Achieving sustainable and durable concrete using high‐volume SiO ₂ : Engineering properties

Abstract

This study explores the potential of high‐volume amorphous silica (SiO ₂ ) replacement for ordinary Portland cement (OPC) in concrete to reduce carbon emissions. Amorphous SiO ₂ , such as silica fume (SF) and CO ₂ mineralization‐produced Si‐rich gel, offers superior properties to concrete but is under‐researched for its use in concrete with high OPC replacement. Therefore, concrete with 20%–60% SF replacement was analyzed in this study for properties like compressive strength, slump, pH of pore solution, porosity, hydration, and phase assemblage. Results show excessive SF negatively affects strength and porosity, but overall performance exceeds OPC concrete. The low pH of high‐volume SF concrete down to 10.5 suggests improved durability for fiber‐reinforced polymer composites. Additionally, the embodied carbon of concrete decreased by 51% with SF, from 300 to 146 kg CO ₂ eq/m ³ , and high volumes of upcycled Si‐rich gel may lead to a negative carbon footprint.