【国外标准】 Standard Test Method for Evaluation of Durability of Rock for Erosion Control Under Wetting and Drying Conditions

5.1 Rock for erosion control consists of individual pieces of natural stone. The ability of these individual pieces of stone to resist deterioration due to weathering action affects the stability and longevity of the integral placement of rock for erosion control and hence, the stability of construction projects, structures, shorelines, and stream banks.5.2 This test method is designed to determine the effects of wetting and drying action on the individual pieces of rock for erosion control and the resistance of the rock to deterioration. This test method is used in conjunction with additional test methods listed in Practice D4992. This test method does not provide an absolute value but rather an indication of the resistance to wetting and drying. Therefore, the results of this test method are not to be used as the sole basis for the determination of rock durability. The data is summarized, and any interpretations of the data are made by the end-user or client.NOTE 1: The quality of the result produced by this standard is dependent upon the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that 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 depend on many factors; Practice D3740 provides a means of evaluation some of those factors.1.1 This test method covers procedures for evaluating the durability of rock for erosion control when exposed to wetting and drying conditions on slabs of rock using both qualitative and quantitative methods. This durability test exposes the rock samples to a cycle of wetting and drying such as those experienced due to fluctuating water levels and weather conditions, with tests done at room temperature as the baseline. The rock slabs, prepared per procedures in Practice D5121, are intended to be representative of the proposed source of erosion control rock and its weaknesses.1.2 The test is appropriate for breakwater stone, armor stone, riprap, and gabion sized rock materials.1.3 The limitations of the test are twofold.1.3.1 First, the size of the cut rock slab specimens may eliminate some of the internal defects present in the rock structure. The test specimens may not be representative of the quality of the larger rock samples used in construction. Careful examination of the rock source and proper sampling is essential in minimizing this limitation.1.3.2 Secondly, the test requires the rock slabs to be exposed to 80 cycles of wetting and drying. The test is time-intensive and would require a minimum of three months and up to six months to complete the sample preparation, testing, and analysis portions of the procedure.1.4 The use of reclaimed concrete and other such materials as rip rap is beyond the scope of this test method.1.5 Units—The values stated in either SI units or inch-pound units [presented in brackets] 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 non-conformance with the standard.1.5.1 The gravitational system of inch-pound units is used when dealing with inch-pound units. In this system, the pound (lbf) represents a unit of force (weight), while the unit for mass is slugs. The slug unit is not given unless dynamic (F=ma) calculations are involved.1.5.2 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 for mass. However, the use of balances or scales recording pounds of mass (lbm) or recording density in lbm/ft3 shall not be regarded as nonconformance with this standard.1.5.3 Calculations are done using only one set of units; either SI or gravitational inch-pound. Other units are permissible, provided appropriate conversion factors are used to maintain consistency of units throughout the calculations, and similar significant digits or resolution, or both are maintained.1.6 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026, unless superseded by this standard.1.6.1 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.1.6.2 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, the 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.1.7 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.1.8 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.