1.1This test method covers the determination of carbonate content of soils and soft rock which can be readily broken down by mechanical effort. It is a gasometric method that uses a simple portable apparatus. Results should be clearly stated as the calcite equivalent in percent because different carbonate species cover a wide range of percent calcite equivalent as shown below for a number of carbonates:
| Species | Cation | Calcite
Equivalent, % |
| Magnesite | Mg | 117.0 |
| Dolomite | Ca, Mg | 108.6 |
| Calcite | Ca | 100.0 |
| Aragonite | Ca | 100.0 |
| Rhodocrosite | Mn | 87.1 |
| Siderite | Fe | 86.4 |
| Smithsonite | Zn | 79.8 |
| Witherite | Ba | 50.7 |
| Cerrusite | Pb | 37.5 |
For example, a 100 % dolomite would be expected to yield 108.6 % calcite equivalent while 100 % siderite would yield only 86.4 % calcite equivalent. Calcite and aragonite reactions will typically complete within about 10 minutes. This method does not distinguish between the carbonate species and such determination must be made using quantitative chemical analysis methods such as atomic absorption.
1.2Units—The values stated in SI units are to be regarded as the standard.
1.3All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.
1.3.1The 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.
1.4This 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 and health practices and determine the applicability of regulatory limitations prior to use. For specific precaution statements, see Section 8.