Sunday, June 02, 2013

Concrete Joints Defined

Contraction Joints - Used to divide large pours of concrete into smaller structural units, contraction joints create a man-made plane of weakness to regulate and control (another name for a contraction joint is a control joint) the location of a crack formed by moisture loss of concrete. Without this formed contraction joint, the concrete would freely crack in unexpected and unattractive locations.

Construction Joints - an interruption of the concrete pour 30 minutes or greater creates a construction joint.

Expansion Joints - Designed to negate the compressive forces from abutting concrete structures that may occur as a result of expansion, loads, or differential movement from settlement. Expansion joints require an actual gap between the concrete pours, which is frequently filled with a compressible joint filler material such as foam, rubber, cork, or cane fiber board.