Soil tensile strength is a critical parameter governing the initiation and propagation of tensile cracking. This study proposes an eco-friendly approach to improve the tensile behavior and crack resistance of clayey soils. To validate the feasibility and efficacy of the proposed approach, direct tensile tests were employed to determine the tensile strength of the compacted soil with different W-OH treatment concentrations and water contents. Desiccation tests were also performed to evaluate the effectiveness of W-OH treatment in enhancing soil tensile cracking resistance. During this period, the effects of W-OH treatment concentration and water content on tensile properties, soil suction and microstructure were investigated. The tensile tests reveal that W-OH treatment has a significant impact on the tensile strength and failure mode of the soil, which not only effectively enhances the tensile strength and failure displacement, but also changes the brittle failure behavior into a more ductile quasi-brittle failure behavior. The suction measurements and mercury intrusion porosimetry (MIP) tests show that W-OH treatment can slightly reduce soil suction by affecting skeleton structure and increasing macropores. Combined with the microstructural analysis, it becomes evident that the significant improvement in soil tensile behavior through W-OH treatment is mainly attributed to the W-OH gel's ability to provide additional binding force for bridging and encapsulating the soil particles. Moreover, desiccation tests demonstrate that W-OH treatment can significantly reduce or even inhibit the formation of soil tensile cracking. With the increase of W-OH treatment concentration, the surface crack ratio and total crack length are significantly reduced. This study enhances a fundamental understanding of eco-polymer impacts on soil mechanical properties and provides valuable insight into their potential application for improving soil crack resistance. (c) 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

The effects of moisture and drying shrinkage can lead to uneven settlement, cracking, and other diseases in loess subgrade. The objective of this study was to investigate the effects of amide polymer (AP) on the permeability, mechanical properties and crack resistance of loess by orthogonal experiments. The basic properties of AP and the permeability, mechanical properties, and dry-wet variation properties of polymer-modified loess were tested, and a scale model verification and simulation analysis were conducted. In this paper, water migration in subgrade is regulated by improving the water sensitivity of loess. By reducing the variation range of subgrade water content, the stress accumulation in subgrade caused by water is weakened. The results show that the curing time and mechanical properties of AP are directly affected by the oxidant and reducing agent, and the mechanical properties of AP are compatible with the characteristics of loess. AP filled the grain gap and reduced the permeability of loess by 34.05-280.83%. The ductility of polymer-modified loess is significantly increased, and the strain of peak strength is increased by 17.21-126.36%. AP can regulate moisture change, reduce the surface tension between particles, and reduce stress concentration. The strength loss rate was reduced by 19.98-51.21% by enhancing the cracking resistance and weakening the strength loss caused by dry and wet cycling. The increase of upper layer moisture content in the scale model of polymer-modified loess subgrade is reduced by 31.38-36.11%.

The most important factor in increasing the efficiency of the development of forest tracts is the development and improvement of the transport and operational condition of the network of logging roads. Inert road construction materials, such as sand, crushed stone, crushed stone -sand mixture or gravel -sand mixture, are traditionally used for the construction of pavements for logging roads. However, in the areas with a shortage of these materials, the cost of road construction increases significantly. An alternative technology that can significantly reduce or completely eliminate the use of inert road construction materials is the stabilization of local soils for the construction of pavement structural layers. The soil stabilization technology consists in mixing them with binders and compacting them at the optimal moisture content of the mixture. In doing so, the resulting material acquires the desired strength and frost resistance. The most effective and common binder for soil stabilization is Portland cement. However, along with high strength properties and frost resistance, cement soils, due to their crystalline structure, have low crack resistance, which worsens transport and operational performance and shortens the service life of road pavements. One of the rational solutions for increasing the security of soil stabilization for the construction of road pavements is the installation of fiber cement soil layers. The object of this research is fiber cement soil for the construction of structural layers of road pavements for logging roads. The aim is to improve the physical and mechanical properties and frost resistance of soils stabilized with Portland cement with the addition of the material based on basalt fiber. Laboratory tests of compressive and tensile strength during splitting, as well as frost resistance of fiber cement soils of various compositions were carried out in accordance with GOST R 70452-2022. According to the data obtained, fiber cement soil has higher strength and frost resistance compared to cement soil. The fibers distributed throughout the cement -soil matrix effectively perceive external loads, providing high physical and mechanical indicators, and therefore crack and frost resistance of the material. The use of fiber cement soil for the construction of pavements for logging roads will increase the durability and reliability of their operation, as well as reduce the costs of construction and operation of road transport infrastructure of forest tracts.