Upload
others
View
0
Download
0
Embed Size (px)
Citation preview
http://www.iaeme.com/IJCIET/index.asp 353 [email protected]
International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 9, September 2017, pp. 353–360, Article ID: IJCIET_08_09_041
Available online at http://http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=8&IType=9
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
© IAEME Publication Scopus Indexed
INFLUENCE OF NANOSIZED SILICA AND
LIME PARTICLES ON THE BEHAVIOUR OF
SOIL
Dr. P. Eswaramoorthi
Professor, Department of Civil Engineering,
Kumaraguru college of Technology, Coimbatore, India
V. Senthil Kumar and P. Sachin Prabhu
Assistant Professor, Department of Civil Engineering,
Kumaraguru college of Technology, Coimbatore, India
T. Prabu
Assistant Professor, Department of Civil Engineering,
Builders Engineering College, Tirupur, India
S. Lavanya
UG Student, Department of Civil Engineering,
Kumaraguru college of Technology, Coimbatore, India
ABSTRACT:
Nanotechnology is the science that deals with the particles which are less than 100
mm. The size of the Nano particles plays a crucial role in behaviour of soil exhibiting
different properties. Use of these Nano particles in stabilization influences shear
strength, dry density of the soil and makes more reactive to soil because of its high
specific surface area. In this investigation, an attempt is made to investigate the
influence of ball milled Nano silica and lime particles in the improvement of soil.
Results indicated that compare to non-nano particles in soil, the nano admixed soil
yielded UCC strength of 589 kN/m2 which is 1.2 times higher than non-nano particles.
Cite this Article: Dr. P. Eswaramoorthi, V. Senthil Kumar, P. Sachin Prabhu, T.
Prabu and S. Lavanya, Influence of Nanosized Silica and Lime Particles on the
Behaviour of Soil, International Journal of Civil Engineering and Technology, 8(9),
2017, pp. 353–360.
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=9
Dr. P. Eswaramoorthi, V. Senthil Kumar, P. Sachin Prabhu, T. Prabu and S. Lavanya
http://www.iaeme.com/IJCIET/index.asp 354 [email protected]
1. INTRODUCTION
Presence of weak soil in the construction sites is a major issue for any type of construction.
To enhance the properties of the weak soil, many methods like soil stabilization, soil
reinforcement, grouting, addition of admixtures etc. are adopted. Addition of admixtures like
Lime, fly ash, Cement, bitumen based on type of soil improves the properties of soil to some
extent. Use of industrial waste as additives is recently under study, but it arises a question of
toxicity. So there is a need for finding a new innovative material.
One of the new innovative fields recently introduced to soil is Nanotechnology.
Nanotechnology is recently been introduced to Geotechnical Engineering. Nanotechnology is
the science that deals with the particles which are less than 100 nm. The size of the Nano
particles plays a crucial role in behaviour of soil exhibiting different properties.
Laboratory experiments conducted by Taha [1] to study the fundamental geotechnical
properties of mixtures of natural soils and its product after ball milling mixture. Lab results
showed that the value of Atterberg limits were higher after Nano-soil addition. However, its
plasticity index reduces which is advantageous in many geotechnical constructions.
Compressive strength of original soil Cement and 1% Nano soil mixture showed double its
value without Nano soil. Thus Nano particles are potentially suitable for improving the
properties of soil/clay for various applications.
The addition of different Nano materials, including Nano Cu, Nano MgO and Nano clay
on the geotechnical properties of soft soil sample from Peneng state was described by Zaid
Hameed Majeed and Taha [2]. The unconfined compressive strength increased as the Nano
material content increased up to a certain percentage in the soil and then decreased afterwards.
Noll, Bartlett and Dochat [3] investigated the use of nano silica particles in enhancing soil
strength against consolidation and permeability. The hydraulic conductivity of soil was
reduced by 3- 4 folds with addition of Nano silica.
2. MATERIALS
2.1. Soil
The soil was collected from Perumbakkam, Chennai at shallow depth after removing the top
0.5 depth soil.
Table 1 Index Properties of Soil
Properties Values
Specific gravity 2.60
Clay % 82
Silt % 14
Sand % 6
Liquid Limit % 80
Plastic Limit % 32
Plasticity Index % 48
Free swell Index % 60
Soil Classification CH
Table 1 shows the index properties of soil. The soil is classified as CH type and based on
FSI value the soil gets high swell classification. The Maximum dry density of the soil is
1.52g/cc and OMC is 25.74%. From Unconfined compression test, it was found that the shear
strength of the soil alone is 254 kN/m2
at OMC.
