as equivalents — see the AIMS supply section below.
For mechanical concrete anchor types (wedge, sleeve, drop-in, masonry screws, plasterboard anchors), see our comprehensive Concrete & Masonry Anchor Guide covering all six anchor families.
How a chemical anchor works — resin bond mechanics
A chemical anchor is a stud bonded to concrete by cured resin, not a mechanical expansion device. The bond mechanism is fundamentally different from wedge, sleeve and drop-in anchors and explains why chemical anchors carry higher loads and work in cracked concrete where mechanical anchors fail.
The five-step bond formation
- Borehole drilled in the concrete to specified diameter and depth (typically stud diameter + 2-4mm)
- Borehole cleaned — the most critical step. Concrete dust on the borehole walls prevents resin-to-concrete adhesion. Minimum 2× compressed air blowout + 2× brush + 2× blowout.
- Resin injected or capsule inserted into the clean borehole
- Threaded stud rotated and pushed into the resin while it's still in working time, displacing resin into the gap between stud thread and borehole wall
- Resin cures — chemically bonding to both the borehole walls and the stud threads, locking the stud in place
The load capacity comes from shear and tensile bond across the entire stud-resin-concrete interface, not from one point of mechanical expansion. A 100mm-deep embedment offers 100mm of bonded surface area on every side of the stud. This is why doubling embedment depth typically doubles tensile load capacity — there's twice as much bonded interface.
Why chemical anchors work where mechanical anchors fail
- Cracked concrete — mechanical anchors lose grip when cracks widen under load. Chemical anchors maintain bond across hairline cracks (when correctly specified for cracked-concrete service)
- Near edges — mechanical anchors transfer expansion force radially, which can spall concrete near an edge. Chemical anchors don't expand and have lower minimum edge distance requirements
- Adjacent anchors — mechanical expansion zones interfere with each other in close groupings. Chemical anchors have smaller load cones, allowing tighter spacing
- Hollow / perforated substrate — through-bonding into hollow brick, perforated block, or precast voids works with chemical anchors (using mesh sleeves) but not mechanical
- Threaded rod / rebar dowelling — long lengths of threaded rod or rebar can be bonded into concrete that no mechanical anchor accommodates
Chemical anchor vs mechanical anchor — when each wins
Both anchor systems install in a drilled hole; both connect a threaded stud to concrete. The difference is in how load transfers from stud to concrete.
| Property | Chemical anchor | Mechanical anchor (wedge/sleeve/drop-in) |
|---|---|---|
| Load transfer mechanism | Resin bond across entire embedded length | Mechanical friction from expansion at fixed depth |
| Tensile load capacity (relative) | Higher — 1.5 to 3× equivalent mechanical at standard embed | Lower |
| Cracked concrete service | Yes (with ETA Option 1 approval) | Limited — most mechanical anchors not rated for cracked concrete |
| Minimum edge distance | Lower — typically 60-80mm at standard embed | Higher — typically 100-150mm minimum |
| Minimum anchor spacing | Lower — typically 5× stud diameter | Higher — typically 8-10× stud diameter |
| Installation speed | Slower — borehole prep + cure time | Faster — drill, drop, tighten |
| Installation skill | Higher — cleaning critical, cure dependent on temperature | Lower — torque to spec |
| Wet / submerged service | Possible with vinyl ester or pure epoxy | Possible but corrosion risk on expansion ring |
| Cure / wait time | 10 minutes to 24 hours depending on resin + temperature | None — immediate load capacity after torquing |
| Cost (relative) | Higher — resin cost + installation labour | Lower |
| Reusable / removable | No — stud is permanently bonded | Sleeve anchors removable; wedge anchors generally not |
Choose chemical anchor when: high load required, edge or spacing constraints exist, cracked concrete service, seismic Category C2, sustained vibration, retrofit reinforcement (rebar dowelling), hollow substrate (with mesh sleeve).
Choose mechanical anchor when: moderate load only, installation speed matters, uncracked concrete with adequate edge distance, working at temperatures where chemical cure is impractical, removable fixings required, low installation skill available. See the Concrete & Masonry Anchor Guide for wedge, sleeve, drop-in, masonry screws and plasterboard anchor selection.
The three resin chemistries — polyester, vinyl ester, pure epoxy
Three resin chemistry families dominate the chemical anchor market. Each offers a different combination of cost, load capacity, cure time, environmental tolerance and approved applications. Selecting the wrong chemistry for the application is the single most common chemical anchor design error.
| Chemistry | Cost | Cure speed | Load capacity | Wet hole | Best for | Avoid |
|---|---|---|---|---|---|---|
| Polyester (unsaturated) | Lowest | Fast (cheapest = fastest cure) | Lowest | No | Light-duty fixings into solid stone, dry conditions, non-structural applications, perforated brick | Wet conditions, structural applications, cracked concrete, seismic, sustained load |
| Vinyl ester (epoxy acrylate) | Middle | Fast to moderate | High | Yes | The workshop and industrial default. Solid + perforated stone, tensile + compression zone of concrete, humid conditions, water-filled boreholes. ETA Option 1 typical. | Sustained heavy load at elevated temperature (specify pure epoxy) |
| Pure epoxy | Highest | Slow (long working time, long cure) | Highest | Yes | Underwater installation, seismic Category C2 with full performance, large-diameter rebar dowelling, long-term durability, retrofit reinforcement, elevated temperature service | Cold-weather installation (cure can take 24+ hours at +5°C) |
Polyester — the budget tier
Unsaturated polyester resins were the original chemical anchor chemistry. They're inexpensive, cure fast (10-20 minutes at room temperature), and work fine for light-duty non-structural fixings into dry concrete or solid masonry. Most polyester resins are NOT approved for cracked concrete, NOT approved for sustained heavy loads, and NOT suitable for humid or wet conditions. They are not a structural-grade product.
