Development and evaluation of cement -based materials for repair of corrosion -damaged reinforced concrete slabs
Abstract
In 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 concrete. Physical and mechanical properties of these mixes, such as compressive strength, static modulus of elasticity, dynamic modulus of elasticity, and shrinkage were evaluated during the laboratory investigation. Durability-related parameters investigated included resistance of concrete to penetration of chloride ions and freeze-thaw resistance testing. The results indicated that chemical and mineral admixtures improved the physical, mechanical, and durability properties of 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 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 the concrete either by delaying the initiation of active corrosion or by reducing the corrosion rate.
Degree
Ph.D.
Advisors
Olek, Purdue University.
Subject Area
Civil engineering
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