Performance Evaluation of Calcined Phosphogypsum Reinforced with Basalt Fiber and Calcium Carbonate Whiskers: A Study on Individual and Mixed Tests.

In an effort to appropriately address the insufficient mechanical properties of calcined phosphogypsum, this research intends to explore how to utilize basalt fiber and calcium carbonate whiskers as reinforcing agents. The study delves deep into their impacts on the flexural and compressive strength, toughness, water resistance, and tensile strength of calcined phosphogypsum. In the individual tests, basalt fibers with different lengths (3 mm, 6 mm, 9 mm, and 18 mm) were added at dosages of 0%, 0.5%, 1.0%, and 1.5%, respectively. As clearly demonstrated by the research findings, basalt fiber effectively reinforces the flexural and compressive strength, toughness, and tensile strength of calcined phosphogypsum, though compromising water resistance. Among the various fiber lengths, the 6 mm fibers impose the most advantageous influence on the performance of calcined phosphogypsum. Afterwards, a test was conducted to explore how cross-scale fibers affect the properties of calcined phosphogypsum by mixing 6 mm basalt fibers and calcium carbonate whiskers. As illustrated by the experimental findings, calcium carbonate whisker refines the pores, thereby elevating the flexural strength and toughness of calcined phosphogypsum. Furthermore, it compensates for the water resistance limitations associated with the sole utilization of basalt fiber while further augmenting the tensile strength and strain capacity. Nonetheless, it is particularly noteworthy that heightening the dosage of both calcium carbonate whiskers and basalt fibers concurrently gives rise to augmented porosity of phosphogypsum and lowered compressive strength.