Evaluation of CO<sub>2</sub> Emissions of Portland Cement and Geopolymers with Mineral Additions from Ecuador

The cement industry represents one of the largest sources of carbon dioxide (CO₂) emissions worldwide, generating approximately 1 ton of CO₂ for every ton of cement produced. With this environmental challenge, geopolymeric materials have emerged as a sustainable alternative to Portland cement due to their lower carbon footprint and comparable mechanical properties. This study compares the CO₂ emissions associated with type General Use (GU) Portland cement with three alkali-activated geopolymeric matrices formulated with different concentrations of sodium hydroxide and mineral additions from Ecuador. The matrices were evaluated based on their chemical composition, activation process, and emission mitigation potential, considering the production phase and partial clinker substitution. The results indicate that although the production cost of the geopolymer is higher, it demonstrates superior durability against acid attacks and can achieve compressive strengths of up to 33.42 MPa. Additionally, it reduces CO₂ emissions by up to 11.8% compared to traditional cement. Mixtures with mineral additions allow optimizing the proportion of alkaline activators, achieving a better balance between technical performance and environmental sustainability. In particular, adding silica fume improves flexural strength in low-alkalinity systems. This study confirms that pumice geopolymers are a viable, low-impact alternative for the construction industry, aligning with global decarbonization goals.