Investigating the Microstructure of Compacted Crushed Callovo-Oxfordian Argillite

Tang, Chaosheng; Tang, Anh-Minh; Cui, Yu Jun; Delage, Pierre; Shi, Bin; Schroeder, Christian

doi:10.1061/41101(374)28

Cited by 8 publications

(7 citation statements)

References 11 publications

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“…oedometer method, constant swell method, etc.) [34,35]. This may invariably lead to considerable disparity in the values of swelling parameters (i.e.…”

Section: Resultsmentioning

confidence: 95%

Mineralogical Compositions of Some Indian Expansive Soils and Their Influence on Swelling Properties

Tahasildar

Rao

Shukla

2017

Int. J. of Geosynth. and Ground Eng.

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“…oedometer method, constant swell method, etc.) [34,35]. This may invariably lead to considerable disparity in the values of swelling parameters (i.e.…”

Section: Resultsmentioning

confidence: 95%

Mineralogical Compositions of Some Indian Expansive Soils and Their Influence on Swelling Properties

Tahasildar

Rao

Shukla

2017

Int. J. of Geosynth. and Ground Eng.

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“…Various other methods can be used for this purpose (see Figure 5b). The "constant-volume" method (path OA) is based on the use of a relatively rigid cell with total pressure measurement (Tang et al, 2011, Wang et al 2012).…”

Section: Interpretation and Discussionmentioning

confidence: 99%

An insight into the unloading/reloading loops on the compression curve of natural stiff clays

Cui

Nguyen²,

Tang³

et al. 2013

Applied Clay Science

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Oedometer tests were carried out with loading/unloading/reloading on natural saturated Ypresian clay taken from several depths. Common unloading/reloading loops were identified. Further examination of the unloading or reloading curves shows that each path can be satisfactorily considered as bi-linear with a small and a larger slopes separated by a threshold vertical stress. This threshold stress can be considered as the swelling pressure corresponding to the void ratio just before the unloading or reloading. Indeed, upon unloading, when the applied stress is higher than the threshold stress or swelling pressure, the mechanical effect is dominant and only small mechanical rebound is observed, corresponding to a small microstructure change; by contrast, when the applied stress is lower than the swelling pressure, physico-chemical effect becomes prevailing, and soil swelling occurs with a larger microstructure change. Upon reloading, when the applied stress is lower than the swelling pressure, the microstructure is not significantly affected thanks to the contribution of the physico-chemical repulsive force, leading to a small volume change; on the contrary, beyond the swelling pressure, the mechanical effect becomes dominant giving rise to larger volume change corresponding to the microstructure collapse. Like unsaturated expansive soils, it is found that there is a good relationship between the swelling pressure (threshold stress) and the void ratio just before the unloading or reloading. This is confirmed by the results from the data reported in the literature on Boom and London clays. It can be then deduced that the unloading/reloading loop is rather due to the competition between the mechanical and physico-chemical effects on the microstructure changes than the viscosity effect as commonly admitted.

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“…For the "constant-volume" method (stress path OA), the devices presented in Figure 3 and Figure 4 were used. The constant-volume cell includes three parts (Figure 3, Tang et al, 2011b): (1) the bottom part containing a porous stone and a drainage system; (2) the middle cell (70 mm inner diameter) used to prevent radial swelling, with two air outlets; (3) the top part incorporating a total pressure sensor to monitor the swelling pressure. Figure 4 presents the setup used to control the suction in the soil sample using the vapour equilibrium technique (see Delage et al, 1998 for more details).…”

Section: Experimental Methodsmentioning

confidence: 99%

“…(iii) there is better compatibility of mineralogical and chemical compositions with host rock, allowing reduction of complex physico-chemical interaction with the host rock (Andra, 2005;Tang et al, 2011a;Tang et al, 2011b). On the other hand, unlike relatively inert sand, claystone contains clay minerals and interaction between claystone and bentonite may occur, affecting the hydro-mechanical behaviour of the compacted mixture.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on the swelling behaviour of bentonite/claystone mixture

Wang

Tang

Cui

et al. 2012

Engineering Geology

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200

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A mixture of the MX80 bentonite and the Callovo-Oxfordian (COx) claystone were investigated by carrying out a series of experiments including determination of the swelling pressure of compacted samples by constant-volume method, pre-swell method, zero-swell method and swell-consolidation method. Distilled water, synthetic water and humidity controlled vapour were employed for hydration. Results show that upon wetting the swelling pressure increases with decreasing suction; however, there are no obvious effects of synthetic water chemistry and hydration procedure on the swelling behaviour in both short and long terms. For the same initial dry density, the swelling pressure decreases with increasing pre-swell strain; whereas there is a well defined logarithmic relation between the swelling pressure and final dry density of the sample regardless of the initial dry densities and the experimental methods. It was also found that swelling pressure depends on the loading-wetting conditions as a consequence of the different microstructure changes occurred in different conditions. Furthermore, it was attempted to elaborate a general relationship between the swelling pressure and the final dry density for various reference bentonites.

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Investigating the Microstructure of Compacted Crushed Callovo-Oxfordian Argillite

Cited by 8 publications

References 11 publications

Mineralogical Compositions of Some Indian Expansive Soils and Their Influence on Swelling Properties

Mineralogical Compositions of Some Indian Expansive Soils and Their Influence on Swelling Properties

An insight into the unloading/reloading loops on the compression curve of natural stiff clays

Experimental study on the swelling behaviour of bentonite/claystone mixture

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