Effect of Moisture Content on Strength of Reinforced Clay Soil

This article explores the effect of moisture content on the strength of reinforced clay soil. It discusses the importance of clay soil stabilization and the various tests used to determine moisture content. The article also highlights the benefits and stakeholders involved in clay soil reinforcement.

1
Effect of Moisture content on strength of reinforced clay clay soil

2
Table of Contents
Introduction......................................................................................................................................2
Objectives........................................................................................................................................2
Keywords.........................................................................................................................................2
Benefits and Stakeholders................................................................................................................2
Literature Review............................................................................................................................3
Water composition.......................................................................................................................3
Aggregate used in polypropolyne fibres......................................................................................4
Tests for estimating the moisture in clay soil..............................................................................4
Significance of the tests...............................................................................................................8
Conclusion.......................................................................................................................................8
References........................................................................................................................................9

3
Introduction
With the increasing demand for land proclamation, the need for testing the integrity of the clay
soil on which construction or agriculture is to be done becomes much more important (Anggraini
et al, 2015). The inferior quality of clay soil thus, has to be the reinforced for the purpose.
Homogeneous reinforcing of clay soil makes use of the natural and man-made fibres. The use of
this method though depends on the optimum condition of clay soil moisture and clay soil mix.It
is fast becoming an accepted way to improve clay soil properties and increasing the strength of
the clay soil for construction and agricultural purposes. The intention of this project is to find the
effects of moisture content on the strength of reinforced clay clay soil. For this project, the
analysis of polypropylene fibres to reinforce clay soil of varying moisture content of various
degrees has been done. There are various previous studies done on it but on non cohesive clay
soil. This project will try to find the same on cohesive clay soil. There has been comprehensive
test done for this using different testing techniques and methods to find out a suitable answer.
Objectives
 To find the effect of moisture content on clay soil stabilization
 To find the effect of moisture content on the fibers used
 To find the results of various compressive tests
 To identify the significance of the various tests for the stakeholders
Keywords
Liquid Limit, Clay soil Integrity and Strength, Undrained Unconsolidated Test, Compaction
Test, Liquid Falcon Test
Benefits and Stakeholders
It has become more and more important to find effectiveness of various clay soil stabilization
techniques with the increasing need of land for various purposes. Various methods of clay soil
stabilization have been used to change the properties of clay soil and its strengths. The clay soil

4
quality degrades as a percentage of wastesand other foreign materials increases in the clay soil.
The clay soil becomes coarse and the texture of the clay soil changes over time which proves
detrimental for construction and agricultural purposes. In such cases, clay soil stabilization
comes to the rescue. The mechanical properties of the clay soil are changed through clay soil
stabilization. The various techniques to be applied for clay soil stabilization depend on the
moisture content of the clay soil. Thus, the effect of moisture content it of the clay soil for
reinforcing the clay soil becomes very important. The strength of the clay soil varies greatly with
density and moisture content of the clay soil (Chang et al, 2015). The farmers, the government
and the construction companies are going to benefit from this. They would then be able to
formulate necessary decisions required by the help of the analytical results of the tests. The
farmers can decide on the type of clay soil to be used for a particular crop and what its optimum
moisture content should be. The builders can use it to determine the type of construction can be
done without loss of property.
Literature Review
Water composition
The moisture content of the clay soil is tested to determine the best combination of the fibres to
be used for increasing the strength of the clay soil. According to Kim and Choi (2015), the
presence of moisture in the clay soil increases the cohesiveness of the clay soil but to some
extent and in a definite proportion. Thus the bearing capacity of the clay soil also increases. With
the breaking of the surface tension between the consequent clay soil particles owing to the
presence of excessive moisture content, the bearing capacity decreases.

