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Concrete Repair Terminology (S)
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Concrete Repair Terminology is prepared by the International Concrete Repair Institute. The cross-referenced terms provide definitions for commonly used words in concrete repair, restoration and protection.

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Revised April 2019

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- S -

sacrificial anode


nonuniform downward flow of a material that occurs between the time of application and setting. (See also sloughing).


a portion of material taken from a larger quantity of material which serves to provide information that can be used as a basis for action on the larger quantity.


identifying and testing or removing materials or components from a structure for the purpose of conducting laboratory tests to determine material or structural properties or to further quantify physical condition.


a process for roughening, cleaning, abrading or finishing a surface using compressed air to propel sand at high velocity against a surface. (See also abrasive blasting and wet blasting.)

sand pocket

a zone in concrete, mortar, or shotcrete containing fine aggregate with little or no cement.

sand streak

a streak of exposed fine aggregate in the surface formed concrete, caused by bleeding.

sanded grout


alkaline hydrolysis of esters to produce the component soaps and alcohols.

saturated surface-dry

condition of an aggregate particle or other porous solid when the permeable voids are filled with water and no water is on the exposed surfaces.


as applied to aggregate or concrete: the condition such that no more liquid can be held or placed within it.

saturation, critical

a condition describing the degree of filling by freezable water of a pore space in cement paste or aggregate that affects the response of the material to freezing; usually taken to be 91.7% because of the 9% increase in volume of water undergoing the change of state to ice.

saw cut

a cut in hardened concrete made by abrasive blades, discs, or diamond wires.


equipment for removal of concrete and coatings by chipping with piston-driven cutting heads placed at a right angle to the surface.


local flaking or peeling away of the near-surface portion of hardened concrete or mortar; also of a layer from metal. (See also peeling and spalling.) Note: light scaling of concrete does not expose coarse aggregate; medium scaling involves loss of surface mortar to 5 to 10 mm in depth and exposure of coarse aggregate; severe scaling involves loss of surface mortar to 5 to 10 mm in depth with some loss of mortar surrounding aggregate particles 10 to 20 mm in depth; very severe scaling involves loss of coarse aggregate particles as well as mortar generally to a depth greater than 20 mm.


milling equipment for removal of concrete or brittle coatings by fracturing and pulverizing with rotary impact cutters held at a right angle to the surface.


the process of scratching, cutting, or chipping a substrate to clean and texture the surface.

Schmidt hammer


erosion of a concrete surface, exposing the aggregate.


1) to strike off concrete lying above the desired plane or shape; 2) a tool for striking off the concrete surface, sometimes referred to as a strikeoff.

screed wire


the operation of forming a surface by the use of screed guides and a strikeoff. (See also strikeoff.)


a barrier against the passage of liquids, solids, or gases.


a material that has adhesive and cohesive properties to form a seal.

sealant, field-molded

a liquid or mastic sealant that is shaped by the joint into which it is placed.

sealant, joint

compressible material used to exclude water and solid foreign materials from joints.

sealant, structural

a sealant capable of transferring required loads between adjacent structural elements.


a liquid that is applied to the surface of hardened concrete to either prevent or decrease the penetration of liquid or gaseous media, for example water, aggressive solutions, and carbon dioxide, during service exposure.

sealing compound

see sealer.

section enlargement


the infiltration or percolation of water through a material to or from the surface.


the differential concentration of the components of mixed concrete, aggregate, or the like, resulting in nonuniform proportions in the mass. (See also bleeding and separation.)


the process whereby a material exhibits flow sufficient to seek gravitational leveling.


divergence from the mass and differential accumulation of coarse aggregate during movement of the concrete; the gravitational settlement of solids from a liquid.

series grouting

service condition

the combination of load and environmental exposure that a structure or material may be subjected to during its design life.

service life

an estimate of the remaining useful life of a structure, component, or material based on the current rate of deterioration or distress, assuming continued exposure to given service conditions without repairs.

service life, design

the period of time used in design of a new structure or repair program to make decisions regarding needed properties of construction materials and potential durability-enhancing features of the design.

service life, economic

time in service until replacement of the structure (or part of it) is economically more advantageous than keeping it in service.

service life, functional

time in service until the structure no longer fulfills the functional requirements or becomes obsolete due to change in functional requirements.

