This study investigated the influence of microbead dosages (0, 5, 10, 15, and 20%) on the frost resistance of expanded polystyrene (EPS) concrete. Five groups of EPS concrete specimens were prepared and subjected to rapid freeze–thaw tests. The freeze–thaw deterioration of EPS concrete was assessed using macroscopic indicators, including mass loss, strength loss, and dynamic elastic modulus loss. The underlying deterioration mechanism was revealed through the analysis of the EPS particle–matrix interface. A concrete damage plasticity model of EPS concrete based on damage mechanics theory was established. The results indicate that the addition of microbeads increased the strength of EPS concrete by 38–53%, reduced the strength attenuation after freeze–thaw damage by 8.1%, and improved the frost resistance level by 10–60 grades. The optimal dosage of microbeads is 15% of the cementitious material. The interfacial transition zone gaps in EPS concrete with added microbeads after freeze–thaw cycles are smaller, contributing to a more complete hydration reaction. The freeze–thaw damage model established in this study accurately reflects the freeze–thaw damage law of EPS concrete and provides a reference for studying the mechanical properties of EPS concrete under freeze–thaw cycles. The research findings of this study can enhance the strength and service life of EPS concrete, expanding its application scope as a structural material. The study provides valuable insights for future research and engineering applications related to the frost resistance of EPS concrete.

This study investigated the emission and diffusion of hydrogen sulfide (H₂S), as one of the odorous gases generated from landfills, in a municipal solid waste landfill of a south Chinese city. To this end, the flux of the H₂S emissions in the working area of the landfill and its diffusion in the surrounding area were measured. The diffusion of the H₂S was simulated at different wind speeds, wind directions, bare working areas of the landfill, heights of the landfill, and angles between the wind direction and the long side of the working area. The results indicated that the concentration of the H₂S around the monitoring point ranged from 0 to 60 µg/m³, and the simulated data were consistent with the measured results. At a uniform wind direction, the pollution range of the H₂S was narrow. Furthermore, with an increase in the height of the waste dump, the concentration of the H₂S decreased in the working area but rose in the surrounding area. Notably, when the angle between the long side of the working area and the wind direction was 0°, the H₂S largely spread along the extension cord of the long side of the working area. When the angle increased to 90°, the influence range of the H₂S extended significantly. The working area in the landfill site should be regulated based on the monitored data to reduce the effect of this harmful gas on the living environment, and the health of the landfill staff and nearby residents.

In view of clay slope instability caused by environmental temperature and rainfall infiltration in summer and autumn, the mechanism of the effect of temperature and saturation on unsaturated clay slope stability is discussed. To achieve this objective, this study uses theoretical and numerical methods. Based on the theory of unsaturated clay and the law of heat conduction, the relationship between cohesion and matrix suction of unsaturated clay was derived considering the influence of temperature and saturation. Taking into consideration the effects of temperature and saturation, the coupling equation for the shear strength of unsaturated clay was constructed under conditions of rainfall infiltration. The coupling equation for temperature and saturation was used using the strength reduction method, and the slope stability was analysed using FLAC software. The results show that: (i) cohesion in the unsaturated clay slope increases with increasing depth; (ii) the safety factor is smaller when taking into consideration the coupled effect of temperature and saturation than when the temperature effect is not taken into consideration; and (iii) the clay slope is unstable when the coupled effect of temperature and saturation is taken into consideration, but is stable when the coupled effect of temperature and saturation is not considered and soil saturation reaches 80%. Thematic collection: This article is part of the Role of water in destabilizing slopes collection available at: https://www.lyellcollection.org/cc/Role-of-water-in-destabilizing-slopes