Evaluation on the thermal and moisture diffusion behavior of sand/bentonite

Li, H.F.; Chen, Meiqian; Fu, B.A.; Liang, Bin

doi:10.1016/j.applthermaleng.2019.01.100

Cited by 28 publications

(5 citation statements)

References 55 publications

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“…In addition, we believe that the microbead effect of bentonite and fly ash fine particles can improve the bonding force between slurry particles [44]. When bentonite is moistened and expanded, its particles will attract one another and form a binding water film when they contact the surface of gangue/tailings particles [45]. The bentonite particles are connected in a chain structure by cations to reduce free water in the slurry, which can significantly reduce the bleeding rate of the filler slurry.…”

Section: Bleeding Ratementioning

confidence: 99%

A Preliminary Study on the Improvement of Gangue/Tailing Cemented Fill by Bentonite: Flow Properties, Mechanical Properties and Permeability

Wang,

Chen,

Guo

et al. 2023

Materials

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Backfill mining has significant advantages in safe mining, solid waste utilization and ecological environmental protection, but solid waste materials (tailings, gangue and coal gasification slag, etc.), as derivative residues of the chemical and metallurgical industries, contain a large number of heavy metal elements, which is posing great challenges to the underground environment after backfill. In order to study the feasibility of bentonite for reducing the permeability of gangue/tailing sand cemented backfill body, relevant tests were carried out from the basic performance index, flow performance and mechanical properties of paste backfill materials. The test results show that bentonite has a significant effect on the water secretion rate of cemented fillers, and also promotes the improvement of slump and diffusion diameter of backfill slurry. The enhancement effect of mechanical properties in the early stage is not obvious, mainly concentrated in the middle and late stages of specimen curing. With the increase of bentonite content, the 28-day uniaxial compressive strength increased from 7.1 MPa and 7.9 MPa to 8.7 MPa and 9.0 MPa, respectively. Bentonite is filled between the pores of the cemented backfill with its fine particles and water swelling, which can reduce the porosity and permeability of the gangue and tailings cemented backfill. Therefore, on the premise of satisfying the flow and mechanical properties of paste backfill, bentonite can be used to improve the permeability of cemented backfill and reduce the leaching and migration of heavy metal ions.

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Section: Bleeding Ratementioning

confidence: 99%

A Preliminary Study on the Improvement of Gangue/Tailing Cemented Fill by Bentonite: Flow Properties, Mechanical Properties and Permeability

Wang,

Chen,

Guo

et al. 2023

Materials

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“…The volumetric heat capacity of geomaterials and mixtures increases with w and bentonite content, because of high percentage of bentonite clay in the mixture leads to absorption of more water due to its swelling potential and water retention properties. Although, the contact between the solid particles diminished with increasing of bentonite, due to formation of double diffuse layer, thereby reduced the thermal conductivity of the mixtures [74]. On the other hand, the rate of increase of thermal conductivity with respect to water content is relatively grater than of the volumetric speci c heat capacity before TWC, but after TWC, increasing rate of thermal conductivity is relatively lower than the volumetric speci c heat capacity [56].…”

Section: Discusionmentioning

confidence: 99%

Thermophysical Properties of Bentonite–Sand/Fly Ash-Based Backfill Materials for Underground Power Cable

2023

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The surrounding (back ll) materials around the underground power cable systems are essential for dissipiating the heat away from it, during the exertion phases. The heat dissipiation restrains the thermal instability and risk of progressive drying of the back ll materials, thus, reduce thermal stress on power cable. Thermal instability is the reduction of thermal properties (conductivity or diffusivity) due to migration of moisture because of heat accumulation. Thus, the back ll materials should have adequate thermal properties and favorable water retention capacity, which will falicitate the heat transfer easily from the heat source to the surrounding area with minimal moisture migration. The bentonite have high water retention capacity, but low thermal conductivity. Sand/ y ash exhibit low water retention and have higher thermal conductivity than bentonite. The addition of bentonite promote the water holding capacity and thermo-physical properties of sand and y ash. Therefore, this study presents the thermal properties of back ll materials, bentonite-y ash (B-F) and bentonite-sand (B-S) at varying weigth-percent of sand and y ash with bentonite. various compositions of the mixtures were compacted to varying dry densities and water contents and thermal properties variation of back ll materials were measured using a dual thermal needle probe 'KD2 Pro 2008' at room temperature. The study deals with systematic evaluation of the volumetric speci c heat capacity, thermal conductivity and diffusivity of back ll materials against varying dry density and water content. The threshold water content (TWC) has been determined from the thermal diffusivity-water content variation curve and it has correlated with plastic limit (PL) and optimum mosite conetn (OMC). Thereafter, the e cacy two thermal conductivity prediction models also were statistically evaluated with respect to experimental results.

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“…The thermal conductivity of buffer is an important factor for HLW disposals which depends on dry density, water content and sand content [14].…”

Section: Materials and Propertiesmentioning

confidence: 99%

Shear Strength Characteristics of a Thermally Cured Sand-Bentonite Mixture

2021

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An experimental program was conducted to investigate the effects of curing time and curing temperature on shear behavior of a sand-bentonite mixture. The specimens were cured at temperatures of 40°C, 60°C and 80°C for 1, 3 and 5 days under 100kPa, 500kPa and 1000kPa confinements. The results of consolidated undrained triaxial shear tests showed that an increase in temperature from 40°C to 80°C at 1, 3 and 5 days of curing increased the shear strength by 25%, 24% and 23%, respectively. Also, the increase in curing time from 1 to 3 and from 1 to 5 days at 80°C increased the shear strength of samples 12% and 24%, respectively. The failure of pre-cured samples occurred in lower strains as a result of more induced brittleness.Moreover, the secant modulus as well as the size of yield loci and critical state line's slope increased by pre-curing. The application of thermal cycles resulted in increasing shear strength and experiencing a negative pore water pressure which shows a transition towards the quasistructured behavior. The results of scanning electron microscopy (SEM) studies confirmed the increase in void ratio during thermal curing.

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Evaluation on the thermal and moisture diffusion behavior of sand/bentonite

Cited by 28 publications

References 55 publications

A Preliminary Study on the Improvement of Gangue/Tailing Cemented Fill by Bentonite: Flow Properties, Mechanical Properties and Permeability

A Preliminary Study on the Improvement of Gangue/Tailing Cemented Fill by Bentonite: Flow Properties, Mechanical Properties and Permeability

Thermophysical Properties of Bentonite–Sand/Fly Ash-Based Backfill Materials for Underground Power Cable

Shear Strength Characteristics of a Thermally Cured Sand-Bentonite Mixture

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