service life, technical

time in service until a defined unacceptable state is reached, such as spalling of concrete, safety level below acceptable limits, or failure of elements.


adequate structural performance under service loads.


the condition reached by a cement paste, mortar, or concrete when it has lost plasticity to an arbitrary degree, usually measured in terms of resistance to penetration or deformation; initial set refers to first stiffening; final set refers to attainment of significant rigidity; also, strain remaining after removal of stress.

set, false

the rapid development of rigidity in a freshly mixed portland cement paste, mortar, or concrete without the evolution of much heat, which rigidity can be dispelled and plasticity regained by further mixing without addition of water. (See also set, flash.)

set, final

a degree of stiffening of a mixture of cement and water greater than initial set, generally stated as an empirical value indicating the time in hours and minutes required for a cement paste to stiffen sufficiently to resist, to an established degree, the penetration of a weighted test needle; also applicable to concrete and mortar mixtures with use of suitable test procedures. (See also set, initial.)

set, flash

the rapid development of rigidity in a freshly mixed portland cement paste, mortar, or concrete, characteristically with the evolution of considerable heat, which rigidity cannot be dispelled nor can the plasticity be regained by further mixing without addition of water; also referred to as quick set or grab set. (See also set, false.)

set, initial

a degree of stiffening of a mixture of cement and water less than final set, generally stated as an empirical value indicating the time in hours and minutes required for cement paste to stiffen sufficiently to resist to an established degree, the penetration of a weighted test needle; also applicable to concrete or mortar with use of suitable test procedures. (See also set, final.)

set, permanent

inelastic elongation or shortening.


1) downward movement of a structure, part of a structure, or underpinning. 2) sinking of solid particles in grout, mortar, or fresh concrete, after placement and before initial set.

settlement shrinkage


an internal force tangential to the plane on which it acts.

shear-bond strength

shear collar

enlarged column section immediately below a slab that aids in transfer of shear stresses from the slab into the supporting column.

shear stress

the stress component acting tangentially to a plane.


enclosure around prestressing steel to avoid temporary or permanent bond between the steel and surrounding concrete. (See also duct.)

shelf life

the length of time packaged materials can be stored under specified conditions and still remain usable.


placing of shotcrete. (See also gunning.)


temporary members added to supplement the gravity or lateral strength of the structure.

shoring Engineer

Licensed Design Professional retained by the contractor to design shoring, bracing, and other temporary support. (330.2-16)

short-pulse radar

a technique for nondestructive detection of delaminations and other types of defects within a concrete mass.


surface preparation method in which steel shot is centrifugally propelled at high velocity onto a surface; the process is confined in an enclosed blast chamber which recovers and separates dust and reusable shot.


mortar or concrete pneumatically projected at high velocity onto a surface; also known as air-blown mortar, pneumatically applied mortar or concrete, and sprayed concrete. (See also shotcrete, dry-mix, pneumatic feed, positive displacement pump, and shotcrete, wet-mix.)

shotcrete, dry-mix

shotcrete in which most of the mixing water is added at the nozzle.

shotcrete, wet-mix

shotcrete in which the ingredients, including water, are mixed before introduction into the delivery hose; accelerator, if used, is normally added at the nozzle.


a decrease in one or more dimensions of an object or material. (See also contraction and volume change.)

shrinkage, carbonation

shrinkage caused by carbonation.

shrinkage, drying

shrinkage resulting from loss of moisture.

shrinkage, plastic

shrinkage that occurs prior to setting of a cementitious material.

shrinkage, settlement

a reduction in volume of concrete prior to the final set of cementitious mixtures, caused by settling of the solids. (See also shrinkage, plastic and volume change, autogenous.)


a characteristic of grout, mortar, or concrete made using an expansive cement in which volume increases after setting, if properly elastically restrained, induces compressive stresses which are intended to approximately offset the tendency of drying shrinkage to induce tensile stresses. (See also cement, expansive.)

shrinkage crack

shrinkage cracking

shrinkage-reducing admixture


a low-molecular-weight compound of silicon and hydrogen, solutions of which are used as penetrating sealers for concrete surfaces.

silica fume

very fine noncrystalline silica produced in electric arc furnaces as a byproduct of the production of elemental silicon or alloys containing silicon.



