The study evaluated, through a series of permeability and diffusion tests, the hydraulic and the attenuation behavior of a compacted clayey soil, with and without the addition of Portland cement (0 to 2%). To evaluate the diffusive response, the specimens were subjected to a vertical static load (100 to 500 kPa), simulating the action of a waste mass, and to an acidic solution enriched with toxic metals Pb or Cd, prepared with pH varying from 1 to 6. The reactive behavior analysis indicated that retention by adsorption increased with the increase of pH, but was not affected by the applied static load. The combination of higher cement contents with higher pH caused precipitation to prevail over adsorption reactions.