scholarly journals Study on Shear Strength of Xanthan Gum-Amended Soil

2019 ◽  
Vol 11 (21) ◽  
pp. 6142 ◽  
Author(s):  
Antonio Soldo ◽  
Marta Miletić
Keyword(s):  
Shear Strength ◽  
Xanthan Gum ◽  
Soil Improvement ◽  
Silty Sand ◽  
Engineering Properties ◽  
Triaxial Tests ◽  
Negative Effects ◽  
Environment Friendly ◽  
Sustainable Engineering ◽  
Different Types

When construction work is planned on soil with inadequate shear strength, its engineering properties need to be improved. Chemical stabilization is one of the solutions for soil strength improvement. Currently, the most common additive that is used for chemical soil improvement is cement. Cement is an effective solution, but it has several negative effects on the environment. Therefore, the urges for environment-friendly solutions that can replace cement and show good potential for sustainable engineering are rising. One of the promising environment-friendly solutions is the use of biopolymers. Therefore, the main aim of the present study was to investigate the effect of the biopolymer xanthan gum on the strength of different types of soil. Xanthan gum was mixed with three different types of soil: sand, clay, and silty sand. The strength of treated and non-treated soil was experimentally investigated by performing unconfined compression, direct shear, and triaxial tests. From the results, it was observed that xanthan gum significantly increased the strength of each soil, which shows its major potential for the future of sustainable engineering.

scholarly journals Three-dimensional numerical simulation of mechanical properties of soil-tire mixture by discrete element method

2019 ◽  
Vol 92 ◽  
pp. 14011
Author(s):  
Mohsen Asadi ◽  
Ahmad Mahboubi
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Damping Ratio ◽  
Strain Curve ◽  
Young Modulus ◽  
Engineering Properties ◽  
Triaxial Tests ◽  
Sand Particle ◽  
Arithmetic Average ◽  
Harmonic Average

Soil engineering properties can be improved employing different methods. Among them is mixing soil with tire derived additives (TDA). TDAs generally increase some parameters of mixture such as damping ratio, permeability, ductility and also in some cases shear strength. Various properties of TDAs from mechanical properties to their geometry can affect the mixture behavior. In this paper using the YADE platform, simulations of triaxial tests on sand tire mixtures are presented. To take compressibility into consideration, each rubber crumb particle is made of several spheres connected elastically to each other. For sand particle generation the clump technique was employed. Shapes of both sand and rubber particles are inspired from real grains. As properties of sand and rubber are different, especially Young modulus, rubber sand interaction is considered as soft rigid contact. Therefor harmonic average and arithmetic average was used to compute contact Young modulus (and then stiffness). The model was validated by comparison of results of triaxial tests simulation on pure rubber sample with literature ones which both exhibited linear stress-strain curve. Then triaxial tests with different sand to rubber ratio were simulated to see whether harmonic average or arithmetic average gives the best match to literature. The results show shear strength reduces by decreasing of sand to rubber ratio. This is the same as what is reported in literature.

scholarly journals Shear Strength Characteristics of Recycled Concrete Aggregate and Recycled Tire Waste Mixtures from Monotonic Triaxial Tests

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7400
Author(s):  
Katarzyna Gabryś ◽  
Algirdas Radzevičius ◽  
Alojzy Szymański ◽  
Raimondas Šadzevičius
Keyword(s):  
Shear Strength ◽  
Construction Projects ◽  
Fine Fraction ◽  
Recycled Concrete ◽  
Engineering Properties ◽  
Triaxial Tests ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Angle Of Internal Friction ◽  
Anthropogenic Soil

Recycled concrete aggregate (RCA) is a promising substitute for natural aggregates and the reuse of this material can benefit construction projects both economically and environmentally. RCA has received great attention in recent years in the form of aggregate as well as a geotechnical material of sand size. Next to RCA, another recycled material, which reduces the waste volume and is a part of the present challenges in civil engineering, is tire waste. Despite the good engineering properties of recycled tire waste (RTW), its use is still limited, even after almost 30 years since they were first introduced. To broaden the applicability of reused concrete and rubber, a further understanding of their properties and engineering behavior is required. For this reason, the main subject of this paper is composite materials that consist of anthropogenic soil recycled concrete aggregate (RCA) and crushed pieces of recycled tire waste (RTW). In this study, a series of isotropic consolidated drained triaxial tests were undertaken to characterize the shear strength of eight mixtures of variable grain-size distribution, rubber inclusion (RC), and fine fraction (FF) content. The results show that the introduction of rubber waste leads to changes in the strength parameters of the tested mixtures. Improvements in RCA shear strength were observed, the largest for the mixture M7 with 10% of recycled tire waste. Similarly, the effect of fine fraction content on the angle of internal friction and cohesion was found. Dilation characteristics were observed in all analyzed composites. Based on the results of all tests performed, including physical, geometric, chemical, and mechanical properties of the created composites, it can be stated that the samples would meet local road authority requirements for sub-base applications.