Common AU polyester products: Ramset ChemSet 800 (general purpose), various supermarket-tier branded chemical anchor cartridges. Polyester is the chemistry that gave chemical anchors a reputation as "DIY products" — it's not what professional installers use for structural work.
Vinyl ester (epoxy acrylate) — the workshop and industrial default
Vinyl ester resins (also marketed as "epoxy acrylate") are the workshop and industrial-trade default. They offer high load capacity (rivalling pure epoxy for short-term and many sustained-load applications), fast cure (30-60 minutes at room temperature), tolerance of humid conditions and water-filled boreholes, and approval for cracked concrete service under ETA Option 1.
Common AU vinyl ester products: Ramset ChemSet 101 / ChemSet Maxima, Hilti HIT-HY 200, Würth WIT-VM 250, Powers AC100+. The Hobson chemical anchor stud kits AIMS stocks are typically used with vinyl ester resin capsules from these suppliers.
Pure epoxy — the premium tier
Pure epoxy resins are the highest-performance chemical anchor chemistry. They cure slowly (long working time is a feature, allowing complex multi-anchor installations to be set in one pour, but cure can take hours), achieve the highest load capacity in cracked concrete + seismic service, and are typically the only chemistry approved for underwater installation, retrofit rebar dowelling, and long-term durability in chemical-exposure environments.
Common AU pure epoxy products: Ramset ChemSet Maxima Plus, Hilti HIT-RE 500 V4, Powers Pure 110+, Würth WIT-PE 1000. Pure epoxy is the chemistry specified by structural engineers when ETA Option 1 cracked-concrete C2 seismic compliance is mandatory.
Capsule system vs injection cartridge — the two delivery methods
Chemical anchor resin is delivered to the borehole in one of two formats: glass capsule (one capsule = one anchor) or injection cartridge (one cartridge = multiple anchors).
Glass capsule system
A pre-measured dose of resin and hardener is packed inside a sealed glass capsule (resin in the outer chamber, hardener in a sealed inner ampoule). The capsule is dropped into a clean borehole, then the threaded stud is rotated and pushed through the capsule using an impact driver or rotary hammer in rotation mode. The rotating stud shatters the glass, mixes the resin and hardener as it screws downward, and bonds in place.
Advantages: pre-measured dose eliminates incorrect mix ratio; no dispensing gun required; long shelf life; clean field operation (no resin waste, no nozzle disposal); works at any temperature within the resin's range.
Disadvantages: one capsule per anchor (no flexibility for varying depth); requires impact driver or rotary hammer to break glass cleanly; capsule must be sized to specific borehole diameter and depth; glass fragments mix into the cured resin.
Common AU capsule products: Ramset ChemSet Maxima glass capsules, Hilti HVA capsule system, Würth W-VIK capsules.
Injection cartridge system
Resin and hardener are stored in separate chambers of a side-by-side cartridge. A dispensing gun (manual or pneumatic) pushes both components simultaneously through a static mixing nozzle attached to the cartridge — the nozzle's helical internal blades mix the two parts during dispensing. The mixed resin is injected into the borehole from the bottom up using extension tubes for deep holes.
Advantages: flexible anchor depth and diameter (one cartridge serves multiple anchor sizes); rapid installation in production runs; precise control of dispensed amount; recommended for overhead and wet-hole installations.
Disadvantages: dispensing gun required (significant capital cost); nozzle is consumable and one-time-use (resin cures inside the nozzle within working time); cartridge has shelf life limits, particularly at hot storage temperatures; first-out portion of each dispensing must be discarded until mix is consistent.
Common AU cartridge products: Ramset ChemSet 101 / ChemSet Maxima Plus cartridges, Hilti HIT-HY 200 / HIT-RE 500, Würth WIT, Powers AC100+ / Pure 110+.
Which to use
| Scenario | Recommended system |
|---|---|
| Single anchor, one-off job | Capsule (no gun investment required) |
| Production run of identical anchors | Capsule (fast, consistent, no nozzle waste) |
| Mixed anchor sizes and depths | Cartridge (flexible) |
| Deep holes (>200mm embedment) | Cartridge with extension tube |
| Wet hole / submerged installation | Cartridge with extension tube to bottom of hole |
| Overhead installation | Cartridge with retainer plug |
| Cold weather installation | Either — confirm resin temperature range |
| Rebar dowelling / threaded rod long lengths | Cartridge mandatory |
Chemset, Hilti, Würth — the AU brand reality
The Australian chemical anchor market is dominated by three brand families. Each offers all three chemistries (polyester, vinyl ester, pure epoxy) and both delivery formats (capsule and cartridge). The trademark and brand-as-generic terminology causes substantial confusion at the customer end.
Ramset — the brand-as-generic
Trademark note: "Chemset" is a registered trademark of Ramset Australia. The term has become widely used in the AU trade as a generic for any chemical anchor system, the same way "Dynabolt" is used for any sleeve anchor and "Tek screw" is used for any self-drilling screw. When a tradesperson asks for "a Chemset", they may mean any chemical anchor.
The Ramset ChemSet product range includes:
- ChemSet 800 — polyester, general-purpose, lowest cost
- ChemSet 101 — vinyl ester, structural workhorse, ETA Option 1 in cartridge form
- ChemSet Maxima — vinyl ester, glass capsule system
- ChemSet Maxima Plus — pure epoxy, premium tier, seismic Category C2
- ChemSet anchor studs — Ramset-branded threaded studs designed for ChemSet resin
AIMS does not sell Ramset Chemset products. Customers who need genuine Ramset Chemset should source through Ramset distributors. AIMS stocks equivalent Hobson chemical anchor stud kits and Epirez structural epoxy products — see the AIMS supply section below.
