Geotextiles—A Versatile Tool for Environmental Sensitive Applications in Geotechnical Engineering

Mycelium-Based Leather-Like Materials for Sustainable Geotechnical Applications

Pulverized coal combustion (PCC) dry bottom ash is a by-product of coal combustion that originates from the burning of pulverized coal to produce electricity. Because of the increasing costs associated with the disposal of bottom ash and the environmental regulations in place, a significant need exists to develop alternate methods for profitable and environmentally safe uses of this waste material. The physical properties of bottom ash are similar to those of natural sand, with particle sizes ranging from fine gravel to fine sand with low percentages of silt and clay-sized particles. Bottom ash has been used in the past as a substitute for aggregates in concrete. However, not much effort has been made in examining the geotechnical engineering properties of bottom ash, and as a consequence its use in geotechnical engineering applications is still very limited. Characteristics of bottom ash depend on the type of coal burned and the type of furnace used to burn the coal. This paper presents the results of an experimental study conducted to obtain technical data on the geotechnical engineering properties of Illinois PCC dry bottom ash amended with bentonite, which data are needed to assess its use for geotechnical engineering applications. Bottom ash modified with up to 20% bentonite by weight of bottom ash was tested to determine the effects of bentonite on consistency, moisture-density relationships, shear strength, and hydraulic conductivity of the bottom ash-bentonite mixtures.

Examining the crucial role of polysaccharide polymers in influencing soil hydraulic conductivity: A comprehensive review

To evaluate the geotechnical properties of a soil mass, different soil specimens were prepared in the lab by mixing various proportions of quartz, smectite, and illite. Liquid limit, plastic limit, and volume change behavior in terms of compression and swelling indices were measured according to the procedure mentioned in the respective ASTM methods. Those minerals are considered as the most common minerals that are found in expansive soils that include mudstone/clay stone, marl and shale. Such expansive soils are always considered as problematic soils in geotechnical engineering. The results show that plasticity index and liquid limit depend on the proportion of smectite and total clay content. A parabolic relationship could be observed between the liquid limit and proportion of smectite. Smectite is mainly controlling the plasticity characteristics. Likewise, volume change properties also depend on the proportion of smectite and liquid limit. A parabolic relationship was observed between the compression index and proportion of smectite, whereas a linear relationship was observed between the liquid limit and compression index. The results clearly show that we can estimate the coefficient of consolidation, and compression and swelling indices of a soil mass with reasonable accuracy with liquid limit and proportion of dominant clay mineral. This finding has a great significance in the geotechnical engineering because with a small amount of soil that can be collected from a boring core, we will be able to evaluate liquid limit, mineralogical composition, and clay content. Those parameters can be used to estimate the compressibility and hydraulic conductivity of a soil mass. They are very important in numerical simulation, foundation design, and many other applications in geotechnical engineering.

SummaryA comparative study of optimization techniques for identifying soil parameters in geotechnical engineering was first presented. The identification methodology with its 3 main parts, error function, search strategy, and identification procedure, was introduced and summarized. Then, current optimization methods were reviewed and classified into 3 categories with an introduction to their basic principles and applications in geotechnical engineering. A comparative study on the identification of model parameters from a synthetic pressuremeter and an excavation tests was then performed by using 5 among the mostly common optimization methods, including genetic algorithms, particle swarm optimization, simulated annealing, the differential evolution algorithm and the artificial bee colony algorithm. The results demonstrated that the differential evolution had the strongest search ability but the slowest convergence speed. All the selected methods could reach approximate solutions with very small objective errors, but these solutions were different from the preset parameters. To improve the identification performance, an enhanced algorithm was developed by implementing the Nelder‐Mead simplex method in a differential algorithm to accelerate the convergence speed with strong reliable search ability. The performance of the enhanced optimization algorithm was finally highlighted by identifying the Mohr‐Coulomb parameters from the 2 same synthetic cases and from 2 real pressuremeter tests in sand, and ANICREEP parameters from 2 real pressuremeter tests in soft clay.

