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Rock-Like Material Characterization and Engineering Properties

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Construction and Building Materials".

Deadline for manuscript submissions: 20 July 2024 | Viewed by 6960

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Dr. Taoying Liu

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Guest Editor

School of Resources and Safety Engineering, Central South University, Changsha 410083, China
Interests: rock materials and engineering
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Jianhua Hu

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Zijin School of Geology and Mining, Fuzhou University, Fuzhou 350108, China
Interests: mining engineering
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Rocks, minerals, and other rock-like materials are the most widely distributed tool materials in nature and in human history. The composition of rock materials is complex, especially after a long period of natural progress, through which a variety of structural planes and tiny defects (cracks, cracks, pores, voids, faults, etc.) form. In recent years, with human exploration activities continuing to go deep into the earth and even up on the moon, Mars, and other complex environment regions, it is necessary to fully understand the characteristics of rock-like materials and determine/predict their engineering properties before project construction, especially under extreme physical conditions such as high confining pressure, high water seepage, and extremely low or high temperatures. A variety of novel experimental research studies, theoretical analyses, numerical simulations, and intelligent algorithms can be used to explore the special material properties and applied to slopes, tunnels, underground caverns, underground mines, and other related projects to benefit engineering design and implementation. The purpose of this Special Issue is to publish original research and critical articles in these fields.

You may choose our Joint Special Issue in Applied Sciences.

Dr. Taoying Liu
Prof. Dr. Jianhua Hu
Guest Editors

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Keywords

complex geological environment
macro-and micro-failure mechanical properties
damage fracture model and failure mechanism
numerical calculations and theoretical analysis
laboratory test and engineering application

Published Papers (6 papers)

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Research

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17 pages, 3974 KiB

Open AccessArticle

Influence Mechanism of Water Content and Compaction Degree on Shear Strength of Red Clay with High Liquid Limit

by Xuemao Feng, Jidong Teng and Hongwei Wang

Materials 2024, 17(1), 162; https://doi.org/10.3390/ma17010162 - 28 Dec 2023

Viewed by 645

Abstract

To investigate the influencing factors and mechanisms of shear strength of red clay with a high liquid limit, which was selected at different milepost locations based on the Nanning Bobai Nabu Section Project of the Nanning Zhanjiang Expressway, the basic physical properties of red clay were determined using a liquid plastic limit test, compaction test, inductively coupled plasma optical emission spectrometer (ICP-OES), and X-ray fully automatic diffractometer (XRD). Red clay with a high liquid limit was selected. Furthermore, the direct shear test was used to study the effect of different water contents and compaction degrees on the shear strength. The experimental results demonstrate that under the same compaction degree, the shear stress of the soil sample increases significantly with an increase in normal stress, and the greater the water content, the smaller the shear stress of the soil sample. At 200 kPa, the shear strength of soil samples with 24% water content is 57%, 46%, and 35% of the shear strength of soil samples with 15% water content under different compaction degrees(K) of 86%, 90%, and 93%, respectively. Under the same moisture content, the shear stress of the soil sample shows an increasing trend with an increase in the degree of compaction, and the greater the compaction degrees, the greater the shear stress of the soil sample. The cohesion c and internal friction angle φ of soil samples increase with an increase in the compaction degree, but the increase in cohesion c is also affected by the water content. Under the condition of low water content, the cohesion c of soil samples can be increased by 1.06 times when the water content is 15% and by 0.47 times when the water content is 18%. Under the condition of high water content, the cohesion c of soil samples with 21% water content only increases by 0.3 times, and that with 24% water content only increases by 0.35 times. Full article

(This article belongs to the Special Issue Rock-Like Material Characterization and Engineering Properties)

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22 pages, 17201 KiB

Open AccessArticle

Engineering Characteristics and Microscopic Mechanism of Soil–Cement–Bentonite (SCB) Cut-Off Wall Backfills with a Fixed Fluidity