Hilti — the European premium
Hilti is the European-headquartered global premium-tier chemical anchor brand. The HIT product range covers vinyl ester (HIT-HY 200) and pure epoxy (HIT-RE 500 V4) chemistries with strong ETA approval coverage and a comprehensive published technical data set. Hilti dispensing equipment is excellent but proprietary — Hilti cartridges typically only fit Hilti guns.
AIMS does not stock Hilti products. Sourced through Hilti distributors or by special request.
Würth — the European generalist
Würth is the European industrial fastener generalist with a broad chemical anchor range under the WIT brand (WIT-VM vinyl ester, WIT-PE pure epoxy). Würth resin cartridges typically fit standard 380mm or 585mm coaxial dispensing guns from multiple manufacturers.
AIMS does not stock Würth products. Sourced through Würth distributors or by special request.
Powers, Simpson Strong-Tie, Fischer, Mungo
Other significant brands in the AU market: Powers (Stanley) AC100+ and Pure 110+; Simpson Strong-Tie SET-XP and AT-XP; Fischer FIS V and FIS EM; Mungo (German) chemical anchor range. AIMS stocks selected Mungo products through our supplier network — contact the team for current availability.
AS 5216:2018 — ETA Option 1, 7, 11 explained
AS 5216:2018 (Design of post-installed and cast-in fastenings in concrete) is the Australian Standard governing post-installed concrete anchor design. It harmonises with the European EOTA TR 029 (now superseded by EOTA TR 048) and EN 1992-4 chemical anchor design framework. Engineers specifying chemical anchors in Australia work to AS 5216 + the manufacturer's European Technical Assessment (ETA) approval data.
ETA approval — the certification that matters
European Technical Assessment (ETA) is the European product approval scheme for post-installed anchors. An ETA approval includes load capacity data, embedment depth requirements, minimum edge distance and spacing, approved concrete grades, approved temperature ranges, and the categories of service the anchor is approved for. AS 5216 design calculations use the values from the manufacturer's ETA.
ETA Options are categories of service approval, ranked by the rigour of testing the product has passed. The three most common in AU practice:
| ETA Option | Service approval | Use cases |
|---|---|---|
| Option 1 | Cracked concrete + uncracked concrete + seismic categories C1 and C2 | Structural fastening to existing concrete (which always has shrinkage cracks), seismic-rated applications, any safety-critical fastening to in-service concrete |
| Option 7 | Uncracked concrete only | New cast-in-place concrete that's verified uncracked, non-structural fastenings, light-duty applications |
| Option 11 | Cracked concrete (without seismic) + uncracked concrete | Structural fastening where seismic isn't a primary consideration |
Why most jobs need Option 1
Existing concrete in service always has shrinkage cracks — they're invisible at the surface but present throughout the slab. Most retrofit fastening is into cracked concrete by definition. Specifying an Option 7 anchor for retrofit work is non-compliant even if the surface appears crack-free. Engineers default to Option 1 for any safety-critical fastening to existing concrete.
Seismic categories C1 and C2 cover earthquake load cycling:
- C1 (low seismicity) — applies to most of Australia outside Newcastle/South Australia coastal zones. Anchor approved for limited seismic cycling.
- C2 (moderate seismicity) — required for buildings in seismic hazard zones (Newcastle, Adelaide, parts of Western Australia, Tasmania). Anchor approved for full seismic load cycling per EN 1992-4 Annex C.
Pure epoxy resins typically carry C2 approval. Vinyl ester resins typically carry C1. Polyester resins typically do not carry seismic approval.
Reading an ETA datasheet
An ETA datasheet for a chemical anchor product lists, per stud diameter:
- Minimum and maximum embedment depth
- Borehole diameter (typically stud diameter + 2-4mm)
- Minimum edge distance for full load capacity
- Minimum spacing between anchors
- Characteristic tensile load (N_Rk) at the listed embedment
- Characteristic shear load (V_Rk)
- Concrete grade applicable (typically C20/25 minimum, sometimes C50/60)
- Temperature range (storage + installation + service)
- Permitted base materials (concrete only, or concrete + perforated brick + solid brick, etc.)
For any safety-critical chemical anchor application, the design engineer should work from the manufacturer's current ETA datasheet, not from generic embedment tables. The values in this guide are typical and indicative only.
Embedment depth — what controls load capacity
Chemical anchor load capacity scales primarily with embedment depth, not stud diameter alone. An M12 stud at 110mm embedment carries higher load than an M12 stud at 80mm embedment, because there's more bonded surface area between resin and concrete.
| Stud size | Borehole diameter | Typical std embedment | Maximum embedment | Minimum edge distance (std embed) | Minimum spacing (std embed) |
|---|---|---|---|---|---|
| M8 | 10mm | 80mm | 160mm | 50-65mm | 40mm |
| M10 | 12mm | 90mm | 200mm | 60-80mm | 50mm |
| M12 | 14mm | 110mm | 240mm | 70-95mm | 60mm |
| M16 | 18mm | 125mm | 320mm | 85-115mm | 80mm |
| M20 | 24mm | 170mm | 400mm | 105-145mm | 100mm |
| M24 | 28mm | 210mm | 480mm | 125-175mm | 120mm |
| M30 | 35mm | 270mm | 600mm | 155-220mm | 150mm |
These values are typical for vinyl ester chemical anchors in C25/30 concrete with Option 1 ETA approval. Confirm specific values from the resin manufacturer's ETA datasheet for the exact product, stud grade and concrete strength used. Pure epoxy products typically achieve full load capacity at shorter embedment than vinyl ester equivalents.
The bond surface area principle
The tensile load capacity of a chemical anchor is governed by the lesser of (a) the resin-to-concrete bond at the borehole walls, (b) the resin-to-stud bond at the thread interface, or (c) the tensile strength of the stud itself. For most standard chemical anchor designs, the controlling failure is concrete cone failure (the concrete pulls a cone out around the anchor) rather than bond or stud failure. The depth at which cone failure equals bond capacity is called the "characteristic embedment depth" and is published in the ETA.
