The research on the durability and physical properties of lightweight aggregate (LWA) with addition of sanitary ceramic wastes and sewage sludge was presented in the paper. The following characteristics of LWA were defined: contact angle (CA), absorptivity, roughness, surface free energy (SFE) before and after the UV radiation durability test, thermal conductivity coefficient lambda, compressive strength, freezing-thawing, salt resistance and others. Open porosity was examined using computed tomography, it reached 20.987 % for the ceramic waste aggregate, and 7.023 % for the reference aggregate. The aggregate with the largest amount of ceramic waste (20 %) and sewage sludge (10 %) has the highest average roughness (Ra), which is 14 % higher than the Ra of the reference aggregate. The contact angle decreased by almost 4 times and samples had higher absorptivity (19.994 %) when 10 % sewage sludge and 20 % sanitary ceramic were added to the aggregate. The sanitary ceramic waste application may enhance the poor durability characteristics of lightweight aggregate with/without sewage sludge. Replacing natural loess with sanitary ceramic waste material brings benefits both in terms of respect for natural resources and also improves the properties of lightweight aggregates.

Silty soil was widely used as filling soil materials for the replacement of expansive soil in cold regions. This paper presents a straightforward approach for the effects of wetting-drying-freezingthawing cycles on mechanical behaviors of silty soil and expansive soil by laboratory tests. The results showed that the silty soil and expansive soil after 7th wetting-drying-freezing-thawing cycles presented the decreases of elastic modulus, failure strength, cohesion and angel of internal friction by 8.9 %-12.0 %, 7.7 %-9.0 %, 7.9 %, 4.5 % and 17.6 %-37.0 %, 20.5 %-29.4 %, 43.2 %, 13.0 %, respectively, indicating that wetting-drying-freezing-thawing cycles had little impact on mechanical property of silty soil and a great influence on that of expansive soil. Among them, the mechanical property attenuation ratio in the first three wetting-drying-freezingthawing cycles accounted for over 90 % of the total. In the meantime, the micro-structure damage, surface crack characteristics and grain size distribution variations of expansive soil were all more significantly than these of silty soil exposed to wetting-drying-freezing-thawing cycles, which brought insight into the causes of the differences in mechanical properties for silty soil and expansive soil. It is found that the silty soil properties were more stable than expansive soil properties, and the silty soil is very effective for replacing the expansive soil below canal structures in cold regions.

Soil frost deformation significantly influences engineering projects in cold regions. The anisotropic behavior of soil, involving surface and internal deformation in three dimensions (3D), introduces inaccuracies in evaluating freeze-thaw geological hazards. To explore the relationship between internal strain and surface displacement of soil in a 3D space during the freezing -thawing process, a platform for monitoring coupled surface -internal deformation in 3D were developed using binocular recognition technology and a novel 3D strain rosette. Subsequently, a freezing -thawing model test of soil in Dalian Offshore Airport filling is conducted using the platform. The results show that, the internal strain of soil is closely associated with the boundary conditions of the test unit. During freezing test, the vertical strain exhibits a more significant increase in comparison to the horizontal strain. Surface displacements in soil primarily occur during the initial freezing and thawing stages. The variation of surface horizontal displacement in each direction is minimal throughout the freezingthawing process. A surface freezing boundary leads to an increment in internal strain, while the deep frozen stress relief causes the soil surface expand during thawing. This study provides a suggestion for the control of the cold source in cold region engineering. (c) 2023 Production and hosting by Elsevier B.V. on behalf of The Japanese Geotechnical Society. This is an open access article under the CC BYNC -ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

The Qinghai-Tibet Plateau (QTP) is a region with an extensive area of permafrost that is very sensitive to climate change. In this study, soil water and thermal dynamic processes in the active layer of the QTP permafrost area at the profile and slope scales were investigated. The results showed that the hydrothermal process in the active layer soil was strongly affected by freezing and thawing processes and external weather conditions. The tem-perature of the active layer fluctuated in tandem with air temperature. The soil water content was more stable during the freezing period and showed a double-hump trend during the thawing period. The correlation co-efficient between soil and air temperature decreased with depth, from 0.896 in the surface soil layer to 0.082 in the deep soil layer; and the correlation coefficient between unfrozen water content and soil temperature during the freezing period showed an overall increasing trend with depth. The soil layers at different depths at the top and bottom of slope profiles differed in their hydrothermal processes due to the physicochemical properties and texture of the soil and vegetation types. The water-heat exchange of the surface soil is more frequent than that of the deep soil, and the frequency is more at the bottom than at the top of the slope. The soil water content at a depth of 0.25 m was the highest in the profile in association with a higher organic matter content and the blocking effect of dense roots. The changes of soil hydrothermal process in the active layer accelerated the hydrological cycle and the spatial-temporal variability in water resources in the frozen soil area. These effects might lead to a series of ecological and environmental problems, such as permafrost degradation and deserti-fication in the QTP alpine meadow ecosystem.