Strength Enhanced White Portland Cement Through the Reactive Release of Ions from Potash Alum Solution for Hydration Performance

<title>Abstract</title> <p> The search for new hydration activators and chemical admixtures to enhance the mechanical and Microstructural characteristics of White Portland Cement (WPC) has been prompted by the development of high-performance and sustainable cementitious materials. This study examines hydration effect of a saturated solution of potash alum (SPA) on WPC as a partial replacement system. Potash alum a double sulfate salt of potassium and aluminium, has strong ionic conductivity due to dissociation in to Al ³⁺ ,K ⁺ and SO ₄ ^2- ions in aqueous solution. This highly impacts the hydration mechanism of CaO.SiO ₂ .Al ₂ O ₃ .Fe ₂ O ₃ (C-S-A-F) phases in white Portland cement. When the alum solution is added to the cement matrix, it facilitates the quick formation of ettringite (3CaO.Al ₂ O ₃ .3CaSO₄.32H ₂ O) and monosulphate (3CaO.Al ₂ O ₃ .CaSO ₄ .12H ₂ O), which improves the development of strength at early ages. At the same time, the presence of Al³⁺ ions speeds up the pozzolanic reaction with Ca(OH) ₂ released during the hydration of tricalcium silicate (C ₃ S) and dicalcium silicate (C ₂ S), resulting in the formation of more calcium silicate hydrate (C-S-H) gel, the main phase that contributes to strength. X-ray diffraction (XRD) analysis shows a decrease in portlandite (Ca(OH)₂) peaks, verifying its effective consumption during secondary hydration, while scanning electron microscopy (SEM) displays a denser microstructure with less capillary porosity. The intensified nucleation influence of K ⁺ and SO₄ ^2- ions leads to a more refined pore structure, which in turn enhances compressive strength and durability properties.et says that The research indicates that using a saturated potash alum solution as a replacement in WPC not only alters hydration kinetics but also boosts microstructural densification, resulting in better overall mechanical performance and long-term durability. This method offers a cost-effective and environmentally friendly approach for creating high-performance cementitious composites. </p>