Core TradesQuestion 4 of 700
The PRIMARY purpose of an isolation (expansion) joint around a column or against an existing wall in a slab-on-grade is to:
a.Let the slab move independently of the column or wall without cracking
b.Transfer bending loads directly into the column base
c.Create a decorative pattern in the finished surface
d.Serve as the location where fresh concrete bonds to hardened concrete
Explanation
An isolation joint fully separates the slab from a fixed element so each can move independently, preventing restraint cracking. It is not meant to transfer load, is not primarily decorative, and a bonded interface is a construction joint, not an isolation joint.
Law Reference: 2025 CA Building Code (CBC) Chapter 19 (Concrete)Practice all 700 questions free — no signup required.
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