In this experimental study, comprehensive laboratory tests were conducted to investigate the mechanical properties of tire-derived aggregate (TDA) Type A and TDA-soil mixtures applicable in the construction of drainage layer, embankment fill, and backfill materials for retaining walls, pipes, and bridge abutments. This study was an investigation of the mechanical properties of TDA, as a lightweight material, and TDA-fine-grained soil mixtures for different mix ratios of 15%, 20%, 35%, 40%, 50%, and 60% of TDA-A relative to the dry weight of the soil. Various composite samples were tested using triaxial and direct shear apparatus. Measured properties include specific gravity, Proctor maximum dry density and optimal water content, unconfined compressive strength, peak compressive strength, shear strength, and hydraulic conductivity. Test results revealed that the addition of TDA to the soil significantly improved the compressive strength under confinement and permeability of the composite specimens. Based on the test results and supporting data from intensive literature reviews, the TDA-soil mixture showed very encouraging results for use in civil engineering applications as a lightweight backfill material.

This study introduces a novel, interdisciplinary method that merges fundamental geomechanics with computer vision to develop an advanced hybrid feature-aided Digital Volume Correlation (DVC) technique. This technique is specifically engineered to measure and compute the full-field strain distribution in fine-grained soil mixtures. A clay-sand mixture specimen composed of quartz sand particles and kaolinite was created. Its mechanical properties and deformation behaviour were then tested using a mini-triaxial apparatus, combined with micro-focus X-ray Computed Tomography (mu CT). The CT slices underwent image processing for denoising, segmentation of distinct phases, reconstruction of sand particles, and feature extraction within the soil specimen. The proposed approach incorporated a two-step particle tracking method, which initially uses particle volume and surface area features to establish a preliminary matching list for a reference particle and then use the Iterative Closest Point (ICP) method for precise target particle matching. The soil specimen's initial displacement field was then mapped onto the DVC method's grid, and further refined through subvoxel registration via a three-dimensional inverse compositional Gauss-Newton algorithm. The proposed method's effectiveness and efficiency were validated by accurately calculating the displacement and strain fields of the soil mixture sample, and comparing the results with those from a traditional DVC method. Given the soil's compositional and microstructural characteristics, these image-matching techniques can be integrated to create a versatile, efficient, and robust DVC system, suitable for a variety of soil mixture types.

This research explores, for the first time, the use of plastic waste to enhance the mechanical properties of Tunis soft clay, a soil known for its low stability. Soil samples mixed with 2%, 5%, and 7% plastic waste were subjected to pre-consolidation tests up to 80 kPa, followed by unloading. The results show a significant reduction in consolidation time and void ratio, along with an increase in undrained cohesion. The optimal percentage of 5%, higher than the commonly reported 4%, provides notable improvements for applications in foundations and embankments. This study opens new perspectives for better plastic waste management while offering an innovative solution to geotechnical challenges. However, further studies on implementation techniques, such as deep compaction, are needed to validate its practical application.

The effective utilization of phosphogypsum (PG) and industrial waste soil is of paramount importance in the real world. The combination of phosphogypsum and soil in a single mixture can simultaneously utilize both materials. In this study, a novel green road material was developed according to the concept of synergistic utilization of multiple solid wastes, which is based on conventional cement stabilized soil. The GGBS was employed to gradually replace cement to stabilize PG-soil mixtures. The curing effect of GGBS replacing cement and the modification effect of PG on stabilized soil were evaluated in three aspects: mechanical properties, water stability, and environmental performance. This evaluation was conducted using the unconfined compressive strength (UCS), softening coefficient, and ionic concentration of heavy and trace metals. Furthermore, microscopic characterization techniques, including a pH meter, UV-visible spectrophotometer, FTIR, XRD, SEM, and EDS, were used to perform further analyses of the curing mechanism. The objective was to enhance the UCS of stabilized soil by incorporating an optimal amount of PG, avoiding the necessity for a complex and costly pretreatment process for PG. The UCS reached approximately 8 MPa in 7 days without immersion in water curing and 4 MPa in 7 days with 1 day immersion in water curing. Despite the decline in water stability resulting from the incorporation of PG, the stabilized soil exhibits superior mechanical properties compared to the majority of studies on the application of PG to stabilized soils. The monitoring of contaminant ions in the stabilized soil over a period of 28 days demonstrated compliance with EPA requirements, indicating that PG-based stabilized soil does not negatively impact the surrounding environment in the presence of water. Additionally, the optimal ratio of GGBS to cement is 1:1. Meanwhile, excessively high or low cement content has a detrimental impact on the properties of stabilized soil. Lastly, the practical engineering application of this novel green road material was achieved, and its mechanical properties and economic benefit were demonstrated to be superior to those of conventional cement stabilized soil. The study of PG in stabilized soil was transformed into the utilization of realworld projects without the necessity for a complex pretreatment process for PG. Concurrently, the replacement of GGBS for cement results in a reduction in both carbon emissions and economic costs, due to an enhanced utilization of solid waste. Additionally, it offers a more detailed analysis of the curing mechanisms in stabilized soils with respect to strength, water stability, and harmful ions.

