Joints in Concrete – Identify the incorrect statement about construction and expansion joints Which one of the following statements is NOT correct regarding the purpose and planning of joints in concrete structures?

Introduction / Context:
Concrete structures require intentional joints for constructability and performance. However, different joint types serve different functions. Confusing construction joints with contraction (shrinkage) or expansion joints can lead to poor detailing and unintended cracking. This item asks you to spot the incorrect statement.

Given Data / Assumptions:

• Cast-in-place concrete work with practical placement lengths.
• Thermal movements expected in exposed components.
• Foundations are buried and experience minimal temperature fluctuation compared with superstructure elements.

Concept / Approach:

Construction joints are planned stoppages in concreting operations due to practical limits on placement volume or time; they are located at structurally suitable points and detailed for shear transfer and continuity. Contraction (control) joints are intentional planes of weakness or pre-formed grooves to control cracking due to drying shrinkage and minor thermal effects. Expansion joints separate adjacent structural parts to accommodate expansion and contraction caused by temperature variations; such joints are typically unnecessary in foundations because temperature swings are small below grade.

Step-by-Step Solution:

Verification / Alternative check:

Design and construction manuals distinguish joint types and show typical details: keys, dowels, and shear connectors at construction joints; sealants and preformed fillers at expansion joints; saw cuts or tooled joints for contraction joints in slabs.

Why Other Options Are Wrong:

They correctly describe joint purposes and typical practice (A, B, D). Only C misattributes function to the wrong joint type.

Common Pitfalls:

Locating construction joints at high shear regions; forgetting curing and timely saw cuts for contraction joints; overusing expansion joints where restraint exists.

Final Answer:

Construction joints are provided to control shrinkage cracks.