Effect of concrete microstructure saturation on the corrosion rate of embedded steel reinforcement

Author(s): Raja Rizwan Hussain
Paper category: Conference
Book title: 2nd International conference on Microstructural-related Durability of Cementitious Composites
Editor(s): Guang Ye, K. Van Breugel, Wei Sun, Changwen Miao
Print ISBN: 978-2-35158-129-2
e-ISBN: 978-2-35158-123-0
Publisher: RILEM Publications SARL
Pages: 1132 - 1142
Total Pages: 10
Language: English

This paper aims at detailed investigation of time dependent corrosion rate in reinforced concrete under the effect of varying moisture content in the gel zone and capillary pores of concrete microstructure. Various ‘concrete corrosion cells’ with different concrete compositions under four different environmental conditions (air dry, submerged, 95% R.H and alternate wetting-drying) were studied under controlled laboratory conditions. From the experiment results of these concrete-corrosion cells for one year, an interesting descending trend in the corrosion rate was observed which was then further explored in detail and modeled by using a constitutive equivalent electro-chemical model based on mass and energy transfer through the porous media (capillary and gel zone) for the corrosion process under various environmental conditions satisfactorily. The reason for decrease in the corrosion rate with time was found to be dependent on the saturated area of concrete acting as electrolyte for the corrosion process which becomes gradually smaller with the passage of time and the age of concrete. As the hydration of cement proceeds with time, the electrolyte of the concrete present in the gel and capillary pore zones reduces with successive reduction in the capillary and gel porosity and saturation over a certain time interval and finite control volume. This phenomenon was investigated considering and simulating the actual field conditions such as by varying concrete cover depth, relative humidity, water-cement ratio etc. The modeling task was accomplished the use of concrete durability model as a finite element computational approach for the effect of saturation in gel and capillary zones and their porosity on the corrosion of embedded steel in relation to W/C, concrete cover, chloride concentration and various environmental humidity conditions. This comprehensive modeling investigation involving variety of materials and environmental variables will help in profound understanding of the electrolyte (saturated area of concrete at the gel and capillary pore zone) controlled time dependent corrosion reaction in RC structures and will enhance/improve the prediction/estimation of corrosion rates over the life time period of reinforced concrete structures.

Online publication: 2013
Publication Type: full_text
Public price (Euros): 0.00