Inspector says the commercial slab needs concrete testing.

On-Site Tests (Fresh Concrete):

1. Slump (ASTM C143): Workability. Target per mix design ±1" (or ±1.5" for high-range water reducer).
2. Air Content (ASTM C231/C173): Freeze-thaw durability. Pressure method (C231) for normal weight; volumetric (C173) for lightweight. Target per spec (typically 4–7%).
3. Temperature (ASTM C1064): Must be 50–90°F (per ACI 301/305/306).
4. Unit Weight (ASTM C138): Yield verification.

Cylinder Handling (ASTM C31 / ACI 301):

• Molding: 4×8" or 6×12" plastic molds. Rod (25 strokes/layer) or vibrate per C31. Fill in 2–3 equal layers. Strike off flat. Cover immediately.
• Initial Cure (CRITICAL): Must stay on site for 24–48 hours.
• Temp: 60–80°F (68–78°F for high-early).
• Moisture: Prevent evaporation (lid on, shaded, damp sand pit, or curing box). Freezing or >85°F invalidates breaks.
• Transport: After initial cure, strip molds (or leave in molds if fragile). Transport within 4 hours of stripping. Keep moist (wet burlap/plastic), upright, padded, <85°F.
• Lab Cure (ASTM C511): Submerge in lime-saturated water or 100% RH room at 73.5°F ±3.5°F until break.

Standard Break Schedule: 7-day (info), 28-day (acceptance), hold spares (56-day). Field Tech Must Be: ACI Grade I certified. Acceptance (ACI 318 §26.12): Average of 3 consecutive tests ≥ f'c; no single test < f'c – 500 psi.

If cylinders froze, dried out, or exceeded temp limits during initial cure, results are invalid—retest or core (ASTM C42).

For commercial slab concrete testing on site, the inspector is likely referring to standard quality control tests required by building codes (e.g., IBC, ACI 318) and project specifications. Here’s what’s typically done and how cylinders must be handled:

On-Site Tests:

1. Slump Test (ASTM C143) – Measures workability; done at the point of placement.
2. Air Content (ASTM C231 or C173) – For air-entrained concrete; critical in freeze-thaw zones.
3. Temperature (ASTM C1064) – Concrete and ambient temp; affects curing and strength gain.
4. Unit Weight (ASTM C138) – Optional, but sometimes required for lightweight concrete.
5. Making and Curing Cylinders (ASTM C31) – Primary strength verification.

Cylinder Handling (Critical):

• Molding: Fill in 3 equal layers, rodded 25 times per layer (6"x12" cyl) or vibrated (per spec). Strike off smooth.
• Initial Curing:
• Keep cylinders on-site, near the slab, protected from sun, wind, and temperature extremes.
• Maintain 60–80°F (16–27°C) and ≥90% RH for up to 48 hours (ASTM C31).
• Use insulated boxes, sand, or curing blankets; do not refrigerate or freeze.
• Transport to Lab:
• After initial curing (max 48 hrs), transport cylinders upright, with minimal jarring.
• Do not let them dry out or freeze during transit.
• Deliver to lab within 48 hours of molding.
• Lab Curing:
• Cured in standard moist room (73.4±3°F, ≥95% RH) until test date (usually 7, 14, 28 days).
• Never test field-cured cylinders for acceptance unless specified (rare for slabs).

Note: If the slab is structural (e.g., suspended, post-tensioned), testing is mandatory. For non-structural slabs-on-grade, testing may still be required by owner or specifier. Unsafe/Unlicensed? No — sampling and cylinder making can be done by trained techs, but lab testing must be by a certified facility (ACI or equivalent). Always follow project specs and ASTM standards.

(Word count: 248)