Formation factor measurements in granite in the laboratory – Comparison of through diffusion and electromigration techniques.

2002 ◽  
Vol 757 ◽  
Author(s):  
Martin Löfgren ◽  
Ivars Neretnieks
Keyword(s):  
Direct Current ◽  
Igneous Rock ◽  
Rock Sample ◽  
Effective Diffusivity ◽  
Diffusive Flux ◽  
Formation Factor ◽  
Granite Sample ◽  
Experimental Time ◽  
Large Samples ◽  
Through Diffusion

ABSTRACTTraditionally the effective diffusivity in and the formation factor of intrusive igneous rock have been measured in the laboratory by through diffusion (TD) experiments, which are very time consuming in larger samples with low porosity. In previous work alternating current (AC) has been used to measure the formation factor directly in large samples. In this paper direct current is used to actually transport the tracers through the rock sample in so called through electromigration (TEM) experiments. In these experiments electoosmosis has to be corrected for. The experimental time is reduced substantially when adding an electromigratory flux to the diffusive flux. TD, TEM and AC experiments were performed on a 15 mm thick unweathered granite sample from Laxemar, Sweden. The tracers uranin and iodide were used. The formation factor measured with the three methods varied between 1.2·10-4 - 2.87·10-4.

Matrix Diffusion Measurements – Through Diffusion versus Electrical Conductivity Measurements

2000 ◽  
Vol 663 ◽  
Author(s):  
Y. Ohlsson ◽  
I. Neretnieks
Keyword(s):  
Electrical Conductivity ◽  
Pure Water ◽  
Effective Diffusivity ◽  
Surface Conductivity ◽  
Bulk Liquid ◽  
Matrix Diffusion ◽  
Conductivity Measurements ◽  
Formation Factor ◽  
Conductivity Method ◽  
Through Diffusion

ABSTRACTMatrix diffusion laboratory experiments in dense porous rock are generally very time consuming and one is limited to rather short diffusion lengths, as well as to a small amount of samples. The large heterogeneity of rock, on the other hand, demands a large quantity of samples that are large enough to exclude effects from e.g. increases in interconnected porosity compared to that of the pristine rock.Electrical conductivity measurements are very fast and larger samples can be used than is practical in ordinary diffusion experiments. The effective diffusivity of a non-charged molecule is readily evaluated from the measurements, and influences from surface conductivity on diffusion of cations can be studied.In this study traditional through diffusion experiments as well as electrical conductivity measurements are carried out on the same rock samples. The formation factor is determined by both methods, and the methods are compared and discussed.The surface conductivity is studied by exchanging the surface sites with Na+, Sr2+ and Cs+. After leaching out the free pore ions the surface conductivity is measured.With the electrical conductivity method the formation factor is determined directly, whereas it has to be calculated using the bulk liquid diffusion coefficient in the diffusion experiments. This causes some uncertainties in the comparison between the experiments. In estimating the bulk liquid diffusivity, the value for infinitely diluted solutions and in pure water environment is commonly used. The calculated formation factor may therefore be somewhat underestimated.

Diffusion of Cs, Np, Am and Co in compacted sand-bentonite mixtures: evidence for surface diffusion of Cs cations

Clay Minerals ◽  
2013 ◽  
Vol 48 (2) ◽  
pp. 411-422 ◽  
Author(s):  
T. Sawaguchi ◽  
T. Yamaguchi ◽  
Y. Iida ◽  
T. Tanaka ◽  
I. Kitagawa
Keyword(s):  
Surface Diffusion ◽  
Pore Water ◽  
Concentration Gradient ◽  
Unit Volume ◽  
Effective Diffusivity ◽  
The Other ◽  
Diffusion Method ◽  
Diffusive Flux ◽  
Diffusive Transport ◽  
Through Diffusion

AbstractWe studied the diffusive transport of Cs, Np, Am and Co in compacted sandbentonite mixtures by using the through-diffusion method. The experiments for Cs were performed under various aqueous compositions. Effective diffusivity (De) values of 4.7×10–10 to 5.9×10–9 m2 s–1 were obtained with a somewhat large variation. Apparent diffusivity (Da) values, on the other hand, showed less variation, ranging from 2.0×10–12 to 6.2×10–12 m2 s–1. The results indicated that diffusive flux was proportional to the concentration gradient on the basis of the amount of Cs in the unit volume of the compacted sand-bentonite mixtures rather than the Cs concentration gradient in pore water. Because the former concentration gradient in the mixtures was nearly equal to that of adsorbed Cs, the diffusion of Cs in the mixtures was probably dominated by the concentration gradient of the Cs adsorbed on the mixtures. In addition, the effective/apparent diffusivity of 237Np(IV) and apparent diffusivity of 241Am(III) and 60Co(II) in the mixtures were determined in 0.3/0.03 mol l–1 (NH4)2CO3/Na2S2O4 solution.

