Mechanistic Empirical Design for Circular Concrete Performance with Glass Powder

This study evaluates finely milled float glass powder (GP) as a supplementary cementitious material (SCM) through a mechanistic–empirical framework based on strength and reactivity assessment. A mechanistic approach was developed to quantify the SCM efficiency of glass powder. Compared with conventional standardized testing procedures, the proposed method enables rapid mechanical performance evaluation with minimal testing. The mechanistic model is evaluated on cementitious systems with GP inclusion and consists of the following stages: (1) Best replacement percentage, as determined by the strength activity index (SAI), evaluated on mortar specimens for 20, 25 and 30% replacements. The highest SAI of 85% is observed for 20% replacement. (2) k-value determination by Abram’s law, wherein compressive strength is used as a reference and GP-based concrete (20% replacement) at 0.42, 0.46, 0.5 and 0.61 water–binder ratios are investigated. This results in an average k-value of 0.5. (3) SAI-based k-value (kSAI), which derives the compressive strength of glass at different water–binder ratios from reference concrete strengths by multiplying by the SAI value 85% and determining the k-value (kSAI) from the resulting compressive strength values using Abram’s law, resulting in 0.43. (4) Equivalent performance of concrete for frost resistance exposure classes (XF1, XF3); according to the SIS-CEN/TR 16639 Dutch method, wherein, if the SCM concrete shows comparable strength to the reference concrete, testing for exposure classes XF1 and XF3 is not required. GP-based concrete with a k-value of 0.5 surpasses the compressive strength reference values of 45 MPa and 43 MPa, respectively. (5) Recycled aggregate-incorporated concrete with a k-value of 0.5 has also been evaluated for equivalent performance, surpassing that of crushed aggregate reference concrete by 7%, which also makes it frost-resistant for exposure classes XF1 and XF3. This approach has the potential to serve as a practical screening tool for the preliminary evaluation of SCMs, thereby accelerating the development and implementation of sustainable cementitious materials.