THE EFFECT OF POLYPROPYLENE GLYCOLS ON THE PROPERTIES OF Fe-RICH ALKALI ACTIVATED MATERIALS

Alkali activated materials (AAM) are emerging as building materials due to their high performance and environmental advantages. Despite their technical advantages1,2,3, AAM high susceptibility to shrinkage (2–4 times higher than OPCcement mortars4) often results in significant volume contraction and severe microcrack formation. To counteract this phenomenon, shrinkage reducing agents have been employed in the AAM formulations. Among them, organic compounds, such as polypropylene glycol (PPG), have been used to produce organic-inorganic polymers showing promising results both in metakaolin and blast furnace slag systems4,5. PPG reduces the surface tension at the pore solution/air interface and broaden AAM pore size distribution contributing to reduce internal capillary stresses. Nonetheless, the effectiveness and effects of PPG on Fe-rich systems remains largely unknown. Considering the expected growing worldwide production of Fe-rich residues, and alkali activation as a possible valorization route, this work intended to explore the feasibility of using PPG to mitigate Fe-rich AAM shrinkage. The effects of PPG molecular weight and dosage on the drying shrinkage, porosity, and mechanical properties are investigated and are here described.