Prescribing compaction at optimum water content in arid and semi-arid climate regions generally leads to unjustified ecological practices. Indeed, to achieve optimum densities for road embankment compaction, significant volumes of water are required, which is perceived as a very scarce resource in drought-prone areas. Dry compaction with the promotion of the use of materials at their natural moisture content can be a promising alternative that could save water resources. Nevertheless, dry compaction can affect the infrastructures’ stability under flooding conditions.

This paper presents field and laboratory tests carried out to investigate the effect of dry compaction on Phosphate Mine Waste Rocks (PMWR) behavior. In situ tests were conducted and the PMWR dry compaction protocol has been defined. Furthermore, the collapse deformation and the shear strength properties were evaluated through double oedometer and triaxial tests, respectively. The microstructural evolution on wetting was evaluated using mercury intrusion porosimetry (MIP) and 3D X-Ray computed tomography techniques. The water retention curve and mineralogical quantification tools were used to explain the influence of hydraulic hysteresis and clay minerals properties on the hydro-geotechnical behavior of PMWR. The results show a significant effect of applied stress level and dry density in addition to the type and amount of clayey expansive minerals on the structural deformation of PMWR on wetting. PMWR showed a maximum collapse settlement of 5.33 % under a pressure of 1500 kPa, while no collapse is expected for stress less than 100 kPa. Low content of clays was identified as well as the swelling shrinkage potential within PMWR. The ability of using PMWR as embankment materials at dry moisture content under total overburden stress below 200 kPa ensuring a dry density of at least 95%.σ_{d max} is confirmed. The results of this work can also be applied to standard materials with similar hydro-geotechnical characteristics.

在干旱和半干旱气候地区规定以最佳含水量压实通常会导致不合理的生态实践。实际上，为了实现路堤压实的最佳密度，需要大量的水，这在干旱多发地区被认为是非常稀缺的资源。干式压实和促进自然水分含量下材料的使用可以是一种有希望的替代方案，可以节省水资源。但是，干压实会影响洪水条件下基础设施的稳定性。

本文介绍了实地和实验室测试，以研究干压实对磷矿Waste石（PMWR）行为的影响。原位进行了测试，并定义了PMWR干压实方案。此外，分别通过双重里程表和三轴试验评估了塌陷变形和抗剪强度特性。使用压汞法（MIP）和3D X射线计算机断层扫描技术评估了润湿时的微观结构演变。用保水曲线和矿物学定量工具解释了水力滞后和粘土矿物特性对PMWR水文地质行为的影响。结果表明，除了黏土膨胀矿物的类型和数量外，施加的应力水平和干密度对湿润PMWR的结构变形也有显着影响。在1500 kPa的压力下，PMWR的最大塌陷沉降为5.33％，应力小于100 kPa时不会发生塌陷。确定了低含量的粘土以及PMWR内的膨胀收缩潜力。在总覆盖应力低于200 kPa的干燥水分含量下使用PMWR作为路堤材料的能力确保了至少95％的干燥密度。_{d max}被确认。这项工作的结果还可以应用于具有类似水力岩土特性的标准材料。