CRUSHED PARTICLES MnDOT PROCEDURE 1214 ASTM D 5821

% 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 PARTICLES Characteristics to Look For: ü Sharp Edges, Rough Surfaces ü Sharp Edges, Smooth Surfaces ü Slightly Blunted Edges, Rough Surfaces

NON CRUSHED PARTICLES Characteristics To Look For : ü Rounded Particles, Smooth Surfaces ü Rounded Edges, Smooth Surfaces

Mn/DOT’s Procedure Allows for CRUSHED PARTICLES UNCRUSHED PARTICLES QUESTIONABLE PARTICLES (not to exceed 20%)

Examples