A Precambrian trondhjemite boulder in Palaeozoic mudstones of NW Malaya

1977 ◽  
Vol 114 (6) ◽  
pp. 479-482 ◽  
Author(s):  
P. H. Stauffer ◽  
N. J. Snelling
Keyword(s):  
Igneous Rock ◽  
Rock Sample ◽  
Source Area ◽  
Alkali Feldspar ◽  
Malay Peninsula ◽  
Precambrian Rock ◽  
Minimum Age

SummaryA boulder of plutonic igneous rock, petrologically perhaps best termed a trondhjemite, which occurs as an isolated megaclast in slumped mudstones of the Singa Formation (mainly Carboniferous) at Pulau Tepor off NW Malaya, has been dated by the potassium–argon method. Two feldspar fractions, thought to represent alkali feldspar and plagioclase (though both are highly sodic) yield ages of 1029±15 Ma and 575±10 Ma, respectively, while a whole-rock sample yields an age of 264±4 Ma. The highest age is taken to give a minimum age for the rock, and the lower ages to indicate differential argon loss. This is the first radiometrically proved Precambrian rock from the Malay Peninsula, and tends to reinforce earlier inferences of a Precambrian continent as a source area for Palaeozoic sediments in the region.

Graph cuts and neural networks for segmentation and porosity quantification in Synchrotron Radiation X-ray μCT of an igneous rock sample

2018 ◽  
Vol 133 ◽  
pp. 121-132 ◽  
Author(s):  
Anderson Alvarenga de Moura Meneses ◽  
Dayara Bastos Palheta ◽  
Christiano Jorge Gomes Pinheiro ◽  
Regina Cely Rodrigues Barroso
Keyword(s):  
Neural Networks ◽  
Synchrotron Radiation ◽  
Igneous Rock ◽  
Rock Sample ◽  
Graph Cuts ◽  
X Ray

Effective diffusivity of neptunium and plutonium in granite from Inada, Ibaraki, Japan under anaerobic conditions

2002 ◽  
Vol 90 (12) ◽  
Author(s):  
Tetsuji Yamaguchi ◽  
S. Nakayama ◽  
H. Okamoto
Keyword(s):  
Effective Diffusivity ◽  
Diffusion Method ◽  
Anaerobic Conditions ◽  
Through Diffusion ◽  
Effective Diffusivities

SummaryThe effective diffusivities of neptunium and plutonium in Inada granite have been determined using the through–diffusion method. Experiments were performed under anaerobic conditions in the presence of carbonate. The actinides are expected to be present as carbonato or carbonatohydroxo complexes. Effective diffusivity (D

Mineralogical Changes of Cement and Bentonite Accompanied ith Their Interactions

2009 ◽  
Vol 1193 ◽  
Author(s):  
Seiichi Hoshino ◽  
Tetsuji Yamaguchi ◽  
Toshikatsu Maeda ◽  
Masayuki Mukai ◽  
Tadao Tanaka ◽  
...  
Keyword(s):  
Tritiated Water ◽  
Effective Diffusivity ◽  
Diffusion Method ◽  
Hardened Cement ◽  
Computational Studies ◽  
Secondary Phases ◽  
Hardened Cement Paste ◽  
Xrd Pattern ◽  
Through Diffusion ◽  
Primary Minerals

AbstractMineralogical changes of cement and bentonite accompanied with their interaction wereexperimentally studied by mixing granulated hardened cement paste and bentonite, and aging the mixture for91 days at 50° C. Mineralogical changes of cement and bentonite were identified by XRD. Hydratedcalcium-silicate phases (C-S-H), Ca(OH)2, ettringite and monosulfate were identified in the unalteredhardened cement. While Ca(OH)2 and monosulfate decreased with aging and disappeared after 91 days,calcite and katoite (Ca3Al2(SiO4)(OH)8) were formed concurrently. Montmorillonite, quartz (and/orchalcedony), clinoptilolite, plagioclase, calcite, analcime and pyrite were identified in the unaltered bentonite.The XRD pattern showed that diffraction intensities of these minerals decreased with aging. It seems thatthese primary minerals dissolved in the course of the alteration. C-S-H appeared in bentonite during the agingas secondary phases, indicating the participation of silicon dissolved from the bentonite and calcium from thecement formed the C-S-H. The formation of C-S-H that had been predicted by previous modeling studieswas confirmed by the present experiments.In addition, diffusivity of tritiated water in mixed specimen with granulated hardened cement andbentonite was determined by a through-diffusion method. The effective diffusivity of tritiated water decreasedwith aging. The result suggests that the mass diffusivity in the interface of cement-bentonite system willdecrease with their interactions. The results of the diffusion experiments are qualitatively consistent with thediffusivity change in cement-bentonite systems predicted by some computational studies.

