Cement Manufacturers Association

21 Sources Capture Compression Transportation Carbon Capture Storage Utilization Figure.3 Carbon dioxide emissions for different cement type Please note that embodied CO 2 with generation and transportation of fly ash and slag are not considered while calculating the total CO 2 emissions associated with different types of cement. 2.2. Carbon Capture, Utilisation and Storage CCUS) In the cement and concrete industry, large amounts of CO₂ are released during the firing of limestone and clay that splits the materials into CO₂ and calcium oxide (CaO). To address this challenge and ensure adoption of the innovative technology, industries are recovering and recycling the CO 2 generated in these processes by adopting CCUS technology. CCUS is a process of capturing carbon dioxide emissions and either using it to make materials or permanently storing them thousands of feet underground. It is a vital technology to reduce carbon emissions in cement processes as it can be implemented in calcium looping process. CO 2 is adsorbed at high temperature into calcium-based sorbents in calcium looping and is captured through carbonation to form CaCO 3 . CaCO 3 is further calcined in oxyfuel calcination to regenerate CaO and pure CO 2 is released. Oxides Cement Clinker (%) GGBS (%) Fly Ash (%) CaO 62 40 >2 SiO 2 22 35 55 Ai 2 O 3 5 14 30 MgO 3 8 <1 Fe 2 O 3 4 0.5 6 Table. 3 Chemical composition of SCMs Blending ratios of the SCMs are as per the Indian standard codes. When it comes to the share of the market based on the cement type, blended cement has 73% while pure OPC captures 27%. Blended cement not only helps in sustainability aspects by reducing Carbon emissions, but also helps in improving the properties of concrete on the technical and durability front. Some of the technical advantages of Blended Cement over OPC include: • Reduced Heat of Hydration • Enhanced workability • Improved ultimate strength and flexural strength • Improved resistance to Sulphate and Chloride attacks • Reduced water demand • Lower drying shrinkage and creep • Lower risk of damage due to alkali silica reaction (ASR) • Improved Durability The world average clinker-to-cement ratio is about 0.7. Efforts are being made to reduce the ratio further by incorporating and innovating new methods to cut down the clinker content. CLINKER 779 740 507 312 351 OPC PPC PSC COMPOSITE CEMENT Type of Blended Cement kg CO2/tonne of Cement kg CO2/tobnne of Cement Figure 4 Carbon Capture Process