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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