The usability of two environmentally important waste materials in cementitious fine grout production was investigated as partial replacement materials. The study is very important in reducing carbon footprint and cost in construction industry, and improving cement properties. The influence of replacement materials on flowability and strength was investigated by rheological and compressive strength tests. With marble powder replacement, a compressive strength of 26 MPa was achieved, which was fairly above the minimum compressive strength of 14 MPa. The flowability and strength of the mixes were heavily dependent on W/C ratio and affected by type and amount of replacement materials. Increasing W/C ratio and fly ash amount increased flowability, but inversely affected strength of the grouts. On the other hand, marble powder was found to increase the strength to a large extent, but decreased the flowability. The highest increase of 24 % and the lowest increase of 5.3 % on average were achieved with 10 % fly ash and 20 % marble powder replaced mixes, respectively. The rheology data, obtained in a wide shear stress-shear rate range, were found very useful in explaining flowability as well as setting behavior (rate) of grout mixes.