As urbanization progresses, the demand for high-rise buildings and underground spaces is growing, and the need for firm geotechnical construction materials, efficient excavation methods, accurate testing instruments, and innovative geotechnical engineering theories and technologies is increasing. By investigating the phenomena of strengthening and toughening in nature, hydrophobic and ice-phobic, friction anisotropy and drilling as well as excavation, etc, researchers have found that organisms have distinctive external morphology and organization. By imitating the external morphology, structural characteristics or movement mechanism of organisms, novel ideas, new principles, and innovative theories can be provided for the innovation and sustainable development of geotechnical engineering. This paper mainly expounds on the bio-inspired application in geotechnical engineering from three perspectives: geo-materials, geotechnical components, and drilling & excavation equipment, and lists typical application cases. In conclusion, this paper presents a summary and prospects of bio-inspired geotechnical engineering, offering fundamental insights for future research.

Red mud, an industrial by-product of the Bayer process for alumina extraction, poses significant environmental and disposal challenges due to its high alkalinity and heavy metal content. However, its physicochemical properties-particularly its fine particle size, pozzolanic potential, and reactivity-also present unique opportunities for sustainable reuse in geotechnical engineering. This review critically examines the utilization of red mud in soil stabilization, subgrade improvement, and embankment construction, with a focus on its interaction with traditional and alternative binders such as lime, cement, fly ash, GGBS, phosphonyls, alkali activators, and biopolymers. Results from experimental studies indicate notable improvements in unconfined compressive strength, bearing capacity, and moisture resistance, while also addressing environmental concerns through immobilization of toxic elements and reduced leachability. The paper also highlights the environmental and sustainability aspects of red mud use, including reductions in carbon footprint and landfill dependence. Challenges such as variability in red mud composition, long-term performance, and regulatory limitations are discussed. This review positions red mud as a viable component in the transition toward circular, and sustainable geotechnical practices.

Cosmic-ray muography has several current and many promising future applications in geosciences, geotechnical engineering, and mining engineering. Muography, if applied to these disciplines, is based on alternating muon flux attenuation in soils and rocks due to anomalous density heterogeneity in the media. Muography can be used for detecting and imaging lithological boundaries, structural geological features, hydrothermal alteration zones, and ore bodies in geological research and mineral exploration. Muography can also be employed for mining planning, tunneling, drifting, and rock mass monitoring. There are possibly a great number of other future applications in geosciences, geotechnical engineering, and mining engineering on Earth and even on Mars and the asteroids. However, one challenge is that muography originates outside the realm of classical physics (and conventional geophysics), and hence most geoscientists, geoengineers, and mining engineers are not yet familiar with its principles and applications. We anticipate the usage and commercial availability of muography will expand in the future, and muographic surveys will become as essential to geophysics as the more traditional methods are today.

Beneficial use of sediments is known as a sustainable and environmentally friendly alternative to confined disposal facilities and open water disposal. Since most of the geotechnical engineering applications such as roads, backfills, berms, and in situ capping require a large amount of material in their construction, the beneficial use of dredged materials in geotechnical engineering applications is a promising implementation. In this study, sediment dredging and management are introduced. The beneficial use of dredged materials in geotechnical engineering applications is reviewed, and the necessary requirements for their beneficial use in these applications are addressed.

Steel slag has similar characteristics with sand, and pure steel slag used as geotechnical backfill material is an effective way to improve the comprehensive utilization rate of waste steel slag. In order to study characteristics of pure steel slag for application in geotechnical engineering, the compressive deformation characteristics and shear strength characteristics of steel slag under different water contents were explored by unidirectional consolidation compression tests and direct shear tests. Change rules of densities, compressive moduli, cohesion and internal friction angles of steel slag under different water contents were analyzed. It can be concluded that the compressive modulus of steel slag decreased with increasing the water content. The compressive modulus of dry steel slag was larger, reaching the level of medium sand. Compression moduli at different water contents were higher than those of silt soil and soft clay. Steel slag can be used as backfill material instead of mud soil and soft clay in the treatment of soft soil foundation. The cohesion of steel slag increased and the internal friction angle decreased with increasing the water content. The shear strength of dry steel slag was similar to that of medium sand, indicating that steel slag was more suitable as roadbed filling above the groundwater level.

