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Carbonation Test PDF

Carbonation of concrete is a chemical process where carbon dioxide reacts with calcium hydroxide in concrete to form calcium carbonate, reducing alkalinity. The carbonation test determines the depth of carbonation by spraying phenolphthalein indicator solution on a freshly broken concrete surface, where the solution remains pink above the carbonated depth and turns colorless below it. Factors like concrete grade, permeability, cover depth, and time impact the carbonation rate.

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Pushpendra Chouhan
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328 views1 page

Carbonation Test PDF

Carbonation of concrete is a chemical process where carbon dioxide reacts with calcium hydroxide in concrete to form calcium carbonate, reducing alkalinity. The carbonation test determines the depth of carbonation by spraying phenolphthalein indicator solution on a freshly broken concrete surface, where the solution remains pink above the carbonated depth and turns colorless below it. Factors like concrete grade, permeability, cover depth, and time impact the carbonation rate.

Uploaded by

Pushpendra Chouhan
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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CARBONATION TEST

1. Objective
Carbonation of concrete is a process by which Carbon di Oxide from the air penetrates into the concrete
and reacts with calcium hydro-oxide to form calcium carbonates. Conversion of Ca(OH)2 into CaCO3 by
action of CO2 by itself is not reactive. In the presence of moisture, CO2 changes into dilute carbonic
acid which attacks the reinforcement and also reduces alkalinity of concrete. In this test
Phenolphthalein solution is used as indicator.

2. Application
Carbonation of concrete is one of the main reasons for corrosion of reinforcement. Oxygen and
moisture are the other components required for corrosion of embedded steel. In this test, the depth of
carbonation is determined. The rate of carbonation depends on the grade of concrete, permeability of
concrete, whether the concrete is protected or not, depth of cover, time, etc.

Fig. 1 : Carbonation Test on Concrete

3. Procedure
1. This test is most commonly carried out by spraying the indicator on freshly exposed surfaces of
concrete broken from the structure.
2. Carbonation depth is accessed by using a solution of phenolphthalein indicator that appears pink in
contact with alkaline concrete with pH value in excess of 9 when the concrete is not carbonized.
3. Colourless at lower levels of pH value when concrete is carbonated and the protective layer gets
destroyed and the steel is exposed to corrosion.

4. Video
Carbonation of Concrete

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