Guidelines for Safety Inspection of Dams - Central Water Commission

Annexure I
Definition of Terms Associated with Durability of Concrete
A.1 Cracks: An incomplete separation into one or more parts with
or without space between.
A.1.1 Cracks will be classified by direction, width & depth: The
following adjectives can be used: Longitudinal, transverse,
vertical, diagonal and random. Three width ranges are
suggested as follows: fine – generally less than 1 mm;
medium – between 1 & 2mm; and wide – over 2 mm.
A.1.2 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, or both.
A.1.3 Checking: Development of shallow cracks at closely spaced
but irregular intervals on the surface of mortar or concrete.
A.1.4 Hairline cracking: Small cracks of random pattern in an
exposed concrete surface.
A.1.5 D-cracking: The progressive formation on a concrete surface
of a series of fine cracks at rather close intervals, often of
random patterns, but in highway slabs paralleling edges, joints
& cracks and usually curving across slab corners.
A.2 Deterioration: Deterioration in any adverse change of normal
mechanical, physical and chemical properties either on the
surface or in the whole body of concrete generally through
separation of its components.
A.2.1 Disintegration: Deterioration into small fragments or
particles due to any cause.
A.2.2 Distortions: Any abnormal deformation of concrete from its
original shape.
A.2.3 Efflorescence: A deposit of salts, usually white, formed on a
surface, the substance having emerged from below the
surface.
A.2.4 Exudation: A liquid or viscous gel-like material discharged
through a pore, crack or opening in the surface.
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