Scarcity of traditional construction materials has motivated researchers to explore alternatives, and besides crushed glass, reclaimed asphalt pavement, and scrap tires, to name a few, plastic waste (unwanted or unusable plastic objects) has also gained attention in recent years. Plastic waste is traditionally re-used or recycled, but it often ends up as trash on curbsides, in landfills, or in our seas and oceans. The substantial amount of plastic waste produced annually worldwide, and its environmental repercussions are the rationale for exploring alternatives in order to recycle plastic waste into construction materials. This exploration can also benefit many industries and would help minimising adverse environmental impacts associated with dumping tones of plastic waste in landfills. Using plastic waste material with soil for soil reinforcement purposes has revealed some improvements in terms of strengths of materials, but nevertheless, this potentiality has not been fully assessed for different types and forms of plastic waste with natural subgrade soil in the road industry. In this paper, ground, flaky, and pelleted shapes of four sorted types of plastic waste from a recycling market were combined with silty or clayey gravel and sand soil of the A-2-7 AASHTO type. These plastic types are: low density polyethylene (LDPE), high density polyethylene (HDPE), polyethylene terephthalate (PETE), and polypropylene (PP) resins. Their various geotechnical properties have been assessed thoroughly. The investigation process entails assessing compaction, Californian Bearing Ratio (CBR), strength, resilient modulus, and permeability properties for both natural sub-grade soil and modified sub-grade soil with the aforementioned types of plastic waste. The results obtained show that the addition of plastic wastes decrease the maximum dry densities of the subgrade soils because of the lower relative density of the plastic material compared to the soil particles. It is also found that the addition of plastic wastes can increase or decrease the CBR and M_R values of the subgrade. The nature of change (increase or decrease) and its magnitude are a function of the plastic content, shape and type. Permeability values of many subgrade soil samples increased with the addition of plastic waste, whereas the hydraulic conductivity of some soils modified with plastic remained unchanged. Subgrade soils with plastic had higher friction angle and lower compressive strength than plastic-free soils. The results of this research suggest that partial replacement of subgrade soil material with plastic waste may prove useful in road subgrade applications.

传统建筑材料的匮乏促使研究人员寻求替代方法，除了碎玻璃，再生的沥青路面和废旧轮胎外，近年来，塑料废物（不需要或无法使用的塑料物品）也引起了人们的关注。传统上，塑料废物是经过再利用或回收的，但通常最终会变成路边，垃圾填埋场或我们的海洋中的垃圾。全世界每年产生大量的塑料废料，其环境影响是探索替代方案以将塑料废料再循环到建筑材料中的理由。这种探索还可以使许多行业受益，并将有助于最大程度地减少与垃圾掩埋场倾倒塑料垃圾有关的不利环境影响。将塑料废料与土壤一起用于土壤加固已显示出材料强度方面的一些改进，但尽管如此，尚未对道路工业中天然路基土壤的不同类型和形式的塑料废料的潜力进行充分评估。在本文中，将来自回收市场的四种类型的塑料废物的粉碎，片状和颗粒状形状与A-2-7 AASHTO类型的粉质或黏性砾石和沙土结合在一起。这些塑料类型包括：低密度聚乙烯（LDPE），高密度聚乙烯（HDPE），聚对苯二甲酸乙二酯（PETE）和聚丙烯（PP）树脂。他们的各种岩土性能已被彻底评估。调查过程需要评估压实度，加利福尼亚轴承比（CBR），强度，弹性模量，具有上述类型的塑料废物的天然路基土壤和改性路基土壤的渗透性和渗透性。获得的结果表明，添加塑料废料会降低路基土壤的最大干密度，这是因为与土壤颗粒相比，塑料材料的相对密度较低。还发现添加塑料废料可以增加或减少CBR和M路基的_R值。变化（增加或减少）的性质及其幅度是塑料含量，形状和类型的函数。随着塑料废料的添加，许多路基土壤样品的渗透率值增加，而一些用塑料改性的土壤的水力传导率保持不变。与不含塑料的土壤相比，带塑料的路基土壤具有更高的摩擦角和更低的抗压强度。这项研究的结果表明，用塑料废料代替路基土壤材料可能在道路路基应用中被证明是有用的。