Aggregate properties and gradation significantly affect workability and finishability of freshly placed concrete and properties of hardened concrete including compressive strength, durability and abrasion resistance. Properties and accepted test methods discussed in this bulletin include: aggregate gradation; fine and coarse aggregate fineness moduli; relative bulk densities of wet, saturated surface dry, air-dry, and oven-dry aggregates; moisture absorption; shape angularity and surface texture; abrasion and impact resistance; permeability resistance to freeze thaw cycles and alkali-silica reaction; and chemical stability. Aggregate types including normalweight, lightweight and heavyweight natural aggregate; blast furnace slag aggregates; and recycled aggregates from crushed reclaimed concrete pavements are covered. Examples are provided on how to calculate and evaluate fineness modulus, batch mixture proportions adjusted for aggregate absorption, batch mixing water proportions, water cementitious ratios and bulk densities. Sampling aggregate methods to estimate average aggregate properties of large volumes or stockpiles, batches, or truckloads of aggregates are also covered.