Loading...

Water retention and volumetric characteristics of intact and re-compacted loess

Wang Wai Ng, C ; Sharif University of Technology | 2016

946 Viewed
  1. Type of Document: Article
  2. DOI: 10.1139/cgj-2015-0364
  3. Publisher: Canadian Science Publishing , 2016
  4. Abstract:
  5. Alaboratory testing program was conducted to investigate the effects of microstructure on the water retention curve (WRC) and wetting-drying induced volume change in loess. The axis translation and vapor equilibrium techniques were adopted to control suction in the range of 0-400 kPa and 4-140 MPa, respectively. Hysteresis in the WRC of loess was observed for the entire range of suction studied. Compared to re-compacted loess, intact loess exhibits a more pronounced hysteresis in the suction range below 20 kPa, which can be explained by the ink-bottle pore neck effect or constricted pores. The hypothesis is supported by microstructural evidence of mercury intrusion porosimetry and scanning electron microscopy tests. However, re-compacted loess exhibits larger hysteresis than intact loess for suctions above 30 kPa. A conceptual model was introduced, which links WRC to the corresponding pore-size density (PSD) function. Regarding volume change, more noticeable drying-induced shrinkage, but yielding at a lower suction, was observed for re-compacted loess. This is consistent with the compression test results. Stress has a significant effect on change of PSD and constricted macropores leading to a shift in the main wetting curve and a less pronounced hysteresis. Intact loess exhibits a stress-dependent wetting-induced collapse and drying-induced shrinkage
  6. Keywords:
  7. Bottles ; Compression testing ; Drying ; Hysteresis ; Mercury (metal) ; Microstructure ; Pore size ; Road construction ; Scanning electron microscopy ; Shrinkage ; Software testing ; Wetting ; Collapse ; Loess ; Mercury intrusion porosimetry ; Scanning electron microscopy tests ; Testing programs ; Vapor equilibrium ; Volumetric characteristics ; Water retention curve ; Sediments
  8. Source: Canadian Geotechnical Journal ; Volume 53, Issue 8 , 2016 , Pages 1258-1269 ; 00083674 (ISSN)
  9. URL: http://www.nrcresearchpress.com/doi/10.1139/cgj-2015-0364#.WQZmlzdoTcc