Global CO₂ uptake by cement materials accounts 1930-2023

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• The cement industry is a major source of global carbon dioxide (CO2) emissions, primarily from clinker production.
• Calcium oxides and alkaline oxides in cementitious materials can naturally sequester atmospheric CO2 via carbonation.
• Understanding the scale of CO2 uptake by cement products is crucial for carbon cycle assessments.

Purpose of the Study:

• To develop and apply a comprehensive analytical model for estimating CO2 uptake by hydrated cement products.
• To quantify the global CO2 sequestration capacity of concrete, mortar, construction waste, and cement kiln dust (CKD).
• To analyze CO2 uptake trends from 1930 to 2023 across major global regions.

Main Methods:

• Utilized a comprehensive analytical model to estimate CO2 uptake.
• Included various hydrated cementitious materials: concrete, mortar, construction waste, and CKD.
• Covered major cement production and consumption regions worldwide over a historical period.

Main Results:

• Global annual cement CO2 uptake reached 0.93 Gt/yr in 2023.
• Cumulative CO2 absorption by cement from 1930 to 2023 was 23.89 Gt.
• This cumulative absorption represents 52.32% of the cement industry's process emissions during the same period.

Conclusions:

• Hydrated cement products significantly sequester atmospheric CO2, partially mitigating the cement industry's carbon footprint.
• The developed model provides annually updated, consistent data for cement emissions and CO2 uptake.
• Accurate quantification of CO2 uptake aids carbon cycle studies and informs climate change adaptation strategies.