Influence of Portland cement type on unconfined compressive strength and linear expansion of cement-stabilized phosphogypsum

This technical note summarizes the results of a laboratory-testing program aimed at evaluating the engineering properties of cement-stabilized phosphogypsum mixtures for road base and subbase construction. Phosphogypsum is a solid byproduct of the production of phosphoric acid, a major constituent of many fertilizers that has chemical and radioactive properties may cause environmental problems. For every ton of phosphoric acid produced, approximately 5.0 tons of phosphogypsum are generated. This magnifies the problem of dealing with growing phosphogypsum stockpiles. The research program described herein, covered the physical characterization of phosphogypsum, and tests that uncovered the influence of cement type and content, curing time, and compaction energy on its unconfined compressive strength and expansion. The laboratory results indicate that cement-stabilized phosphogypsum mixtures have potential applications as road base and subbase materials.