Along the bottom 12 inches of one wall the concrete is coarse and porous with open voids between the stones, and in two places a horizontal bar is exposed to view. What is the correct inspector action?
- AApprove the wall, because the affected zone sits below the finished grade and will be hidden by backfill against the outside face in any case.
Being out of sight is not the same as being sound. Honeycombed concrete has reduced strength and an open path for water, and backfill loads that wall harder than anything it sees later, so the hidden zone is where it matters.
- BApprove the wall once the crew rubs a cement slurry across the porous area so that the open surface is sealed against water.
A slurry rub is a cosmetic surface treatment. It closes the appearance of the voids without restoring section or bond, and the code asks for defective concrete to be evaluated and repaired by a method the official approves.
- CApprove the wall if the test cylinders taken from that same truck break at or above the compressive strength specified.
Cylinder breaks report the strength of the mix as delivered, not the strength of the wall as placed. Honeycombing comes from placement and consolidation, so a passing cylinder says nothing about the zone in question.
- Withhold approval and require the defective concrete to be evaluated and repaired by an approved method before dampproofing and backfill.
Why D is correct
Honeycombed concrete has neither the strength nor the cover the design assumed, and it sits at the base of the wall where load and water pressure are greatest. Approval is withheld until the unsound material is cut out and repaired by a method the building official accepts, and that repair must happen before anything covers it.
What this question is testing
Whether the candidate reads honeycombing as a structural and durability defect rather than a finish complaint, and understands that strength testing of cylinders does not certify in-place consolidation.
On the job
Honeycombing clusters at the bottom of tall walls, at window bucks and around congested steel, and it is usually the result of a pump crew placing fast without a vibrator. The right time to see it is the hour the forms come off, which is often the same hour the dampproofing sprayer shows up. Once tar covers the wall the defect is invisible until the basement leaks. Inspectors in busy jurisdictions ask builders to schedule the wall inspection before, not after, the coating.
Memory technique
If you can see the rock and the rebar, there is no concrete doing the work.
Exam tip
Watch for choices that substitute a test result or a cosmetic coating for an actual repair of missing material.
Where to look it up
IRC Chapter 4, the concrete materials and placement requirements under R402 and R404.