ACI Aggregate Level 2 cheat sheet

Sieve analysis: percent passing = (mass passing sieve / total dry mass) × 100; cumulative retained is subtracted from 100 to get percent passing.

Fineness modulus = sum of cumulative percent retained on the 4.75, 2.36, 1.18, 0.600, 0.300, and 0.150 mm sieves divided by 100.

Nominal maximum size is the smallest sieve through which 100 percent of the sample passes; maximum size allows up to 100 percent passing the next larger sieve.

Specific gravity (bulk, SSD, apparent) uses A/(B−C) forms where A = oven-dry mass, B = SSD mass, C = submerged mass; absorption = (B−A)/A × 100.

Los Angeles abrasion: percent loss = (initial mass − retained mass after 500 revolutions) / initial mass × 100.

Sodium sulfate soundness loss = (initial mass − final mass after cycles) / initial mass × 100; magnesium sulfate uses the same formula with its own limit.

Flat and elongated particles are measured with a proportional caliper at a 3:1 or 5:1 ratio, reported as mass percent of the retained sample.

Clay lumps and friable particles: percent = (mass of lumps retained after wet sieving) / total dry mass × 100.

Proctor compaction: dry unit weight = (moist mass / volume of mold) / (1 + moisture content); peak of the curve is optimum moisture content.

Relative compaction = field dry unit weight / laboratory maximum dry unit weight × 100; typical base acceptance is 95–100 percent of maximum.

Sieve analysis on base material checks gradation against the specification band; percent passing each control sieve is compared directly to the band limits.

Atterberg limits: liquid limit by Casagrande or cone method; plasticity index = liquid limit − plastic limit; PI near zero indicates non-plastic base.

California Bearing Ratio: CBR = (test load / standard load) × 100 at a given penetration; standard loads are 1000 psi at 0.1 in and 1500 psi at 0.2 in.

Sand equivalent: SE = (sand reading / clay reading) × 100; higher values indicate cleaner, less plastic fines.

Moisture-density curve shape depends on fines content: plastic fines widen the curve and lower maximum dry unit weight compared to clean granular base.

Field density by sand cone or nuclear gauge must be corrected for moisture; dry density uses the oven-dry moisture at the time of testing.