In this study, the effects of tuff natural pozzolan on properties of Portland cement were investigated. The durability and mechanical properties of concrete made by these cements were studied. It was found that using the natural pozzolan does not significantly affect the mechanical properties of the Portland cement. Furthermore, the natural pozzolan-containing concrete did not perform well in freeze and thaw and sulfate expansion tests. Considerable improvements in depth of water penetration, expansion due to alkali—silica reaction, alkali reactivity and a slight improvement in chloride ion permeability were observed.