a silicon and oxygen-based compound, also containing carbon and hydrogen, used as a penetrating sealer for concrete surfaces.


the formation of a solid membrane on the top of a liquid, caused by partial curing or drying of a coating during storage.


the process of either raising concrete slabs or filling voids under them, or both, by pressure injecting cementitious or noncementitious materials under the slabs.


slag cement

slant-shear bond strength


movement occurring between steel reinforcement or other embedded items and concrete, indicating degraded or ineffective anchorage.

slip resistance

the frictional force opposing movement of an object across its surface. (See also coefficient of friction.)


subsidence of shotcrete, or other repair materials placed vertically or overhead; also called sagging.


pulsating and intermittent flow of shotcrete material due to improper use of delivery equipment and materials.


a measure of consistency of freshly mixed concrete, mortar, or stucco equal to the subsidence measured to the nearest 1/4 in. (5 mm) of the molded specimen immediately after removal of the slump cone.


a mixture of water and any finely divided insoluble material, such as portland cement, slag, or clay in suspension.

slush grouting

sodium chloride

common salt.


the underside of an element or structure, such as a beam, staircase, arch, or cornice.

solids content

the percentage by weight of the nonvolatile matter in an adhesive.


a liquid capable of dissolving another material.

solvent entrapment

the encapsulation of solvent within a cured coating because of improper drying conditions; results in a discontinuous coating system.

sonic echo

a nondestructive testing method for determining the length of deep foundations or the location of cracks or constrictions; a hammer is used to impact the surface and a receiver monitors reflected stress wave.


a technique to evaluate the condition of hardened concrete by striking the surface with a hammer; sound concrete will exhibit a clear ringing sound, whereas dull or hollow sounds indicate delaminated areas. (See also chain drag or, more broadly, acoustic impact.)

sounding well

a vertical pipe, with closely spaced openings, positioned in a mass of coarse aggregate for grout injection of preplaced aggregate concrete, a float on a measured line indicates the grout level.


the freedom of a solid from cracks, flaws, fissures, or variations from an accepted standard; a qualitative measure of the suitability of concrete to perform as a solid substrate or base for a maintenance or repair material; sound concrete substrates usually exhibit strength and cohesiveness without excessive voids or cracks.


a fragment, usually in the shape of a flake, detached from a larger mass by a blow, by the action of weather, by pressure, or by expansion within the larger mass; a small spall involves a roughly circular depression not greater than 20 mm in depth and 150 mm in any dimension; a large spall, may be roughly circular or oval or in some cases elongated, is more than 20 mm in depth and 150 mm in greatest dimension.


the development of spalls.

specific gravity

the ratio of the mass of a volume of a material at a stated temperature to the mass of the same volume of distilled water at a stated temperature.


an explicit set of requirements to be satisfied by a material, product, system, or service.

specification, performance-based

a specification in which the requirements are stated in terms of required results with criteria for verifying compliance rather than specific composition, design, or procedure.

spectral analysis of surface waves (SASW)

a nondestructive test method for determining the stiffness profile of a pavement system or the depth of deteriorated concrete; impact is used to generate a surface wave and two receivers monitor the surface motion.


connection of reinforcing bars or prestressing tendons to one another by lapping, welding, mechanical couplers, or other means.

splice, center stressing

a device that allows stressing and splicing to occur from an intermediate location along the length of a tendon. Also called a stressing coupler or colloquially a “dogbone” coupler because of its shape.

splice, coupler

a device for connecting reinforcing bars or prestressing tendons end to end.

splice, Y

a device that provides for tendon stressing at a splice location.

splitting tensile strength

sprayed concrete

see shotcrete.

spray-up application

technique in which continuous-strand roving is fed into a chopper gun, which chops the roving into predetermined lengths and simultaneously sprays the chopped fibers and a cementing matrix onto a surface.


material or structural resistance to change, especially sudden change or deterioration.

stability, global

stability of the overall structure with respect to uplift, overturning, sway instability, or sliding failure.

stability, local

the stability of an individual member, part of an individual member, or a material in an existing structure.

stage grouting


discoloration by foreign matter.


a downward-pointing deposit formed as an accretion of mineral matter produced by evaporation of dripping water from the surface of rock or of concrete, commonly shaped like an icicle.


an upward-pointing deposit formed as an accretion of mineral matter produced by evaporation of dripping water from the surface of rock or of concrete, commonly conical in shape.


