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Loess, featured by its low permeability and cost-effectiveness, has become an increasingly popular material for landfill cover systems. However, the occurrence of cracks in loess caused by rainfall and evaporation poses challenges to the performance and durability of these cover systems. This study aims to comprehensively investigate variations in air permeability of compacted loess under normal and dry-wet cycle conditions. The conventional triaxial instrument was modified to meet the requirements of the air permeability test of loess. The influence of factors such as permeability pathway, water infiltration time, dry density, and water content as well as dry-wet cycles on the air permeability was thoroughly explored. And the applicability of established models in describing loess air permeability was assessed. The results confirmed that the airflow in compacted loess followed Darcy’s law, and there was a clear correlation between air permeability and these influencing factors. Loess samples with a diameter of 38 mm and a height of 76 mm were found to be more suitable for air permeability testing. Cracking in loess significantly increases air permeability, with longitudinal cracking having a greater effect than transverse cracking. Lower-density samples exhibit more pronounced cracking than higher-density samples. Both initial water content and humidification water content were identified as influential factors during dry-wet cycling and have a substantial impact on the variation of air permeability. These findings contribute to a better understanding of the air permeability characteristics of compacted loess in landfill cover systems, enabling improved design and performance evaluation for sustainable waste management practices. [ABSTRACT FROM AUTHOR]

PA1012/calcium silicate whisker nanocomposites with contents of whisker ranging from 10 wt% to 40 wt%, are prepared by twin screw extruder without any additions of coupling agent. The effect of whisker on the matrix is analyzed by the studies of morphology, the mechanical properties, water absorption and thermal stabilities. SEM micrographs obviously demonstrate, even under the high filler content of 40 wt% and without surface treatment, calcium silicate whisker can be homogeneously dispersed in polyamide, directly leading to the enhanced mechanical properties. The mechanism of higher efficiency of reinforcement is needle-like shape whisker, having access to be intercalated, and mutual affinity caused by hydrogen bonding interaction between carbonyl group in polyamide chain and hydroxyl group in whisker surface. Both aspects attach matrix with excellent stress-transfer properties. In addition, with the assistance of whisker, the nanocomposite favors an improved water absorption as well as thermal stability, which is intimately associated with physical performance. [ABSTRACT FROM AUTHOR]