An approach towards achieving net-zero-carbon concrete

Carbon dioxide is the primary greenhouse gas contributing to climate change. The construction industry is a main contributor to carbon dioxide emissions worldwide and must make conscious efforts towards becoming a green industry by using materials that are better for the environment. This study investigated innovative approaches to reduce carbon dioxide emissions in concrete production by replacing traditional Portland cement and paving the way to achieving net-zero-carbon concrete. Geopolymer mixes were evaluated as cement alternatives. In addition, alternative partial replacements for cement like ground granulated blast furnace slag, alongside the incorporation of various admixtures such as titanium dioxide, zinc oxide, and biochar, were tested. Tests were conducted to evaluate the compressive strength, durability, and carbon dioxide emissions. Comparisons to conventional Portland cement concrete were performed to quantify the environmental benefits of the developed concrete mixtures. The full replacement using a geopolymer was a significant step towards net-zero carbon emissions. It yielded higher strength and durability than the ordinary Portland cement concrete. The geopolymer concrete showed promising results with no curing and better results after 1 day of heat curing, which set this material steps ahead of other alternatives. Alongside the admixtures, the studied concrete model maintained the characteristics needed for structural concrete while reducing the contribution to the carbon dioxide present in the atmosphere and providing greater strength. The use of admixtures like titanium dioxide and biochar effectively enhanced geopolymer concrete while increasing its carbon dioxide absorption.