by Tan Zhou, Jianhua Hu, Taoying Liu, Fengwen Zhao, Yanjun Yin and Mengmeng Guo

Materials 2023, 16(14), 4971; https://doi.org/10.3390/ma16144971 - 12 Jul 2023

Viewed by 1051

Abstract

Soil–cement–bentonite (SCB) backfill has been widely used in constructing cut-off walls to inhibit groundwater movement in contaminated sites. This study prepares SCB backfill with fixed fluidity. We conducted a series of experiments to investigate the engineering characteristics and microscopic mechanism of the backfill. The results indicate that the water content in the slurry was more sensitive to the bentonite content. The unconfined compression strength (UCS) value increased with an increase in the cement content, and the change with an increase in bentonite content was not noticeable. The permeability coefficient decreased distinctly with an increase in the cement and bentonite contents. The porosity of the SCB backfill increased with increasing bentonite content and decreased with increasing cement content. The UCS of SCB backfill was linearly and negatively correlated with the porosity; the permeability coefficient was not significantly related to the porosity. The percentage of micro- and small-pore throats in the backfill increased with increasing bentonite and cement contents. As cement and bentonite content increased by 6% in the backfill, the proportion of micro- and small-pore throats increased by 0.7% and 1.2%, respectively. The percentage of micro- and small-pore throats is deduced to be more suitable as a characterization parameter for the permeability of the SCB backfill. The overall results of this study show that the reasonably proportioned SCB backfill has potential as an eco-friendly and cost-effective material. Based on the requirements of strength and permeability coefficient (UCS > 100 kPa, 28 days permeability coefficient <1 × 10⁻⁷ cm/s), we suggested using a backfill with 12% bentonite and 9% cement as the cut-off wall mix ratio. Full article

(This article belongs to the Special Issue Rock-Like Material Characterization and Engineering Properties)

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15 pages, 49497 KiB

Open AccessArticle

Study of the Macro and Micro Characteristics of and Their Relationships in Cemented Backfill Based on SEM

by Fengwen Zhao, Jianhua Hu, Taoying Liu, Tan Zhou and Qifan Ren

Materials 2023, 16(13), 4772; https://doi.org/10.3390/ma16134772 - 1 Jul 2023

Cited by 2 | Viewed by 871

Abstract

Nuclear magnetic resonance can only quantitatively obtain porosity and pore size distribution, but as a conventional microstructure observation technology, scanning electron microscope (SEM) can select different magnifications to observe the microstructure of backfill materials. However, the processing of SEM images is not deep enough. In this paper, Image-Pro Plus 6.0 software was used to extract the data from SEM images, and the parameters of the area, and the perimeter, aspect ratio and roundness of the pores in the SEM images were obtained. The fractal characteristics of the pores in the SEM image were obtained by using the slit island method fractal theory. The concretization and quantification analysis of the pores’ complexity were achieved. A functional relationship model for the strength and pore parameters was constructed; thus, the influence law of pore characteristics on strength was quantitatively analyzed. The conclusions included: (1) Pore parameters indicate that most pores in backfill are irregular, and only a few pores are regular—however, the whole structure has good fractal characteristics (R² > 0.96). (2) The fractal dimension of pores is directly proportional to the roundness, the aspect ratio, and the pore content of pores—which indicates that the complexity of pores is related to both pore shape and pore content. (3) The strength had a linear inverse relationship with the roundness, aspect ratio, pore content, and fractal dimension—which indicates that all characteristics of pores have a certain influence on the strength. Full article

(This article belongs to the Special Issue Rock-Like Material Characterization and Engineering Properties)

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18 pages, 4700 KiB

Open AccessArticle

Comparison of the Permeability of Potential Ballast Rocks from Northern Rio de Janeiro State under Different Fouling Rates after Sodium Sulfate Attack

by Rodolpho N. Souza, Gustavo de Castro Xavier, Kelly de Oliveira Borges da Costa, Jonas Alexandre, Rogério P. Ribeiro and Afonso R. G. de Azevedo

Materials 2023, 16(10), 3806; https://doi.org/10.3390/ma16103806 - 18 May 2023

Viewed by 903

Abstract

This paper aimed to analyze the reduction in the ballast layer permeability simulated in a laboratory in saturated conditions by the presence of rock dust as a contaminant of three types of rocks explored in different deposits in the northern region of the state of Rio de Janeiro, Brazil, through laboratory testing relating the physical properties of rock particles before and after sodium sulfate attack. Sodium sulfate attack is justified by the proximity of some sections of the planned EF-118 Vitória-Rio railway line to the coast and of the sulfated water table to the ballast bed, which could degrade the material used and compromise the railway track. Granulometry and permeability tests were performed to compare ballast samples with fouling rates of 0, 10, 20, and 40% rock dust by volume. A constant head permeameter was used to analyze hydraulic conductivity and establish correlations between the petrography and mercury intrusion porosimetry of the rocks, namely two types of metagranite (Mg1 and Mg3) and a gneisse (Gn2). Rocks, such as Mg1 and Mg3, with a larger composition of minerals susceptible to weathering according to petrography analyses, tend to be more sensitive to weathering tests. This, in conjunction with the climate in the region studied, with average annual temperature and rainfall of 27 °C and 1200 mm, could compromise track safety and user comfort. Additionally, the Mg1 and Mg3 samples showed greater percentage variation in wear after the Micro-Deval test, which could damage the ballast due to the considerable changeability of the material. The mass loss caused by abrasion due to the passage of rail vehicles was assessed by the Micro-Deval test, with Mg3 (intact rock) declining from 8.50 ± 1.5 to 11.04 ± 0.5% after chemical attack. However, Gn2, which exhibited the greatest mass loss among the samples, showed no significant variation in average wear, and its mineralogical characteristics remained almost unchanged after 60 sodium sulfate cycles. These aspects, combined with its satisfactory hydraulic conductivity rate, indicate that Gn2 is suitable for use as railway ballast in the EF-118 railway line. Full article

