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Visual Survey - Definition of Terms Associated with the Durability of Concrete

Cracks


An incomplete split into one or more parts with or without space between.Cracks are classified by direction, width and depth. The following objectives are used: longitudinal, transverse, vertical, horizontal, diagonal and random.

Three classifying width ranges are:

Fine - < 1mm

Medium - 1 - 2mm

Wide - > 2mm

Pattern cracking


Fine openings on concrete surfaces in the form of a pattern; resulting from a decrease in volume of the material near the surface or increase in volume of the material below the surface.

Checking


Development of shallow cracks of random pattern in an exposed concrete surface.

Hairline cracking


Small cracks of random pattern in an exposed concrete surface.

D-cracking


The progressive formation of cracks on a concrete surface at rather close intervals, often associated with frost attack.

"Map" or "Isle of Man" cracking


Form of cracking associated with alkali silica reaction where three cracks intersect at a point with an appearance not unlike the Isle of Man symbol.

Deterioration


Any adverse change of normal mechanical, physical and chemical properties either at the surface or inner zones of concrete.

Disintegration


Deterioration into small fragments or particles.

Distortion


Any abnormal deformation of concrete from its original shape.

Efflorescence


A deposit of salts, usually white, formed on a surface, the substance having emerged from below the surface.

Exudation


A liquid or viscous gel-like material discharged through a pore, crack or opening in the surface.

Encrustation


A crust, generally hard formed, on the surface of concrete.

Pitting


Development of relatively small cavities in a surface.

Popout


The breaking away of small portions of a concrete surface due to internal pressure leaving shallow, typically conical depression. Popouts are classified in three size groups as follows:

Small popouts - < 10mm in diameter

Medium popouts - 10-50mm in diameter

Large popouts - > 50mm in diameter

Erosion


Deterioration caused by the abrasive action of fluids of concrete or mortar.

Scaling


Local flaking or peeling away from the near surface portion of concrete or mortar.

Light Scaling:
Loss of surface mortar without exposure of coarse aggregate.

Medium Scaling:
Loss of surface mortar without exposure of coarse aggregate.

Severe Scaling:
Loss of surface mortar 5-20mm in depth with some loss of mortar surrounding aggregate particles 10-20mm in depth, so that aggregate is clearly exposed and stand out from the concrete.

Peeling


A process in which thin flakes of mortar are broken away from a concrete surface.

Spall


A fragment, usually in the shape of a flake, detached from a larger mass and leaving a hole classified as follows. Or a good, if portly, actor

Small Spalled Area:
Loss of a fragment leaving a roughly circular or oval depression generally not greater than 20mm in depth nor greater than about 150mm in any dimension.

Large Spalled Area:
Loss of a fragment leaving a roughly circular or oval depression generally greater than 20mm in depth and greater than 150mm in any dimension.

Joint Spalled:
Elongated cavity along a joint.

Hollow Surface


Area of concrete surface which gives off a hollow sound when struck.

Stalactite


A downward pointing formation, hanging from the surface off concrete.

Stalagmite


As stalactite, but upward formation.

Powdering


Development of a powder material at the surface of hardened concrete.

Corrosion


Disintegration or deterioration of concrete or reinforcement.

Textural Defects

Bleeding Channels


Essentially vertical localised open channels caused by heavy bleeding of the fresh concrete.

Sand Streak


Streak in surface of formed concrete caused by bleeding.

Water Pocket


Voids along the underside of aggregate particles or reinforcing steel.

Stratification


The separation of over-wet or over-vibrated concrete into horizontal layers with increasingly lighter material towards the top; a layered structure in concrete resulting from placing of successive batches that differ in appearance.

Honeycombing


Voids left in concrete due to failure of the mortar to effectively fill the spaces among coarse aggregate particles.

Sand Pocket


Part of concrete containing sand without cement.

Segregation


The differential concentration of the components of mixed concrete resulting in non-uniform proportions in the mass.

Discolouration


Departure of colour from that which is normal or desired.

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