Abstract
In this study the fundamental strength properties of phosphogypsum-based mixtures subjected to impact as well as static compaction are presented. The principal objective is to find potential uses for phosphogypsum in road, building, and other suitable applications.Three types of phosphogypsum-based mixtures were investigated: plain phosphogypsum, portland cement-based mixtures (phosphogypsum-cement and phosphogypsum-sand-cement), and phosphogypsum with other binders (tar, RC-70, etc) mixtures. In general, the effects of impact compaction energy, static compaction pressure, compaction moisture content, mix proportions, curing and testing conditions, on the strength properties of these mixtures are presented. In particular, the tensile-compressive strength relationship, modulus of elasticity in compression, and flexural fatigue property of the portland cement-based mixtures are derived. In addition, the strength variations of plain phosphogypsum and phosphogypsum-cement mixtures, using phosphogypsum from 8 phosphate companies in Florida, are reported.Good strength results obtained in the laboratory, along with the success demonstrated by recent engineering projects in the field, indicate that phosphogypsum-based mixtures can be utilized for road (flexible and rigid) base and subbase courses construction. Favorable strength properties of plain phosphogypsum and phosphogypsum-cement mixtures under high-pressure compaction further indicate, with the development of industrial manufacturing process in progress, the feasibility of using these mixtures for the production of precast building products.