Control Joints In Concrete Slab On Metal Deck

Let the cracks occur and control the crack width by using reinforcing steel.

Control joints in concrete slab on metal deck.

In other words if the concrete does crack you want to have an active role in deciding where it will crack and that it will crack in a straight line instead of randomly. For this reason control joints parallel to the corrugations will not be successful. Concrete repair restoration concrete art surface preparation vol. Both of these types of joints while very different help take stress off of the concrete slab.

You can create control joints in concrete while pouring the concrete or you can wait until the slab has cured just enough so it won t chip when you cut into it. Control joints are planned cracks which allow for movements caused by temperature changes and drying shrinkage. When shrinkage is restrained by contact with supporting soils granular fill adjoining structures or reinforcement within the concrete tensile stresses develop within the concrete section. 3 june july 2006 joints.

Ryan indicates that contraction joints in concrete slabs on metal decks are of little value and that cracking between joints is inevitable. An article published in concrete construction august 1999 called let it crack by j. The topping containing welded wire fabric should not have control joints either. Cracks will generally occur over supporting beams in the negative moment regions.

Find a local concrete contractor to help with your project. Concrete slabs on metal decks are usually built with reinforcement and should not contain control joints. Concrete control joints should be no less than of the total thickness of the slab 1 deep for a 4 thick pour and placed no less than 2 3 times in feet the thickness in inches of the slab 8 12 feet apart for a 4 thick pour. Grooving tools made of bronze or heavy gauge stainless steel are used for scoring freshly poured concrete and cost just 25 to 35.

Control joints are most effective in slabs which can slide on a smooth base as drying shrinkage progresses. Control joints running perpendicular to the corrugations can be spaced at intervals of 15 to 25 times the thickness of the concrete. Contraction control joints are placed in concrete slabs to control random cracking. He recommends using no contraction joints allowing random cracks to form and patching only those that affect the.

A fresh concrete mixture is a fluid plastic mass that can be molded into virtually any shape but as the material hardens there is a reduction in volume or shrinkage.