Effect of Carbonation on Existing Reinforced Concrete Building

Abstract

Concrete is one of the most important materials that is being used on the earth for the purpose of construction. It has innumerable uses in our day-to-day life. The deterioration of concrete occurs in three main forms physical, chemical, and corrosion. One of the major forms of environmental attack is when carbon dioxide diffuses into the concrete and dissolves in a pore solution to form carbonic acid, which neutralizes the alkalis in the concrete pore solution and combines with calcium hydroxide to form calcium carbonate causing a decrease in the pH of concrete pore solution. A reduction of pH to a lower level causes loss of passivity and initiates corrosion of reinforcement which leads to cracking and fragmentation of concrete and corrosion of the reinforcing steel and a subsequent reduction in the strength, serviceability, and aesthetics of the structure.

This paper presents the results of the field and an experimental investigation of the accommodation building at the National Cancer Institute in Sabratha. Site inspection and destructive tests were conducted including the effect of carbonation diffusion. The results showed the depth of carbonation exceeds the location of steel bars in most element structures. It is also indicated that the compression strength of concrete decreases with the depth of carbonation increase. However, the density of concrete increases with a carbonation depth increase. Evaluation of the building is necessary and important due to the advanced age of the existing structure. This evaluation leads to either rehabilitation or removal as a result of the spread of corrosion in most of the structural elements of the building.