ACI Aggregate Level 1 flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Representative sample
- A portion of aggregate that has the same proportions of particle sizes and properties as the entire lot it represents, obtained by proper sampling and reduction.
- Riffle splitter
- A device with an even number of alternating chutes that divides a flowing aggregate sample into two portions of essentially equal mass and similar gradation.
- Quartering
- A sample reduction method that mixes the sample into a flattened cone, divides it into four quarters, and retains two opposite quarters for further reduction.
- Sample reduction
- The process of decreasing the mass of a field sample while preserving its particle-size distribution, typically by mechanical splitting or quartering.
- Moisture content formula
- Moisture content percent equals wet mass minus oven-dry mass, divided by oven-dry mass, multiplied by 100; the denominator is always the dry mass.
- Oven drying temperature
- Standard aggregate moisture determination dries samples at 110 plus or minus 5 degrees Celsius to constant mass, with masses recorded to the balance readability.
- Absorption formula
- Absorption percent equals saturated surface-dry mass minus oven-dry mass, divided by oven-dry mass, multiplied by 100, expressed as a percentage.
- Dry bulk density
- The mass of oven-dry aggregate divided by the total volume it occupies, including internal permeable and impermeable pores, reported in mass per unit volume.
- SSD condition
- A saturated surface-dry state in which the aggregate pores are filled with water but no free moisture remains on the particle surface.
- Percent passing
- The total sample mass minus the cumulative mass retained on a sieve, divided by the total sample mass, multiplied by 100.
- Percent retained
- The mass retained on an individual sieve divided by the total dry sample mass, multiplied by 100, reported for each sieve in the stack.
- Nominal maximum size
- The smallest sieve opening through which the entire sample passes, or the largest sieve retaining some material, depending on the specification definition used.
- Fineness modulus
- The sum of cumulative percent retained on a specified series of sieves divided by 100, used as an index of fine aggregate coarseness.
- Wash test
- A procedure that washes material through a fine sieve to determine the mass of fines finer than the sieve opening, reported as percent passing.
- Sieve verification
- Periodic inspection and measurement of sieve openings to confirm they remain within tolerance, with out-of-tolerance sieves removed from service.
- Bulk specific gravity
- Oven-dry mass divided by the volume of the particle including permeable pores, computed as A divided by (B minus C).
- Apparent specific gravity
- Oven-dry mass divided by the volume excluding permeable pores, computed as A divided by (A minus C), where C is the submerged mass.
- Unit weight
- The mass of aggregate that fills a container of known volume, determined by filling and compacting the container and dividing mass by volume.
- Voids in aggregate
- The percentage of the bulk volume not occupied by solid particles, computed from the bulk density and the particle density of the aggregate.
- Submerged mass
- The apparent mass of a saturated aggregate sample weighed while suspended in water, used with SSD mass to determine particle volume by displacement.
- Sulfate soundness
- A durability test in which aggregate is soaked in sodium or magnesium sulfate solution and dried through repeated cycles, with mass loss measured.
- Los Angeles abrasion
- A test measuring aggregate resistance to impact and abrasion in a rotating drum with steel balls, reported as percent loss by mass.
- Soundness loss
- The initial sample mass minus the final mass after the specified sulfate cycles, divided by the initial mass, multiplied by 100.
- Freeze-thaw durability
- A test in which saturated aggregate is repeatedly frozen and thawed, with mass loss and visual deterioration used to judge resistance.
- Specification limit
- A pass or fail boundary stated in the specification for a test property; results outside the limit require verification and possible rejection of the lot.
- Aggregate size designation
- A standardized label such as No. 57 or No. 8 that defines the required percent passing ranges for each sieve in the gradation.
- Acceptance sampling
- A planned procedure specifying sample size, sampling frequency, and decision rules used to accept or reject a lot based on test results.
- Balance calibration
- Verification of a balance against traceable check weights across its range, documented with date, standard used, and the technician performing the check.
- Oven verification
- Confirmation that a drying oven holds 110 plus or minus 5 degrees Celsius, checked with a calibrated thermometer at multiple locations.
- Out-of-tolerance equipment
- Equipment found outside calibration limits must be removed from service and prior test results evaluated for impact on reported data.
- Silica dust hazard
- Airborne crystalline silica from dry aggregate is a respiratory hazard requiring dust control, ventilation, and appropriate respiratory protection in the laboratory.
- Data traceability
- The ability to link each reported result to its original sample, raw measurements, test method, equipment, and technician through complete records.