Concrete Wall Expansion Joint Spacing

Control joints are not intended to stop cracking but rather control cracking.

Concrete wall expansion joint spacing.

Plan out your control joint spacing 24 36 times the depth of your concrete slab. Joints are most effective when the aspect ratio of the slab is kept to 1 1 for example 5m x 5m if the slab is a narrower than it is long it is possible to increase this to a maximum aspect ratio of 1 5 for example 2m x 3m don t leave the placing of concrete expansion joints to chance and enlist the services of a structural engineer if. Joint spacing varies with amount and grade of shrink age and temperature reinforcement. Joint spacing in feet contraction joints may be tooled into the concrete surface at the time of placement.

For example locating control joints at the ends of lintels may compromise arching action. Consideration must also be given to the effect of control joint placement on load distribution within the wall. Greased steel dowels are often cast horizontally into the wall to tie adjacent sections together. It is best to cut joints as early as possible either while finishing with a concrete groover or within 6 18 hours after finishing with a concrete saw.

Joint spacing that is greater than 15 feet require the use of load transfer devices dowels or diamond plates. Use projecting strips to reduce wall thickness by at least one fourth ref. The hight shear force is applied at the horizontal construction joints located at the lower level. Concrete joints are used to compensate when concrete expands or shrinks with changes in temperature.

Hunter 1953 80 ft 25 m for walls and insulated roofs 30 to 40 ft 9 to 12 m for. Author spacing lewerenz 1907 75 ft 23 m for walls. Recommended spacing of vertical contraction joints modified from ref. Joint spacing in meters.

There is a special check to be done at the construction joints when larger retaining walls or structures having very high lateral loads are designed. The friction of the concrete is the key factor that limits the movement. Table 1 2 expansion joint spacings. Concrete joints are normally used to prevent cracks when the concrete shrinks by creating forming tooling sawing and placing joint formers.

Expansion joints should be located at intervals up to 90 feet. Joints are commonly spaced at distances equal to 24 to 30 times the slab thickness. Adjacent to corners of walls or intersections within a distance equal to half the control joint spacing. Vertical expansion joints are incorporated into the wall to account for expansion due to temperature changes.

These joints may be filled with flexible joint fillers. Joints in poured walls by kim basham and bruce suprenant effective methods for controlling unsightly wall cracking f i g u r e 1.