BIM-Based Embodied-Carbon Assessment of Sustainable Concrete Mixtures Incorporating Fly Ash, GGBS, and Silica Fume: A Progressive Element-to-Building Framework for Bahrain

Reducing the carbon emissions associated with reinforced-concrete materials requires effective comparison of material alternatives before project-scale implementation. This study develops and demonstrates a progressive element-to-building environmental assessment framework that combines quantity extraction from Autodesk Revit with global warming potential (GWP) factors obtained from IDEMAT. Following benchmark checks, a standardized reinforced-concrete beam measuring 3.0 m × 0.20 m × 0.40 m was used to screen 25 concrete mixture scenarios comprising ordinary Portland cement (OPC), single supplementary cementitious materials (SCMs), binary SCM blends, and ternary SCM blends. Selected scenarios were subsequently applied to two residential building information modeling (BIM) models in Bahrain. Assuming a common target compressive strength of 35 MPa, the calculated carbon emissions per beam were 119.7 kg CO2e for OPC concrete, compared with 76.8, 76.5, and 75.7 kg CO2e for the G60, B6, and T5 mixtures, respectively. Across the two residential buildings, the calculated structural-system GWP decreased from 94.99 t CO2e for OPC to 60.05 t CO2e for T5, representing a reduction of approximately 36.8%. These comparisons are conditional on the adopted mixture assumptions and emission factors; equivalent mechanical and durability performance was not experimentally verified. The assessment is limited to the defined system boundary and does not constitute a whole-life carbon assessment. BIM enables project-scale comparisons by linking environmental estimates to material quantities and their distribution across structural elements.