Abstract: In order to investigate the applicability of watertight bentonite in arid and cold areas, the antifreezing properties of three kinds of bentonite, collected from different places, were studied. Results showed that, after Yellow River water was frozen and thawed for 31 timers, the free expansion volume, average EC value and shear stress of bentonite were increased by 32.8%, 27.7% and 40.6%, but the cumulative filtrating volume, filtration loss and thickness of filtered bentonite cake were decreased by 23.5%, 23.4% and 15.4 %, respectively. On the other hand, the results of ANOVA showed that the effects of freezingthawing process on the free expansion volume, EC value of solution, shear stress and cumulative filtrating volume were significant(F＞F_0.01); the microstructure parameters of bentonite varied in a range from 86.02 μm to 372.12 μm, the pores were dominated by the plate and irregular shapes, the F value varied in a range from 0.12 to 0.40, and the fractal dimension of pore surface in a range of 1.18-1.21.

Key words: font-family: 宋体, mso-bidi-font-family: 宋体, mso-font-kerning: 1.0pt, mso-ansi-language: EN-US, mso-fareast-language: ZH-CN, bentonite')">mso-bidi-language: AR-SA">bentonite, freezingfont-family: 宋体, mso-bidi-font-family: 宋体, mso-font-kerning: 1.0pt, mso-ansi-language: EN-US, mso-fareast-language: ZH-CN, thawing process')">mso-bidi-language: AR-SA">thawing process, ')">filtration loss, ')">rheology, microstructure