Investigation of the effect of corrosion inhibitor on blast furnace slag mortar properties

Concrete structures, produced at high costs, are affected by environmental conditions over time, reducing their durability before reaching their economic lifespan. Structures are expected not only to have high strength values but also a long service life. Thus, the concept of durability is important. One factor negatively impacting durability is reinforcement corrosion. To prevent corrosion, various protective methods are applied. Among these methods, corrosion inhibitors are used due to their numerous advantages. Additionally, during concrete production, pozzolanic mineral additives such as fly ash, granulated blast furnace slag, and silica fume are added to increase impermeability. This enhances the resistance of the reinforcement to corrosion, improving the structure's overall performance. additives increase impermeability, enhancing the reinforcement's resistance to corrosion. In this thesis, calcium nitrite was used as an inorganic corrosion inhibitor and granulated blast furnace slag as a mineral additive. The produced mortar samples were subjected to standard water curing for 28 days and then exposed to both standard curing and aggressive environment conditions (5% Na2SO4 + 5% NaCl) for comparison. The ultrasound pulse velocity, unit weight, flexural strength, and compressive strength of the samples were investigated. The results showed variations depending on the additive ratios and curing durations. Mortar samples cured under standard conditions and exposed to the aggressive environment (5% Na2SO4 + 5% NaCl) exhibited the highest strength values with 3% calcium nitrite (CN) and 10% granulated blast furnace slag (GBFS). This demonstrates that the combination of CN and GBFS positively impacts the performance of the mortar. In the series where GYFC replaced cement, significant improvements in durability were observed with extended curing times, resulting in 1.02% higher strength compared to the control sample. Additionally, the use of a 3% CN inhibitor, combined with extended curing, led to a 1.89% increase in results. When the most effective ratios of both GYFC and CN inhibitors were applied, both additives positively affected the physical, mechanical, and durability properties of the samples. This demonstrates the potential of GYFC and CN inhibitors to improve overall material performance when used in optimal proportions. Keywords: Corrosion, Inhibitor, GBFS, Durability, XRD, FE-SEM