This study focuses on carbonation of underground concrete pipes and its results. Carbonation is a natural process in which concrete absorbs carbon dioxide from the air and reacts with calcium hydroxide to form calcium carbonate. The aim of this study is to investigate the factors influencing the carbonation process and to calculate the total CO2 of underground concrete pipes.

The method for theoretical understanding and analysis of carbonation equations is to study academic papers and reports such as Google Scholar and DiVa. The main formulas were derived with the help of Heidelberg Materials and KTH. The construction and specifications of concrete pipes were examined and numerical solutions were used to calculate the CO2 uptake of pipes both above and below the groundwater level.

To gain a deeper understanding of concrete carbonation, it is important to understand the various factors that affect its performance, such as environmental conditions and concrete structure. By calculating the total amount of carbon dioxide absorbed by a concrete pipe over its lifetime, the climate impact can be estimated. 

The results show the carbonation of 500 mm and 800 mm diameter concrete pipes both below and above the groundwater level. Carbonation decreases as the water level rises in the pipe, and is lower in pipes below the groundwater level. For 500 mm pipes under water, the uptake varies between 6,4 and 5,6 kg per meter pipe depending on the water level, and for pipes above water, it varies between 7,3 and 6,5 kg per meter pipe. For 800 mm pipes under water, the uptake varies between 10,2 and 8,9 kg per meter pipe, and above water, between 11,7 and 10,4 kg per meter pipe. The carbonation of these pipes is generally lower than corresponding one of concrete block pavers and flags due to the reduced contact with air and the inhibitory effect of water covering the concrete surface.