Estimation of alkali diffusivity from dynamic leaching test

摘要

The reuse of waste materials from manufacturing plants in order to decrease the material volume to be disposed to landfill is increasingly receiving public interest. This research is focused in the evaluation of alkali diffusivity using a short term dynamic leaching test. Such tests are necessary because of environmental regulations. In this study, several concrete mixes were used in order to test the applicability of the method. Concentration profiles of calcium, sodium, potassium and chloride are interpolated with a semi-empirical expression based on diffusion-like leaching behaviour. Although a simplification is introduced, preliminary results indicate that the calculated diffusion coefficient agree with those reported in several other findings. Moreover, the presence of recycled materials slightly increases the ion leachability (K, Na, Cl) and the substitution of fine fraction aggregate results in a lower net leaching suggesting an increase in pozzolanic activities.