1) a physical reference used as a basis for comparison or calibration; 2) a concept that has been established by authority, custom, or agreement to serve as a model or rule in the measurement of quality or the establishment of a practice or procedure.

steel reinforcement

bars, wires, strands, tendons, fibers, mesh or other steel elements that are embedded in a matrix primarily to resist tensile forces.

steel reinforcement, epoxy coated

steel reinforcement with a fusion-bonded epoxy coating designed to increase corrosion resistance.

steel reinforcement, galvanized

steel reinforcement that has been passed through a molten bath of zinc at a temperature of around 860 °F (460 °C); typically used for applications requiring resistance to corrosion.

steel reinforcement, high-strength

steel reinforcement with a high yield point; in the case of reinforcing bars, a minimum of 60,000 psi (414 MPa) with typically higher strengths of 75,000 and 100,000 psi (517 and 690 MPa).

steel reinforcement, prestressing

high-strength steel, most commonly strand, wire, or bars used to impart permanent prestress forces to concrete.

steel reinforcement, stainless

steel alloy with a minimum of 11% chromium content by mass; more resistant to corrosion compared to conventional steel reinforcement.

Stern-Geary equation

equation relating the polarization resistance to the current density in an electrochemical cell.

stiffening, early

the early development of an abnormal reduction in the working characteristics of a hydraulic-cement paste, mortar, or concrete, which may be further described as false set, quick set, or flash set.

stitch drilling

procedure for removal of concrete with overlapping bore holes along the perimeter of the section to be removed.


a method for repair of cracks that involves drilling holes on both sides of the crack and grouting in stitching dogs (U-shaped metal units with short legs) that span the crack; may be used when tensile strength must be reestablished across major cracks.


a rigid, straight piece of either wood or metal used to strikeoff or screed a concrete surface to proper grade or verify the planeness of a finished grade. (See also rod, screed, and strikeoff.)


the change in length per unit of length, in a linear dimension of a body; a dimensionless quantity that may be measured conveniently in percent, in inches per inch, in millimeters per millimeter, but preferably in millionths.


a prestressing tendon composed of a number of wires twisted above the center wire or core.


the separation of overwet or over vibrated concrete into horizontal layers with increasingly lighter material toward the top; a layered structure in concrete resulting from placement of successive batches that differ in appearance.

stray current corrosion

the corrosion caused by electric current from a source external to the intended electrical circuit, for example, extraneous current in the earth such as leakage from direct current railroads or non-continuous reinforcement influenced by an impressed current cathodic protection system.


the ability of a material to resist strain or rupture induced by internal or external forces.

strength, bond

resistance to separation of a repair from the existing substrate or from reinforcing and other materials with which it is in contact.

strength, compressive

the measured maximum resistance of a test specimen to axial compressive loading; expressed as force per unit cross-sectional area.

strength, flexural

the property of a solid that indicates its ability to resist failure in bending. (See also modulus of rupture.)

strength, pull-off

the tensile bond strength or tensile strength calculated by dividing the tensile load at failure by the area of the test specimen.

strength, shear-bond

a measure of the ability of a repair to resist shear stresses along the interface between the repair material and the concrete substrate.

strength, slant-shear bond

adhesive bond strength measured by applying a compressive force to a cylinder or prism that is comprised of two segments joined along a surface diagonal to the direction of the compressive force.

strength, splitting tensile

tensile strength of concrete determined by a diametrical compression test.

strength, tensile

maximum unit stress that a material is capable of resisting under axial tensile loading; based on the cross-sectional area of the specimen before loading.

strength, tensile bond

the unit stress, applied in direct tension, required to separate a hardened repair material from other materials with which it is in contact with failure occurring in or near the bonded interface.


the process of restoring the capacity of weakened components or elements to their original design capacity or increasing the strength of components or elements of a concrete structure.

strengthening, active

systems that typically engage the structure instantaneously; may be accomplished by introducing external forces to a member that counteract the effects of internal forces.

strengthening, external

application of bonded or anchored reinforcing or post- tensioning elements, e.g., steel or fiber-reinforced polymer composites, on exterior of structural members to increase the flexural, shear, axial strength, or ductility of existing structural elements; external strengthening elements including plates, wraps, tendons, and the like.

