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Construction deterioration & building durability glossary

Article & glossary hosted by A. Sebastian Engineering and Investigation Services

Function: noun
Etymology: Middle English "jointe", from Old French, from "joindre"
Date: 13th century
1. a: place where two elements or parts are joined; b : space between the adjacent surfaces of two bodies joined and held together (as bricks bonded by mortar); c: fracture or crack in concrete, masonry, rock not accompanied by dislocation; d : the junction of two or more members of a framed structure; e: a union formed by two abutting rails in a track including the elements (as bars and bolts) necessary to hold the abutting rails together; f: an area at which two ends, surfaces, or edges are attached
- "joint·ed" /'join-t&d/ adjective
- "joint·ed·ly" adverb
- "joint·ed·ness" noun

2. masonry joints: masonry specific connection, usually between the individual masonry units via a mortar interface

Bed ~: New units are laid on a horizontal mortar bed which lays on the top of previously laid course. With the right combination of masonry unit caracteristics and mortar mix design, this should bond the top of the previous course with the bottom of the new course. If not go back to your masonry consultant or materials engineer before pointing fingers to everybody in sight.
Head ~: New units within the course are laid beside previously laid units with a vertical mortar joint in between. See bond related statement above.
Collar ~: This is the vertical longitudinal mortar filled space between the two or more wythes which are to be bonded together as in composite wall construction.
Full Bed ~ or Full Head ~: Application of mortar to entire bedding surface. Anything less will reduce the life of the masonry element; this is rarely attainable in commercial work without knowledgeable full time inspection.
Slushing of joints: The vertical joint is filled after the new unit is in place by "throwing" mortar into the joint cavity. This is not a recommended practice!
3. movement joints: Because construction materials experience changes in volume at various rates, a system of movement joints is necessary to allow these movements to occur. Movement joints should not be used interchangeably: each type is designed to perform a specific task:
expansion joints are used to separate the building into segments in order to prevent stresses and cracking due to changes in environment (temperature, moisture expansion), elastic deformation due to loads, and creep. They may be horizontal or vertical. The joints are formed of highly elastic materials placed in a continuous, unobstructed opening through an element such as a brick wythe (this allows the joints to close as a result of compression exercized by the brickwork increase in size). Expansion joints must be located so that the structural integrity of the building element is not compromised. control joints are used in concrete or concrete masonry to create a plane of weakness which, used in conjunction with reinforcement or joint reinforcement, controls the location of cracks due to volume changes resulting from shrinkage and creep. A control joint is usually a vertical opening through the concrete masonry wythe and may be formed of inelastic materials. A control joint will open rather than close. Control joints must be located so that the structural integrity of the concrete masonry is not affected.
isolation joints (building expansion ~) are used to separate a building into discrete sections so that stresses developed in one section will not affect the integrity of the entire structure. The isolation joint is a through-the-building joint. construction joint (cold joint) is used primarily in concrete construction where construction work is interrupted. Construction joints are located where they will least impair the strength of the structure.

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