Compressive strength and corrosion behavior of steel bars embedded in concrete produced with ferronickel slag aggregate and fly ash: an experimental study

Waste slag from the metallurgical industry such as ferronickel slag (FNS) is a promising material to replace natural sand (NS) in the production of sustainable concrete. This study experimentally investigated the performance of concrete containing 50% FNS as well as the replacement of 15 and 30% of cement with FA by determining the slump, density, and axial stress–strain behavior under compression load. Furthermore, an accelerated corrosion test was conducted by subjecting the reinforced concrete specimens to a 3% NaCl solution and a constant voltage of 10 V up to 240 h in order to evaluate their corrosion resistance performance. The test results showed that the slump and density of concrete increased due to the presence of FNS and FA compared to the control concrete. It was discovered that all the specimens expressed linear behaviors till when the peak stress was reached under compression load. Moreover, the peak stress, peak strain, modulus of elasticity, and toughness of FNS-FA concretes are higher than the values for the control concrete but their ultimate strain is lower at approximately 12.27–17.59%, thereby, indicating the brittleness of FNS-FA concretes. The findings also showed that concrete considered to be durable against corrosion can be produced using 50% FNS and 30% FA with approximately 1.4 and 2.2 times longer initial time to first cracking and lower weight loss, respectively, than the control specimen. Therefore, the concrete mixture of 50%FNS-30%FA is a viable option in designing sustainable concrete structures exposed to a chloride environment.