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Abstract Phosphogypsum is an excellent industrial by-product to produce road base cement with slow coagulation and small expansion. In this paper, the regulation and mechanism of phosphogypsum on the setting and hardening process of micro-expansion road base cement were studied. By adjusting the content of phosphogypsum (5%~17%), combining with XRD, SEM and property tests, the effects of phosphogypsum on the setting time, strength, expansion property, hydration product composition and microstructure of cement in the early stage of hydration were revealed. The results showed that the setting time of the road base cement increased significantly with the increase of phosphogypsum content, and the initial and final setting time increased linearly, which was mainly due to the reaction of soluble impurities in phosphogypsum with cement components to form insoluble salt, which delayed the cement hydration process. The compressive strength of mortar increased first and then decreased with the increase of phosphogypsum content. The addition of phosphogypsum significantly promoted the formation of ettringite, which ensured the sustainable development of micro-expansion of the road base cement. At high phosphogypsum content, ettringite crystal nucleation was accelerated in the early stage of hydration, and the amount of ettringite generation was obviously increased, but the rapid andmassive generation of ettringite led to the decline of the early mechanical properties of cement.
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Published: 30 May 2025
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2025, Vol. 0 
