Properties of green concrete containing stainless steel oxidizing slag resource materials

• Replacing the natural aggregate with SSOS improves the compressive strength.
• The expansion of the 100% SSOS aggregate is less than the requirement.
• The durability of the SSOS aggregate concrete is enhanced.
• No heavy metals leach from the SSOS aggregate material or mixed concrete occurred.
• This study shows that the optimal aggregate replacement ratio for SSOS is 100%.

This study aims to investigate the engineering properties of green concrete containing stainless steel oxidizing slag (SSOS). The goal of this study is to determine the best substitution proportion of the SSOS for fine and coarse aggregates. The results indicated that a 100% substitution of SSOS for the natural fine aggregate creates a mortar with better compressive strength. A 100% SSOS substitution also produces better hardened concrete properties, such as the compressive strength, surface resistance and ultrasonic pulse velocity, than the natural coarse aggregate. Furthermore, X-ray diffractometer (XRD) and energy dispersive spectrometer (EDS) microstructure analyses show that the CH content tend to decrease with increasing SSOS aggregate substitution, and the alkaline elements sodium (Na) and potassium (K) dissolve into the mortar and coarse aggregate interfaces. These alkaline reducing agents help improve the concrete durability. Additionally, heavy metals do not leach from the SSOS concrete. Thereby, the SSOS could be considered a green concrete material as it is a recycled resource.