Because resin bonds to whatever the hole wall is coated with, and after drilling that is dust.

Drilling leaves a fine layer on the wall that behaves like a release agent. The adhesive grips it, it does not grip the concrete, and the anchor pulls out at a fraction of its rated load.

Manufacturers publish a specific sequence - usually blow, brush, blow, with a stated number of repetitions and a brush sized to the hole.

The brush size matters. An undersized brush passes down the hole without touching the wall it is meant to clean.

Compressed air removes more than a hand pump in deep holes, and some systems require it above a certain depth.

Cleaning is the single largest source of variation between a laboratory pull-out figure and a site one.

From the base of the hole upward, withdrawing the nozzle as the resin fills behind it.

Injecting from the mouth traps air at the bottom, which is exactly where the anchor is most highly stressed.

Deep holes need an extension tube so the nozzle reaches the base; the tube is drawn out steadily as the hole fills.

The hole is filled to roughly the proportion the manufacturer states - not to the top - so that inserting the element brings resin to the surface without excessive waste.

The element is inserted with a slow twisting motion to work the resin around the thread and displace remaining air.

Resin visible at the mouth once the element is home is the field check that the hole filled properly.

Yes, with a sleeve - and without one the resin disappears into the voids.

A mesh or perforated plastic sleeve is inserted into the hole first. Resin injected into it is contained but extrudes through the mesh into the cavities, forming a key inside the unit.

That key is what carries load in a hollow substrate, since there is no continuous material to bond to.

Solid masonry generally does not need a sleeve, but it is more porous than concrete and may need a larger resin volume.

Capacities in masonry are much lower and much more variable than in concrete, because the units themselves vary.

For anything carrying real load in masonry, a site pull test is the only dependable evidence.

Considerably - both the cartridge temperature and the base material temperature, and in different ways.

Cold resin is stiff and hard to dispense, so cartridges are often conditioned before use in cold weather.

The base material temperature drives the cure. A cold substrate lengthens both working time and full cure, sometimes by a large factor.

Heat does the reverse: working time shortens, and in hot conditions a hole may gel before the element is inserted.

Every product has a minimum installation temperature below which it is not approved at all, and winter-grade formulations exist for that reason.

In-service temperature is a separate limit. Adhesive anchors lose capacity as temperature rises, and sustained elevated temperature is a design case.

Only if the product states it - some systems are approved for damp, water-saturated or even flooded holes, and many are not.

Water interferes with bonding for most chemistries and is a common cause of unexplained low results.

Approved wet-hole systems have their own cleaning sequence, which usually differs from the dry one and may require more flushing.

Published capacities for wet holes are typically lower than the dry figures for the same product, and both are given.

Standing water must generally be removed even where damp is permitted.

Where conditions are uncertain, choosing a system qualified for the worst likely case is cheaper than discovering the limitation afterwards.

The first material through is unmixed, and a nozzle left in place cures solid - both waste cartridges rather than anchors, provided the discard rule is followed.

A static mixer blends the two components as they pass through its internal helix. Until the helix is full, what emerges is unmixed and will never cure properly.

Manufacturers state a quantity to discard at the start of each cartridge and after each nozzle change, and that material must not go into a hole.

Between holes the nozzle can be left on a part-used cartridge only for as long as the resin's working time; beyond that it sets solid and a new nozzle is needed.

Reusing a nozzle after it has begun to cure gives poorly mixed resin with no visible warning.

Keeping spare nozzles with the cartridges is the practical answer, since a missing nozzle stops the work entirely.

Embedment depth, hole diameter, concrete strength, edge distance and spacing - and the installation quality behind all of them.

Deeper embedment gives more bond area and more concrete engaged, and it is the main variable the installer controls.

Adhesive anchors can be designed to fail in the steel rather than the concrete, which is a deliberate and often preferred outcome.

Edge distance and spacing reduce capacity as they reduce the volume of concrete available to resist breakout.

Cracked concrete substantially reduces adhesive anchor performance, and products qualified for cracked concrete are assessed separately.

Design rules differ between markets, so a capacity table from one region should be checked against the local approval before it is used.