Statistical Modelling of Carbonation Process in Reinforced Concrete Structure

Area of Science:

• Civil Engineering
• Materials Science
• Environmental Science

Background:

• Reinforced concrete structures are susceptible to carbonation, which degrades their durability.
• Understanding the factors influencing concrete carbonation is vital for predicting and mitigating structural damage.

Purpose of the Study:

• To quantitatively analyze factors affecting reinforced concrete carbonation.
• To establish a carbonation coefficient model based on extensive test data.
• To clarify the specific effects of various parameters on concrete carbonation under different environmental conditions.

Main Methods:

• Development of a carbonation coefficient model using 1834 groups of test data.
• Application of multiple nonlinear regression analysis.
• Fitting the model in two sections based on environmental exposure and relative humidity thresholds (<70% and >70%).

Main Results:

• Identified key factors influencing concrete carbonation: environmental temperature, CO2 concentration, relative humidity, water-cement ratio, fly ash replacement, compressive strength, curing time, compaction type, salt environment exposure, and environmental exposure classes.
• Quantified the impact of fly ash replacement, compressive strength, relative humidity, and CO2 concentration when relative humidity is below 70%.
• Determined the significant impact of CO2 concentration, relative humidity, compressive strength, curing time, and exposure classes when relative humidity exceeds 70%.

Conclusions:

• The developed carbonation coefficient model accurately predicts concrete carbonation.
• Relative humidity significantly influences concrete carbonation, with different key factors at humidity levels below and above 70%.
• Fly ash replacement, relative humidity, and CO2 concentration promote carbonation below 70% RH, while only CO2 concentration promotes it above 70% RH.