Evaluation of field and laboratory produced burnt clay pozzolans

This study evaluated the properties of laboratory and field burnt clay pozzolans from three sites in Northern Oman (Fanja, Al-Fulaij and Bahla). The raw clays were burnt at 740 °C for two hours. The parameters investigated included chemical compounds, setting times, slump, consistency, compressive strength, and absorption. Compressive strength was measured after 7, 14, 28 and 90 days of curing. The results showed that Fanja and Al-Fulaij clays comply with the ASTM standard for production of good pozzolans whereas Bahla clay falls below the minimum standard requirement. Fanja and Al-Fulaij laboratory-burnt and kiln-burnt clay pozzolans showed generally similar values in terms of consistency and compressive strength. Fanja laboratory-burnt sample attained the highest strength of 26.50 MPa at 90 days whereas Bahla kiln-burnt sample showed the lowest strength of 4.82 MPa at the same duration. Both Fanja and Al-Fulaij samples showed similar results in terms of durability tests length change. All samples showed similar trend in surface absorption test, with high value in the first 10 min, then reducing to almost a constant value afterwards.