Pore-scale analysis of bulk volume change from crystalline interlayer swelling in Na+- and Ca2+-smectite
Likos, William J. (University of Missouri-Columbia. Department of Civil and Environmental Engineering)
Lu, Ning (Colorado School of Mines. Engineering Division)

Date:	2006
Abstract:	Water-vapor sorption experiments were conducted to quantify bulk volume change of compacted expansive clay specimens resulting from interlayer hydration and dehydration in the crystalline swelling regime. Effects of interlayer cation type and pore fabric are examined by comparing results for natural Na-smectite and Ca-smectite specimens compacted over a range of initial bulk densities. Transitions in interlayer hydration states are reflected in the general shape of the sorption isotherms and corresponding relationships between humidity and volume change. Hysteresis is observed in both the sorption and volume-change response. Volume change for Ca-smectite specimens is significantly greater than for Na-smectite over the entire range of packing densities considered. Loosely compacted specimens result in less volume change for both clays. Results are interpreted in light of a conceptual framework based on previous SEM and TEM observations of particle and pore fabric for Na and Ca smectite at high suctions. A pore-scale microstructural model is developed to quantitatively assess changes in interlayer and interparticle void volume during hydration. Modeling suggests that the relatively small volume changes observed for Na-smectite are attributable to a reduction of interparticle void volume as expanding quasicrystals encroach into surrounding larger-scale pores. Volume change hysteresis is attributed to unrecovered alterations in interparticle fabric required to accommodate the swelling process. The results provide new insight to address volume change upscaling, hysteresis, and the general evolution of bi-modal pore fabric during crystalline swelling.
Rights:	Aquest material està protegit per drets d'autor i/o drets afins. Podeu utilitzar aquest material en funció del que permet la legislació de drets d'autor i drets afins d'aplicació al vostre cas. Per a d'altres usos heu d'obtenir permís del(s) titular(s) de drets.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Crystalline Swelling ; Dehydration ; Hydration ; Interlayer ; Smectite ; Upscaling
Published in:	Clays and Clay Minerals, Vol. 54, Núm. 4 (2006) , p. 515-528, ISSN 1552-8367

DOI: 10.1346/CCMN.2006.0540412

14 p, 467.6 KB  UAB restricted access

The record appears in these collections:
Articles > Research articles
Articles > Published articles