This experimental laboratory study examines the potential use of tire-derived aggregate (TDA) products as an additive to alleviate the inferior geotechnical properties of a subgrade deposit of clay soil with high expansivity. A total of ten mix designs—the unamended soil and nine soil–TDA blends prepared at 5%, 10% and 20% TDA contents (by dry mass) using three different TDA gradations/sizes—were examined. The experiments included standard Proctor compaction, oedometer swell and unconfined compression tests. The TDA materials’ lower specific gravity, hydrophobic character and higher energy absorption capacity compared with the soil solids led to notable reductions in the soil compaction characteristics. The amendment of the soil with TDA resulted in notable decreases in the rate and magnitude of swelling—the observed reductions were in favor of higher TDA contents, with larger TDA particle size being a secondary factor. Further, for any given TDA size, the variations of strength and toughness with respect to TDA content exhibited rise–fall relationships, peaking at 5% TDA and then decreasing for higher TDA contents. The stiffness and ductility parameters, however, were found to monotonically decrease and increase with the TDA content, respectively. Finally, TDA contents of up to 10%, with gradations equivalent to those of medium and coarse sands, were found to reduce the soil’s swelling potential from high to moderate expansivity, while simultaneously improving its strength-related features, and thus can be deemed as optimum mix design choices from a geotechnical perspective.

中文翻译：

---

用不同等级的轮胎衍生骨料改良膨胀土的改良土工行为

这项实验性实验室研究检查了轮胎衍生集料（TDA）产品作为添加剂的潜在用途，这些产品可减轻高膨胀性粘土土路基沉积物的劣等岩土性能。使用三种不同的TDA等级/大小，共检查了十种混合料设计，即未改性的土壤和九种土壤-TDA混合料，其TDA含量为5％，10％和20％（按干重计）。实验包括标准的Proctor压实，里程表膨胀和无限制压缩测试。与土壤固体相比，TDA材料的比重，疏水性和能量吸收能力较低，导致土壤压实特性显着降低。用TDA改良土壤会导致溶胀率和溶胀程度显着降低-观察到的降低有利于更高的TDA含量，而更大的TDA粒径是次要因素。此外，对于任何给定的TDA尺寸，强度和韧性相对于TDA含量的变化都表现出上升-下降的关系，在5％TDA时达到峰值，然后在较高TDA含量时下降。然而，发现刚度和延性参数分别随TDA含量单调减少和增加。最后，发现TDA含量高达10％，其等级与中，粗砂相等，从而降低了土壤的溶胀潜力。相对于TDA含量而言，强度和韧性的变化表现出上升-下降的关系，在5％TDA时达到峰值，然后在较高TDA含量时下降。然而，发现刚度和延性参数分别随TDA含量单调减少和增加。最后，发现TDA含量高达10％，其等级与中，粗砂相等，从而降低了土壤的溶胀潜力。相对于TDA含量而言，强度和韧性的变化表现出上升-下降的关系，在5％TDA时达到峰值，然后在较高TDA含量时下降。然而，发现刚度和延性参数分别随TDA含量单调减少和增加。最后，发现TDA含量高达10％，其等级与中，粗砂相等，从而降低了土壤的溶胀潜力。高至中等的膨胀性，同时改善其强度相关的特性，因此从岩土技术的角度来看，可以将其视为最佳的混合料设计选择。