Experimental Investigation on Strength of Corroded Reinforced Fly Ash Concrete Beam

Abstract

The principal reason behind the deterioration of structures is the corrosion of newlinereinforcing bars in reinforced concrete (RC). This corrosion prompts an increase in volume due newlineto the corrosion products and a reduction in the cross-sectional areas of the bars, resulting in newlineconcrete cracks. The harmful expansion caused by corroding steel is prevented by using newlinecorrosion-inhibiting admixtures in the concrete mix. These admixtures, either organic or newlineinorganic, form a protective layer on the steel, slowing down corrosion. Additionally, ecoand#65534;friendly options like silica fume and fly ash (FA) can be used. These supplementary newlinecementitious materials not only improve concrete properties but also potentially enhance its newlinecorrosion resistance, protecting the embedded steel reinforcement. The present study has been newlinedeveloped in two phases. Phase I explores the effect of different levels of corrosion on the newlineflexural strength of RC beams containing FA corrosion inhibitors. In Phase II, the focus is on newlineunderstanding the influence of varying degrees of corrosion on the torsional strength of RC newlinebeams with FA corrosion inhibitors. To simulate the effects of long-term corrosion, the newlineexperiment used an accelerated corrosion process on the RC beams. This technique induced newlinecorrosion in the embedded reinforcing bars within concrete. A half-cell potential test was used newlineto assess the corrosion resistance of longitudinal and transverse reinforcement in concrete newlinecontaining fly ash (FA) at different replacement percentages (10%, 20%, and 30%). The results newlineshowed that concrete with 30% FA replacement offered the greatest resistance to corrosion. newlineAfter the test, the actual level of corrosion was evaluated for both the longitudinal and newlinetransverse reinforcement bars by removing them from the concrete. newlinePhase I examined the effects of corrosion on the RC beams and analyzed flexural newlinestrength, load-deflection behavior, moment-curvature relationships, failure modes, and newlinecracking patterns. The replacement of 20% cement with FA increased the flexural strength of newlinecorroded beams. However, a significant rise in corrosion (from 10% to 15%) drastically newlinereduced their maximum flexural strength. This highlights the impact of corrosion on the ability newlineof the beam to absorb energy (ductility ratio). Additionally, increased rust volume exerted newlinepressure on the concrete, leading to various cracking mechanisms. Overall, Phase I newlinedemonstrates the significant influence of corrosion on both the reinforcing bars and the overall newlineperformance of the beam, including its load capacity, stiffness, ductility, and deflection. newlinePhase II examined the effects of corrosion on the RC beams subjected to pure torsional newlinemoments and analyzed the relationship between torque applied and the resulting twist (torque- newlineExperimental Investigation on Strength of Corroded Reinforced Fly Ash Concrete Beam newline viii Dr. Vishwanath Karad MIT World Peace University, Pune, India newlinetwist), crack patterns, and the ability of the beam to absorb energy (energy dissipation capacity newlineor EDC). Beams with the same reinforcement but varying fly ash (FA) content (10%, 20%, and newline30%) were tested under pure twisting forces with different levels of corrosion (10% and 15%). newlineThe maximum twisting capacity of the beams dropped significantly with increased corrosion. newlineThe results also showed a clear decrease in the ability of the beam to absorb energy as corrosion newlineincreased. To confirm these findings, the experimental data from the twisting tests was newlinecompared to a reliable model from previous research and further validated using computer newlinesimulations (finite element analysis).