ACI Aggregate Level 1 cheat sheet

Sampling must produce a test portion representative of the entire lot; a grab sample from one location is not acceptable for acceptance testing.

Use a sample splitter (riffler) with an even number of chutes for reducing large samples; alternating chutes discharge into two equal portions.

Quartering: mix the sample, flatten into a cone, quarter it, retain two opposite quarters, and repeat until the desired mass remains.

Minimum sample masses are set by nominal maximum size; larger maximum sizes require larger field samples before reduction.

Sample mass for gradation typically must exceed the mass retained on the largest sieve plus enough fines to be representative.

When using a mechanical splitter, feed the sample at a uniform rate across the full width of the hopper to avoid segregation.

Moisture samples must be sealed in airtight containers immediately after sampling and weighed promptly to prevent drying loss.

Record sample location, depth, date, sampler, and lot identification; chain-of-custody documentation supports acceptance decisions.

Moisture content (%) = [(wet mass − oven-dry mass) / oven-dry mass] × 100; total moisture is based on dry mass.

Standard oven drying is at 110 ± 5 °C to constant mass; record masses to the nearest 0.1 g for small samples.

Absorption (%) = [(saturated surface-dry mass − oven-dry mass) / oven-dry mass] × 100.

Bulk density (dry) = mass of dry soil/aggregate ÷ total volume; density is expressed in kg/m³ or lb/ft³.

For coarse aggregate bulk specific gravity, use the SSD mass in air and the submerged mass to obtain volume by displacement.

Moisture content by microwave or hot plate is a rapid field method; verify against oven-dry results because it can over-dry.

Sample mass for moisture must be large enough that a 0.1% change is detectable relative to the balance readability.

Density determinations require the sample to be at a known moisture state; document whether results are dry, SSD, or as-received.

Sieve analysis: stack sieves in decreasing opening order, shake to completion, and record mass retained on each sieve and pan.

Percent passing = [(total mass − cumulative mass retained) / total mass] × 100, computed to the nearest 0.1%.

Percent retained on a sieve = (mass retained on that sieve / total sample mass) × 100.

Nominal maximum size is the largest sieve through which most, but not all, of the material passes; maximum size passes 100%.

Sieves must be verified and inspected for damaged mesh; a torn sieve invalidates the gradation result.

The No. 200 (75 µm) wash test removes fines; wash loss is the difference between dry mass before and after washing.

Fineness modulus = sum of cumulative percent retained on specified sieves ÷ 100; typical fine aggregate values are 2.3 to 3.1.

Gradation curves plot percent passing on a logarithmic sieve-size axis; compare against specification bands for acceptance.

Oven-dry bulk specific gravity = A / (B − C), where A = oven-dry mass, B = SSD mass, C = submerged mass.

SSD bulk specific gravity = B / (B − C); apparent specific gravity = A / (A − C).

Absorption (%) = [(B − A) / A] × 100, using the same A, B, and C definitions.

Unit weight (bulk density) = (mass of aggregate in container − mass of empty container) / container volume.

Voids (%) = [(bulk density of aggregate × 100) / (bulk density of aggregate particles)] subtracted from 100.

SSD condition is reached when a saturated sample rolls freely and the surface is dry but the pores remain filled.

Specific gravity values for most natural aggregates range roughly 2.4 to 2.9; values outside this range warrant verification.

Unit weight depends on compaction method, container size, and maximum size; use a container at least several times the maximum particle size.

Soundness testing immerses aggregate in sodium or magnesium sulfate solution through repeated wet-dry cycles and measures mass loss.

Magnesium sulfate is generally more aggressive than sodium sulfate; the two solutions are not interchangeable for acceptance.

Soundness loss (%) = [(initial mass − final mass) / initial mass] × 100 after the specified cycle count.

Los Angeles abrasion resistance measures degradation from steel-ball impact and abrasion; result is percent loss by mass.

Los Angeles loss (%) = [(initial mass − mass retained on 1.70 mm sieve) / initial mass] × 100.

Freeze-thaw durability is evaluated by mass loss and visual inspection after repeated freezing and thawing in water.

Sulfate solutions must be maintained at specified specific gravity and temperature; verify solution strength before each test.

Samples for durability tests must be washed, oven-dried, and screened to the specified size fractions before cycling.

Acceptance is based on comparing test results to specification limits for gradation, durability, and physical properties.

A specification limit is a pass/fail boundary; a target value is the desired midpoint used for process control.

Percent passing tolerances typically apply to individual sieve results; a single out-of-limit sieve may require retest.

Aggregate size designations (e.g., No. 57, No. 8) define required percent passing ranges for each sieve.

When a test result falls outside limits, verify sampling, splitting, and equipment before rejecting the lot.

Acceptance sampling plans define sample size, frequency, and decision rules; results apply to the lot represented.

Deleting or averaging out-of-specification results without documentation violates data integrity requirements.

Specifications often limit flat and elongated particles, clay lumps, and friable particles in addition to gradation.

Balances must be calibrated over their range and verified with check weights before use; record readability and capacity.

Sieves require periodic verification of opening size; damaged or out-of-tolerance sieves must be removed from service.

Ovens must maintain 110 ± 5 °C and be verified with a calibrated thermometer at multiple locations.

Sample splitters and riffles must be checked for even chute spacing and free flow before use.

Reference masses and check weights are traceable standards; document the standard used and the date of verification.

Test equipment logs must record calibration date, due date, and the identity of the calibrating technician.

Thermometers, timers, and balances used in acceptance testing must be within their calibration interval at time of use.

Equipment found out of tolerance requires evaluation of prior test results to determine the impact on reported data.

Wear safety glasses, dust protection, and gloves when handling dry aggregate; silica dust is a respiratory hazard.

Oven-dried samples and hot plates cause burns; use heat-resistant gloves and allow samples to cool before weighing.

Report test method, sample identification, date, technician, equipment used, and calculated results with units.

Record raw masses and intermediate calculations so results can be independently recalculated.

Rounding rules apply at the final reported value, not to intermediate calculations; retain extra digits until the end.

Corrections to reported data must be made with a single line-through, initials, date, and reason for the change.

Chemical solutions and sulfate salts require proper labeling, storage, and disposal per laboratory safety procedures.

Data quality requires that results be traceable to the sample and that reported values match the recorded raw data.