Exploring the mechanical response of low-carbon soil improvement mixtures

2021 ◽  
Author(s):  
Alessandro Fraccica ◽  
Giovanni Spagnoli ◽  
Enrique E. Romero Morales ◽  
Marcos Arroyo ◽  
Rodrigo Gómez
Keyword(s):  
Colloidal Silica ◽  
Mechanical Response ◽  
Ground Improvement ◽  
Soil Improvement ◽  
Silty Sand ◽  
Triaxial Tests ◽  
Granular Soils ◽  
Low Carbon ◽  
Cyclic Triaxial Tests ◽  
Curing Conditions

As society moves towards decarbonisation it is important to assess the hydro-mechanical behaviour of binders that could offer a low-carbon alternative to Portland cement in ground improvement technologies. This work considers two such alterna-tives: one still largely unexplored (metakaolin-based geopolymers) and a better known one (colloidal silica). Results from unconfined compressive strength, permeability tests, undrained monotonic and cyclic triaxial tests on granular soils (sand and silty sand) treated with those two binders are presented and discussed, emphasizing simili-tudes and differences with the response of similar soils treated with other conventional and unconventional binders. Effects of silt content, curing conditions and soil/binder ratios are examined. Both colloidal silica and metakaolin-based geopolymer signifi-cantly improve the mechanical properties of the treated soils, although the geopolymer results in a stronger and stiffer material. Both treatments reduce much the permeabil-ity of the treated soil, but the reduction achieved with CS is larger.

Test Research on Modified-Soils of Foam-Conditioned for Metro Shield Tunneling Engineering

2010 ◽  
Vol 168-170 ◽  
pp. 1566-1571
Author(s):  
Bo Liu ◽  
Li Huang ◽  
Guo Gang Qiao ◽  
Tao Li
Keyword(s):  
Shear Strength ◽  
Soil Properties ◽  
Soil Improvement ◽  
Engineering Properties ◽  
Clay Soils ◽  
Shield Tunneling ◽  
Foaming Agent ◽  
Tunneling Engineering ◽  
Ground Damage ◽  
Properties Of Soil

Soil improvement is one of the most important problems to be solved for shielding tunneling in the complex strata. Now the foam modifying soils technique has been widely used in shield tunneling construction. A new foaming agent used for soil properties improvement is developed and presented in this paper. This paper presents test research of soil properties improvement on sand in rich-water strata and clay soils from permeability, fluidity, compressibility and shear strength. Compared with the imported and domestic foaming agent, the basic performances of the newly developed foaming agent are obtained. Some conclusions are drawn in the paper, and it is significant to improve the engineering properties of soil and reduce the ground damage in shield tunneling construction.

scholarly journals The Mechanical Response of a Silty Sand Stabilized with Colloidal Silica

Geotechnics ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 243-259
Author(s):  
Antigoni Vranna ◽  
Theodora Tika
Keyword(s):  
Shear Strength ◽  
Colloidal Silica ◽  
Mechanical Response ◽  
Axial Strain ◽  
Undrained Shear Strength ◽  
Silty Sand ◽  
Triaxial Tests ◽  
Cyclic Straining ◽  
Sand Stabilized ◽  
Undrained Shear

This paper presents a laboratory investigation into the mechanical response of a silty sand, with a fines content of 10%, stabilized with colloidal silica (CS). To this end, a series of unconfined compression tests as well as monotonic and cyclic triaxial tests was performed on a silty sand, comprising a mixture of a clean sand and a silty sand, stabilized with two concentrations of CS. The effect of various parameters on the behaviour of the stabilized silty sand was studied, such as CS concentration, soil density, and the presence of fines. The test results were compared with the corresponding of the untreated silty sand as well as the parent clean sand. It is shown that stabilization, even at the lowest CS = 6% concentration studied, significantly improves the undrained shear strength as well as the liquefaction resistance of the stabilized silty sand. Both the monotonic and cyclic response of the stabilized soil are only slightly affected by density. Furthermore, cyclic straining up to at least 5% of double-amplitude axial strain does not influence the undrained shear strength of the stabilized silty sand.

