Over the past few years, cement production has seen a significant increase. Due to this, the cement sector has emerged as the third-largest source of carbon dioxide (CO2) emissions caused by human activities, following emissions from the burning of fossil fuels and land use change. The burning of fossil fuels, deforestation, and alterations to land such as crop burning and mining are the major contributors to CO2 emissions. Cement, a binding material used in construction for centuries, is the main source of emissions in the construction industry. The manufacturing of cement has seen significant growth since World War 2 and continues to thrive.
The burning of fossil fuels is necessary to generate the substantial amount of energy required to heat the raw materials used in the cement production process to temperatures beyond 1000 degrees Celsius. This energy, which also encompasses the energy obtained via purchased electricity, has the potential to raise the total emissions by an additional 60 percent. The cement sector is responsible for 8 percent of global carbon dioxide (CO2) emissions. Throughout the production process, a single kilogram (kg) of ordinary Portland cement (OPC) releases approximately one kg of carbon dioxide (CO2) into the environment. Concrete, the final product made from cement, is rapidly approaching the point when its total weight will exceed that of all living creatures worldwide.
The use of the term “green” in “green cement” denotes a product that is eco- friendly and contributes to the improvement of the environment. Green cement is becoming increasingly acknowledged as crucial by all governments. This trend may be ascribed to global symposiums that are advocating for the dissemination of knowledge on sustainability and climate change. Utilizing green cement is essential for the building sector to transition towards a more sustainable and ecologically aware future. This will facilitate the construction of buildings and infrastructure with minimal ecological consequences and improved resilience to the impacts of climate change.
Green cement is cement that is manufactured through the implementation of sophisticated technological processes that minimize emissions during unit operations. The production of green cement reduces the use of traditional cement and utilizes discarded industrial wastes such as fly ash and blast furnace slag as its primary raw materials. Hybrid green cement is a specific type of green cement that possesses desirable qualities such as elevated long-term strengths and increased ductility. The production process of green cement entails a substantial reduction in the emission of CO2. Green cement has the potential to decrease the carbon footprint by 40 percent.
Geopolymer cement, another variety of green cement, is manufactured using aluminosilicates instead of the ecologically harmful calcium oxide. Aluminosilicates are derived from industrial waste materials such as fly ash. Geopolymer cement demonstrates a comparable performance and cost to standard portland cement while exhibiting a remarkable 95 percent reduction in CO2 emissions
Alkali-activated cement (AAC), which is predominantly derived from commonly available industrial waste, is a cost-effective alternative to OPC. It offers comparable performance to OPC but with notable advantages such as reduced CO2 emissions, cheaper cost, enhanced durability, increased lifespan, and a high proportion of recycled materials. Various types of AAC offer several advantages compared to OPC such as improved resistance to chemical attacks such as chloride and sulfate, rapid strength development, superior performance in marine environments, and the ability to repurpose industrial waste.
In spite of the advantages mentioned, green cement technologies often entail more upfront expenses when compared to conventional methods of producing portland cement. Companies exhibit reluctance to allocate funds towards adopting novel technologies or alternative materials that necessitate extra capital investment, particularly if they anticipate uncertain financial gains or if they operate within a fiercely competitive market with narrow profit margins. Additionally, the availability and dependability of substitute materials employed in the manufacturing of environmentally friendly cement, such as fly ash, slag, or calcined clay, may fluctuate based on geographical circumstances, market requirements, and legal limitations. Corporations may encounter difficulties in obtaining reliable sources of these materials, which can impede the general use of environmentally friendly cement
In order to accelerate the global acceptance of green cement as the prevailing norm in the construction sector and to successfully reduce CO2 emissions, it is crucial for policymakers to enact a comprehensive plan by enhancing research and development, providing incentives to cement manufacturers etc to combat climate change.
Written by Binnu Jacob Eapen, Edited by Navina Hasper
Photo credit: Anaya Katlego, Unsplash
