AGGREGATE BASE COURSE ‎

Aggregates consist of both fine and coarse fragments of crushed stone, or crushed gravel mixed or blended with sand, screenings, or other similar approved materials. Crushed stone consists of hard, durable particles or fragments of stone.

The crushed gravel consists of hard, durable stones, rock, and boulders crushed to specified size. Produce aggregate free from excess flat, elongated, soft or disintegrated pieces, dirt, or other objectionable matter. The method used in production of crushed gravel shall be such that the fractured particles occurring in the finished product shall be constant and uniform and shall result in at least 45 percent of material retained on a No. 4 mesh (4.75 mm) sieve having one or more fractured faces. If necessary to meet this requirement or to eliminate an excess of fine, uncrushed particles, screen the gravel before crushing. Stones, rocks, and boulders of inferior quality in the pit shall be wasted.

Crushed coarse aggregate shall not have more than 50 percent wear at 500 revolutions as determined by ASTM C 131. When the fraction of the aggregates retained on the No. 4 mesh (4.75 mm) sieve is subjected to five cycles of the sodium sulphate soundness test (ASTM C 88), the weighted loss shall not exceed 18 percent by weight, unless otherwise provided in the Contract. Incorporate material passing the No. 4 mesh (4.75 mm) sieve produced in the crushing operation of either stone or gravel in the base material to the extent permitted by the gradation requirements. Oversized stones, rocks and boulders occurring in the pit or quarry material shall be wasted; those of acceptable quality may be crushed and become a part of the base material, provided the blend meets the specified gradations.

The aggregate shall be free from vegetation, lumps, or excessive amounts of clay and other objectionable substances.