On the basis of measurements of slurries made with ash from fluidized bed and from fly ash without flue gas desulphurization from the power plant "X" and salt mine water from coal mine "Y", which density is equal to 1023 g/dm3, following conclusions can be formulated: 1. Independently to the type of fly ash, increasing amount of mine water in the slurry results in increasing table spread test results and decreasing density. For the same values of S/W ratio slurries with fluidized bed ash achieve significantly lower spread diameter than the slurries with fly ash, which does not contain flue gas desulphurization by-products (see Figs. 1 and 2). 2. Independently to the type of fly ash, increasing amount of mine water in the slurry increases volume of bleeding water. For the same values of S/W ratio slurries with fluidized bed ash achieve significantly larger spread diameter than the slurries with fly ash, which does not contain flue gas desulphurization by products (see Fig. 3). 3. Independently to the type of fly ash, increasing amount of water in the slurry (larger spread diameter) increases volume of water being absorbed by the fly ash. For the same values of S/W ratio slurries with fluidized bed ash achieve almost two times higher absorption capacity than the slurries with fly ash, which does not contain flue gas desulphurization by-products (see Fig. 4). 4. Independently to the type of fly ash, with increasing amount of salt water in the slurry setting and binding times are also increasing. For the same values of S/W ratio slurries with fluidized bed ash achieve significantly shorter setting and binding times than the slurries with fly ash, which does not contain flue gas desulphurization by-products (see Figs. 5, 6, 7 and 8). 5. Independently to the type of fly ash, compressive strength of all tested fly ash - water slurries decreases with increasing spread diameter. Slurries with fluidized bed ash achieve significantly higher compressive strength than the slurries with fly ash, which does not contain flue gas desulphurization by products. Slurries made with the last type of fly ash do not express any strength after 7 and 14 days of curing. After 28 days of curing their compressive strength ranges from 0.11 to 0.17 MPa, while slurries with fluidized bed ash achieve after 28 days of curing compressive strength in the range from 3.39 to 4.20 MPa (see Figs. 9 and 10). 6. Soak resistance tests have show that all slurries made with fly ash without flue gas desulphurization by-products did not express any resistance to soaking. Although slurries made with fluidized bed ash are characterized by soak resistance in the range between 9.29 and 27.7%, which increases with increasing spread diameter (see Figs. 11 and 12).