ACI CLTT-2 cheat sheet

Slump test (ASTM C143): fill the cone in three equal layers, rod each layer 25 strokes, then measure the drop of the slumped specimen to the nearest 6 mm (1/4 in.).

Slump is not applicable to very dry or very wet mixes; ASTM C143 does not apply to concrete with slump below 15 mm or to no-slump/nonplastic mixes.

Compressive strength cylinders: standard 150 x 300 mm (6 x 12 in.) cylinders; length-to-diameter ratio of 2.0 is required, and strengths are corrected if the ratio differs.

Cylinder curing: standard moist cure at 23 ± 2 °C; test at 28 days unless an age is specified; cap ends within tolerance (0.05 mm on a plane) before testing.

Compressive strength = load at failure divided by cross-sectional area (f = P/A); report to the nearest 0.1 MPa (10 psi).

Air content by pressure meter (ASTM C231): meter must be calibrated for the aggregate type; Type A/B meters use water or a known-volume correction; report to nearest 0.1%.

Air content by volumetric method (ASTM C173) is used for lightweight or highly porous aggregate where the pressure method is unreliable.

Unit weight and yield (ASTM C138): unit weight = mass of concrete in the measure divided by the measure volume; yield = total batch mass / unit weight.

Concrete temperature (ASTM C1064): measure in the middle of the sample, at least 75 mm from the container, with the thermometer immersed at least 75 mm; read after 2-5 minutes.

Sieve analysis (ASTM C136): stack sieves in decreasing opening order, shake to completion (a sieve is done when material passing in 1 minute is <0.5% of retained mass), and report percent passing by mass.

Fineness modulus = sum of cumulative percent retained on the specified sieve series divided by 100; typical fine aggregate FM is 2.3 to 3.1.

Coarse aggregate gradation uses standard sieves; the nominal maximum size is the smallest sieve through which the entire sample passes (one sieve larger than the maximum size).

Moisture content = [(wet mass - dry mass) / dry mass] x 100; absorption = [(SSD mass - oven-dry mass) / oven-dry mass] x 100.

Specific gravity (ASTM C127/C128): bulk specific gravity = oven-dry mass / (SSD mass - submerged mass); apparent SG uses oven-dry mass in the denominator numerator and excludes permeable voids.

SSD condition: surface-dry saturated aggregate has a damp but non-shiny surface; obtained by drying with a towel for fine aggregate or rolling coarse aggregate.

Los Angeles abrasion (ASTM C131/C535): percent loss = (original mass - final mass) / original mass x 100; measures resistance to degradation, lower loss means tougher aggregate.

Sodium/magnesium sulfate soundness (ASTM C88): percent loss after immersion/drying cycles; magnesium sulfate solution is more severe than sodium sulfate.

Clay lumps and friable particles (ASTM C142) and organic impurities (ASTM C40) are acceptance tests; color darker than the reference standard indicates possible organic contamination.