Embedment shorter than ETA-specified causes early failure mode change from bond to combined cone+bond failure with reduced load. Embedment longer than the standard depth increases load capacity (in resin-bond-controlled designs) up to the maximum embedment value, beyond which stud tensile failure becomes the limit.
Edge distance and the concrete cone
When a chemical anchor pulls toward concrete failure, it lifts a roughly conical mass of concrete around the anchor. If the anchor is too close to an edge, the cone intersects the edge and the concrete spalls outward at significantly reduced load. Minimum edge distances in the table above are based on full-cone formation. Anchors closer to edges than the minimum require either deeper embedment or design recalculation per AS 5216 + ETA reduction factors.
Anchor spacing
When multiple chemical anchors are loaded simultaneously, their concrete failure cones overlap if spacing is too close. The combined load capacity of a closely-spaced anchor group is less than the sum of individual anchor capacities. Minimum spacing values in the table prevent this interaction. Anchors spaced closer than minimum require AS 5216 group reduction factor calculations.
Cure time vs temperature — the field reality
Chemical anchor cure time is heavily dependent on ambient temperature. The same product can take 6× longer to cure in a Tasmania winter installation than a North Queensland summer installation. Ignoring temperature is a major cause of premature loading failures.
| Ambient temperature | Working time (typical vinyl ester) | Load time (full cure) |
|---|---|---|
| +5°C | 30-45 minutes | 4-6 hours |
| +10°C | 15-25 minutes | 2-3 hours |
| +20°C (room temp) | 6-10 minutes | 45-60 minutes |
| +30°C | 4-6 minutes | 30-45 minutes |
| +40°C | 2-4 minutes (rapid) | 20-30 minutes |
The temperature reference is concrete + ambient combined — the substrate temperature dominates because the resin contacts more concrete than air. Hot substrate cures resin fast; cold substrate slows cure dramatically regardless of air temperature.
Three time concepts — working, gel, load
- Working time (gel time) — how long the installer has, after mixing/injecting resin, to insert the stud before the resin becomes too viscous to displace properly. Exceeding working time means stud cannot be fully seated.
- Initial cure time — when the resin has set enough to handle the stud without disturbing the bond. Touch-stable.
- Full load time — when the resin has cured sufficiently to handle the design load. Manufacturer-specified, based on the worst-case temperature for the product.
The most common temperature-related failure: hot summer install with resin pulled from a hot ute tray, working time drops to 2-3 minutes, installer doesn't get the stud fully seated before the resin gels, and bond capacity drops by 30-50%. Or the opposite — winter install at +5°C, installer applies load at the 45-minute mark assuming room-temperature cure, and the bond shears at well below design load.
Cold weather installation
Below +5°C, most chemical anchor resins should not be installed. Cure times become extremely long and many resins do not achieve full mechanical properties at temperatures below their minimum. Cold-weather products exist (rated to -10°C or below) but require specific product selection — confirm the temperature range on the manufacturer datasheet before specifying.
Hot weather installation
Above +35-40°C, the inverse problem appears. Working time drops to almost nothing. Installations require either (a) chilled resin (storage in ice or air-conditioned shade), (b) cooler substrate (early-morning or late-afternoon installation), or (c) specialty hot-weather resin. Resins stored in hot vehicles can also pre-react during storage, reducing shelf life and field performance — always confirm cartridge storage conditions.
Borehole prep — hammer drill mandatory, why diamond core fails
The single most common reason for chemical anchor pull-out is inadequate borehole preparation. Two issues account for almost all field failures: the drilling method used, and the cleaning protocol followed.
Hammer drilling is mandatory; diamond coring is not approved
Almost all chemical anchor ETA approvals specify hammer-drilled (rotary hammer or SDS hammer drill) boreholes only. Diamond-cored boreholes are explicitly excluded from most approvals.
The reason is mechanical: hammer drilling creates a rough, porous borehole wall with exposed concrete aggregate, micro-cracking, and a high surface area for resin penetration and mechanical interlock. Diamond core drilling creates a polished, smooth borehole wall with sealed-over aggregate, no micro-cracking, and minimal surface area for bond. Tested side-by-side, diamond-cored holes show 30-60% lower pull-out capacity than equivalent hammer-drilled holes.
If diamond coring is the only practical drilling method (large diameter holes, vibration-sensitive substrate, post-tensioned slabs where hammer drilling is prohibited), the resin product MUST be one specifically approved for diamond-cored boreholes — these exist (Hilti HIT-RE 500 V4 with diamond-core option, Würth WIT-PE 1000 with DC approval) but are not standard. Confirm before specifying.
Hole cleaning — the protocol that determines pass or fail
After drilling, the borehole is full of fine concrete dust. The dust forms a loose layer on the borehole walls. If left in place, the resin bonds to the dust layer instead of the concrete — and the dust layer pulls away under load. Cleaning the borehole removes the dust and exposes fresh concrete substrate for the resin to bond to.
The standard ETA-mandated cleaning protocol (typically 2× compressed air blowout + 2× wire brush + 2× compressed air blowout):
- Blow the hole clear with compressed air from a calibrated blower or compressor — extending the nozzle to the bottom of the hole. Two complete blowouts.
- Brush the hole with a steel wire brush sized to the borehole diameter. The brush must be longer than the borehole. Two complete brushing passes — in and out twice.
- Blow the hole again with compressed air — twice. The hole should be visibly dust-free at completion.
Some premium resin products (Hilti SafeSet, Würth WIT-PE 1000 SafeSet) include reduced-cleaning approvals — the resin is formulated to tolerate residual dust at a small load capacity penalty. These are specifically labelled "no cleaning required" or "reduced cleaning" and are the exception, not the rule.
