Concrete Construction Inspection: Duties, Documents, and Field Controls
The Inspector's Role
An ACI special inspector works for the owner (or the owner's agent), not the contractor, and documents whether work conforms to the approved plans, specifications, and referenced standards. Know the hierarchy: code and specifications govern, the approved drawings define geometry and reinforcement, and approved submittals and mix designs fill in details. When documents conflict, the inspector records the conflict and requests clarification in writing rather than choosing a side.
Core Field Controls
Candidates must understand pre-placement verification (formwork dimensions, cleanliness, release agent, reinforcement size, spacing, cover, supports, and lap splices), placement controls (conveying, free fall limits, consolidation, cold-joint location, hot- and cold-weather precautions), and curing requirements. Also know sampling frequency rules for strength specimens and slump/air tests, and the requirement that samples be taken at the point of discharge.
Common Traps
Questions often hinge on who is responsible: the inspector verifies and reports but does not direct the contractor's means and methods or approve changes. Another trap is confusing "nonconformance" with "rejection" - the inspector documents and notifies; the building official or engineer of record decides acceptance. Watch for items requiring correction before placement versus items that can be corrected after.
Worked Example
A specification requires one set of strength specimens per 100 cubic yards (or fraction) and at least once per day of placement. A footing pour is 260 cubic yards placed in one day. Required sets: 260/100 = 2.6, rounded up to 3 sets, and the daily minimum of 1 is already satisfied by 3. Rule of thumb: always round sampling quantities up, never down.