ACI Special Inspector flashcards
ACI Special Inspector · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Slump test standard
- ASTM C143 measures consistency of fresh concrete. Fill cone in three equal layers, rod 25 strokes each, lift mold vertically and measure slump to nearest 1/4 in.
- Cylinder compressive strength
- ASTM C39 test of hardened concrete. 6x12 in. cylinders loaded at 35 ± 7 psi/s; result is the average of at least two cylinders, reported to nearest 10 psi.
- Pressure air meter
- ASTM C231 method for air content of normal-weight concrete. Concrete must be free of aggregate over 1.5 in.; daily calibration with known air content is required.
- Volumetric air test
- ASTM C173 method using isopropyl alcohol to determine air content. Used for lightweight or porous aggregate concrete where pressure method is unreliable.
- Sampling fresh concrete
- ASTM C172 requires sampling from middle portion of discharge, minimum 1 ft³, composite from several locations, remixed before testing.
- Concrete temperature test
- ASTM C1064: probe inserted at least 3 in. into concrete mass, reading taken within 5 minutes of sampling, reported to nearest 1 F.
- Standard-cured cylinders
- Cylinders cured at 60-80 F in moist environment for first 24 hours then lime water or moist room. Represent potential strength of the mix.
- Field-cured cylinders
- Cylinders cured in the field under the same conditions as the structure. Used to determine when formwork or shoring may be removed.
- ACI 318 strength acceptance
- Average of any three consecutive strength tests must equal or exceed f'c. No single test may fall below f'c minus 500 psi.
- Slump tolerance
- Permitted variation from specified slump: ±1 in. when specified is 2 in. or less; ±2 in. for 3-4 in.; ±3 in. for 5 in. or more.
- Formwork removal strength
- Vertical forms may be removed when concrete reaches 500 psi. Shore removal for structural members requires 70% of design strength unless approved.
- Consolidation spacing
- Internal vibrator insertion points spaced no more than 1.5 times the radius of action; vibrator inserted vertically and slowly withdrawn.
- Construction joint preparation
- Joint surface roughened to 1/4 in. amplitude, cleaned of laitance, and pre-wetted before placing new concrete to ensure shear transfer.
- Hot weather concrete limit
- Concrete temperature as placed must not exceed 90 F (32 C) unless otherwise specified; cooling methods include chilled water and ice.
- Cold weather protection
- Maintain concrete at 50 F minimum for 7 days, or 40 F for 3 days with insulating protection, to ensure adequate strength development.
- Minimum cover requirements
- Cast-in-place concrete not exposed to weather: 1.5 in. for slabs and walls, 2 in. for beams and columns, 3 in. for footings.
- Post-tensioning elongation check
- Measured elongation compared to calculated elongation; agreement within ±7% is typically required before acceptance of the stressing operation.
- Concrete placement free fall
- Concrete should not free-fall more than 3 to 5 ft; use drop pipes or chutes to prevent segregation during placement.
- Curing duration
- Concrete surfaces must be cured for at least 7 days when Type I cement is used; 3 days for accelerated or Type III mixes.
- Reinforcement cover purpose
- Adequate cover protects steel from corrosion, provides fire resistance, and ensures bond between concrete and reinforcement.
- Sulfate-resistant cement
- Type V cement used where high sulfate exposure exists; Type II provides moderate sulfate resistance. Selection based on soil or water sulfate content.
- Water-cement ratio
- Ratio of water mass to cementitious material mass. Lower w/c increases strength and durability; typical structural range is 0.40 to 0.50.
- Yield per batch
- Actual volume produced per batch compared to design volume. Yield deviation beyond 1% signals batching or moisture errors.
- Air content tolerance
- Total air content must be within ±1.5% of specified value for air-entrained concrete; check with ASTM C231 or C173.
- Moisture correction
- Aggregate stockpile moisture must be measured and deducted from batch water; free moisture differs from absorption capacity.
- Test result averaging
- Compressive strength test result is average of two cylinders; if they differ by more than 10%, a third cylinder is tested.
- Yield test frequency
- Yield, air content, and slump are tested at least once per day of placement and for each 150 yd³ of concrete placed.
- Concrete density check
- Unit weight of fresh concrete per ASTM C138; used to calculate yield and verify air content when combined with theoretical density.
- Accelerated curing
- Warm-water or steam curing used to predict 28-day strength; correlation with standard-cured cylinders must be established.
- Laitance removal
- Weak surface layer of cement and fines must be removed from joints by wire brushing or chipping before new concrete is placed.
- Vibration duration
- Vibrator should be inserted until concrete surface just becomes glossy; typically 5 to 15 seconds per insertion to avoid segregation.
- Concrete sampling frequency
- Strength test specimens taken at least once per day, once per 150 yd³, and for each mix design used in a day.