بررسی مشخصات تراکم پذیری و مدول الاستیک مخلوط‌های حاوی مصالح بتن بازیافتی، آجرخردشده و pet جهت استفاده به عنوان پرکننده خاکریزها

Waste recycling plays a crucial role in enabling the efficient use of natural resources and mitigating the negative environmental impacts caused by mineral extraction. One significant type of waste that can be recycled is construction and demolition waste (CDW), which includes materials such as concrete, bricks, and wood from building sites. This waste can be processed and recycled for use in various construction applications, particularly in geotechnical engineering, where it serves as fill materials or base layers in foundations. The management and reuse of CDW not only help in reducing landfill waste but also contribute to the conservation of natural aggregates. When utilizing CDW as fill materials, it is essential to determine the compressibility properties of these materials. The compressibility coefficient is a key factor that influences the behavior of materials under load, which directly impacts the stability and durability of construction structures. The compressibility behavior of various types of CDW, including recycled concrete and crushed bricks, is influenced by their physical and chemical properties, such as particle size distribution and mineral composition. Consequently, understanding the compressibility characteristics of CDW requires more detailed and comprehensive studies. The authors of this study aimed to investigate the compressibility properties of CDW that had been stabilized through the addition of polyethylene terephthalate (PET), a type of plastic waste. PET is increasingly being explored as a stabilizing agent for various construction materials due to its beneficial effects on enhancing mechanical properties. The study also aimed to compare the performance of stabilized CDW with that of natural construction materials, such as natural stone aggregates, to assess their viability as substitutes in geotechnical applications. To achieve the study objectives, a series of oedometer tests were conducted using a hydraulic consolidation apparatus. These tests were performed under both saturated and optimum moisture content conditions for CDW, which included recycled concrete and crushed bricks mixed in different proportions. A reference sample (BM) made of natural stone aggregates with a similar gradation to the recycled materials was also tested for comparison. The key parameters measured in the study included compressibility coefficients, one-dimensional secant elastic modulus, and the Particle Breakage Index of the materials. The results of the study revealed that the compressibility of the materials increased with higher percentages of PET and crushed brick content. This suggests that the addition of PET and crushed brick enhances the compressibility of the materials. Additionally, the study found that with the increase in PET and crushed brick content, the hardness of the materials decreased. A key finding from the comparison between the saturated and optimum moisture content conditions was that compressibility was lower and hardness was higher under optimum moisture content. However, during the unloading and reloading phases of the test, greater crushing of the particles in the optimum moisture content condition led to a change in the gradation of the sample. As a result, the compressibility coefficient increased, and the hardness decreased, indicating that the material underwent more significant particle breakage in the optimum moisture content condition. Based on these findings, the study recommends that the percentage of crushed brick in recycled aggregates be limited to 30 percent to avoid excessive crushing and degradation of the material. Furthermore, it is suggested that when crushed brick is included in the recycled waste, 2 percent PET should be added to prevent further particle breakage and to improve the mechanical properties of the aggregates, ensuring better performance in construction applications. These recommendations provide valuable insights for engineers and practitioners looking to incorporate CDW in sustainable construction practices.