Slag is a steel-industry-waste categorized as potential environmentally harmful, containing heavy metals such as Arsenic (As), Lead (Pb), Chromium (Cr), Cuprum
(Cu) and Zinc (Zn). A major Steel Plant in Semarang, Indonesia produces steel - slag that is suspected of polluting soil and groundwater. In this study attempts have
been made to utilize this slag-waste as substitute for the aggregates used in concrete. Since in hardened concrete the slag will be concealed totally by the cement paste, it was hoped that the environmental impact can be controlled.
The investigation was based on the substitution method whereas the coarse as well as the fine aggregates are replaced with slag. The research covers a range of concrete’ strengths and the percentage of slag substitute were set as variable.
The study demonstrated that the compression-strength-to-conventional-concrete ratio increases, as the coarse slag content ascends. However, the addition of fine slag will decrease the compression strength significantly. From the results it was also proven that with a 100% of slag substitution the heavy-metal leaching concentration rate is below the assigned border mandated by the Department of
Industry regulations and supports the International Atomic Energy Agency margins
