Introduction:
This web site is dedicated to rock aggregates, their properties, durability, and uses. More specifically, it describes the nature of aggregates based on their geologic origin, and how their origin affects their properties. The rocks' petrographic and pore properties largely dictate their suitability as building materials.
The important properties of aggregates are those that affect their use and durability. Since aggregates are used in long-lasting structures, their inherent longevity in use, and the longevity or durability that they impart to the structure are important. The effect of environment on their properties determines their durability: wetting-drying, freezing-thawing, wear and impact, and application of chemicals, such as deicing salts.
The principal properties of aggregates is their tensile and compressive strengths, and their pore size and distribution. Most aggregates are inert, but some react with solutions to which they are exposed: salt solutions and alkalis of cement.
Most durability concerns arise when they are used in concrete. Since concrete comprises about 70% of aggregates by volume, the properties and durability of aggregates will affect the durability and property of concrete, all other conditions being equal.
