Crushed Rock

Definition

Hard natural rock reduced to fragments by mechanical crushing or breaking. (Preparation of ore minerals also requires crushing but that is to secure crushed mineral rather than crushed rock and is not within this definition.)

Synonyms

Crushed stone

Introduction

Hard rock is mechanically crushed or broken mainly for construction aggregates and fill. Sources are primarily limestone, dolomite, sandstone, and igneous rock but sometimes quartzite and metamorphic rocks such as marble and granulite. Sources are widespread where bedrock is at or near the surface and is not significantly weathered or hydrothermally altered. Mineralogical composition, grain size, grain sorting, cementation, compaction, porosity, and weathering state directly affect potential uses. Selection depends on a variety of physical and chemical tests.

Crushing and Grading

Large blocks brought directly from the quarry blast pile are reduced to a few tens of centimeters or less, in primary crushers then further...