Research Article
Consolidation Characteristics of Artificially Structured
Kaolin-Bentonite Mixtures with Different Pore Fluids
Nguyen Thanh Duong
1
andDuongVanHao
2
1
Hanoi University of Mining and Geology, Hanoi 100000, Vietnam
2
Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam
Correspondence should be addressed to Nguyen anh Duong; nguyenthanhduong@humg.edu.vn
Received 18 June 2020; Revised 27 July 2020; Accepted 7 September 2020; Published 15 September 2020
Academic Editor: Claudia Vitone
Copyright © 2020 Nguyen anh Duong and Duong Van Hao. is is an open access article distributed under the Creative
Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the
original work is properly cited.
e consolidation characteristics of kaolin, bentonite, their mixtures, and natural clays have been widely evaluated. However, the
effect of pore fluid on the consolidation characteristics of artificially structured kaolin-bentonite mixtures should be more
investigated. In this study, the oedometer tests were carried out on mixtures of kaolin with 10%, 20%, and 30% bentonite
reconstituted with distilled water and 1 M NaCl. e testing samples with an “artificial structure” were prepared using the
preconsolidation procedure. e test results show that bentonite greatly affects the consolidation behavior of mixture samples,
especially when the pore fluid is distilled water. In the case of distilled water, the addition of bentonite to kaolin clay significantly
increased the compression index (C
c
), swelling index (C
s
), and coefficient of volume change (m
v
). In this case, the m
v
of mixture
samples increased significantly at low effective axial stress (σ′
a
) levels (less than the preconsolidation pressure) and then decreased
as the σ′
a
further increased. In the case of 1 M NaCl as the pore fluid, the C
c
, C
s
, and m
v
slightly changed with the increase of
bentonite content. e research results also confirmed that the effect of saline water on the compression index was noticeable
when the liquid limit of soil with distilled water was higher than 110%, and the compression index of soil with distilled water was
higher than 1. Regarding the coefficient of consolidation (C
v
), the C
v
of kaolin sample increased as the σ′
a
increased, and this trend
was independent of the pore fluid chemistry. By contrast, the C
v
- σ′
a
trend of mixture samples depended not only on the pore
fluids but also on the stress level.
1.Introduction
e compressibility of clays is one of the most important
aspects in geotechnical engineering, especially regarding the
settlement calculation. It has been widely studied in terms of
different clay minerals and different pore fluids [1–8]. e
results indicated that there was a significant difference in the
compression behavior of bentonite and kaolinite with dif-
ferent pore fluids. It may be attributed to the difference in
surface charge and clay mineral structures [7, 9–14]. For
bentonite, the compression behavior accords with the
double layer theory and strongly depends on the pore fluid
chemistry. e increase in ion valence and ion concentration
of the pore fluid leads to a decrease of the compressibility
and swelling ability. For kaolinite, the pore fluid also affects
the compressibility but with a smaller degree than for
bentonite. Robinson and Allam [7] and Sridharan and Rao
[8] noted that the compressibility of kaolinite was mainly
governed by mechanical factors, while it of bentonite was
mostly controlled by physicochemical effects. However,
Chen et al. [3] noted that the compressibility and swelling of
kaolinite were controlled by both chemical and physico-
chemical factors. e compressibility of kaolinite was in-
dependent of pore fluid properties under stresses of 300 kPa.
e controlling factors of compression may affect the
consolidation coefficient (C
v
). Robinson and Allam [7]
showed that the C
v
increased with consolidation pressures
when the controlling factor of compression behavior was
mechanical and decreased with consolidation pressure when
the controlling factor was physicochemical. Recently, Dutta
Hindawi
Advances in Civil Engineering
Volume 2020, Article ID 8856404, 9 pages
https://doi.org/10.1155/2020/8856404