Quality Control & Materials
18% of this examConcrete, rebar, and soils quality control: what each field test measures, why curing and lift thickness matter, and how mockups set the workmanship bar. Most questions are definitional — match the test to the property it measures.
Core concepts
Match the test to the property
Slump measures consistency and workability of fresh concrete — not strength. Strength (f'c) is verified by compression-testing cast cylinders at 28 days; 7-day breaks give an early indicator at roughly 65–75% of 28-day strength. The Proctor test sets the maximum dry density and optimum moisture content used as the field compaction benchmark (specs commonly require 95% of Proctor).
Curing is moisture and temperature over time
Strength comes from cement hydration, which needs retained moisture and favorable temperature. Water curing, wet coverings, and curing compounds prevent premature drying; concrete that dries early ends up weaker and prone to plastic shrinkage cracking.
Rebar position is structural
Chairs and bolsters hold reinforcing steel at its designed height so bars aren't trodden down during the pour. Correct position and concrete cover protect the member's strength and the steel against corrosion.
Lifts and mockups
Compactive effort fades with depth — structural fill goes in thin controlled lifts (commonly 8–12 inches loose), each compacted and tested; a 3-foot lift fails at depth. A full-size mockup establishes the approved standard of materials and workmanship against which production work is judged, before full production begins.
Key facts to know cold
Where it lives in your books
The real exam is open book. Knowing which book — and which tab — answers this domain is worth as much as memorizing it.
Concrete References
Testing questions are definitional: slump = workability, cylinders at 28 days = strength, Proctor = compaction benchmark. Tab the test-methods chapter.
4 recommended tabs
Construction PM
Scheduling math (float, forward/backward pass) must be done, not found — practice it until the lookup is just a formula check.
5 recommended tabs
Lookup strategy
- · Tab the field-testing chapter of Design and Control of Concrete Mixtures (slump, cylinders, air content) and the curing chapter — those two answer most concrete questions.
- · Rebar support and cover questions point to Placing Reinforcing Bars; soils and compaction sit in the PM text's earthwork chapter.
Reading isn't learning — retrieval is.
11 questions in this domain, each with an explanation and source.