Phosphogypsum Slag Aggregate-Based Asphaltic Concrete Mixes

Abstract

Phosphogypsum is a by-product from the production of phosphoric acid used in the fertilizer and chemical industries. Large production rates and problems associated with its stockpiling have led researchers to seek alternative uses for phosphogypsum, primarily as a construction material. One such use is the extraction of sulfur dioxide for the production of sulfuric acid, a process that also generates a by-product slag aggregate. This study investigated the feasibility of using this slag aggregate in asphaltic concrete binder course mixes. The physical properties of the slag aggregate, such as gradation, specific gravity, absorption, unit weight, and void content, were determined, as well as its durability and environmental characteristics. The Marshall mix design method was used to obtain the optimum asphalt content for this aggregate, while moisture susceptibility was examined using the boiling and modified Lottman tests. Indirect tensile, resilient modulus, and dynamic creep tests were performed on the mix to evaluate its performance potential. The results of the study indicate that phosphogypsum-based slag aggregate can be successfully employed in asphaltic concrete binder course mixtures.