IMPROVEMENT OF EXPANSIVE SOIL BY ELECTRO-KINETIC METHOD

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Tran Thi Thanh Thuy ◽  
Doni Prakasa Eka Putra ◽  
Wawan Budianta ◽  
Hemanta Hazarika
Keyword(s):  
Shear Strength ◽  
Calcium Chloride ◽  
Pure Water ◽  
Expansive Soil ◽  
Soil Improvement ◽  
Undrained Shear Strength ◽  
Soil Samples ◽  
Atterberg Limits ◽  
Engineering Properties ◽  
Undrained Shear

The roadway in Karangjati, Ngawi Regency, East Java, Indonesia, which is underlain by expansive soil, is susceptible to damage due to volume change. This research aims to improve the engineering properties, such as consistency limits, compressibility, and undrained shear strength of the montmorillonite dominated soil in this area using an electrokinetic stabilization method. Four electro-kinetic experiments were conducted using different electrolytes (calcium chloride or pure water) under different conditions (no-flow or flow water). The results show that, pH values of all soil samples decreased at anolyte and increased at catholyte. Atterberg limits of the soil samples were found to increase, where the liquid limit (LL) range of 79.72– 86.14%, plastic limit (PL) 25.22–30.80%, and plasticity index (PI) 53.28–60.92, liquidity Index (LI) 0.91–1.08. The compression index Cc was 0.50– 0.742. Undrained shear strength of treated soil range of 7–11 kPa. Moreover, strengthening degree of the treated soils achieve 304–556%. The soil improvement was achieved by decreasing the Atterberg limits, and compressibility and increasing the undrained shear strength. Applying calcium chloride and flow water condition were the most effective methods for the soil improvement. The mineralogical compositions of the soil samples did not change after the treatment. Keywords: Electro-kinetic stabilization, electro chemical injection, clayey soil improvement.

scholarly journals Not all biases are bad: equitable and inequitable biases in machine learning and radiology

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mirjam Pot ◽  
Nathalie Kieusseyan ◽  
Barbara Prainsack
Keyword(s):  
Machine Learning ◽  
Human Error ◽  
Technical Problem ◽  
Social Dimension ◽  
Patient Treatment ◽  
Technical Solution ◽  
Negative Effects ◽  
Different Types ◽  
Human Decision

AbstractThe application of machine learning (ML) technologies in medicine generally but also in radiology more specifically is hoped to improve clinical processes and the provision of healthcare. A central motivation in this regard is to advance patient treatment by reducing human error and increasing the accuracy of prognosis, diagnosis and therapy decisions. There is, however, also increasing awareness about bias in ML technologies and its potentially harmful consequences. Biases refer to systematic distortions of datasets, algorithms, or human decision making. These systematic distortions are understood to have negative effects on the quality of an outcome in terms of accuracy, fairness, or transparency. But biases are not only a technical problem that requires a technical solution. Because they often also have a social dimension, the ‘distorted’ outcomes they yield often have implications for equity. This paper assesses different types of biases that can emerge within applications of ML in radiology, and discusses in what cases such biases are problematic. Drawing upon theories of equity in healthcare, we argue that while some biases are harmful and should be acted upon, others might be unproblematic and even desirable—exactly because they can contribute to overcome inequities.

Experimental Research on the Engineering Properties of Foam-Improved Red Clay Soil

2011 ◽  
Vol 261-263 ◽  
pp. 1831-1835
Author(s):  
Guo Gang Qiao ◽  
Da Jun Yuan ◽  
Bo Liu
Keyword(s):  
Experimental Research ◽  
Clay Soil ◽  
Soil Improvement ◽  
Engineering Properties ◽  
Screw Conveyor ◽  
Test Results ◽  
X Ray Diffraction ◽  
Shield Tunneling ◽  
Red Clay ◽  
Improvement Measures

Red clay soil is widely distributed in south China, the microstructure of red clay soil was studied applying scanning electron microscopy (SEM), and the X-ray diffraction analysis (XRD) test found that a large number of swelling inducing minerals, for example, montmorillonite, illite-montmorillonite or chlorite-smectite were contained in the red clay soil. Shield tunneling in this kind of stratum is prone to arising “cake” and “arch” phenomena and it prone to lead screw conveyor device unsmooth dumping, so soil improvement measures must be taken. Foam as the most advanced soil conditioner has been widely used in shield construction. Using self-developed foam agent, experimental research on foam conditioning red clay soil was carried out, test results show that foam can not only significantly reduce the soil shear strength, but also can greatly enhance the soil's compressibility and fluidity, which is significant for the smooth dumping and excavation face stability maintenance.

