11015 Factors Affecting the Corrosion Rate at Intersection Points of Steel Rebar Mat in Reinforced Concrete Structures

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Product Number: 51300-11015-SG

ISBN: 2011 11015 CP

Author: Dr. Raja Rizwan Hussain, Abdulrahman Alhozaimy, Rajeh Al Zaid and Abdulaziz Al Negheimish

Publication Date: 2011

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This paper investigates high corrosion observed at intersections of steel rebars in the mat as compared to low corrosion in all other areas observed in a typical reinforced concrete structure at multi-scale from macro to micro level. This is a rather new and unusual finding having limited research in the past and needed further investigation to clarify the mechanisms involved therein. Therefore, chloride contaminated reinforced concrete slabs were cast and laboratory controlled experiments were conducted for half-cell potential, corrosion current, concrete resistivity, SEM and MIP measurement. The experimental measurements at the intersection of steel bars were found to be actually much higher than the areas in between them. This high corrosion rate at the steel bars intersections observed in the field in an actual RC structure and verified by experimental measurements in this paper was further investigated to document the effect of variation in rebar spacing, connection type as well as the binding wire material. This research is expected to result in improved steel rebar fixing and placement methods in the future for all reinforced concrete structures. This research will result in established knowledge and material engineering behavior of high corrosion rate at the intersection points in steel mat of reinforced concrete. This research will enable future advances and trends in understanding the effect of steel bar overlapping on the corrosion rate at the microstructure level of reinforced concrete engineering material as well as clarification of the phenomenon involved therein. As a scope for future research, the experiment results presented in this paper can be utilized in the future for the effective role of reinforcement steel arrangement in the mat to improve the corrosion resistance and protection of concrete in civil engineering industry.

Key words: Corrosion, steel reinforced concrete, rebar intersections, rebar spacing, connection type, binding wire material, scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP).