Materials, Methods and Testing
Materials compliance is judged against the approved plans, the specifications, referenced standards, and manufacturer instructions. Know the common field tests and what each one actually proves - and does not prove.
What questions test
For concrete: mix design and batch tickets, slump (ASTM C143), air content, concrete temperature, cylinder sampling and curing (ASTM C31), and compressive strength testing (ASTM C39), typically reported at 7 and 28 days. Slump measures consistency, not strength; adding water in the field changes the water-cement ratio and is not a cure for a stiff mix. Cylinders must be handled, cured, and transported correctly or the results are meaningless. For soils: laboratory moisture-density (Proctor) establishes the target, and field density testing verifies compaction. Structural steel welding and high-strength bolting, certain masonry, and other items listed in the code require special inspection by qualified agencies under a statement of special inspections. Fire-resistance depends on listed assemblies, correct board thickness and fastening, and firestopping of penetrations; interior finish ratings reflect flame spread classes. Wood must carry grade stamps.
Rule of thumb
A test report is only evidence for the material it sampled, on the day it was sampled. Verify project name, mix or material, location, date, sampling method, technician, and lab accreditation before accepting it.
Worked example: The specification permits a maximum 4-inch slump; the field test reads 6 inches. The correct action is to document the result, notify the contractor and code official, and hold the placement - not to allow water or retempering to bring the number into range.