Supplemental Cementitious Materials (SCMs) refer to materials that are added to concrete mixtures as a partial replacement for Portland cement. These materials are typically industrial by-products or waste materials that possess cementitious properties. When combined with cement, SCMs enhance the performance and properties of concrete while reducing its environmental impact. SCMs can include various materials such as fly ash, slag cement (ground granulated blast furnace slag), silica fume, and metakaolin. These materials are finely divided and react chemically with calcium hydroxide in the presence of water, forming additional cementitious compounds. This reaction improves the strength, durability, and workability of concrete, as well as its resistance to chemical attacks and shrinkage. The use of SCMs in concrete offers several benefits. First, it reduces the amount of Portland cement required, which helps conserve natural resources and decrease carbon dioxide emissions associated with cement production. Additionally, SCMs can enhance the long-term performance of concrete, improving its resistance to cracking, sulfate attack, and alkali-silica reaction. They also contribute to the reduction of waste materials by repurposing industrial by-products that would otherwise be disposed of in landfills. SCMs are commonly used in sustainable construction practices and are encouraged by green building standards and certifications. By incorporating these materials into concrete mixtures, construction projects can achieve both environmental and performance goals, promoting a more sustainable and efficient use of resources in the construction industry.