Department of Geology

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    Evaluation Of Limestone as Coarse Aggregate in Concrete and Cobblestones: A Case study from Mekelle Area, Northern Ethiopia
    (Mekelle University, 2024-11-25) Muez Aregawi
    Engineering geological investigation is essential for evaluating the quality of construction materials and ensuring the durability of engineering structures. This study assessed the physical and mechanical properties of limestone aggregates from selected quarries in the Mekelle area to determine their suitability for concrete and stone-paved road applications. A total of twelve representative samples and 50 kg of coarse aggregates were collected according to ASTM D75 from the Shugala, Kokolo, Mayalem, Mossobo, Chanadug, and Genha quarry sites and tested for gradation, specific gravity, unit weight, water absorption, moisture content, flakiness index (FI), aggregate crushing value (ACV), Los Angeles abrasion value (LAAV), and unconfined compressive strength (UCS), with results compared to ASTM and BS standards. The results indicate that the tested aggregates largely satisfy international specifications. Specific gravity values ranged between 2.43 and 2.83, while unit weight varied from 1.47 to 1.65 g/cm³. According to ASTM C33 classification, these unit weight values confirm that the aggregates are normal weight. Water absorption values (0.11%–0.78%) fall within the required range, indicating low porosity and good durability. Moisture content is very low (0.012–0.39%), significantly below the 4% limit, ensuring that the aggregates are dry. Mechanical tests revealed flakiness index values ranging from 12.11–20.30%, ACV values from 10.66–22.16%, LAAV values from 19.18– 25.40%, and UCS values from 105–117 MPa, indicating that all samples fall within the “highstrength” category (>55 MPa). Sieve analysis further revealed that aggregates from Chanadug, Genha, Mossobo, and Mayalem quarries exhibit favourable particle size distribution, making them highly suitable for construction, while those from Shugala and Kokolo did not meet gradation criteria.