Abstract: Germanium slag, as the solid wastes in the process of mineral resources exploration and utilization, but the storage of slag for long-term not only causes the waste of resources, but also seriously affects the surrounding environment. The physico-chemical properties of germanium slag was researched, and the germanium can be used as cement admixture. Na₂CO₃, AlCl₃·6H₂O, Ca(OH)₂ as well as NaAlO₂ could be used as activator to enhance the comprehensive strength of samples, NaAlO₂ has the most activition, NaAlO₂ and hydration products Ca(OH)₂ reaction and generated octahedral [Al(OH)₆]^2-, which reaction with gypsum under alkaline environment and ettringite was generated and would enhance the sample strength.

Key words: Germanium slag, Activator, Cement admixture