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Concrete Decor - Index

Concrete Decor - Concrete Decor Magazine, The Journal for Decorative Concrete - Index

74 | www.ConcreteDecor.net | Dec. ’07/Jan. ’08
WOC Booth
N3110
The Rules of
Contraction
According to the American Concrete Institute’s
online Cement and Concrete Terminology guide,
contraction joints (also called control joints, among
other names) exist to “create a weakened plane
to regulate the location of cracking resulting from
the dimensional change of different parts of the
structure.”
Contraction joints are broadly categorized by
ACI according to their function.
Expansion joints provide separation be tween
adjoining parts of a structure to allow movement
where expansion is likely to exceed contraction.
Isolation joints provide a separation between
adjoining concrete structure compo nents to allow
movement.
Construction joints exist between two successive
placements of concrete — for instance,
where work has stopped one day and continued the
next.
An electronic search performed by ACI staff of
the most current Manual of Concrete Practice and
other publications turned up no reference to curved
contraction joints.