The drainage performance of unbound granular material (UGM) is an important consideration in pavement design because premature failures can occur due to the presence of excess moisture in UGM layers. Recently, transportation agencies have been evaluating their granular base and subbase drainage and mechanical performance to ensure sufficient drainage capacity while maintaining adequate structural support to produce more sustainable pavement structures. Relating performance to UGM construction specification requires accurate characterization of physical and gradation parameters and their effects on the mechanical and drainage performance of UGM. These evaluations led to an update of the specification requirements of UGM in many jurisdictions including Manitoba.

In this study, resilient modulus and constant head hydraulic conductivity tests were performed to characterize the mechanical and drainage performance of nine UGM samples. The laboratory test results were also used to investigate the reliability of the estimated hydraulic conductivity from the Moulton prediction model, and from the Enhanced Integrated Climatic Model (EICM). Test results showed an improvement in resilient modulus and drainage quality for samples in gradation bands that specify larger maximum aggregate size and limited fines. A statistical analysis of the test results showed that D₁₀ larger than 0.2 mm and D₆₀ larger than 8 mm would guarantee higher stiffness and better drainage performance with a time-to drain of less than 5 days for typical pavement cross-sections and a resilient modulus value exceeding 200 MPa. The Moulton prediction model was found to provide a better approximation of hydraulic conductivity of the materials included in this study, while the EICM model was found to significantly overestimate the hydraulic conductivity for most of the samples.

未粘结的颗粒材料（UGM）的排水性能是路面设计中的重要考虑因素，因为UGM层中存在过多的水分会导致过早的破坏。最近，运输机构一直在评估其颗粒状基础和次基层的排水和机械性能，以确保足够的排水能力，同时保持足够的结构支撑，以生产更可持续的路面结构。与UGM施工规范相关的性能需要准确表征物理和渐变参数，以及它们对UGM的机械和排水性能的影响。这些评估导致包括曼尼托巴省在内的许多司法管辖区对UGM规范要求的更新。

在这项研究中，进行了弹性模量和恒定头部水力传导率测试，以表征9个UGM样品的机械性能和排水性能。实验室测试结果还用于根据Moulton预测模型和增强型综合气候模型（EICM）估算的水力传导率的可靠性。测试结果表明，在指定较大的最大骨料尺寸和有限的细度的渐变带中，样品的弹性模量和排水质量得到了改善。测试结果的统计分析表明，D ₁₀大于0.2 mm，D ₆₀大于8毫米将保证更高的刚度和更好的排水性能，对于典型的路面横截面，排水时间少于5天，且弹性模量值超过200 MPa。研究发现，Moulton预测模型可以更好地估算材料的水力传导率，而EICM模型则可以大大高估大多数样品的水力传导率。