5
Figure 1: Assessing clay soil composition
Source: (Steemit, 2019)
Evidently, the bearing capacity i.e. the surface tension between the particles breaks at around 4%
moisture content. The bulking of the clay soil also increases with increasing moisture content,
the density goes on decreasing. The bearing capacity also decreases with the density as it has
direct relationship with it (Consoliet al, 2016).
Aggregate used in polypropolyne fibres
Although the water addition to the clay soil is also an effective compaction method, the bearing
capacity rises to a maximum at saturation state than at completely dry condition. According to
Diab et al. (2018), the durability and strength of the polypropolyne fibres used can be done by
various tests like compaction tests, undrained unconsolidated tests, liquid limit and liquid falcon
tests. The fibres are stretched and mobilized by the application of stress which can be used to
calculate the strength of the fibres to be used. The shear content and cracks are also much more
tentative at low moisture or dry state as per the Australian standards AS 1289 .6.2.-1998
(Saiglobal, 2019).
Tests for estimating the moisture in clay soil
Compaction Test: According to Guo et al. (2016), the method of experimentally determining in
laboratory the moisture content of the clay soil is through the compaction test. The test shows the
percentage of moisture at which the clay soil will become most dense to get optimal dry density.
The test is conducted to show so that dry density of the clay soil depends on the moisture content
of the soul for any compactive effort carried out while clay soil compaction. The method of
compaction test involves the moulding of the clay soil to be tested in a cylindrical mold having
standard dimensions. Then, a compactive effort is applied on it in a controlled manner using a
standard weight of hammer. The hammer is dropped from a particular height a number of times.
The test is also repeated several times with varying moisture content and a graph is drawn.

6
Figure 2: Compaction test
Source: (Theconstructor, 2019)
As guided by Benessalah et al. (2016), the graph of dry densities with the moisture content peaks
at a particular point and the corresponding moisture content is noted. This moisture content is
known as the optimal moisture content for getting maximum strength through compaction of the
clay soil.
Undrained Unconsolidated Test: According to Giger et al. (2018), based on the nature of the
load and conditions of drainage, it is a type of compression tests.The undrained unconsolidated
triaxial emulator is used for this purpose. It consists of five sensors of deformation out of which
four are radial deformations and the other is a vertical deformation. There is also a sensor for
axial pressure. The emulator also takes into account the height of the sample to be tested,
diameter of the clay soil, cell pressure etc.

7
Figure 3: Undrained Unconsolidated Test
Source: (Researchgate, 2018)
According to Spagnoli et al (2018), the result obtained from the test is used to draw graphs of
radial strain vs stress, vertical strain vs stress etc. The importance of this test also increases due
to the fact that comprehensive tests cannot be done after the construction of structures but has to
be carried out. Hence, these tests give us elaborate data to determine the various aspects required
for clay soil compaction.
Liquid Limit:The measures of the water content of the clay soil is done by the liquid limit. It is
one of the Atterberg limits. According to Chang et al. (2015), the content of moisture at which
the property of the clay soil to be tested changes from plastic to liquid is known as the liquid
limit.The liquid limit of the clay soil can be used to determine the various kinds of clay and their
properties. The engineering of the construction will also greatly vary according to the type of
clay.

8
Figure 4: Liquid Limit test
Source: (Theconstructor, 2019)
According to Haigh (2015), the liquid limit is defined as the percentage of moisture content to
cause the clay soil to come closer by a distance of 0.50 in. The clay soil shows with various
properties of expansion or retention depending on the moisture content of the clay soil. The
extent of expansion or contraction depends on the ability of the clay soil to absorb water.
According to Dantas et al (2017), the clay soil also reacts with the moisture to change its size
and thus shear strength varies. So, to establish the clay soil has correct proportion of shear
strength and no considerable changes in the volume of the clay soil occurs due to change in the
moisture content, these test are carried out.
Liquid Falcon Test:The geothermal reservoir analysis and simulation used for THMC
geosystems on the basis of the MOOSE framework is known as the liquid falcon test (Github,
2019). It is a finite element reservoir. It helps in solving the equations relating to the flow of
fluids, transfer of heat and fracture and deformation of rocks. It is an extensibly abstract interface
which can take into account multi-phase and multi-species system of testing.

9
Significance of the tests
The various compressive tests are an effective tool to check the cohesiveness of the clay soil.
The strength, flexural toughness and the ductility of the fibre to be used for clay soil stabilization
is tested by the use of varying percentages of fibres.
Conclusion
The technique of clay soil stabilization varies according to the components of the clay soil, its
moisture content and quality of clay soil. This research project has been instrumental in
educating me on the various clay soil stabilization techniques. I have learned about the various
methods of clay soil stabilization for varying kinds of clay soil. The integrity and strength of the
clay soil is influenced by the moisture content of the clay soil and thus must be studied for
obtaining an optimal circumstance. This project has also taught me that the percentage
composition of the fibres used for this purpose also must change with changing percentage of
optimal moisture content. Various percentage of fibre are used while testing which gives us real
time data of the type of clay soil and the kind of fibres that need to be used for clay soil
stabilization. It has also greatly enriched my research skills which will help me in my future
career prospects.