Shape-Tailored TiO2 Photocatalysts Obtained in the Presence of Different Types of Carbon Materials

2021 ◽  
Vol 21 (4) ◽  
pp. 2360-2367
Author(s):  
Krisztina Vajda ◽  
Klára Hernádi ◽  
Cosmin Coteţ ◽  
Gábor Kovács ◽  
Zsolt Pap
Keyword(s):  
Carbon Materials ◽  
Uv Light ◽  
Carbon Aerogel ◽  
Low Carbon ◽  
Negative Effects ◽  
Tio2 Photocatalysts ◽  
Uv Light Irradiation ◽  
Specific Morphology ◽  
Different Types ◽  
Photocatalytic Applications

Titania and carbon materials are intensively studied in composite materials including photocatalytic applications. Both positive and negative effects were described in the literature, including charge separation, adsorption enhancement and short-circuiting of the photoelectrons as well. In the present study a more sparsely investigated properties of carbon materials will be highlighted, namely their role as crystallization promoters for titania, during hydrothermal synthesis of the composites. Therefore, carbon nanotubes, carbon coils, activated carbon, graphite and carbon aerogel was used to identify the importance of carbon during the time dependent crystallization of titanium dioxide. The crystal phase composition, morphology, optical properties and photocatalytic activity was followed, and it was found that the anatase and rutile crystallization depended on the used carbon material. The morphology of the particles varied from single anatase sheet-like crystals to hierarchical microball-like structures, while in some cases no specific morphology was observed. Furthermore, it was found that despite the low carbon content (2 wt.%) and microcrystalline structure of TiO2 the composites were proven to be efficient in the degradation of Rhodamine B under UV light irradiation.

scholarly journals Biochemical Enhancement of Geotechnical Properties of Marginal Soils

2018 ◽  
Vol 203 ◽  
pp. 03010
Author(s):  
Murtala Hassan Mohammed ◽  
Ado Yusuf Abdulfatah
Keyword(s):  
Hydraulic Conductivity ◽  
Treatment Duration ◽  
Soil Improvement ◽  
Engineering Properties ◽  
Treatment Technique ◽  
Reagent Concentration ◽  
Soil Variables ◽  
Treatment Conditions ◽  
Metabolic Activities ◽  
Marginal Soil

Microbially-induced calcite precipitation (MICP) is a relatively new and sustainable soil improvement technique. This technique utilizes bio-activity of microorganism to precipitate calcite through metabolic activities of the organisms which decompose urea in to ammonium and carbon dioxide. The carbonate so produced combined with the supplied calcium to precipitate calcite. This calcite improves engineering properties of soil through the formation of coating and bonds between soil particles. Preliminary results have proved the feasibility of the isolated bacteria in MICP treatment technique to improve the engineering properties of marginal soil. The main objective of this study is to determine the preference conditions for effective MICP treatment in improving the soil engineering properties (Unconfined Compressive Strength, California Bearing Ratio and Hydraulic Conductivity) of a typical marginal soil. Variables such as; treatment duration (24, 48, and 72hours), reagent concentration (0.1, 0.25, 0.5, and 0.75M), and concentration of the isolates (1×105, 1×106, and 1×107cfu/ml) were considered in the MICP treatment. The results suggested that the preference treatment conditions were 72hours treatment duration, 0.75M reagent concentration, and 1×107cfu/ml concentration of the isolates. The corresponding alterations recorded were 94.86KN/m2 (295%) and 30.8% (92.5%) increment for CBR and UCS while 0.93X10-6m/s (78.95%) reduction was recorded for hydraulic conductivity. The calcite content showed a reasonably good comparison with the improvements in the soil engineering properties. The pH of effluents increased during MICP treatment indicating the presence of urease bio-activity.

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