MODULE 4 -SPECIFIC GRAVITY, WATER ABSORPTION, ABRASION, DENSITY AND UNIFORMITY OF AGGREGATES

Aggregates

are inert materials derived from igneous, sedimentary; and metamorphic rocks or manufactured from clays, shales, slates and slags.

Natural sands and gravels

are generally available and therefore constitute the major source of aggregates.

Crushed stone

is the next most widely used class of concrete aggregate.

FINE AGGREGATES

are commonly known as sands and are composes of particles smaller than 3/16 inch nominal.

Sand or fine aggregate

is generally the product of natural disintegration of silica-bearing or calcium bearing rock.

COARSE AGGREGATES

are composed of particles larger than the clear opening of a No. 4 sieve (0. 185 inches), comes from natural grave deposits and also known as natural gravel which are formed by water, wind or glacial action.

Specific gravity

determines the weight and strength of aggregates

Abrasion resistance

is one of the most important attributes of aggregates and factor to consider in resisting wearing, crushing, degradation and disintegration

Bulk density or unit weight

is the ratio of mass or weight of aggregates to a specified unit volume.