429
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
1
Mechanisms of binder interactions and their role in strengthening Kuttanad clay
Mécanismes d’interaction des liants et leur rôle dans le renforcement de l’argile de Kuttanad
Suganya K. ,Sivapullaiah P.V.
Indian Institute of Science, Bangalore, India
ABSTRACT: The present investigation is on a soft organic soil from Kuttanad region in Kerala, India wherein a detailed laboratory
study was undertaken to contemplate the interaction of various components of soil with cement and cement admixtures. An attempt
was made to understand the influence of cement as binder based on parameters such as Clay water/ Cement (W/C) ratio, Initial water
content of clay (IW) and curing period by studying the Unconfined Compressive Strength (UCC) of stabilized soil. The results
showed that the UCC strength increased with decreasing W/C ratio irrespective of the IW used. Binder combinations involving partial
replacement of Cement with Lime, Fly ash and Slag were not effective in improving the strength of soil when compared to the
performance of cement alone as binder. On the other hand, addition of Sodium Silicate to cement enhanced the strength of the soil
significantly.
RÉSUMÉ : Le travail présenté porte sur un sol mou organique de la région de Kuttanad, dans le Kerala, en Inde, pour lequel une
étude de laboratoire détaillée a été menée pour analyser les interactions de différents composants du sol avec le ciment et les adjuvants
ajoutés. Une tentative a été faite pour comprendre l'influence du ciment en tant que liant, en se basant sur l’étude de paramètres tels
que le rapport eau de l’argile / ciment (W / C), la teneur en eau initiale de l'argile (IW) et la période de cure, en étudiant la résistance à
la compression simple (UCC) du sol traité. Les résultats ont montré que la résistance à la compression simple augmente avec la
diminution du rapport W / C, quelle que soit la valeur de IW. Différentes formulations de liants basées sur le remplacement partiel du
ciment par de la chaux, des cendres volantes et du laitier ne se sont pas avérées efficaces pour améliorer la résistance du sol par
rapport au ciment seul. D'autre part, l'ajout de silicate de sodium au ciment améliore de manière significative la résistance du sol.
KEYWORDS: Kuttanad soil, Minerology, Binders, Organic content, Shear strength
MOTS-CLÉS : sol du Kuttanad, minéralogie, liants, teneur en matière organique, résistance au cisaillement
1 INTRODUCTION
Soft soils are more prominently found in coastal regions and
low land areas where many important cities and ports are
located. And also in today’s scenario of increased rate of
infrastructural development to match the population growth, it
has become mandatory to construct on soft grounds.
Soft clays
normally exist with high liquidity indices and presence of soft
clay as a foundation material in any construction project
demands proper engineering judgment as it is associated with
inherent problems of excessive settlement and low shear
strength. In addition to it presence of organic content in soft
clays further worsens the ability of the deposit to support even
moderate loads. Such problematic soft soil deposits with
inadequate geotechnical properties are present in Kuttanad
region of Kerala, India. This soft soil used in the present study
also contains organic matter (Thiyyakkandi and Annex 2011)
and is found to be acidic (Muralidharan et al. 1999). There are
many geotechnical failures reported in Kuttanad region (Ayyar
1966) and hence improving the properties of the soil have been
a matter of intense research (Bindu and Vinod 2008, Dipty and
Girish 2009).
Compared to other methods of improving the soft ground,
introducing deep mixed cement columns and mass stabilization
with binders are rapid techniques of ground improvement.
Successful case histories are reported on soft grounds improved
with soil stabilization techniques (Bergado et al. 1999, Lin and
Wong 1999). It is important to note that the success of the
method is by the interaction of the binders with the soft clay and
the extent of improvement in strength depends on factors such
as the type and amount of binder, water content, soil type and
curing period (Lorenzo and Bergado 2004, Horpibulsuk et al.
2005). However little is understood about the role of organic
matter and clay type on the binder soil interaction. Hence in the
present study an attempt is made to evaluate the mechanism of
strength development with various binders along with other
additives.
2 MATERIALS AND METHODS
2.1 Soil Sample
Clay collected from Kuttanad region, Kerala from a depth of 2
m was used in experimental investigation. The clay is classified
as organic clay of high plasticity (OH) according to IS 1498
(Part 1) - 1987. The specific gravity of the soil was determined
based on the code IS 2720 (part 3) – 1980. The Cation
Exchange Capacity (CEC) of the Kuttanad clay was measured
as per the guidelines of ASTM D7503. Organic content of the
soil was determined as per the
code, ASTM D2974. Unconfined
compressive strength of the soil at a water content of 125 % was
found to be 10 kPa. The properties of the clay used in the study
are given in Table 1.
Table 1. Properties of Kuttanad clay.
Colour
Black
Specific gravity
2.48
Soil classification
OH
Organic content
17 %
Natural water content
100 to 200 %
CEC
17 meq/100 g
pH
3.6
