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<p>Phosphogypsum, a byproduct of phosphoric acid production, is underutilized, causing environmental concerns due to waste accumulation. This study enhances phosphogypsum utilization by examining stabilizer effects on composites through single and compound doping methods. The road performance of the modified phosphogypsum composites was assessed at different curing ages through unconfined compressive strength tests, water stability tests, and dry shrinkage tests. Furthermore, X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were performed to identify hydration products and elucidate the underlying hydration mechanism. The strength results indicate that when phosphogypsum, calcined phosphogypsum, cement, and lime are mixed in a ratio of 81:10:7:2, with 2% sodium silicate and 0.5% calcium chloride as stabilizers, the compressive strength of the phosphogypsum mixture reaches 11.51&#xa0;MPa after 28 days of standard curing, representing a 31.1% improvement over unmodified phosphogypsum composites. From a microscopic perspective, sodium silicate and calcium chloride increase alkalinity, accelerating cement hydration with calcium hydroxide. This primarily forms C-S-H gel and ettringite (Aft), where the adhesive C-S-H densifies the matrix while embedded Aft crystals reinforce the structure, substantially enhancing strength. This study not only mitigates the low utilization rates of phosphogypsum but also broadens its potential applications in construction and infrastructure materials.</p> Graphical abstract <p></p>

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Performance characteristic and mechanistic of modified phosphogypsum-based composite materials

  • 期刊论文

  • 发表日期：

    2026年2月11日

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  • Xianzeng Shi,
  • Yangyang Pan,
  • Kai Huang,
  • Meng Zhao,
  • Lei Xu,
  • Xinxin Zhang,
  • Yu Qiao,
  • Wentao Dong,
  • Wei Wu

摘要

Phosphogypsum, a byproduct of phosphoric acid production, is underutilized, causing environmental concerns due to waste accumulation. This study enhances phosphogypsum utilization by examining stabilizer effects on composites through single and compound doping methods. The road performance of the modified phosphogypsum composites was assessed at different curing ages through unconfined compressive strength tests, water stability tests, and dry shrinkage tests. Furthermore, X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were performed to identify hydration products and elucidate the underlying hydration mechanism. The strength results indicate that when phosphogypsum, calcined phosphogypsum, cement, and lime are mixed in a ratio of 81:10:7:2, with 2% sodium silicate and 0.5% calcium chloride as stabilizers, the compressive strength of the phosphogypsum mixture reaches 11.51 MPa after 28 days of standard curing, representing a 31.1% improvement over unmodified phosphogypsum composites. From a microscopic perspective, sodium silicate and calcium chloride increase alkalinity, accelerating cement hydration with calcium hydroxide. This primarily forms C-S-H gel and ettringite (Aft), where the adhesive C-S-H densifies the matrix while embedded Aft crystals reinforce the structure, substantially enhancing strength. This study not only mitigates the low utilization rates of phosphogypsum but also broadens its potential applications in construction and infrastructure materials.

Graphical abstract