This specification covers the quality of rock to be used in the construction of rock riprap. Individual rock fragments shall be dense, sound, and free from cracks, seams, and other defects conducive to accelerated weathering. Except as otherwise specified, the rock fragments shall be angular to sub rounded. The least dimension of an individual rock fragment shall be not less than one-third the greatest dimension of the fragment. ASTM D 4992 provides guidance on selecting rock from a source. Except as otherwise provided, the rock shall be tested and shall have the following properties: Rock type 1 • Bulk specific gravity (saturated surface-dry basis)—Not less than 2.5 when tested in accordance with ASTM C 127 on samples prepared as described for soundness testing. • Absorption—Not more than 2 percent when tested in accordance with ASTM C 127 on samples prepared as described for soundness testing. • Soundness—The weight loss in 5 cycles shall not be more than 10 percent when sodium sulfate is used or more than 15 percent when magnesium sulfate is used. Rock type 2 • Bulk specific gravity (saturated surface-dry basis)—Not less than 2.5 when tested in accordance with ASTM C 127 on samples prepared as described for soundness testing. • Absorption—Not more than 2 percent when tested in accordance with ASTM C 127 on samples prepared as described for soundness testing. • Soundness—The weight loss in 5 cycles shall be not more than 20 percent when sodium sulfate is used or more than 25 percent when magnesium sulfate is used. Rock type 3 • Bulk specific gravity (saturated surface-dry basis)—Not less than 2.3 when tested in accordance with ASTM C 127 on samples prepared as described for soundness testing. • Absorption—Not more than 4 percent when tested in accordance with ASTM C 127 on samples prepared as described for soundness testing. • Soundness—The weight loss in 5 cycles shall be not more than 20 percent when sodium sulfate is used or more than 25 percent when magnesium sulfate is used.
