Can horizontal joint reinforcement be field fabricated to create 90 degree corners?

ANSWER: 

Yes, straight lengths of horizontal joint reinforcement can be field-fabricated to form a continuous corner as follows:  cut one longitudinal wire and then bend the other longitudinal wire to form a 90-degree angle.1,2 Then bend the cut ends of the longitudinal wire 90 degrees to lap the other cut sections of the longitudinal wire to form the required minimum 6 inch lap splice. Figure 1 depicts a 90-degree outside corner of joint reinforcement that has been field fabricated with the required lap splice. The same configuration can be used at an inside corner.

Prefabricated joint reinforcement corners are available from joint reinforcement manufacturers, but field-formed corners have some advantages over prefabricated corners:16-faq-figure5-2

  • No extra lead time needed for ordering
  • No additional cost to purchase
  • More likely to be installed, because the material is available on the project site
  • Can be custom cut to length and lapped per course, when building a corner lead (racking back)

The Specification for Masonry Structures, TMS 602-11/ACI 530.1-11/ASCE 6-113does not include a requirement for continuity of horizontal joint reinforcement at corners and, therefore, does not address how to achieve continuity at corners.  Nevertheless, constructing joint reinforcement with continuity at corners is good practice and reduces the potential for shrinkage cracking at wall corners.

According to Dr. Thomas J. Langill, Technical Director, American Galvanizers Association, susceptibility to corrosion at the bend, due to potential damage to the zinc galvanizing, is not a concern: “In the case of bending the wire the usual thickness of galvanized coating on the wire makes the potential of coating cracking or crazing during bending very low.  Even small cracks in the coating at the bend will not significantly affect the corrosion performance.”4

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