Tuffs which are known as a trass are used as the additive material in the manufacture of the portland composed cement. Zeolitic tuffs (ZT) are porous, natural volcanic tuffs that contain zeolite mineral. The most important feature of zeolite mineral is the ability of changing ion. In the first stage of this study, zeolitic tuff sample was taken from rock mass and grinded alone in order to be used as additive material to portland cement of 42,5. The usability of zeolitic tuff sample as trass was investigated and chemical, physical, mechanical properties were also determined and were inspected in accordance with TS 25 standard. In subsequent stage of this study, ZT were used in the ratio %0, %10, %20, %30 and %40 instead of Portland cement of 42,5. Tap water and sea water were used in two different ways as mixture water and mature water to produce cement paste and 40x40x160 mm mortar prisms: In the first group production tap water was used as mixture water, used tap water was used as mature water (TT), in the second group production was used sea water as mixture water, used tap water as a mature water (ST). The use of sea water as mixing water and the addition ratio of ZT into the cement effect on setting time, volume expansion of cement paste and compressive and flexural strength for 7, 28, 90 days were tested. After control samples, the highest compressive and flexural strength value of %10 were obtained ZT additive cement mortars.