Abstract
The objective of this paper is to examine the effect of Cr, Mn, Pb, and Zn, on the mechanical and leaching characteristics of cement-based materials. Three different matrices (i) Portland cement, (ii) Portland cement and silica fume, and (iii) Portland cement and natural zeolites, were investigated. The results of both mechanical and leaching tests showed the importance of the contaminant/matrix pair considered. The setting time was reduced in presence of chromium and delayed in presence of manganese, lead and zinc. Although the early strength development was quite affected in presence of all four contaminants, the long-term strength was comparable to the controls. From 56 days of curing onwards, partial replacement of cement by silica fume was proven to increase the strength of all materials. Conversely, zeolite replacement reduced strength compared to the cement matrix, which was attributed to the high water/binder ratio used. The increased strength and reduced ANC observed in presence of silica fume, are both due to the pozzolanic reaction, which consumes portlandite to form CSH.