This research aimed to analyze the effects of using tuff and limestone as supplementary pozzolanic materials on the permeability of a classic C12/15 concrete composition. There were designed two types of concrete compositions with different degrees of permeability, namely P8 10 and P12 10 as reference concrete compositions and eight experimental concrete compositions with tuff in 6% and 10% of the cement quantity and with limestone in the same proportions. According to results, the tuff and limestone led to the decrease of concrete permeability, the best values being registered in the case of using 10% tuff in the concrete composition with P8 10 class of permeability.

There exists an interest to realize impermeable concrete, which would have many applications in bridges and water transport / storage structures, such as tanks, reservoirs, gutters and pipes. Furthermore, it would be possible to use such a type of concrete in other structures where the water pressure represents an exterior action, such as basement walls, caissons and slab foundations. However, absolutely impermeable concrete is almost impossible to be obtained, hence low – permeability concrete could be the correct technical term. In the current article, several samples of such concrete (containing active admixtures) are detailed and relevant conclusions are drawn.