Grouting curtain can effectively reduce seepage in dam foundation, decrease the uplift pressure of the dam foundation, and enhance foundation stability. Grouting parameters and effects vary significantly based on geological conditions and grout materials. Prior to implementation dam curtain engineering, it is essential to conduct effective grouting tests to determine grouting parameters. Cement or pozzolana-cement mixtures can both be used as cementitious materials for grout. At present, there is little relative research on pozzolana-cement grout. This paper disscussed the first grouting curtain test conducted in Tanzania using pozzolana-cement grout. Firstly, a qualitative analysis was conducted on the groutability of the rock mass by studying the basical geological and hydrological condition. Secondly, different cement ratios and water-cement ratios were studied in the laboratory to obtain the optimal grout. Thirdly, in-situ grouting tests with different borehole spacing in the slightly weathered jointed rock mass are carried out and verify the grouting effect with water pressure test results of check holes. The results show: (1) The joints of slightly weathered rock mass in the study area has good hydraulic connections in its natural state, proving it has good grouting conditions; (2) Comparative analysis of the different grout proportions shows that grout has good fluidity, impermeability, and compressive strength with water-cement ratio of less than 80% and pozzolana content of 40%; (3) There is no typical relationship between rock mass quality indicators, hydrogeological indicators and grout or cement absorption; (4) The inspection in check holes confirm that the diffusion radius of the grout in a single hole is 1.0–1.25 m; (5) After the implementation of the project, the observed flow rate of the drain holes in the drainage gallery is less than the design value, the measured reduction coefficient of the uplift pressure of the dam foundation meets the design value.