Value-Added Reuse of Fine Phosphorus Slag Powder in Composite Cementitious Materials

Utilizing phosphorus slag as a construction material is an environmentally conscious approach; however, a comprehensive understanding of the nuanced properties of fine phosphorus slag (FPS) is imperative. This study investigated the intricate dynamics of the hydration process, micromorphology, pore structure, and mechanical attributes of composite pastes incorporating 10%–30% FPS. The results showed that FPS delays the early setting of the pastes, as evidenced by increases of 176% and 146% in the initial and final setting times with 30% FPS addition, respectively. Furthermore, FPS decreases the hydration degree of the composite paste, reducing early hydration products, thus exacerbating pore structure irregularities and significantly decreasing strength. Conversely, with the increase of time, the pozzolanic reaction of FPS was activated, consuming calcium hydroxide and generating more hydration products. Incorporating 10% FPS catalyzed increased hydration kinetics, facilitating enhanced microstructural development and concomitant improvement in compressive strength. At 14 and 28 days, the activity indices of FPS10 surpassed the threshold of 100%, indicating its efficacy in promoting cementitious hydration.