Prepared in cooperation with the Indiana Department of Transportation and Federal Highway Administration.
AbstractIn this study, the results of an extensive laboratory investigation conducted to evaluate the properties of concrete mixes used as patching materials to repair reinforced concrete slabs damaged by corrosion are reported.Seven special concrete mixes containing various combinations of chemical or mineral admixtures were developed and used as a patching material to improve the durability of the repaired slabs. Physical and mechanical properties of these mixes, such as compressive strength, static modulus of elasticity, dynamic modulus of elasticity, and shrinkage were evaluated. Durability-related parameters investigated included resistance of concrete to penetration of chloride ions and freeze-thaw resistance. The results generated during this research indicated that chemical and mineral admixtures improved physical, mechanical, and durability properties of repair concrete.In addition, the ability of various repair mixes to reduce the progress of corrosion was monitored using half-cell potential, polarization resistance, and electrochemical impedance spectroscopy techniques. Half-cell potential measurements provided information about the possibility of corrosion taking place on the steel surface. Polarization resistance measurements were used to determine the corrosion current density, and provided a quantitative estimation of the corrosion rate. Electrochemical impedance spectroscopy technique was used to monitor the corrosion rate, the change in resistivity of concrete, and change in polarization resistance.The results obtained from 21 reinforced concrete slabs exposed to cycles of wetting and drying indicated that both organic corrosion inhibitor and calcium nitrite (anodic corrosion inhibitor) delayed the initiation of active corrosion on the steel surface. Silica fume concrete, fly ash concrete, latex modified concrete, and concrete with shrinkage reducing admixture had low permeability and high resistivity. These properties improved the durability of repaired slabs either by delaying the initiation of active corrosion or by reducing the corrosion rate.
Key WordsCorrosion, rehabilitation, concrete, durability, reinforcing steel, bridge deck, chloride ion, corrosion rate, polarization resistance, electrochemical impedance spectroscopy.
Distribution StatementNo restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161 SPR-2141 Final Report
Development and Evaluation of Cement-Based Patching Materials for Repair of Corrosion-DamagedReinforced Concrete Slabs
IntroductionDamage of bridge decks due to corrosion of reinforcing steel resulting from the application of deicing salts is often extensive and typically requires expensive repairs.A common method of bridge decks repair involves removal of the contaminated and delaminated concrete, sandblasting of the steel surface and, in most extreme cases, replacement of damaged steel bar...
