Effect of thermally activated sparingly soluble additives on rheological and strength properties of cements for vibration-resistant transport structures

This study investigates the influence of thermally activated sparingly soluble additives – phosphogypsum, limestone, and fly ash – on the rheological behavior and strength characteristics of Portland cement. Additives were incorporated in amounts of 1-5 % into clinkers from the Kuvasoy and Bekabad plants and evaluated for workability, water-cement ratio, and compressive strength. The results demonstrate that thermal activation (200-400 °C) enhances the surface reactivity of additives, promoting accelerated hydration of calcium silicates and improved microstructural densification. Compressive strength reached 534×10 5 Pa at 28 days for mixtures containing 5 % limestone activated at 200 °C. These improvements are particularly relevant for vibration-resistant transport structures – such as bridge decks, pavements, and railways – where enhanced flowability and durability are essential. The research also supports sustainable cement production through the valorization of industrial by-products like phosphogypsum and fly ash.