Cold joint, and concrete blocks by comparison?

[saturnstroll]

With regards to ICF homes, and vertical wall pours..

If a contractor significantly delays between pours and a cold joint occurs, how is this any different than blocks and mortar?

In this scenario, there is sufficient rebar traveling perpendicular to cold joint.

Seems to me that building residential walls with concrete blocks and mortar with occassional rebar amounts to many many intentional cold joints.

Are they both weak? Suspect to water infiltration?

 

[Ron]

Yes and Yes.

 

[ATSE]

A cold joint (the code refers to this as a construction joint) in concrete will always be superior to masonry. The bond between mortar and block is much weaker than concrete to concrete. In addition, rebar minimums are higher in concrete compared with masonry.
Water-blasting the construction joint will improvement bond. However, depending on how the ICF blocks are laid, this may not be possible.