The State-of-the-Art Review on Road Harmless Utilization Technology of Phosphogypsum

Abstract

The “Guiding Opinions on the Comprehensive Utilization of Bulk Solid Waste during the 14th Five-Year Plan” issued by the Ministry of Ecology and Environment in 2021 pointed out that by 2021, China’s cumulative bulk solid waste stockpiles are about 60 billion tons, and the annual new stockpiles are nearly 3 billion. At the same time, there is a problem of low solid waste utilization rate, occupying a large amount of land resources, and a large hidden danger to the ecological environment. In order to further improve the utilization of solid waste, reduce the cost of road construction, and reduce the damage and impact of solid waste accumulation on the environment. This paper analyzes phosphogypsum impaction of the incorporation of various solid wastes on asphalt penetration, softening point, ductility and other properties, as well as the impact on the high temperature stability, low temperature crack resistance and water stability of asphalt mixtures, and the summarize and evaluate the microscopic modification mechanism and other aspects. At present, there is a relatively lack of research on the reuse of some solid wastes in asphalt in China. This review can provide reference and reference for judging a variety of solid wastes as asphalt modifiers, promote the green reuse of solid wastes, and reduce the construction of asphalt pavements.

Interfacial Water Stability between Modified Phosphogypsum Asphalt Mortar and Aggregate Based on Molecular Dynamics

“…Due to the large volume and wide application of asphalt mixtures, applying phosphogypsum as a filler instead of traditional mineral powder filler in the asphalt mixture of a road project can not only solve the problem of shortage of natural minerals, but also promote the regeneration and utilisation of phosphogypsum waste resources, which has a wide range of social and economic benefits [2,3]. Disposing of the trace elements present in phosphogypsum poses a challenge, impeding its use in road base soils [1] while full-scale experimentation of phosphogypsum application in asphalt materials for pavements is currently ongoing [1,4]. In order to ensure that its water stability approaches that of generic asphalt mixtures, a silane coupling agent is usually selected as an external dopant to modify the phosphogypsum.…”

“…However, coupling agent modification of phosphogypsum is essentially a chemical modification process, and the products of various types of coupling agents reacting with phosphogypsum are the main factors affecting the water stability of phosphogypsum mortar. Recently, researchers have primarily focused on examining the high temperature stability and other mechanical traits of PAM, with only a few investigations into its water stability [4].…”