Abstract
This paper presents an investigation on a deteriorated slab of a two-story building located in Johannesburg, South Africa. The structure has been in use as a residential building for more than 60 years. The top slab of the first floor was delaminated and reinforcement bars were severely corroded. Condition assessment of the building was done using the Schmidt hammer test, cover-meter survey and half-cell potential measurements. In addition to the non-destructive tests done, X-ray diffraction and scanning electron microscopy were also conducted on the deteriorated concrete.
Highlights
Reinforced concrete is the most widely used construction material due to its great versatility
The interaction of carbon dioxide in the atmosphere with the alkaline hydroxides in the concrete causes a reduction in pH which can lead to carbonationinduced corrosion
X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) were conducted on the concrete samples taken from the deteriorated slab
Summary
Reinforced concrete is the most widely used construction material due to its great versatility. The steel reinforcement is thermodynamically unstable under normal atmospheric conditions and converts into its natural state which is iron oxide or rust This phenomenon of steel conversion into rust or iron oxide is the corrosion process [1]. When carbon dioxide dissolves in pore water it forms carbonic acid that neutralizes the alkalis and forms calcium carbonates As this reaction continues, it reduces the pH of concrete from 12.5 to a level below 9.0 at which steel corrosion can take place with available sufficient air and moisture. Chloride ions can penetrate into concrete from sea water, salty groundwater or de-icing salts Once they come into contact with the steel in concrete, chlorides facilitate the breakdown of the passive layer of oxide on the steel and lead to corrosion [2,3,4,5,6]. X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) were conducted on the concrete samples taken from the deteriorated slab
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