Glossary of Concrete Anchors and Fastener Terminology

ACI – American Concrete Institute

Admixture – An ingredient added to the core ingredients of concrete to change its properties. Examples include water repellent, coloring, and agents to retard or hasten setting time.

Aggregate – A granular material that is used with a cementing medium to form a hydraulic cement concrete or mortar. Examples include sand, gravel and crushed stone.

Aggregate, Lightweight – An aggregate with a dray, loose weight maximum of 70 lbs per cubic foot (pcf).

Aerated Concrete – Extra workable concrete that is protected against freeze-thaw damage. Aeration is achieved by mixing the concrete with air-entraining additives.

AISC – American Institute of Steel Construction

Allowable Load – The maximum static load that should be applied on an anchor.

ANSI – American National Standards Institute

ASTM – American Society for Testing and Materials

Base Material – The material that an anchor and load are being applied to. Common base materials include concrete, substrates that have the properties of concrete, brick, tile and stone.

Brick – A solid masonry unit of clay or shale, formed into a rectangular prism while plastic and burned or fired in a kiln that may have cores or cells comprising of less than 25 % of the cross sectional area.

Cast-In-Place Anchor – An anchor that is cast directly into cement rather than drilled in after the concrete is set.

Combined Load – A load that apply stress with the properties of both tension and shear loads.

Concrete – A mixture of portland cement and any other hydraulic cement, fine aggregate, course aggregate and water. The approximate weight of cement is 150 pcf.

Concrete Block – A hollow concrete masonry unit (CMU) made from portland cement, water and aggregates.

Concrete Brick – A solid concrete masonry unit (CMU) made from portland cement, water and aggregates.

Concrete Compressive Strength (f’C) – The pounds per square inch that categorize a base material’s compressive load carrying capacity.

Concrete Masonry Unit (CMU) – The term to describe either a solid or hollow masonry unit.

Core Drill – The term used to describe the process of using a special drill attachment to create a smooth hole in any base material.

Creep – Movement under a sustained load over time.

Drop-In Anchor – An anchor that is dropped, rather than set, into concrete. Drop-in anchors are internally threaded to accept a bolt or threaded rod.

Edge Distance --

Edge Distance (C) – The distance between the centerline of an anchor and the free edge of the base material.

Critical Edge Distance (Ccr) – The minimum distance at which the allowable load capacity for an anchor holds true.

Minimum Edge Distance (Cmin) – The minimum distance from the free edge of the base material that anchors are tested.

Embedment Depth – The distance from the surface of the base material to the installed end of the anchor. Embedment depth is determined prior to installation of the anchor.

Expansion Anchor – A category of mechanical anchors that is placed into the base material. The anchor expands inside the base material during installation and engages the sides of the base material in order to create shear and/or tension resistance.

Expansion Joint – A control joint in the concrete designed to allow for concrete movement.

Friction Anchor – A category of anchors that creates friction within the base material. The friction created determines load resistance.

Green Concrete – Concrete before it is completely set.

Grout – A mixture of cementious material and aggregate that has enough water added to make give it pouring consistency. The addition of water does not segregate the constituents.

Grouted Masonry – Masonry in which the hollow core is completely filled with grout.

Grouted Anchor – An anchor that is held in the base material with grout.

Lightweight Concrete – Concrete, not exceeding a weight of 115 pcf, that is composed of a light weight aggregate.

LVDT, Linear Variable Displacement Transducer – A device that creates fine movements to displace an anchor under a test load.

Masonry – Base materials bonded with mortar to form a structure.

Mercaptan – A curing agent used in epoxy.

Mortar – The mixture of aggregates used to bond masonry units.

Oblique Load – Same as combination load. A load that apply stress with the properties of both tension and shear loads.
Portland Cement – Hydraulic cement consisting of finely pulverized compounds of silica, lime, and alumina.

Post-Tension – A method of pre-stressing in which tendons are tensioned after concrete has hardened.

Precast Concrete – Concrete that is made off site or on site, but that is first formed and then moved into its final place within the structure.

Prestressed Concrete – Structural concrete in which internal stresses have been introduced to reduce potential tensile stresses in concrete resulting from loads.

Pretensioning -- A method of pre-stressing in which tendons are tensioned before concrete is placed.

Rebar – Reinforcing steel that is deformed and whose surface contains ridges that give it better gripping within concrete or adhesive material.

Reinforced Masonry – Masonry units that is bonded to reinforcing steel with mortar or grout.

Set Time – The amount of time it takes for an adhesive anchor to reach its maximum load strength.

Shear Cone – An anchor failure in which the concrete fracture appears in a cone shape. Shear cone failure is usually the result of a tension load.

Shear Load – A load applied perpendicular to the axis of an anchor.

Shotcrete (Gunite) – Pneumatically projected concrete or mortar.

Sleeve Anchor – A stud type anchor with a full-length expansion mechanism made from a sheet of metal.

Slump – A measure of consistency of concrete according to a strict standard ASTM C143 procedure. Slump is the sag or a truncated cone shape of free standing concrete.

Smooth Dowel – Steel with a smooth surface that is used to tie new concrete to an existing slab.

Spacing

Spacing (S) – The distance between the centerline of one anchor to the centerline of another.

Critical Spacing (SCR) – The minimum space allowed between two anchors for load capacity to hold true.

Minimum Spacing (SMIN) – The minimum spacing at which anchors are tested for recognition.

Tendon – A steel element used to pre-stress concrete.

Tension Load – The load applied parallel to the axis of anchor.

Torque – The measure of the force applied to a member to produce rotational motion usually measured in foot-pounds. Torque is determined by multiplying the applied force by the distance from the pivot point to the point where the force is applied.

Ultimate Load – A load that when applied to an anchor will result in failure.

Undercut Anchor – Anchor that develops its load capacity by expanding into a void created by a secondary drilling operation or the anchor itself.

Unreinforced Masonry (URM) – Masonry units that do not contain reinforcing steel.

Wedge Anchor – A stud type anchor with a limited length expansion mechanism and cone that creates and initial friction fit and then is seated when the cone is drawn inside the expansion mechanism.

Wythe – A continuous vertical section of masonry one unit in thickness.