The present work aims to contribute to finding more recycling routes for phosphogypsum (PG) and its potential uptake in the material construction industry as paving blocks. Laboratory testing was conducted to formulate mixes using PG as fine sand replacement. An optimal 20% substitution rate was proved. Industrially processed paving blocks were made for high-quality experimental investigation. The most interesting testing results of PG paving blocks are the low water absorption coefficient of 5.7% and excellent mechanical properties, including high compressive and flexural strengths at early age (20.7 and 4.65 MPa at 7 days, respectively). Compressive strength evolves with respect to the curing period: 26% increase at 28 days and 36% increase at 90 days; flexural strength evolves from 6% at 28 days to 10% at 90 days. The leaching test showed low levels of heavy metals released, and their concentrations were lower in the mix than in the raw PG. For all the aforementioned results, PG waste from a phosphate plant in Gabès, Tunisia was proved to have high potential for reuse in the manufacturing of paving blocks with low health risks and excellent properties. Reusing PG waste in paving blocks would thus contribute to solving an environmental issue and reduce the use of sand, which is prone to depletion as a non-renewable resource.

中文翻译：

---

磷石膏在铺路砖中的潜在用途

目前的工作旨在为磷石膏 (PG) 寻找更多回收途径及其在材料建筑行业作为铺路砖的潜在吸收做出贡献。进行实验室测试以使用 PG 作为细砂替代品配制混合物。证明了最佳的 20% 替代率。工业加工的铺路砖用于高质量的实验研究。PG 铺路砖最有趣的测试结果是 5.7% 的低吸水系数和优异的机械性能，包括早期的高抗压和抗弯强度（分别为 20.7 和 4.65 MPa，7 天）。抗压强度随固化时间而变化：28 天增加 26%，90 天增加 36%；弯曲强度从 28 天时的 6% 发展到 90 天时的 10%。浸出试验表明释放的重金属含量很低，它们在混合物中的浓度低于原始 PG 中的浓度。对于上述所有结果，来自突尼斯加贝斯磷酸盐厂的 PG 废料被证明具有很高的再利用潜力，可用于制造健康风险低且性能优异的铺路砖。因此，在铺路砖中重复使用 PG 废物将有助于解决环境问题并减少沙子的使用，沙子作为不可再生资源很容易枯竭。