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D5079-08 – Standard Test Method Technical Guide
The ASTM D5079-08 standard establishes comprehensive practices for the preservation, transportation, storage, cataloging, retrieval, and post-test disposition of rock core samples. These practices are critical for maintaining sample integrity from the field to the laboratory, ensuring that test results accurately reflect in-situ conditions. This standard is issued under the fixed designation D5079 and applies to both hard and soft rock.
🗂️ Classification of Core Care Levels
D5079-08 defines distinct levels of care based on sample sensitivity and intended use. Selecting the appropriate protection level is fundamental to successful core handling. The standard defines four key tiers:
| 🟦 Care Level | 📐 Definition | 🎯 Key Application |
|---|---|---|
| Routine Care | Non-sensitive, non-fragile samples. General visual identification is sufficient. Samples will not change or deteriorate before testing. | Visual inspection only, bulk samples for non-critical analysis. |
| Special Care | Fluid sensitive samples requiring later testing. Includes requirements of Routine care. | Samples where fluid content or saturation is relevant to testing. |
| Critical Care | Fragile or fluid/temperature sensitive samples. Includes the requirements of Routine and Special care. | Fractured zones, weak rock, reservoir intervals for petrophysical analysis. |
| Soil-like Care | Poorly consolidated materials requiring soil sampling procedures (D4220) to obtain intact core pieces. | Weak sandstone, shale, highly weathered or friable rock formations. |
💡 Hierarchical Protection System: The care levels are nested. Critical Care encompasses all the requirements of Special Care, which in turn includes Routine Care. Selecting a higher tier automatically satisfies the lower tiers of protection.
📦 Preservation, Handling, and Transportation Practices
Preservation techniques escalate with the care level. Routine care may involve simple wrapping and basic labeling. Special care introduces fluid retention methods (e.g., sealing in plastic, applying wax). Critical care requires strict moisture, temperature, and physical integrity controls, often involving rigid containers and climate monitoring. For soil-like care, procedures from Practice D4220 are adapted. Cataloging, core photography, and clear marking per the guidelines ensure full retrieval and post-test disposition capabilities as stated in the scope.
The standard specifically references Practice D2113 for Rock Core Drilling and Sampling, which details the initial extraction methods. Proper coordination between drilling and preservation protocols is essential to prevent mechanical damage and desiccation immediately upon core recovery.
⚠️ Scope Limitations and Technical Exclusions
D5079-08 applies to hard and soft rock but explicitly excludes ice and permafrost (Section 1.2). Furthermore, Section 1.3 provides critical limitations. These practices do not apply when changes in volatile gas components, contamination of pore fluids, or mechanical stress relaxation will significantly affect the intended use of the core. These scenarios require specialized preservation protocols beyond the scope of this standard.
| ⚡ Exclusion Category | 📌 Reason for Exclusion from Standard |
|---|---|
| Volatile Gas Components | Standard preservation methods cannot prevent changes in gas composition. |
| Pore Fluid Contamination | Requires inert, non-reactive preservation and handling materials. |
| Mechanical Stress Relaxation | Zero-stress conditions cannot be maintained during handling and transport. |
| Ice and Permafrost | Specialized temperature and phase-change controls are required beyond the standard’s scope. |
⚠️ Professional Judgement Required: Per Section 1.5, this document cannot replace education or experience. It must be used in conjunction with professional judgement, especially for projects with unique geological or geotechnical aspects. The word “Standard” in the title means it has been approved through the ASTM consensus process, but it does not represent or replace the standard of care for a given project.
❓ Frequently Asked Questions
🔍 What is the difference between Special Care and Critical Care?
Special Care is for fluid-sensitive samples requiring testing. Critical Care extends this by also requiring protection for samples that are fragile or temperature sensitive. Critical Care includes all the requirements of both Special and Routine care, making it the highest level of protection under the standard.
💡 Does this standard apply to permafrost or ice samples?
No. Section 1.2 explicitly excludes ice and permafrost from these practices. Core samples in these conditions may require a different set of preservation and temperature control protocols not covered by D5079-08.
⚡ When should “Soil-like Care” procedures be used?
Soil-like Care is required for materials that are so poorly consolidated that standard rock coring and handling techniques would be detrimental. In these cases, the procedures from Practices D4220 (Preserving and Transporting Soil Samples) must be employed to obtain intact pieces of core for analysis.
📌 What are the units of measure used in this standard?
Per Section 1.4, the values stated in inch-pound units are to be regarded as the standard. Values provided in parentheses in SI units are mathematical conversions for information only and are not considered standard.