In this study, the mechanical properties and permeability variation in single joint rock samples filled with a gypsum layer were investigated. In order to simulate the inclined infilled joint, the solid cylinders were saw-cut at the dip angles of 90°, 60°, 45°, 30° or 0° with respect to the samples’ axes, and then joined together with gypsum. Triaxial compression experiments with permeability measurements were then performed using these prepared samples. The results indicated that the peak strength and failure modes change with the inclined angles. In comparison with the theoretical analysis of rock with a clean joint, infilling has a marked influence on the mechanical properties to some extent. In regards to the initial permeability, the results showed decreases of approximately two orders of magnitude with the increasing of the prefabricated joint angle, and the initial permeability of the samples with a prefabricated joint were all larger than the intact sample. The evolutionary trends of the permeabilities in triaxial compression in the sandstone samples were shown to be varied with a joint filled with gypsum at different angles, due to the fact that the changes of the inner structure are quite different during the loading process.

Plastic materials are extensively utilized in various aspects of daily life. However, the substantial amount of plastic waste generated can cause significant global environmental issues without efficient waste management practices. To address this problem, the utilization of waste plastics in high-value applications such as highway construction through hot mix asphalt (HMA) has been deemed ideal. Polyethylene terephthalate (PET), low-density polyethylene (LDPE), and high-density polyethylene (HDPE) are the three most prevalent types of plastic waste found in municipal solid waste. The impact of plastic-type and content on the mechanical, volumetric, and durability properties of hot mixed asphalt (HMA) was investigated by utilizing varying plastic contents of PET, LDPE, and HDPE. Tests were conducted in accordance with ASTM standards on twelve HMA mixtures made with an optimal binder content (OBC) of 4.3%, and plastic contents of 3%, 6%, 9%, and 12% by weight of OBC. Marshall stability and flow tests were conducted to ascertain the optimal plastic content for each tested mixture. The findings indicated that the stability and flow values improved as the plastic content was raised. 9% LDPE mix gave a maximum Marshal stability value of 12 kN. Additionally, as the plastic content increased, the values for air voids and voids filled with asphalt decreased in all 12 mixes tested. This research aligns with the United Nations 2030 sustainable development goals (SDGs), including SDGs 9, 11, 12, 13, 14, and 15, and presents a viable method for implementing the 3Rs approach towards sustainable plastic waste management.