6Construction Joints Can be constructed of multiple types of joints: DoweledTiedKeyedButt JointAre spaced and or located to facilitate constructionConcrete quantity limitationSequencing of construction tasks
12Joint SpacingFunction of concrete thickness, coarse aggregate size and concrete slumpPCA recommends the joint spacing be 2 to 3 times (in feet) the concrete thickness (inches)Example: a 5 inch slab would have joints spaced 10 to 15 feetIt is good practice to maintain a square shape in so much as practical
14Joint SpacingStructure geometry and other elements such as interior walls, columns and piers may dictate layout.
15Recommendations for Hydraulic Structures Contraction joints:Should be doweled or tiedSaw cut floorsFormed with chamfer strips for wallsTry to maintain a square shape between jointsMay need waterstop and or joint sealantConstruction joints:Should be doweled or tied and keyedUse chamfer strips for adequate consolidationMay need special attention regarding drainage because of hydraulic loading.
16ReferencesBureau of Reclamation, “Concrete Manual,” 8th Edition Revised, 1981Ringo & Anderson, “Designing Floor Slabs on Grade,” 1992Spears & Panarese, Concrete Floors on Ground, EB075.2D, Portland Cement Association, Skokie, IL, second edition 1983; revised 1990.Young & Paxson, Undermining of Spillway Chutes, Safety of Dams Conference, Seattle, WA, Fall 2010.