Rock Mechanical Properties and Resource Potential of Dimensional Stone and Terrazzo in Tigray, Ethiopia - A Geological and Geomechanical Assessment
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2024-10-09 |
| Journal | Rock mechanics letters. |
| Authors | Zelealem Haftu, N. Rao Cheepurupalli, Yewuhalashet Fissha, Sri Chandrahas N, Blessing Olamide Taiwo |
| Institutions | Aksum University, G Pulla Reddy Dental College & Hospital |
| Citations | 3 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis study provides a geological and geomechanical assessment of granite and marble resources in the Tigray Region of Ethiopia, confirming their high potential for dimensional stone and terrazzo production for both domestic and global markets.
- Resource Quality Confirmation: Granite and marble deposits were verified to possess high quality, meeting essential parameters including durability, workability, cutability, and polishability, aligning with international standards (BS, ASTM, DIN).
- Mechanical Performance: Granite demonstrated superior mechanical properties, exhibiting compressive strengths up to 135 kg/cm2 and low porosity (0.42% to 1.12%), making it suitable for heavy-duty structural and external applications.
- Aesthetic Suitability: Marble, characterized by high polishability and diverse colors (white, gray, pink, green), is highly recommended for internal decorative uses, such as flooring and wall cladding, despite its lower strength (81-83 kg/cm2).
- Substantial Reserves: Geological mapping identified vast estimated reserves, such as Dichenama marble (9.2 x 109 m3) and Negash granite (5.8 x 107 m3), supporting long-term, large-scale industrial exploitation.
- Extraction Feasibility: Resources are widespread and structurally intact, allowing for extraction using relatively simple technology (diamond wire saws, wedging) with minimal environmental impact and low initial investment requirements.
- Petrographic Uniformity: Analysis confirmed mineral dominance (quartz/feldspar in granite; calcite in marble) and low impurity levels, ensuring color homogeneity and texture uniformity crucial for commercial viability.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value Range (Granite) | Value Range (Marble) | Unit | Context |
|---|---|---|---|---|
| Compressive Strength | 105 to 135 | 81 to 83 | kg/cm2 | Structural load-bearing capacity (ASTM C 170). |
| Porosity (P) | 0.42 to 1.12 | 0.57 to 1.98 | % | Indication of micro-voids and water permeability. |
| Water Absorption | 0.082 to 0.156 | 1.1 | % | Marble shows significantly higher absorption, limiting external use. |
| Dry Density | 2.703 to 2.739 | 2.69 to 2.71 | kg/cm2 | Measured according to ASTM D 153. |
| Flexural Strength | 2.697 to 2.730 | 2.627 to 2.75 | kg/cm2 | Resistance to bending (ASTM C 880). |
| Abrasion Resistance | 0.11 to 0.31 | 1.51 to 1.71 | Mm | Granite is significantly harder and more abrasion-resistant. |
| Soluble Matter | 0.12 to 0.34 | 0.36 to 0.5 | % | Low solubility, meeting ASTM D 2196 limits (0.4% for marble, 0.25% for granite). |
| Hardness (Mohs) | > 3 (Quartz presence) | 3 (Calcite dominance) | Scale | Affects cutting and polishing processes. |
| Estimated Reserve (Max) | 7.6 x 108 (Kisadgaba) | 9.2 x 109 (Dichenama) | m3 | Potential for large-scale industrial exploitation. |
Key Methodologies
Section titled âKey MethodologiesâThe assessment employed a combination of field investigation, laboratory testing, and data correlation analysis:
- Geological Mapping and Sampling: Detailed geological mapping was conducted at quarry sites and exposures. A total of 30 representative samples (15 granite, 15 marble) were systematically collected, ensuring coverage of lateral and vertical lithological variations.
- Petrographic Analysis: Thin sections were prepared and examined under cross-polarized light (XPL) to determine mineralogy (e.g., modal proportions of K-feldspar, quartz, calcite), texture (fine to coarse-grained), fabric, and the presence of relict textures or impurities (chloritization, epidotization).
- Physico-Mechanical Testing: Tests were performed according to established standards (ASTM C 170, C 880, D 2196, C 128, etc.) to quantify key engineering properties:
- Density and Porosity: Calculated using dry weight (Wo), saturated weight (W2), and weight in water (W1).
- Strength Tests: Uniaxial Compressive Strength and Flexural Strength (simple beam, quarter-point loading) were measured.
- Durability Tests: Water Absorption, Abrasion Resistance (measured as thickness loss after 352 revolutions), and Matter Soluble in Water were determined.
- Luster and Hardness Assessment: Luster (ranging from dull/grainy in granite to whitish/cloudy in marble) and Hardness (Mohs scale) were assessed to evaluate aesthetic and processing characteristics.
- Data Correlation: A Pearson correlation plot was generated to illustrate the relationships between all measured physical and mechanical properties, aiding in the optimization of material selection.
Commercial Applications
Section titled âCommercial ApplicationsâThe high-quality granite and marble resources identified are suitable for diverse applications across several industries:
- Construction and Architecture:
- Granite: Used for structural foundations, exterior cladding, urban road surfaces (curbs, cobblestones), and high-durability applications like kitchen countertops and stair treads.
- Marble: Highly recommended for internal decorative applications, including polished floor tiles, wall cladding, windowsills, and columns, due to its superior polishability and aesthetic appeal.
- Manufacturing and Processing:
- Terrazzo Production: Crushed marble and granite aggregates serve as essential components for manufacturing terrazzo, a composite material used for flooring and decorative surfaces.
- Stone Fabrication: The production of semi-finished and finished products (slabs, cut-to-size tiles) for both domestic consumption and export.
- Infrastructure Development:
- Utilized in civil engineering projects requiring durable, high-strength materials, such as dams, coastal defenses, retaining walls, and monuments.
- Global Export Market:
- The confirmed high quality and compliance with international standards position these resources, particularly the large, uniform blocks of granite (Negash, Kisadgaba) and marble (Dichenama, Naeder), for entry into competitive global stone markets (e.g., China, Turkey, Saudi Arabia).
View Original Abstract
Dimension stone and terrazzo are quarried rocks following specific dimensions, generally huge in tonnage than ore minerals. Dimension stone and Terrazo resource development opportunities in the Tigray Region, Ethiopia, are studied regarding their potential to make dimension and terrazzo, geology and deposit nature, physio-mechanical properties, rock petrography, and opportunity for exploitation. The granite and marble are quarried as dimension stones and they meet the quality parameters of the rocks, which include, being durable, easy to quarry, work, cut, and polish. It was conducted through the integration of new geological descriptions, interpretation of thin sections, and physico-mechanical tests. Both surface and quarry rock samples were used for the study. 15 from granite and 15 from marble deposits in total 30 samples were used for petrographic analysis and physico-mechanical tests. Based on petrographic and physicomechanical results, granite is harder than marble this may be due to silicates being less dissolved than carbonates. The accessory minerals in both granite and marble deposits limit the quality of the deposits as being impurities. The integrated results indicate that the marble and granite deposits in the area are good in quality and quantity. In addition, they are geologically widespread, technologically do not need sophisticated technology and economically they do not need huge investment and have less effect upon the environment. Diamond wire saws and diamond belt saws separated the dimension stone, which are oblate to curved in shape with 1m width. In the area, investment has been at a relatively low stage more investment will significantly increase production of the dimension stone for local usage, export, and economic growth of the region.