1
0
References
Anggraini, V., Asadi, A., Huat, B.B. and Nahazanan, H., 2015. Effects of coir fibers on tensile
and compressive strength of lime treated soft soil. Measurement, 59, pp.372-381.
Benessalah, I., Arab, A., Villard, P., Sadek, M. and Kadri, A., 2016. Laboratory study on shear
strength behaviour of reinforced sandy soil: effect of glass-fibre content and other
parameters. Arabian Journal for Science and Engineering, 41(4), pp.1343-1353.
Chang, I., Im, J., Prasidhi, A.K. and Cho, G.C., 2015. Effects of Xanthan gum biopolymer on
soil strengthening. Construction and Building Materials, 74, pp.65-72.
Chang, I., Im, J., Prasidhi, A.K. and Cho, G.C., 2015. Effects of Xanthan gum biopolymer on
soil strengthening. Construction and Building Materials, 74, pp.65-72.
Consoli, N.C., Quiñónez, R.A., González, L.E. and López, R.A., 2016. Influence of molding
moisture content and porosity/cement index on stiffness, strength, and failure envelopes of
artificially cemented fine-grained soils. Journal of Materials in Civil Engineering, 29(5),
p.04016277.
Dantas, G.H.S., Furlan, A.P., Fabbri, G.T.P. and Suárez, D.A.A., 2016. On Gyratory Compaction
of a Clayey Soil. EJGE, 21(17), pp.5725-5733.
Diab, A.A., Najjar, S.S., Sadek, S., Taha, H., Jaffal, H. and Alahmad, M., 2018. Effect of
compaction method on the undrained strength of fiber-reinforced clay. Soils and Foundations,
58(2), pp.462-480.
Giger, S.B., Ewy, R.T., Favero, V., Stankovic, R. and Keller, L.M., 2018. Consolidated-
undrained triaxial testing of Opalinus Clay: Results and method validation. Geomechanics for
Energy and the Environment, 14, pp.16-28.
Giger, S.B., Ewy, R.T., Favero, V., Stankovic, R. and Keller, L.M., 2018. Consolidated-
undrained triaxial testing of Opalinus Clay: Results and method validation. Geomechanics for
Energy and the Environment, 14, pp.16-28.

1
1
Github, 2019. [online] Available at: https://github.com/idaholab/falcon [Accessed 22nd Pr 2019]
Guo, L., Tabil, L.G., Wang, D. and Wang, G., 2016. Influence of moisture content and hammer
mill screen size on the physical quality of barley, oat, canola and wheat straw briquettes.
Biomass and bioenergy, 94, pp.201-208.
Haigh, S., 2015. Consistency of the Casagrande liquid limit test. Geotechnical Testing Journal,
39(1), pp.13-19.
Kim, H. and Choi, M., 2015. Impact of soil moisture on dust outbreaks in East Asia: Using
satellite and assimilation data. Geophysical Research Letters, 42(8), pp.2789-2796.
Researchgate, 2018. [online] Available at:
https://www.researchgate.net/publication/323256947_Fundamentals_of_Foundation_Engineerin
g_and_their_Applications [Accessed 22nd Apr 2019]
Saiglobal, 2019. [online] Available at:
https://www.saiglobal.com/pdftemp/previews/osh/as/as1000/1200/s622.pdf [Accessed 22nd Apr
2019]
Spagnoli, G., Sridharan, A., Oreste, P., Bellato, D. and Di Matteo, L., 2018. Statistical variability
of the correlation plasticity index versus liquid limit for smectite and kaolinite. Applied Clay
Science, 156, pp.152-159.
Steemit, 2019. [online] Available at: https://steemit.com/steemstem/@fona/experiment-to-show-
the-presence-of-living-organisms-in-the-soil [Accessed 22nd Apr 2019]
Theconstructor, 2019. [online] Available at: https://theconstructor.org/geotechnical/dry-density-
of-soil-by-core-cutter-method/2680/ [Accessed 22nd Apr 2019]