Development of Nano silica based cement composites to scale down the marine bridge column corrosion rate

Abstract

For sustainable infrastructure development, India proposed a newlinespending plan of $1.67 trillion USD for 2024 to 2030. These infrastructure newlineprojects are designed for a service life exceeding fifty years. However, newlinepremature deterioration, particularly from steel corrosion in Reinforced newlineConcrete (RC) structures, often reduces their lifespan. Notably, the newlinemaintenance and repair costs of corrosion in India account for 4-5% of the newlineGross Domestic Product (GDP). In marine environments, coastal bridge newlinecolumns are especially vulnerable to corrosion caused by the continuous newlineingress of sea salts and humidity, which accelerates with the presence of newlinecapillary pores in the column cover. This study aims to mitigate corrosion by newlinereducing the porosity of High-Performance Concrete (HPC) through enhanced newlineparticle packing density, achieved by incorporating secondary binders. newline The secondary binders used in this study are sourced from newlineagricultural and industrial by-products. To address pore reduction at the newlinenanoscale, all concrete blends are formulated with nano-silica, varying the newlineproportions of secondary binders relative to the primary binder. Two different newlinetypes of primary binders, Ordinary Portland Cement (OPC) A and B, of the newlinesame grade from commercially available brands, were analyzed for their newlinephysical and chemical characteristics, including shape, size distribution (D10, newlineD50, and D90), specific gravity, and chemical composition. Optimizing the newlineparticle packing in these cementitious systems is challenging using newlineconventional methods, so the Modified Andreassen and Andreasen (MAA) newlineparticle packing model was employed with a distribution factor q of 0.3, newlineassuming an infinitesimally small particle size. newline newline