Wet hole cleaning
For boreholes in saturated concrete or below waterline:
- Initial cleaning — wire brush + compressed air to remove loose debris
- Water flush — flood the hole with clean water and brush vigorously
- Final water flush — refresh with clean water
- Brush again with fresh clean water
- Insert resin (specified for wet hole service) via extension tube to the bottom of the hole, allowing the resin to displace water as it fills upward
Wet-hole approved resins (vinyl ester and pure epoxy varieties) are typically marked "for wet conditions" or "for submerged installation" on the cartridge label.
Installation procedure — step by step
Standard chemical anchor installation procedure for an injection cartridge system into dry, hammer-drilled, properly-cleaned concrete:
- Mark anchor location — confirm location is clear of buried services and reinforcement
- Hammer-drill borehole to specified diameter and depth (stud diameter + 2-4mm typical; depth per ETA for the resin product and stud size)
- Clean borehole per the 2× air + 2× brush + 2× air protocol described above. Verify visually clean.
- Prepare resin cartridge — attach static mixing nozzle (and extension tube for deep holes), insert into dispensing gun
- Discard first dispensing — pump until the resin colour is consistent (typically the first 50-100mm of nozzle output). Inconsistent mix at the start of dispensing is the most common cause of localised bond failure.
- Inject resin into the borehole from the bottom up, withdrawing the nozzle slowly as the borehole fills. Fill to approximately 2/3 of borehole depth so that stud insertion displaces resin upward without overflow waste.
- Insert stud immediately — within the resin's working time at the current temperature. Push the stud to the bottom of the borehole with a slow rotating motion. Confirm full depth seating.
- Maintain alignment — wedge the stud or use a bracket to hold it perpendicular (or at the specified angle) until initial cure.
- Wait for full cure per the temperature-cure curve. Do not apply load before cure time.
- Apply load — torque the nut to the design value. See our Metric Bolt Torque Chart for stud grade torque values.
Capsule system variant
For glass capsule systems, replace steps 5-7 with:
- Drop the correctly-sized capsule into the cleaned borehole
- Mount stud in impact driver or rotary hammer chuck adaptor
- Drive the stud through the capsule with rotation + light hammer action, continuously rotating until stud reaches full depth
- Continue rotation for 10-15 seconds after full depth to ensure complete mix
- Stop rotation, allow to cure undisturbed
The continuous rotation during insertion is critical — pausing partway through stops the mixing, and the resin can gel mid-insertion with the stud only partially seated. Maintain rotation until the stud is fully bottomed.
Stud selection — Grade 4.6, 5.8, 8.8 or 316 SS
The threaded stud bonded into the resin must match the application's load + corrosion requirements. Chemical anchor service is mechanically demanding (sustained load) and often involves chemical or moisture exposure that drives corrosion.
| Stud grade | Tensile strength | Best for | Avoid |
|---|---|---|---|
| Grade 4.6 mild steel zinc-yellow | ~400 MPa | Light-duty fixings, dry indoor service | High load, outdoor, marine, chemical service |
| Grade 5.8 mild steel zinc-yellow | ~500 MPa | Standard structural fixings, dry to moderately humid service. The AIMS Hobson kit standard. | Marine, chemical, food-grade service |
| Grade 5.8 HDG (hot-dip galvanised) | ~500 MPa | Outdoor service, moderate corrosion exposure, agricultural, light industrial | Marine, chloride, food-grade service |
| Grade 8.8 HDG | ~800 MPa | Heavy structural loads, high-tensile applications outdoors | Marine, chemical service requiring stainless |
| 304 / A2-70 stainless | ~700 MPa | Outdoor, mild chemical, food grade, mild marine | Continuous seawater, severe chloride, swimming pool chemistry |
| 316 / A4-70 stainless | ~700 MPa | Marine, severe chemical, chloride service, food + dairy + beverage processing, swimming pool plant rooms | Extreme aggressive media — specialty alloys required |
The galvanic corrosion trap
A galvanised stud installed with chemical anchor resin in a chloride-exposed environment (marine, swimming pool, food processing wash-down) corrodes from inside the borehole. The galvanic coating is consumed; the underlying mild steel rusts; the bond eventually fails as the corroded stud loses cross-section. For any chloride-exposed service, always specify 316 stainless steel studs, not galvanised. See our Stainless Steel Fasteners Guide for grade selection detail.
Chisel point vs flat top — what to look for
- Chisel point — pointed tip designed to break a glass capsule cleanly. Used with capsule system. The point geometry ensures the glass breaks evenly and the resin mixes properly.
- Flat top / flat cut — squared-off stud end. Used with injection cartridge system. The flat face displaces resin uniformly during insertion without point cavitation.
Using the wrong stud profile causes installation issues — a flat-top stud with a capsule may not break the glass evenly (incomplete mix); a chisel-point stud with cartridge resin can create an air void at the bottom of the borehole. The Hobson chemical anchor stud kits AIMS stocks include both profiles depending on intended use.
