Investigating the Effects of Copper Slag and Silica Fume on Durability, Strength, and Workability of Concrete

Abstract

Workability, strength, durability, economic considerations, and attention to sustainable development issues are some crucial factors in designing an appropriate mix. The use of copper slag as a partial replacement of cement is an effective method of pollution reduction and conservation of resources, since it reduces cement use. In addition, silica fume is used in combination with copper slag to make concrete structures more durable. The main purpose of this study was optimizing important variables of concrete mix design including cement factor, water-to-binder ratio (w/b), copper slag, and silica fume to improve concrete durability. To achieve this goal, an experimental research was carried out, based on standards, to optimize changes in the said fields. Concrete durability is determined by experiments considering electrical resistance of concrete, bulk electrical conductivity, and chloride migration coefficient. Interfacial transition zone and cement microstructure were evaluated using X-ray analysis and scanning electron microscopy. The results of this research indicated that simultaneous use of copper slag and silica fume with appropriate values of other factors (cement factor and w/b ratio) yields a more durable, workable and strengthened mix design. The optimized mix introduced a workable, durable, resistant, and economical mix design with 7% and 20% of cement replaced with silica fume and copper slag, respectively. This innovative study included simultaneous use of copper slag and silica fume as a replacement for cement.