A Study of Rock Matrix Diffusion Properties by Electrical Conductivity Measurements

1999 ◽  
Vol 556 ◽  
Author(s):  
Y. Ohlsson ◽  
I. Neretnieks
Keyword(s):  
Electrical Conductivity ◽  
Effective Diffusivity ◽  
Crystalline Rock ◽  
Surface Conductivity ◽  
Matrix Diffusion ◽  
Sample Length ◽  
Conductivity Measurements ◽  
Rock Matrix ◽  
Formation Factor ◽  
Short Period

AbstractTraditional rock matrix diffusion experiments on crystalline rock are very time consuming due to the low porosity and extensive analysis requirements. Electrical conductivity measurements are, on the other hand, very fast and larger samples can be used than are practical in ordinary diffusion experiments. The effective diffusivity of a non-charged molecule is readily evaluated from the measurements, and influences from surface conductivity on diffusion of cations can be studied. A large number of samples of varying thickness can be measured within a short period, and the changes in transport properties with position in a rock core can be examined.In this study the formation factor of a large number of Äspö diorite samples is determined by electrical conductivity measurements. The formation factor is a geometric factor defined as the ratio between the effective diffusivity of a non-charged molecule, to that of the same molecule in free liquid. The variation of this factor with position along a borecore and with sample length, and its coupling to the porosity of the sample is studied. Also the surface conductivity is studied. This was determined as the residual conductivity after leaching of the pore solution ions. The formation factor of most of the samples is in the range 1E-5 to 1E-4, with a mean value of about 5E-5. Even large samples (4-13 cm) give such values. The formation factor increases with increasing porosity and the change in both formation factor and porosity with position in the borecore can be large, even for samples close to each other.The surface conductivity increases with increasing formation factor for the various samples but the influence on the pore diffusion seems to be higher for samples of lower formation factor. This suggests that the relation between the pore surface area and the pore volume is larger for samples of low formation factor.

Infrared Thermal Image Study on Failure of Granite with Hole

2007 ◽  
Vol 353-358 ◽  
pp. 2313-2316 ◽  
Author(s):  
Zhi Hong Tan ◽  
Chun An Tang ◽  
Wan Cheng Zhu
Keyword(s):  
High Temperature ◽  
Thermal Effects ◽  
Rock Sample ◽  
Failure Process ◽  
Close Relation ◽  
Local Area ◽  
Thermal Image ◽  
Image Study ◽  
Granite Sample ◽  
Infrared Thermal Images

The changing behavior for infrared thermal image omen of the rock with fracture is essential for the geotechnical engineering. In order to study the behavior, the infrared thermal images for the failure process of rock with hole are carried out. The size of the rock sample is 20cm×10cm×2cm with hole at the center of the sample and the diameter of the hole is 1cm. Considering the fact that sample will effect the results of the observation for infrared thermal image during the experiment, the laminated granite sample was used to replace the cylinder or cuboid sample. The achieved results under uniaxial compression indicate that intensity of the micro ruptures have a close relation with the thermal effects. When the main fractures happen, there is a strip of high temperature that will appear at the destructed local area. During loading process, the abnormity of infrared temperature has two kinds of behaviors as follows: (1) temperature rises and falls alternately, rises before the fracture; (2) temperature falls slowly at beginning, and then rises slowly, then rises quickly before the fracture appears. Even for the same rock sample, the behaviors of the infrared phenomenon may be different during failure.

Diffusion of Cesium and Iodine in Compacted Sodium Montmorillonite Under Different Saline Conditions

2009 ◽  
Vol 1193 ◽  
Author(s):  
Yukio Tachi ◽  
Kenji Yotsuji ◽  
Yoshimi Seida ◽  
Mikazu Yui
Keyword(s):  
Diffusion Model ◽  
Effective Diffusivity ◽  
Dry Density ◽  
Sodium Montmorillonite ◽  
Through Diffusion ◽  
Sorption Parameters ◽  
Factor Α ◽  
Concentration Curves ◽  
Good Agreement ◽  
Depth Concentration

Diffusion and sorption of cesium (Cs) and iodine (I) were investigated in a purified and moderately compacted sodium montmorillonite (dry density of 800 kg m-3) saturated with 0.01, 0.1 and 0.5M NaCl solutions. The effective diffusivity (De) and capacity factor (α) for Cs and I were measured by through-diffusion experiments, coupled with multiple curve analyses, including tracer depletion, breakthrough and depth concentration curves, which could be fitted with a conventional diffusion model using only one set of parameters. The De values obtained for Cs were of the order of 10-9-10-10 m2 s-1 and decreased as salinity increased, and those for I were of the order of 10-11-10-12 m2 s-1 and showed the opposite dependency. The distribution coefficient (Kd) of Cs decreased from the order of 100 to 10-2 m3 kg-1 as salinity increased. Diffusion and sorption parameters for Cs were also obtained by in-diffusion and batch sorption experiments and showed good agreement with those obtained by the through-diffusion experiments. The diffusion model, based on homogeneous pore structure and electrical double layer (EDL) theory, predicted the salinity dependence of De reasonably well, showing the effect of cation excess and anion exclusion as a function of salinity. The apparent diffusivity (Da), which includes sorption effects, was also interpreted by a coupled sorption model.

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