Aggregates — Worked Examples

A dry fine-aggregate test portion has an initial mass of $500.0\text{ g}$. The masses retained on the sieves and pan are 10, 55, 110, 100, 120, 85, and 20 g. Verify mass closure before calculating gradation.

For the same $500\text{ g}$ sample, masses retained are: No. 4 = 10 g, No. 8 = 55 g, No. 16 = 110 g, No. 30 = 100 g, No. 50 = 120 g, No. 100 = 85 g, pan = 20 g. Determine the fineness modulus using cumulative percentages retained on No. 4 through No. 100.

A coarse aggregate has oven-dry mass in air $A=3250\text{ g}$, SSD mass in air $B=3300\text{ g}$, and saturated apparent mass in water $C=2080\text{ g}$. Determine bulk dry, bulk SSD, apparent relative density, and absorption.

A concrete mixture requires $1000\text{ kg}$ of coarse aggregate at SSD. Aggregate absorption is 0.80% and measured total moisture is 2.80%, both on an oven-dry basis. Determine wet batch mass and free water above SSD.

A mixture requires $800\text{ kg}$ SSD fine aggregate. Absorption is 1.5%, but the stockpile total moisture is only 0.5% on an OD basis. Determine the wet scale mass and the additional water needed for the aggregate to reach SSD during mixing.

Aggregate A has 15% passing the 9.5 mm sieve and Aggregate B has 95% passing. A preliminary blend target is 55% passing on that sieve. Determine the required mass fractions for this single-sieve constraint.

Two coarse-aggregate sources are tested by the same specified Los Angeles abrasion procedure. Source X reports 21% loss and Source Y reports 38% loss. Explain what can be concluded without inventing an acceptance limit.

A technician collects a single bucket of fine aggregate from the clean, dry top of a large stockpile after rain. The laboratory result shows 1.0% moisture, but concrete production later exhibits large slump and yield variation. Diagnose the sampling problem.