% CRUSHED PARTICLES

Mn/DOT PROCEDURE – 1214

ASTM D 5821

Natural Aggregates vs Processed Aggregates

Natural Aggregates: typically from river or glacial deposits. (Pit Run)

Processed Aggregates: in most cases they are quarried. But can include natural

aggregate that has been crushed and separated into size fractions

PURPOSE

• The intended purpose of crushing aggregates is to change the particle surface texture from smooth to rough and the particle shape from round to angular (cubical).

• These characteristics will aid in the aggregate particles interlock and adhesion.

FRACTURED FACE• A fractured face is defined as being a broken surface,

caused either by mechanical means or by nature

• Natural fractures, to be accepted, must be similar to fractures produced by a crusher.

• The fractured face should have sharp or slightly blunted edges.

• The surface of the fractured face should be rough (not smooth nor polished) in texture.

CRUSHED PARTICLE

Defined as a particle of aggregate having at least one fractured face or two fractured faces, as required by

the specifications.

CRUSHED PARTICLESCharacteristics to Look For:

Sharp Edges, Rough Surfaces

Sharp Edges, Smooth Surfaces

Slightly Blunted Edges, Rough Surfaces

NON CRUSHED PARTICLESCharacteristics To Look For :

Rounded Particles, Smooth Surfaces

Rounded Edges, Smooth Surfaces

Mn/DOT’s Procedure Allows for

CRUSHED PARTICLES

UNCRUSHED PARTICLES

QUESTIONABLE PARTICLES(not to exceed 20%)

Examples