Failure modes — why your chemical anchor pulled out
When a chemical anchor fails in service, the failure mode points to the root cause. Diagnosing the failure mode is essential for understanding what to do differently next time.
| Failure mode | What it looks like | Root cause | Prevention |
|---|---|---|---|
| Bond failure (interface) | Stud pulls out cleanly with cured resin attached to the stud surface, leaving a clean borehole behind | Inadequate borehole cleaning — dust layer prevented bond to concrete | Strict 2× air + 2× brush + 2× air protocol |
| Bond failure (stud-resin) | Stud pulls out clean, leaving cured resin in the borehole | Stud surface contamination (oil, mill scale, mould release) prevented bond | Use clean studs; degrease if uncertain |
| Concrete cone failure | Concrete pulls out around the anchor in a roughly conical shape | Inadequate edge distance, low concrete strength, or excessive load | Increase edge distance, deeper embedment, or relocate |
| Stud tensile failure | Stud snaps at thread root, typically at concrete surface | Load exceeded stud tensile strength (rare in well-designed systems) | Upgrade stud grade or diameter |
| Incomplete cure | Stud pulls out with soft / partially cured resin | Load applied before full cure time; ambient too cold during cure | Wait full cure time per temperature; cold weather product selection |
| Working time exceeded | Stud not fully seated; visible resin extrusion around stud collar; bond uneven | Resin gelled before stud insertion completed (hot temperature, slow installer) | Cooler substrate; faster installation; chilled cartridge in summer |
| Wet hole failure | Cured resin shows water inclusion; bond is weak or fragmented | Wet borehole filled with non-wet-rated resin (typically polyester in wet conditions) | Vinyl ester or pure epoxy with wet-hole approval |
| Galvanic corrosion failure | Stud breaks at concrete surface after years of service; corroded stud visible | Galvanised stud in chloride environment | 316 SS stud for marine + chloride service |
| Group / spacing failure | Multiple anchors fail simultaneously; concrete fractures between them | Anchor spacing below ETA minimum, group load reduction not applied | Re-space anchors or apply group reduction factor |
| Capsule glass mix-fail | Cured resin shows colour streaks (incomplete mix); bond weak | Insufficient rotation during capsule break, or pausing partway through | Continuous rotation to full depth, 10-15s additional rotation at bottom |
AIMS supply — Hobson stud kits + Epirez structural epoxy
AIMS does NOT sell Ramset Chemset, Hilti or Würth chemical anchor cartridges and capsules. We stock equivalents and supporting products for chemical anchor installation:
Hobson chemical anchor stud kits
Hobson is the AIMS-stocked chemical anchor stud kit brand — comprehensive metric range from M8 to M24 in three finishes:
- Metric Stud Chemical Anchor Kit Grade 5.8 — Hot-Dip Galvanised — M10, M12, M16, M20, M24. Outdoor + moderate corrosion service.
- Metric Stud Chemical Anchor Kit Grade 5.8 — Zinc Yellow Finish — M8, M10, M12, M16, M20. Standard indoor structural service.
- Metric Galvanised Flat Cut Stud Chemical Anchor — M10, M12, M16, M20, M24. Flat-cut profile for injection cartridge installation.
- M8 x 110mm Chisel Point HDG Box of 10 — chisel point for glass capsule installation.
The Hobson kits include the threaded stud, nut and washer. Resin (vinyl ester capsule or cartridge) is sourced separately from the customer's preferred resin supplier (Ramset, Hilti, Würth, Powers, Simpson Strong-Tie, Fischer or others).
Epirez structural epoxy products — adjacent supply
The Epirez range covers structural epoxy products that complement chemical anchor work — grouts, repair compounds, primers, surface preparation chemicals:
- Chockfast Red Deep Pour Epoxy Grouting Compound 94kg — heavy machinery baseplate grouting
- Chockfast Orange Marine & Industrial Chocking Compound 3.4kg — marine + industrial chocking
- Class A Superstrength Grout 20kg — construction-grade structural grout
- High Performance Epoxy Grout 280S 30kg — premium structural epoxy grout
- High Early Strength Epoxy Grout 5137HES 10kg — rapid-strength applications
- Heavy Duty Backing Grout 5137 10kg — equipment baseplate backing
- Instant Grout Rapid Strength 15kg — fast-set cement-based grouting
- Acid Resistant Epoxy Binder 133AR 20L — chemical-exposed service
- Crack Repair Epoxy Sealer 123 300ml + 1.5L — concrete crack repair
- Concrete Etch and Cleaner 5L — surface preparation before bonded fixings
- Epoxy Accelerator D1419 250ml — speed cure time in cold weather
- Highway Patch Rapid Set Repair Mortar 15kg — concrete repair
- Epoxy Mastic Metal Primer 215 1L — surface preparation
- Epoxy Casting Compound 8837 6kg — structural casting
- Epoxy Grout Aggregate Extender QA30 18L — bulk-fill structural grout
Allthread + threaded rod stock for long-bond chemical anchor service
For chemical anchor applications requiring long threaded rod (rebar dowelling, deep retrofit fixings, tall plant baseplate hold-downs), AIMS stocks allthread / threaded rod in M6 to M24 across mild steel HDG and 316 SS finishes. See the Threaded Rod Guide for grade selection and cutting procedure.
Honest scope — sourced through supplier network on request
The following are NOT in standard AIMS stock and are sourced through our supplier network on request:
- Ramset Chemset 101 / Chemset 800 / Chemset Maxima / Chemset Maxima Plus resin cartridges and capsules
- Hilti HIT-HY 200 / HIT-RE 500 V4 resin cartridges
- Würth WIT-VM 250 / WIT-PE 1000 resin cartridges
- Powers AC100+ / Pure 110+ resin cartridges
- Simpson Strong-Tie SET-XP / AT-XP / AT-3G resin cartridges
- Fischer FIS V / FIS EM resin cartridges
- Mungo MIT-PE / MIT-VEX chemical anchor systems
- Dispensing guns (manual, pneumatic and cordless) for any of the above
- Diamond-cored borehole approved chemical anchor resins (specialty)
- Hot-weather and cold-weather rated chemical anchor resins (specialty)
- Pure epoxy systems for cracked-concrete C2 seismic applications
- Underwater chemical anchor systems
For any of these, contact our team or call (02) 9773 0122 with the application + load + concrete condition + seismic category, and we'll quote the right product from our supplier network.
Selection checklist — the 9 questions to answer before ordering
- What load is the anchor carrying? Tensile, shear, combined? Static or dynamic? Sustained or short-term? Engineer's design load is the basis for everything else.
