Corrosion Measurements in Reinforced Fly Ash Concrete Containing Steel Fibres Using Strain Gauge Technique

Corrosion of steel bars in concrete is a serious problem leading to phenomenal volume expansion and thereby leading to cover concrete spalling. It is well known that the reinforced concrete structures subjected to chloride attack during its service life cause these detrimental effects. The early detection of this damage potential can extend the service life of concrete. This study reports the comprehensive experimental studies conducted on the identification of corrosion mechanism in different types of reinforced concrete containing class-F fly ash and hooked steel fibres. Fly ash replaced concrete mixes were prepared with 25% and 50% fly ash containing steel fibres at 0.5%, 1.0%, and 1.5% by volume fraction. Corrosion process was investigated in an embedded steel bar (8？mm diameter) reinforced in concrete by passing an impressed current in sodium chloride solution. Strain gauge attached to the rebars was monitored for electrical measurements using strain conditioner. Strain gauge readings observed during the corrosion process exhibited the volume changes of the reinforcement embedded inside the concrete. The corrosion potential of different steel fibre reinforced concrete mixes with fly ash addition showed higher resistance towards the corrosion initiation. 1. Introduction Reinforced concrete corrosion studies have drawn significant attention owing to high potential for the deterioration of structures during its service life. The process of corrosion occurs in reinforced concrete due to depassivation of protective layer in steel. This can occur when the concrete quality is deteriorated over time as a result of improper material design. Permeability of concrete is the process by which the deterioration starts in cementitious systems. Also, the initiation of corrosion is primarily dependent on the alkalinity of concrete surrounding the steel bars. Depending upon the alkalinity, the process of depassivation occurs in concrete leading to formation of anodic sites on the steel bars. It was shown in many research studies that the incorporation of fine filler materials or the pozzolanic inclusions can form a refined microstructural formation in concrete. This also ensures a good quality of concrete which can serve better for long term durability. However, corrosion in reinforced concrete needs to be identified in the initial stages in order to protect and take remedial measures for protecting it. Several studies indicated that the addition of large volume fly ash in cement concrete provides adequate refinement of pore structure leading to impermeability. It