strengthening, passive

systems that are typically engaged only when additional loads, beyond those existing at the time of installation, are applied to the structure; including steel plates or fiber-reinforced polymer (FRP) composites bonded to members.

strengthening, primary

type of system required when design service loads (without load factors) exceed the nominal strength of an unstrengthened element; including section enlargement, span shortening, and supplemental supports.

strengthening, section enlargement

placement of additional concrete on an existing structural concrete member; the addition may be reinforced structural concrete to increase load-carrying capacity or protective concrete to improve fire resistance or protect against mechanical and environmental damage.

strengthening, span shortening

erection of new intermediate supports some distance from existing supports for an overstressed member; including vertical columns, diagonal bracing, and lateral beams.

strengthening, supplemental

type of system appropriate for situations where design service loads (without load factors) are less than the existing capacity of unstrengthened element.


intensity of internal force (i.e., force per unit area) exerted by either of two adjacent parts of a body on the other across an imagined plane of separation.

stress corrosion

the process in which the damage caused by stress and corrosion acting together is significantly greater than that produced when they act individually.

stress-corrosion cracking

stress relaxation

the time-dependent decrease in stress in a material held at constant strain. (See also creep.)


to remove material in excess of that which is required to fill the form or repair cavity evenly and bring the surface to grade; performed with a straightedge piece of wood or metal by means of a forward sawing movement or by a power operated tool appropriate for this purpose; also the name applied to the tool. (See also screed and screeding.)

structural adhesive

a bonding agent used for transferring required loads between adjacent structural elements.

structural sealant

styrene butadiene

a synthetic resin which is a copolymer of styrene and butadiene; available as a latex emulsion and in a form which can be dissolved in aromatic solvents to form alkali-resistant coatings.


the layer immediately under a layer of different material to which it is typically bonded; an existing concrete surface that receives an overlay, partial-depth repair, protective coating, or some other maintenance or repair procedure.

sulfate attack

either a chemical or a physical reaction or both between sulfates usually in soil or water and concrete or mortar; the chemical reaction is primarily with calcium aluminate hydrates in the cement-paste matrix, often causing deterioration.


supplemental reinforcement

additional reinforcement installed in a repair section when the original reinforcement was inadequate, the reinforcement has lost cross section, or the existing member is to be strengthened.

surface hardeners

metallic particles or hard mineral aggregate usually passing No. 16 sieve size, mixed with cement; generally applied by sprinkling on the surface of plastic concrete, or other repair material, and repeated troweling to produce a dense layer.

surface impregnants

low viscosity, surface penetrating liquids which impart a degree of water repellency to the surface.

surface preparation

the process whereby a method or combination of methods is used to remove deteriorated or contaminated concrete and roughen and clean a substrate to enhance bond of a repair material or protective coating.

surface profile

the topographic contour of the exposed surface of a material or substrate.

surface repair

repair of a concrete surface, e.g., application of an overlay, or repair of near- surface concrete that constitutes only a small portion of the depth of a member or element. (See also repair, partial-depth.)

surface retarder

a retarder applied to the contact surface of a form or to the surface of newly placed concrete, to delay setting of the cement, to facilitate construction joint cleanup, or to facilitate production of an exposed-aggregate finish.

surface sealers

1) in epoxy injection, the material placed over cracks to contain the liquid adhesive during the injection process before the adhesive gels; 2) protective surface treatments 10 mils (0.25 mm) or less in thickness which are generally applied with brush, roller, squeegee, or spray.

surface tension

a measure of surface energy created by the predisposition of molecular forces at the surface of a liquid to confine the volume of the liquid to a minimum area.

surface texture

degree of roughness or irregularity of the exposed surfaces.

surface vibrator

a vibrator applied to the surface of freshly placed repair materials to consolidate the mass; four principal types exist: vibrating screeds, pan vibrators, plate or grid vibratory tampers, and vibratory roller screeds.


a relatively coarse, noncolloidal dispersion of solid particles in a liquid.


increase in either length or volume. (See also contraction, expansion, volume change, and volume change, autogenous.)


the exudation of small amounts of liquid from a gel accompanied by contraction of the gel.

synthetic fibers

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