are designed to remain fixed in base material once they are set.
Concrete and masonry fasteners are unique. They are placed into a
drilled hole in concrete, brick or block. Once set, it is not possible
to remove them without damaging the base material that they are set in.
The base material is the weakest link when working with concrete and
masonry fasteners. If pulled on hard enough, the base material will fail
and the anchor will become detached. This will leave a hole in the
concrete that is the shape of an upside down cone. The amount of force
required to remove the anchor is called the ultimate pullout or ultimate
tension load. The pullout value is determined by the diameter of the
anchor and the depth of embedment of the concrete anchor in the base
material. Also, each type of fastener has a different holding value for
the same diameter and depth of embedment.
Types of Concrete Fasteners & How to Remove Them from Base Material
Male Type Anchors
(fasteners that protrude from the base material)
Wedge anchors: When drilling a hole for a wedge anchor,
drill it 2x the length of the wedge anchor. This will allow for the
wedge anchor to be pounded into the hole until flush with the concrete.
Wedge anchors can be sawed off with a hacksaw or cutoff wheel at the
surface of the concrete.
Tapcon® Concrete Screws: Tapcons are removable because
they are threaded screws that taps threads into the concrete, brick or
block. By simply turning the screw counterclock wise, these concrete
screws will thread its way out of the base material. The holding values
of Tapcons will be deteriorated if they are reinserted into the same hole.
Sleeve Anchors: Drill the hole 2x the length of the sleeve
anchor being used. Remove the nut and washer and the round or flat head
of the sleeve anchor. Pound the threaded stud of the sleeve anchor into
the base material. If the sleeve anchor cannot be pounded into the base material, then cut the stud off with either a hacksaw or cutoff wheel.
Hammer Drive Anchors: Hammer drive anchors have a tamper
resistant head style that needs to be removed before the fixture can be
removed. Using a hacksaw or cutoff wheel, cut off the head of the hammer drive anchor.
This may be difficult to do without damaging the fixture that is
attached with the hammer drive anchor. Once the head of the hammer drive
anchor has been removed, then the body of the anchor can be drilled out
using a high-speed bit.
Strike Anchors: Strike anchors cannot be pounded into the hole and must be cut off using either a cutoff wheel or saw. The design of the strike anchor doesn't allow for them to be pounded into a base material.
Split Drive Anchors: Split drive anchors are
made with either a countersunk or round head and are tamper resistant.
The only way to remove one without damaging the base material is by
cutting off the head of the anchor. This can be done with a saw or
cutoff wheel. Since the head of the split drive anchor is tight against
the fixture, it is very difficult not to damage the fixture when cutting
off the head of the anchor.
Female Type Concrete Anchors
(are designed so they sit below the surface of the base material
and a bolt is inserted into them through the fixture being fastened)
Drop in Anchors: Drop in anchors
are designed to be set into concrete with the use of a setting tool.
Once set, the anchor cannot be removed without damaging the concrete.
Once the bolt or threaded rod is removed from the drop in anchor, the
anchor is not visible above the surface. The anchor can be patched over
or just left in place.
Lag Shield Anchors: These anchors require the insertion of
a lag screw which expands the lag shield anchor. Removing the screw may
un-expand the anchor. Many times, the anchor will stay expanded which
makes the anchor unable to be removed. Sometimes the anchor can be
removed simply by pulling it out of the hole. As with all female type
anchors, the lag shield anchor can be left in the hole as it doesn't stick out above the surface.
Machine Screw Anchors: Machine screw anchors
are set into the base material with the use of a setting tool. Once
set, the anchor can't be removed without damage to the base material.
Once the bolt and fixture are removed, there will be nothing visible
above the surface.
It is possible to remove both male and female type anchors if the
proper steps are taken. It is also important to determine whether it is
likely that the fixture and anchor will need to removed before deciding
which type of concrete anchor should be used in an application.
As with any anchoring project, it is important to keep safety in mind and follow instructions carefully.
Always remember to wear safety goggles, handle all tools with extra care and follow all technical specifications.
This article is meant to serve only as a basic explanation of concrete fasteners.
Always refer to manufacturer's instructions or consult a contracting expert during any anchoring project.
Article Written By:
Mike Pistorino, Vice-President Operations
Concrete Fasteners, Inc. has over 40 years of experience selling concrete fasteners. We can ship out one box or a whole pallet of concrete anchors. Our products are of the highest quality... "your satisfaction is guaranteed". We ship all orders the same day the order is received.