This research is the result of work on implementing a closed-loop economy in geotechnics, which aligns with the broader concept of a circular economy in construction by promoting the use of waste materials and reducing environmental impact. The research presented in the article focuses on the use of fluidized bed furnace bottom ashes, a by-product of coal combustion in fluidized bed boilers, in the production of cement-soil jet grouting slabs. Samples were analyzed for their structural and mechanical properties to assess their suitability for geotechnical applications. The mixtures were distinguished between those using CEM I and those using CEM II. Mixes based on two types of cements had an additional division based on the amount of additives: reference mix, 5% ash, 15% ash, and 10% ash + 5% microsilica. The conducted experiments aim to determine the physico-mechanical parameters of the new mixtures, highlighting the potential of these materials in mining and geotechnical technologies. The research took into account the impact of time over a period of two years for mortars and 28 days for cement-soil. The authors' studies included determining the compressive strength, bending strength, and imaging using computed tomography. Computed tomography allowed imaging of the internal structure and porosity analysis. Employing CEM II as the primary binding material slows early strength gain, but adding microsilica significantly enhances strength, compaction, and durability. Despite improved properties, CT imaging revealed increased cracking in mixtures with CEM II, indicating reduced water tightness and highlighting areas for further study.

To increase the difference in the particle size distribution of root tuber and soil aggregates and further promote the segregation effect of the binary mixture under external force. The present study investigates the bulbs of Fritillaria thunbergii (BFT) as the research subject. Initially, static compression and dynamic impact tests were conducted on BFT and soil aggregates. Subsequently, a breakage model of BFT and soil aggregates was established based on the Tavares UFRJ Breakage Model, and the accuracy of the breakage model and mechanical parameters was verified. Lastly, the optimal structural and operating parameters of the screening device with a crushing function were determined through single-factor testing and multi-objective optimization. The results indicate that the breakage resistance of BFT was significantly higher than that of soil aggregates, as evident from the differences in fracture energy and damage parameters. Furthermore, the optimal operating parameters of the new vibrating screen were determined by maximizing the soil aggregate breakage rate and minimizing the BFT breakage rate.

Ground vibration during earthquakes can lead to loss of soil strength and structural damage. Rubber-soil mixtures (RSM) show promise in mitigating the residual ground deformation under dynamic loading. The influence of clay minerals on soil frictional strength and system stability is essential in the context of earthquake mechanics. This study employs molecular dynamics (MD) simulations to investigate the friction behavior of the rubber-clay interface within the RSM system. The results indicate a direct correlation between normal stress and friction force, with denser soil systems exhibiting higher friction forces, analogous to natural soils. The increase in friction can be achieved by compacting the rubber and clay components in the RSM systems. The inclusion of rubber in the RSM significantly reduces the stick-slip motion at the montmorillonite-rubber interface, providing a damping effect that reduces the intensity of the stick-slip vibration during sliding. The friction force between the montmorillonite and rubber exhibits a velocity enhancement behavior. The higher the sliding velocity, the less the adaptation time for interfacial atoms, resulting in a higher friction force. The rubber/montmorillonite surface exhibits a higher friction coefficient at higher sliding velocities, effectively limiting the buildup of shear stress responsible for initiating stick-slip behavior. Comparisons with experimental data validate the accuracy of the calculated mechanical properties, work of adhesion, and friction coefficients. These results contribute to a better understanding of the friction behavior within the RSM system, facilitating its application in improving seismic resistance.