Concrete Repair & Restoration Flashcards
7 cards from real ACI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Concrete Repair & Restoration flashcards as text
Honeycombing in a concrete wall is most commonly caused by:
Answer: Inadequate consolidation or insufficient mortar to fill voids around aggregate
Honeycombing results when mortar does not flow around coarse aggregate, typically from insufficient vibration or improper mix proportions.
Before applying a cementitious repair mortar over corroded steel, the reinforcement should be cleaned to a minimum SSPC standard of:
Answer: SSPC-SP 3 (power tool cleaning to bare metal)
ACI 546 recommends power tool cleaning to bare metal (SSPC-SP 3) or better to remove all loose rust before applying repair materials.
A map crack pattern appearing on a concrete flatwork surface within the first week after placement most likely indicates:
Answer: Plastic shrinkage cracking
Plastic shrinkage cracking occurs within the first few hours to days when evaporation rate exceeds bleed water supply, forming a shallow map pattern.
The 'crack monitor' device used during a condition survey is intended to:
Answer: Track whether a crack is active by measuring changes in width over time
A crack monitor (Demec gauge or tell-tale) records crack width at intervals to determine if the crack is dormant, seasonal, or actively growing.
Rapid-setting repair mortars are primarily used when:
Answer: The repair must return to service quickly, such as on highways or airport runways
Rapid-setting mortars gain strength quickly (often 3,000 psi in 1–4 hours) to minimize traffic closure time.
When applying shotcrete (wet or dry process) for concrete repair, the rebound material should be:
Answer: Removed from the work area and discarded
Rebound contains high proportions of aggregate with little cement paste and, if reused, will weaken the shotcrete repair.
Which test is used on-site to evaluate the soundness of existing concrete before determining repair boundaries?
Answer: Chain drag or hammer sounding to detect delaminations
Chain drag and hammer sounding detect hollow-sounding areas that indicate delaminated or debonded concrete layers requiring removal.