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Joints in Concrete Construction

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Presentation on theme: "Joints in Concrete Construction"— Presentation transcript:

1 Joints in Concrete Construction
Matt Mettler, P.E. DOWL HKM

2 Joint Definition Isolation Joints Construction Joints
Contraction Joints Expansion Joints

3 Joint Construction Doweled Tied Keyed Tooled Insert (zip strips)
Butt Joints

4 Isolation Joints Type of control joint
Allows for drying shrinkage and other movements Provides no vertical or horizontal restraint May act as an expansion joint if needed

5 Isolation Joint

6 Construction Joints Can be constructed of multiple types of joints:
Doweled Tied Keyed Butt Joint Are spaced and or located to facilitate construction Concrete quantity limitation Sequencing of construction tasks

7 Construction Joint

8 Contraction Joint Also known as control joints
Controls cracking due to drying shrinkage May be constructed from a variety of methods: Hand tooled Saw Cut (my preference) Inserts

9 Contraction Joints

10 Expansion Joints Used primarily in exterior conditions
Can be doweled but not keyed or tied Allows for un-restrained movements due to temperature gradients Can be sealed

11 Expansion Joint

12 Joint Spacing Function of concrete thickness, coarse aggregate size and concrete slump PCA 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 feet It is good practice to maintain a square shape in so much as practical

13 Joint Spacing

14 Joint Spacing Structure geometry and other elements such as interior walls, columns and piers may dictate layout.

15 Recommendations for Hydraulic Structures
Contraction joints: Should be doweled or tied Saw cut floors Formed with chamfer strips for walls Try to maintain a square shape between joints May need waterstop and or joint sealant Construction joints: Should be doweled or tied and keyed Use chamfer strips for adequate consolidation May need special attention regarding drainage because of hydraulic loading.

16 References Bureau of Reclamation, “Concrete Manual,” 8th Edition Revised, 1981 Ringo & Anderson, “Designing Floor Slabs on Grade,” 1992 Spears & 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.

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