5.1 Rock for erosion control is composed of pieces of natural rock that are placed on construction projects, shorelines, streambeds, bridge abutments, pilings, and other structures to minimize the effects of erosion. The ability of rock to withstand deterioration from weathering affects both the effectiveness of the project and its cost. The specific gravity and absorption of rock provide useful information that can be used in evaluating the durability of the rock as well as its resistance to movement by water.

5.2 The absorption of water into rock may affect its durability under freezing conditions and salt crystallization conditions. In addition, the absorption test has been used as an index test in determining whether additional tests are needed to evaluate the durability of a rock.

5.3 Test specimens equal in size to the proposed design size would provide the best correlations between laboratory tests and actual field performance, however this is usually neither practical nor economically feasible.

5.4 The results of these tests are not to be used as the sole basis for determination of rock durability, and shall be used in conjunction with the results of other tests.

5.5 These test methods have been used to evaluate different types of rocks. There have been rare occasions when test results have provided data that have not agreed with the durability of rock under actual field conditions. For example, some rocks with low absorption values have fragmented in actual usage and some with high absorption values have proven to be durable.

Note 2: The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies which meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depends on many factors; Practice D3740 provides a means of evaluating some of those factors.

1.1 This test method covers the determination of specific gravity and absorption of rock for erosion control. The specific gravity may be expressed as bulk specific gravity or apparent specific gravity. Bulk specific gravity and absorption are based on a 24 ± 4-h soaking time for the rock specimens tested. This test is appropriate for breakwater stone, armor stone, riprap, and gabion sized rock materials, or similar.

1.2 The use of reclaimed concrete and other materials is beyond the scope of this test method.

1.3 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.

1.3.1 The gravitational system of inch-pound units is used when dealing with inch-pound units. In the system, the pound (lbf) represents a unit of force (weight), while the units for mass is slugs. The slug unit is not given, unless dynamic (F = ma) calculations are involved.

1.3.2 It is common practice in the engineering/construction profession to concurrently use pounds to represent both a unit of mass (lbm) and of force (lbf). This practice implicitly combines two separate systems of units; the absolute and the gravitational systems. It is scientifically undesirable to combine the use of two separate sets of inch-pound units within a single standard. As stated, this standard includes the gravitational system of inch-pound units and does not use/present the slug unit of mass. However, the use of balances and scales recording pounds of mass (lbm) shall not be regarded as nonconformance with this standard.

1.4 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026, unless superseded by this standard.

1.4.1 For purposes of comparing measured or calculated value(s) with specified limits, the measured or calculated value(s) shall be rounded to the nearest decimal or significant digits in the specified limits.

1.4.2 The procedures used to specify how data are collected/recorded or calculated, in this standard are regarded as the industry standard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do not consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the user’s objectives; and it is common practice to increase or reduce significant digits of reported data to be commensurate with these considerations. It is beyond the scope of this standard to consider significant digits used in analytical methods for engineering design.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.