A laser based ultrasonic technique is explored for predicting the mechanical integrity and durability of cementitious materials. It is well known that these properties depend on the mechanical properties, and structural properties including porosity and permeability. The technique used involves the measurement of the phase velocity of fast and slow longitudinal waves in water saturated cement paste. The slow wave velocity is related to the specimen's tortuosity, which is closely related to the permeability. The fast wave speed is dependent on the elastic properties of porous solid. Experimental results detailing the generation and detection of fast and slow wave waves in freshly prepared and aged water-saturated cement samples with varying water-to-cement ratios are presented.