(This article belongs to the Special Issue Rock-Like Material Characterization and Engineering Properties)

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20 pages, 9225 KiB

Open AccessArticle

Laboratory Experiments and Numerical Simulation on Dynamic Response of Island Reclamation Coral Sand under Aircraft Load

by Jianxiu Wang, Ansheng Cao, Dongsheng Song, Bo Feng, Huboqiang Li, Yanxia Long and Zhenhua Ye

Materials 2023, 16(9), 3465; https://doi.org/10.3390/ma16093465 - 29 Apr 2023

Cited by 1 | Viewed by 858

Abstract

The construction of island airports on coral reefs inevitably encounters the impact load of aircraft takeoff and landing. However, previous studies have not presented a detailed description of the dynamic response of the coral sand beneath the runways of island reclamation airports under aircraft load. In the current study, the coral sand of Mischief Reef Airport in the Nansha Islands, China, was selected as the background. The pore water pressure and strain characteristics of reshaped coral sand under aircraft loads with different dynamic stress amplitudes and vibration frequencies were studied using dynamic triaxial tests. Particle discrete element software was employed to study the deformation characteristics of coral sand with different particle sizes and porosities under aircraft loads. Results show that when the dynamic stress amplitude and vibration frequency were small, the pore water pressure and strain of the coral sand samples gradually increased with the number of load cycles, and the growth rate became increasingly small. When the dynamic stress amplitude and vibration frequency were large, the axial strain of the coral sand samples increased with the vibration frequency, and the growth rate exhibited an increasing trend. The deformation of the coral sand samples increased with porosity under aircraft loading. The larger the variation range of the coral sand particle size was, the larger the coral sand deformation caused by aircraft takeoff and landing load was. These results can provide a reference for the treatment and repair of the airstrip foundation of island airports. Full article

(This article belongs to the Special Issue Rock-Like Material Characterization and Engineering Properties)

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Review

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28 pages, 2002 KiB

Open AccessReview

Methods for Evaluating Pozzolanic Reactivity in Calcined Clays: A Review

by Valber Domingos Pinheiro, Jonas Alexandre, Gustavo de Castro Xavier, Markssuel Teixeira Marvila, Sergio Neves Monteiro and Afonso Rangel Garcez de Azevedo

Materials 2023, 16(13), 4778; https://doi.org/10.3390/ma16134778 - 2 Jul 2023

Cited by 5 | Viewed by 1867

Abstract

The search for alternative materials to replace ordinary Portland cement has been the object of work that enhances the investigation of the use of pozzolanic materials and the reduction of the carbon footprint with supplementary cementitious materials. However, not all materials are available to meet the large-scale demand for cement replacement. A relevant exception is the calcined clay, a material found worldwide that, when subjected to appropriate heat treatment, presents pozzolanic reactivity and can be used as a supplementary material to cement. This review presents, through a systematic search, methods for measuring the pozzolanic reactivity of calcined clays, namely, direct, indirect, qualitative, quantitative, chemical and physical methods such as electrical conductivity (Lùxan), the force activity index, the modified Chapelle, R³, Frattini test, thermal analysis, X-ray diffraction and X-ray fluorescence spectrometry. The most usual methods to assess the pozzolanic reactivity of calcined clays were exposed and analyzed. It should be pointed out that there is greater use of the Frattini and modified Chapelle methods as well as the analysis of the mechanical strength behavior of the material in cementitious matrices. X-ray diffraction and thermal analysis were exposed as the most used correlation methods but it was also concluded that different tests are needed to generate accurate results. Full article

(This article belongs to the Special Issue Rock-Like Material Characterization and Engineering Properties)

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