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Construction Joints | Key Topics

Concrete is going to crack; costing you or your client in repair, maintenance, facility down time and valuation. Designing a slab incorporating positive load transfer at construction joints can reduce or eliminate joint deterioration, random cracking and spalling.

Construction joints are designed to minimize restraint and allow for the movement of the concrete during the curing process and throughout the life of the slab. The most common joints found in concrete slabs on ground and/or pavements are formed construction joints, saw-cut contraction joints and isolation joints.

Formed Construction Joints

Formed construction joints are installed to define pre-determined individual placements of the concrete pour and define where adjacent placements meet. These construction joints are designed to permit movement and transfer load between slabs. The Diamond Dowel® System is used at construction joints to ensure positive load transfer between pours and to maintain proper dowel alignment. CoVex® Series dowels are used for expansion of existing slabs. Armor-Edge® Joint assemblies are used for interior floor designs to provide joint edge protection for high traffic areas, freezer/cold storage buildings and locations where construction joints are expected to open up more than 1/8”.

Saw-Cut Contraction Joints

Saw-cut contraction joints are used to eliminate costly continuous reinforcement throughout the mid panel and offer a more effective and economical load transfer design. Formed by sawing in a continuous line across the slab to create a weakened plane, the joint intentionally creates a crack directly below the saw cut. This type of joint allows the slab or pavement to shrink and can prevent mid-panel cracking by eliminating slab restraint. Placement of PD3 Basket® assemblies at contraction joints permits parallel and perpendicular movement at the saw-cut, stable dowel support and reliable alignment during installation.

Isolation Joints

Isolation joints are used to allow concrete free movement without inducing stress on adjacent concrete pours.  By isolating parts of a structure, such as columns, walls, stairways or bollards, the isolation joint enables vertical and horizontal movement without inducing cracking.