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16 pages, 4118 KB

Open AccessReview

A Review of Particle Packing Models and Their Applications to Characterize Properties of Sand-Silt Mixtures

by Ching S. Chang and Jason Chao

Geotechnics 2024, 4(4), 1124-1139; https://doi.org/10.3390/geotechnics4040057 - 1 Nov 2024

Viewed by 2584

This paper reviews particle packing models and explores their application in geotechnical engineering, specifically for sand-silt mixtures. The review covers key models, including limiting case, linear, and non-linear packing models, focusing on their mathematical structures, physical principles, assumptions, and limitations through the concept of excess free volume. The application of particle packing models in geotechnical engineering is explored in characterizing the properties of sand-silt mixtures, offering insights into maximum, minimum, and critical void ratios and inter-granular void ratio, and the prediction of mechanical properties. Full article

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18 pages, 6791 KB

Open AccessArticle

A Simplified Silty Sand Model

by Nopanom Kaewhanam and Krit Chaimoon

Appl. Sci. 2023, 13(14), 8241; https://doi.org/10.3390/app13148241 - 16 Jul 2023

Cited by 3 | Viewed by 2450

Abstract

A unified critical state model has been developed for both clean sand and silty sand using the modified Cam-clay model (MCC). The main feature of the proposed model is a new critical state line equation in the e-ln(p) plane that is capable of handling both straight and curved test results. With this feature, the error in calculating plastic volumetric strain is, in theory, eliminated. Another crucial feature of the model is the transformed stress tensor based on the SMP (spatially mobilized plane) criterion, which takes into account the proper shear yield and failure of soil under three-dimensional stresses. Additionally, the proposed model applies the intergranular void ratio with the fines influence factor for silty sand. Only eight soil parameters are required for clean sand, and a total number of twelve soil parameters are needed for silty sand. This model not only enhances the predictive accuracy for granular soils but also broadens the applicability of the model to encompass silty sand in both drained and undrained analyses. Full article

(This article belongs to the Section Civil Engineering)

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11 pages, 6845 KB

Open AccessArticle

Densification of Two Forms of Nanostructured TATB under Uniaxial Die Pressures: A USAXS–SAXS Study

by Yan Zhou, Jing Shi, Mark Julian Henderson, Xiuhong Li, Feng Tian, Xiaohui Duan, Qiang Tian and László Almásy

Nanomaterials 2023, 13(5), 869; https://doi.org/10.3390/nano13050869 - 26 Feb 2023

Cited by 1 | Viewed by 2107

Abstract

Sequential ultra-small-angle and small-angle and X-ray scattering (USAXS and SAXS) measurements of hierarchical microstructure of a common energetic material, the high explosive 2,4,6-Triamino-1,3,5-trinitrobenzene (TATB), were performed to follow the microstructure evolution upon applied pressure. The pellets were prepared by two different routes—die pressed from a nanoparticle form and a nano-network form of TATB powder. The derived structural parameters, such as void size, porosity, and the interface area, reflected the response of TATB under compaction. Three populations of voids were observed in the probed q range from 0.007 to 7 nm⁻¹. The inter-granular voids with size larger than 50 nm were sensitive to low pressures and had a smooth interface with the TATB matrix. The inter-granular voids with size of ~10 nm exhibited a less volume-filling ratio at high pressures (>15 kN) as indicated by a decrease of the volume fractal exponent. The response of these structural parameters to external pressures implied that the main densification mechanisms under die compaction were the flow, fracture, and plastic deformation of the TATB granules. Compared to the nanoparticle TATB, the applied pressure strongly influenced the nano-network TATB due to its more uniform structure. The findings and research methods of this work provide insights into the structural evolution of TATB during densification. Full article

(This article belongs to the Special Issue Functionalization Chemistry in Porous Nanomaterials)

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16 pages, 45333 KB

Open AccessArticle

The Effect of Fines Content on Compressional Behavior When Using Sand–Kaolinite Mixtures as Embankment Materials

by Panyabot Kaothon, Su-Hyung Lee, Yeong-Tae Choi and Chan-Young Yune

Appl. Sci. 2022, 12(12), 6050; https://doi.org/10.3390/app12126050 - 14 Jun 2022

Cited by 7 | Viewed by 4032

Abstract

In South Korea, Honam High-Speed Railway has a relatively large residual settlement issue and high fines content has been pointed out as one of the causes. Design guidelines regulate not to use soils containing fines content higher than 25%. However, there is no background information on the effect of fines content on settlement. Therefore, this paper aims to investigate compressional behavior according to fines content using sand and kaolinite. Oedometer test results showed that the compression index is lowest with fines content of 15% to 20% at which the mixture produced maximum density. The optimum fines content for inducing low settlement would be 15% to 20% for the sand–kaolinite mixture. Transition fines content (TFC), which shows sand-like to claylike behavior, was observed to have between 21% and 26% of fines content. Critical fines content (fcrit) where a minimum void ratio occurs was estimated as 21.67%. These behavioral changes appear when fines content is greater than the optimum fines content. SEM also shows that the kaolinite particles were overlapped, creating flat surfaces with a fines content higher than 30%, and showing clay-like behavior. Based on the analysis results, engineers can simply identify the behavior of embankment materials to ensure optimum fines content and consequently minimize long-term settlement potential. Full article

(This article belongs to the Topic Advances in Construction and Project Management)

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10 pages, 2005 KB

Open AccessArticle

Characteristics of Compacted Fly Ash as a Transitional Soil

by Katarzyna Zabielska-Adamska

Materials 2020, 13(6), 1387; https://doi.org/10.3390/ma13061387 - 19 Mar 2020

Cited by 11 | Viewed by 2639

Abstract

Cohesive and non-cohesive soils show a number of properties typical of a given category. Cohesive soils are characterized by cohesion, and the properties of compacted soils closely depend on moisture at compaction. However, many researchers have found the existence of so-called mixed or transitional soils. Compacted transitional soils, macroscopically recognized as non-cohesive, are characterized by mechanical properties and hydraulic conductivity which are strictly dependent on the moisture content at compaction. The aim of this work is to show the influence of the content of fine particles in fly ash on the variation of California Bearing Ratio (CBR) values as a parameter strictly dependent on initial compaction. The CBR values were interpreted in terms of moisture at compaction, void ratio and intergranular void ratio. Three different research samples were selected with fine contents of 45%, 55% and 70%; all samples corresponded in terms of grading with sandy silt. Fly ash containing only non-plastic fines behaved as cohesive soils despite the lack of plasticity. The CBR values decreased with increasing moisture at compaction or void ratio. The CBR values, plotted as a function of the intergranular void ratio, have lower penetration resistance together with fine content. Full article

(This article belongs to the Section Construction and Building Materials)

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