- What concrete strength + condition? Concrete grade (C20/25, C32/40 etc.), cracked or uncracked, dry / damp / wet / submerged. Determines resin chemistry + ETA Option requirement.
- Seismic category? Most AU service is C1; Newcastle / Adelaide / WA / Tasmania zones may require C2. Determines whether pure epoxy is mandatory.
- What stud size + grade? M8 to M30; Grade 4.6 / 5.8 / 8.8 mild steel; 304 / 316 stainless. See Stainless Steel Fasteners Guide for grade selection.
- What embedment depth? Per ETA datasheet for the resin product + stud diameter + concrete strength. Deeper embedment = higher load.
- What edge distance + spacing available? Compare to ETA minimums. If below, increase embedment or relocate.
- What ambient + substrate temperature at install? Confirms working time + cure time. Hot summer or cold winter installations require product selection adjustment.
- Capsule or cartridge? Capsule for single anchor / production runs of same size; cartridge for mixed depths, deep holes, wet holes, overhead.
- Any regulatory standard required? AS 5216:2018 + the resin manufacturer's ETA. Engineer's design calculation references both.
For complex or safety-critical chemical anchor specifications, the design engineer should work directly from the manufacturer's current ETA datasheet for the resin product + stud combination chosen. The values in this guide are typical and indicative only — not engineering design data. For sizing assistance, brand cross-reference, or unusual service conditions, contact our team or call (02) 9773 0122.
Frequently asked questions
What is a chemical anchor and how does it work?
A chemical anchor is a threaded stud bonded into a drilled hole in concrete by cured two-part resin (typically polyester, vinyl ester, or pure epoxy). The resin is injected from a cartridge or delivered as a glass capsule, the stud is rotated into the borehole while the resin is fluid, and the resin cures to bond the stud to the concrete through chemical adhesion to both the concrete walls and the stud threads. Load is carried through resin-concrete and resin-stud bond across the entire embedded length — not through mechanical expansion like a wedge or sleeve anchor. This bond mechanism is why chemical anchors can carry higher loads and work in cracked concrete and close to edges where mechanical anchors fail.
Is Chemset the same as a generic chemical anchor?
Chemset is a registered trademark of Ramset Australia for their chemical anchor product range. The Chemset brand has become so dominant in the AU trade that 'Chemset' is now used as a generic term for any chemical anchor (the same way 'Dynabolt' is used for any sleeve anchor). Functionally, Ramset Chemset is one specific brand within the chemical anchor product category. Equivalent chemical anchor products are made by Hilti (HIT-HY, HIT-RE), Würth (WIT-VM, WIT-PE), Powers (AC100+, Pure 110+), Simpson Strong-Tie (SET-XP, AT-XP), Fischer (FIS V, FIS EM) and others. AIMS does not sell Ramset Chemset products — we stock Hobson chemical anchor stud kits and source Chemset equivalents through our supplier network on request.
Polyester vs vinyl ester vs pure epoxy — what's the difference?
Three resin chemistries dominate the chemical anchor market. Polyester is the cheapest, fastest-curing, lowest-load-capacity chemistry — suitable for light-duty fixings into dry concrete or solid masonry. Vinyl ester (also marketed as epoxy acrylate) is the workshop and industrial-trade default — high load capacity, fast cure, tolerance of humid conditions and wet boreholes, ETA Option 1 approval for cracked concrete. Pure epoxy is the highest-performance chemistry — highest load capacity, slow cure, only chemistry typically approved for underwater installation, retrofit rebar dowelling, and seismic Category C2 service. Pure epoxy costs significantly more than vinyl ester, which costs more than polyester.
How long does chemical anchor take to cure?
Cure time depends heavily on ambient and substrate temperature. For a typical vinyl ester chemical anchor at +20°C ambient, working time (time available to insert the stud after injecting resin) is 6-10 minutes; full load cure is 45-60 minutes. At +5°C cure can take 4-6 hours. At +35-40°C working time drops to 2-4 minutes and full cure can be as fast as 20-30 minutes. Pure epoxy resins have longer working times and longer cure times than vinyl ester at all temperatures. Always check the manufacturer's temperature-cure curve on the cartridge datasheet — do not apply design load until full cure time has elapsed at the actual installation temperature.
Can I use chemical anchor in a wet borehole?
Yes, but only with a resin specifically approved for wet conditions. Polyester resins typically fail in wet boreholes — the water prevents proper bond formation. Vinyl ester and pure epoxy resins are commonly available in wet-hole-approved formulations (Ramset ChemSet 101 Plus, Hilti HIT-HY 200 wet-hole option, Würth WIT-PE 1000). Cartridge label will explicitly state 'for wet conditions' or 'submerged installation approved'. Wet-hole installation procedure also requires the resin to be injected from the bottom of the borehole using an extension tube, allowing the resin to displace water as it fills upward.
What's the difference between Chemset capsule and Chemset injection?
Chemset capsule (Chemset Maxima) uses pre-measured resin packaged in a sealed glass capsule. The capsule is dropped into a clean borehole; the threaded stud is rotated through the capsule using an impact driver or rotary hammer, breaking the glass and mixing the resin as the stud descends. One capsule = one anchor. Chemset injection (Chemset 101) uses a two-part resin cartridge dispensed through a static mixing nozzle attached to a dispensing gun — the gun pushes both components simultaneously and the nozzle's helical blades mix the resin during dispensing. One cartridge = multiple anchors. Capsule is faster for production runs of identical anchors; injection is flexible for mixed sizes and depths, and required for wet-hole, overhead, and deep-hole installations.
How deep does a chemical anchor need to go?
