A Generalized Relationship for Determination of Tensile Strength of Fine-Grained Soils from Shrinkage Characteristics

Uday, K. V.; Jayanthi, Prathyusha; Singh, Devendrá

doi:10.1080/07373937.2013.873804

Cited by 6 publications

(3 citation statements)

References 36 publications

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“…Shrinkage and subsequent crack formation are important phenomena in sludge drying because the sample loses its moisture and exhibits volumetric reduction, and then the internal stresses exceed the tensile strength. [11][12][13][14][15] First, mathematical modeling for determination of diffusion coefficients was established and convective drying experiments of sludges and sawdust=sludge mixtures were done. X-ray tomography, a non-destructive imaging technique, is used to get the volume, surface, and porosity of the sample bed directly.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Shrinkage Effect on Mass Transfer During Convective Drying of Sawdust/Sludge Mixtures

Bennamoun

Fraikin

et al. 2014

Drying Technology

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Convective drying of wastewater sludges and sawdust/sludge mixtures was studied. The first part of this work was an experimental study performed in a cross-flow convective dryer using 500 g of wet material extruded through a disk with circular dies of 12 mm. The results showed that the sawdust addition has a positive impact on the drying process from a mass ratio of 2/8, on a dry basis, with observed drying rates higher than the original sludge. The second part of this work consisted of developing a drying model in order to identify the internal diffusion coefficient and convective mass transfer coefficient from the experimental data. A comparison was made between fitted drying curves, well represented by the Newton's model, and the analytical solutions of the diffusion equation applied to a finite cylinder. Variations of dimensional characteristics, such as the volume and exchange surface of the sample bed, were obtained by X-ray tomography. This technique allowed us to confirm that shrinkage, which is an important phenomenon occurring during sludge and sawdust/sludge mixture drying, must be taken into account. The results showed that both the internal diffusion coefficient and convective mass transfer coefficient were affected by mixing and sawdust addition. The internal diffusion coefficient changed from 7.77 Â 10 À9 m 2 /s for the original sludge to 7.01 Â 10 À9 m 2 /s for the mixed sludge and then increased to 8.35 Â 10 À9 m 2 /s for the mixture of a mass ratio of 4/6. The convective mass transfer coefficient changed from 9.70 Â 10 À8 m/s for the original sludge to 8.67 Â 10 À8 m/s for the mixed sludge and then increased to 12.09 Â 10 À8 m/s for the mixture of a mass ratio of 4/6. These results confirmed that sawdust addition was beneficial to the sludge drying process as the mass transfer efficiency between the air and material increased. Reinforcing the texture of sludge by adding sawdust can increase the drying rate and decrease the drying time, and then the heat energy supply will be reduced significantly. The study also showed that neglecting shrinkage phenomenon resulted in an overestimation for the internal diffusion coefficient for the convective drying of sludges and sawdust/sludge mixtures.

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Section: Introductionmentioning

confidence: 99%

Analysis of the Shrinkage Effect on Mass Transfer During Convective Drying of Sawdust/Sludge Mixtures

Bennamoun

Fraikin

et al. 2014

Drying Technology

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“…Results obtained from these techniques were critically evaluated vis-à-vis those obtained from triaxial tests and empirical relationships available in the literature. It has been observed that there is a unique relationship between the results of the thin and thick samples and hence thin samples of expansive clays can be employed for determining their tensile strength [207,214,215]. This shows the usefulness of the proposed techniques for measuring the tensile strength of the finegrained that too expansive soils.…”

Section: Role Of Environmental Stresses: Cracking Of Fine-grained Soilsmentioning

confidence: 78%

Novel Techniques to Simulate and Monitor Contaminant–Geomaterial Interactions

Singh

2019

Indian Geotech J

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Generation of huge amount of the toxic and hazardous wastes coming out of various industrial and domestic activities is becoming a major threat to the society. In the long run, mainly because of nonscientific storage, disposal and closure, and due to the presence of undesirable concentration(s) of chemicals and radionuclides, elevated temperatures and microbial activity, these wastes (read contaminants) interact with geomaterials, viz., soils, rock mass, groundwater. This interaction, termed as contaminant-geomaterial interaction, depending upon the severity of the contaminant(s) and interaction time, might alter overall characteristics of the geomaterials. Unfortunately, conventional laboratory and field instrumentation techniques are not well equipped to capture such interaction(s) and the mechanisms that prevail in the geomaterials. Hence, to achieve these objectives, evolving adequate and workable strategies, and modalities, that are nondestructive, noninvasive and economical is desirable. In this context, author's association with several industries resulted in development of innovative, cost-effective, yet efficient techniques that facilitate laboratory and/or in situ simulation and monitoring of such interaction(s). Details of these techniques, the philosophy behind their creation and the way they can be employed for safeguarding geoenvironment, from deterioration, are presented and discussed in this paper. Also, a brief discussion on some of the real-life situations where such techniques can be applied easily, by suitably modifying them, is presented for the benefit of the aspiring researchers and professionals.

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“…Most tensile strength experiments are induced by external loading and not by the internal desiccation stresses [1] or fail to incorporate stage-wise drying of soils [2], which is essential for investigations related to cracking characteristics in clays. Commonly studies investigate full saturated conditions, few researchers performed experiments on initially unsaturated and compacted clays.…”

Section: Introductionmentioning

confidence: 99%

The influence of saturation on the cracking process in compacted desiccating clays

2016

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Abstract. Tensile failure in unsaturated cohesive soils during desiccation is important for the design of geotechnical applications such as capping systems of landfills and sealing material of dikes. This study presents the results of different initial parameters of compacted clay samples such as gravimetric water content, dry density and degree of saturation. These parameters are varied systematically for each test to find the correlation between those parameters and the tensile failure. The tensile failure for all tests occurred by a comparable constant change of the degree of saturation. The soil specific saturation ratio Sr,s is defined as the quotient of saturation changes ΔSr to initial saturation Sr,0. This parameter related to the total suction shows an equal course for all results. All in all, the course of the soil specific saturation ratio Sr,s is independent of all initial parameters. These results provide a physical and hydraulicmechanical description for modelling the desiccation process. To demonstrate the initiation and progress of tensile failure, the experimental results are modelled with a Discrete Element Method (DEM) approach.

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A Generalized Relationship for Determination of Tensile Strength of Fine-Grained Soils from Shrinkage Characteristics

Cited by 6 publications

References 36 publications

Analysis of the Shrinkage Effect on Mass Transfer During Convective Drying of Sawdust/Sludge Mixtures

Analysis of the Shrinkage Effect on Mass Transfer During Convective Drying of Sawdust/Sludge Mixtures

Novel Techniques to Simulate and Monitor Contaminant–Geomaterial Interactions

The influence of saturation on the cracking process in compacted desiccating clays

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