Investigating soil swelling potential is indeed a critical research area in geotechnical engineering, given its significant influence on the stability and longevity of civil structures. This study aims to predict and assess the one-dimensional vertical free swelling potential of soils using ensemble machine learning models. Within the study context, a large dataset encompassing a wide array of soil parameters from 210 soil samples, including moisture content, unit weight, plasticity, and clay content, will be used. These parameters are critical in understanding the swelling behavior of soils under varying environmental and load conditions. The novel approach of this research lies in the application of ensemble machine learning techniques, which offer a robust framework to analyze complex, nonlinear relationships within soil properties. Another key aspect of this research is the parametric assessment, where the influence of individual soil properties on swelling potential is investigated using feature importance and partial dependence analyses. These analyses provide valuable insights into the relative importance of different soil parameters on soil behavior. The outcomes of this study contribute to soil mechanics and machine learning applications in geotechnical engineering and offer practical implications for engineers and practitioners. Besides, the predictive models developed in this study aid in more informed decision-making in the design and construction of civil structures, particularly in swelling-prone areas.

The characterization and analysis of the cementation properties of novel biopolymer binders in soils are essential for their potential application in geotechnical engineering. This study investigates the cementation effect of a novel zein biopolymer binder on sandy soils. Soil specimens are mixed with various contents of zein biopolymer ranging from 0 to 5%. The mechanical and microscopic characteristics of the treated specimens are evaluated using unconfined compression tests and scanning electron microscopy, respectively, after curing for 3, 7, and 28 days. The results show a consistent increase in compressive strength and elastic modulus of treated soils with increasing curing periods and biopolymer contents. A small amount (1%) of zein biopolymer increases soil strength and elasticity regardless of gradation. Additionally, the bonding force between the soil–zein biopolymer increases linearly with soil uniformity. Therefore, the application of zein biopolymer can be potentially used as a binder for fine- and coarse-grained soils in geotechnical engineering considering its stabilization and sustainability properties.

Piezoelectric sensors have many applications in geotechnical engineering, especially in characterizing soils through measurement of wave velocities. Since mechanical properties of a material are closely associated with wave velocities, piezoelectric sensors provide a reliable and non-destructive method for the determination of soil properties. This paper presents results of recent research on measuring stiffness of a wide range of soils such as clay, sand, and gravel, characterizing anisotropic properties of soil induced by external loading, measuring stiffness of base and subgrade materials in the pavement, determining soil properties in a centrifuge model during the flight of a centrifuge, and understanding wave propagation in granular materials under micro-gravity environment using this technique.

The artificial neural network (ANN) is a machine learning technique, which can simulate the physiological structure and mechanism of human brain. The study aims to review the principles of ANN algorithm and their application in geotechnical engineering. Firstly, the basic principles of ANN algorithm are introduced. Secondly, the application of ANN algorithm is presented. The review suggests that ANN can classify soil accurately, and it is able to group rock mass, predict the stability of slopes exactly, which could be used for risk assessment. The predicted settlement that is generated by ANN is near real value.

Geotechnical challenges in contemporary engineering necessitate the construction of structures on poor soils and vulnerable slopes due to limited land availability. The stability of soil slopes under seismic conditions is crucial for designing safe infrastructures. Conventional slope reinforcement techniques, such as geosynthetics, are effective but costly. This study explores the use of coconut fibers as a cost-effective, temporary reinforcement for improving slope stability under seismic loading. The research involved horizontal and vertical shake table tests on slopes of varying heights and angles, both with and without surcharge loads. Coconut fibers were mixed into the soil at different percentages to assess their effectiveness in reducing displacements and settlements during seismic events. Linear Variable Differential Transformers (LVDTs) measured displacements at various heights on the slopes. Results indicate that slopes reinforced with coconut fibers exhibit significantly reduced vertical and horizontal displacements compared to unreinforced slopes under both vertical and horizontal seismic loading. The reinforced slopes showed improved stability, particularly under higher surcharge loads and increased shaking frequencies. This study demonstrates that coconut fibers can serve as an effective, eco-friendly reinforcement method for temporary slope stabilization, offering a sustainable alternative to synthetic materials. The findings contribute to the broader understanding of natural fiber applications in geotechnical engineering, especially for regions prone to seismic activities.