Date: January 15, 2016

News - Aggregate Sizing Explained

Loading a Dump Truck with Gravel

The term “aggregates” as used in the construction industry is a broad category of coarse and fine particulate material including sand, gravel, crushed stone, slag, recycled concrete, and geosynthetic aggregates and are actually the most mined materials in the world.  Aggregate serves as a reinforcement to add strength to composite materials such as concrete.

Aggregates can be categorized into three groups: fine aggregate, coarse aggregate, or all-in aggregate.

Fine aggregate, such as concrete or masonry sand is defined as material that mostly passes through a 4.75 mm IS sieve.  This is then broken down into four types of grading Zones 1 through Zone 4 with Zone 4 being the most fine.

Coarse aggregate can be described as uncrushed, crushed, or partially crushed gravel or stone.  This type of aggregate is described as how it is graded.  For example, ¾” nominal size graded aggregate means that most of the aggregate passes a 3/4” sieve. 

All-in aggregate, similar to that of its name, is aggregate containing a proportion of material of all sizes from a pit, crushing plant or river bed.  Also known as Ballast, this type of material is generally used to repair small cracks and pavement foundations.

Where does the basis for this sizing come from?  These sizing standards originate from the ASTM C 33 or “Standard Specification for Concrete Aggregates.”  The particle size is determined by the percentage of material that passes through wire-mesh sieves with square openings.  There are seven standard sieves for fine aggregates ranging from No. 100 to 3/8” and 13 standard sieves for coarse aggregate ranging from No. 16 to 4”.

For example coarse aggregate has a standard grading requirement for each different size from #1 to #8.  A #1 aggregate is a nominal size of 3 ½ to 1 ½ inches and a #8 aggregate is a nominal size of 3/8 to 0.094 inch.  More specifically, a #57 aggregate is the combination of #5 and #7 aggregates ranging from 1 to 0.19 inch. 

Chaney Enterprises’ aggregate materials meet the ASTM C 33 Standard and can be found at our various locations throughout Maryland, Virginia, and Delaware.

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