Search

• Cement-replacing with tailings is one of the practical management approaches. • The use of tailings in the concrete matrix reduced the leaching rate of heavy metals. • Mechanical activation of LZTs without addittive causes the formation of new phases. • Mechanical activation increases the LZTs reacitivty for concrete construction. • Concrete containing activated LZTs represented a more uniform elements distribution. Use of mine tailings as a replacement for cement in concrete construction is a highly efficient method to reduce the environmental pollution of tailings' accumulation including toxic elements, acid mine drainage, and dust emission. Thus, safe management and accurate reuse of tailings is necessary. In this research, lead–zinc mine tailings (LZTs) were used and their reactivity were improved through mechanical activation. The compressive strength, mercury intrusion porosimetry (MIP), and toxicity characteristic leaching procedure (TCLP) tests were performed on the concrete samples. The TCLP test revealed that an increase in curing days led to a significant reduction in heavy metal leaching rate (cobalt, zinc, lead, nickel, copper, arsenic, cadmium and chromium) to a permissible limit. This indicates that the application of LZTs in concrete construction would lessen environmental concerns. The MIP test indicated that mercury intrusion volume in the activated sample with 20 % cement-replacement (T A20) was lower than that of the raw sample with 20 % cement-replacement (T R20) and control (C 100) samples. The results from X-ray diffraction (XRD) analysis showed that upon activating and increasing the curing time, the hatrurite converted to scawtite in samples containing activated tailings. The compressive strength results after 28 and 90 curing days revealed a rise in the strength from 16.9 MPa to 19.8 MPa for concrete samples T R20. However, upon prolonging the curing time from 28 up to 90 days, the compressive strength of the concrete samples T A20 grew from 28.35 MPa to 45.5 MPa. This indicates that the mechanical activation enhanced the hydration process and the cohesion of samples. The results of scanning electron microscopy (SEM) revealed that hydration products were also observed in concrete samples containing activated tailings. Overall, the results showed that mechanically activated LZTs, up to 40 % (by weight), can be a suitable substitute for cement in concrete production. [ABSTRACT FROM AUTHOR]