Determination of some physico-thermal and mechanical characteristics of hydrated Jordanian Lajjun oil shale ash

The hydration of oil shale ash at different water-to-ash weight (W/A) ratios ranging from 0.4 to 0.8 was experimentally investigated. The ash hydrateâs physical characteristics, its particlesâ elemental composition, and the existing crystalline phases were identified using N2 Brunauer-Emmerich-Teller (N2-BET), Energy Dispersive X-ray (EDX) and X-ray Powder Diffraction (XRD) measurement techniques. The formed hydration cementitious products were found to be stratlingite (2CaO·Al2O3·SiO2·8H2O), ettringite (6CaO·Al2O3·3SiO3·32H2O), and melilite (2CaO·Al2O3·SiO2 ) in the oil shale ash hydrated at W/A = 0.6. These same phases with different relative amounts were found in the oil shale ash hydrated at W/A = 0.8 in addition to calcium silicate hydrates (CSH). The drop in the physico-thermal properties (bulk density and thermal conductivity) of the hydrated ash was attributed to the formation of cementitious products, mainly to stratlingite, melilite, and ettringite. The hydrated ashâs mechanical properties (bending and compressive strengths) were found to increase at higher W/A due to the formation of cementing materials, particularly CSH