Embedment depth is specified by the resin manufacturer's ETA datasheet for each combination of stud diameter and concrete strength. Typical standard embedments: M8 at 80mm, M10 at 90mm, M12 at 110mm, M16 at 125mm, M20 at 170mm, M24 at 210mm. Embedment depth controls load capacity — doubling embedment depth typically doubles tensile load (in resin-bond-controlled designs). Maximum embedment is approximately 2-3× standard embedment for most products. Embedment shorter than ETA-specified causes early failure mode change with reduced load. For safety-critical designs, work from the actual manufacturer's ETA datasheet, not from generic tables.
What size hole do I drill for an M12 chemical anchor?
For an M12 chemical anchor, the standard borehole diameter is 14mm — that's the stud diameter (12mm) plus 2mm clearance. The 2mm gap accommodates the resin bond layer. Some products specify 16mm boreholes for M12 studs in pure epoxy systems; some specify 13mm for vinyl ester capsules. Always confirm the exact borehole diameter on the resin manufacturer's ETA datasheet for the specific product you're using. Drilling oversized borehole (e.g. 16mm hole for M12 stud in a product spec'd for 14mm) reduces bond capacity because the resin layer is too thick to maintain consistent strength. Drilling undersized borehole prevents stud insertion to full depth.
Can chemical anchors be used outdoors or overhead?
Yes, with appropriate product selection. For outdoor service, use HDG (hot-dip galvanised) studs in moderate environments and 316 stainless steel studs in marine, chloride or chemical-exposed environments. For overhead installation, use a cartridge-system resin specifically rated for overhead application — these resins have higher viscosity to prevent the resin from running out of the borehole during cure. Capsule systems are typically not suitable for overhead installation. Vertical-up boreholes are also commonly addressed with retainer plugs that hold the resin in place until cure.
What is AS 5216 and what ETA option do I need?
AS 5216:2018 is the Australian Standard for design of post-installed and cast-in fastenings in concrete. It harmonises with the European EN 1992-4 framework and uses manufacturer European Technical Assessment (ETA) data for load capacity. ETA Options are categories of service approval: Option 1 covers cracked + uncracked concrete + seismic C1 and C2 (the default for structural fastening to existing concrete, which always has shrinkage cracks); Option 7 covers uncracked concrete only (limited applicability — most retrofit work is into cracked concrete); Option 11 covers cracked + uncracked without seismic. Most AU structural fastening requires Option 1 — confirm with the design engineer for safety-critical applications.
Are chemical anchors stronger than mechanical anchors?
For an equivalent stud size and embedment depth, chemical anchors typically carry 1.5 to 3× higher tensile load than mechanical wedge or sleeve anchors. The bond surface area along the full embedded length carries load, rather than a single mechanical expansion point. Chemical anchors also have significantly lower minimum edge distance and anchor spacing requirements than mechanical anchors, making them the only viable option for high-load fastening close to slab edges or in tight anchor groupings. Chemical anchors are also typically the only option approved for cracked concrete service under AS 5216 + ETA Option 1. The trade-off is higher installation cost (resin price + cleaning labour + cure time) and higher installation skill requirement.
What temperature does chemical anchor work at?
Standard vinyl ester chemical anchor resins work at substrate temperatures from approximately +5°C to +40°C. Below +5°C, cure becomes extremely slow and many resins do not achieve full mechanical properties — cold-weather resins (rated to -10°C or below) exist but require specific product selection. Above +40°C, working time drops to almost nothing and pre-reaction during cartridge storage becomes a problem. Hot-weather installation typically requires chilled cartridge storage, cooler substrate (early-morning or late-afternoon installation), and specialty hot-weather formulations. Pure epoxy resins generally have wider temperature ranges than vinyl ester. Always confirm temperature range on the resin manufacturer's datasheet.
Does chemical anchor work on brick or only concrete?
Chemical anchors work on both concrete and solid masonry. For perforated brick or hollow block, the chemical anchor must be installed with a mesh sleeve (called a 'screen' or 'tubular insert') that contains the resin within the hollow void and creates a controlled bond zone. For solid brick and stone, chemical anchors work directly into the drilled borehole. Polyester resins are commonly used for solid stone and perforated brick fixings where the load is not heavy. Vinyl ester and pure epoxy resins are typically specified for higher-load fixings into solid concrete and structural masonry. Confirm the resin product's ETA approval covers the specific substrate (concrete, solid brick, perforated brick, etc.) before specifying.
Why did my chemical anchor pull out?
Chemical anchor pull-out almost always traces to one of several causes. Inadequate borehole cleaning is the most common — a dust layer on the borehole walls prevents the resin from bonding to fresh concrete, and the dust layer pulls away under load. Other causes include: load applied before full cure time at the actual installation temperature, working time exceeded due to hot conditions causing the stud to not seat fully, wrong resin chemistry for the substrate condition (e.g. polyester in a wet hole), inadequate embedment depth, edge distance below minimum causing concrete cone failure, or galvanic corrosion of a galvanised stud in chloride environment. Diagnosing failure by examining the failure mode (clean stud, resin-coated stud, cone-shaped concrete failure, snapped stud) points to the root cause and what to do differently.
How do I install a chemical anchor?
Standard installation procedure: (1) Hammer-drill the borehole to the specified diameter and depth per the resin manufacturer's ETA. (2) Clean the borehole thoroughly — minimum 2× compressed air blowout, 2× wire brush passes, 2× compressed air blowout. The borehole must be visibly dust-free. (3) For cartridge systems: attach static mixing nozzle, discard first 50-100mm of dispensing until colour is consistent, inject resin from the bottom of the borehole upward to approximately 2/3 fill. (4) Insert the threaded stud immediately, within the resin's working time at the current temperature — rotate slowly while pushing to displace resin upward. (5) Hold the stud in alignment until initial cure. (6) Wait the full cure time per the manufacturer's temperature curve before applying load. For capsule systems, drop the capsule into the cleaned borehole and drive the stud through with continuous rotation until full depth.