Influence of Nanosized Silica and Lime Particles on the Behaviour Of Soil
http://www.iaeme.com/IJCIET/index.asp 355 [email protected]
2.2. Additives and their characterization
The two different additives silica and lime were collected and stored. Lime powder collected
from local market. Silica powder collected from Chettinad Moorrum Private Limited, OMR
road, Chennai, Tamilnadu. From HRTEM analysis the particle sizes of raw Silica in the range
of 2µ - 14µ and Lime in the range of 30µ - 150µ were calculated. Chemical composition of
the additives was obtained by EDAX test. Results shows that Silica consists nearly 50% of
silica and lime consisted 31% calcium and 17% magnesium as its major contributed
chemicals.
3. METHODOLOGY
Silica and lime are taken as additives to mix with soil. Silica is mixed with soil upto 15%
(5%, 10% &15%) with the addition of lime from 2% to 10% (2%, 6% & 10%). For the
optimum mix, Nano materials of those additives mixed with soil and tested. Nano materials
were prepared by using ball milling. Characterization test carried out on unmilled additive and
milled additive to compare particle size and chemical composition. The index properties,
compaction test, UCC test were carried out in soil and Nano materials. These identical
samples were prepared for their maximum dry density at optimum water content based on
compaction curves obtained. The samples are tested for 7 days curing.
3.1. Preparation of Nano Particles
Nano particles are commonly prepared by bottom up method and top down method. Top
down method begin with bulk materials (top) that are subsequently reduced into
Nanostructures (down) by the way of physical, chemical and mechanical processes for
examples mechanical ball-milling, grinding etc. Preparation of Nano particles has done by
planetary ball milling. A specific quantity of (about 100gms) silica and lime milled for 6 hrs
and for 12 hrs respectively.
Figure 1 HRTEM images of ball milled SILICA particles
Figure 2 HRTEM images of ball milled LIME particles
Dr. P. Eswaramoorthi, V. Senthil Kumar, P. Sachin Prabhu, T. Prabu and S. Lavanya
http://www.iaeme.com/IJCIET/index.asp 356 [email protected]
From HRTEM analysis, the particle sizes of milled Silica in the range of 24nm - 72 nm
and milled Lime in the range of 31nm – 62nm were calculated (figure 1 and figure 2). After
ball milling process, particle size got reduced compare to raw additives.
4. RESULTS AND DISCUSSIONS
Influence of Non - Nano Sized Additives on the Index, Compaction and UCC
Strength Properties of Soil
4.1.1. Effect of Silica + Lime Mix on Index Properties of Soil
The effect of silica and lime mix with soil on liquid limit is presented in fig 3 and 4. Fig 3
shows the liquid limit of soil is decreased linearly for 5%, 10% and 15% of silica admixed
soil with addition of lime and beyond that, the liquid limit value is nearly constant for further
increment of lime.
Figure 3 Effect of lime content on liquid limit of soil + silica mix
Figure 4 Effect of silica content on liquid limit of soil + lime mix
Figure 5 Effect of lime content on plasticity index of soil+silica mix
Influence of Nanosized Silica and Lime Particles on the Behaviour Of Soil
http://www.iaeme.com/IJCIET/index.asp 357 [email protected]
From fig 5, it is observed that the plasticity index of soil is decreased for 5%, 10% and
15% silica admixed soil with increase in lime content.
Figure 6 Effect of silica content on plasticity index of soil +lime mix
The plasticity index of silica admixed soil is decreased for increase in lime content upto
4% as inferred from figure 6. Beyond 4% lime content, the variation in plasticity index of
silica admixed soil is almost marginal.
4.1.2. Effect of Silica + Lime Mix on Compaction Characteristics of Soil
As per IS 2720 part VII, compaction test is carried out for the soil alone and soil mixed with
additives. The value of maximum dry density and corresponding optimum moisture content
are inferred from compaction curves. The results are tabulated below in table 2.
Table 2 Effect of Silica-Lime mix on the compaction characteristics of soil
Description γ dmax (g/cc) OMC (%)
Soil alone 1.52 25.74
Soil+5%Silica
2% Lime 1.50 26.31
6% Lime 1.49 26.80
10% Lime 1.48 27.01
Soil+10%Silica
2% Lime 1.47 27.86
6% Lime 1.46 28.03
10% Lime 1.46 28.75
Soil+15%Silica
2% Lime 1.45 28.98
6% Lime 1.44 29.21
10% Lime 1.43 29.81
From proctor compaction test, the γ dmax values are 1.50g/cc, 1.47 g/cc and 1.45 g/cc
respectively for 5%, 10%, 15% silica with 2% lime. The OMC values are in the range of
26.31% to 28.98%.
For 6% lime, the γ dmax values are 1.49g/cc, 1.46 g/cc and 1.44g/cc respectively for 5%,
10%, 15% silica. The OMC values are in the range of 26.80% to 29.21%. The γ dmax values
Pla
stic
ity I
nd
ex, %
% of Lime
5%
Si…
Dr. P. Eswaramoorthi, V. Senthil Kumar, P. Sachin Prabhu, T. Prabu and S. Lavanya
http://www.iaeme.com/IJCIET/index.asp 358 [email protected]
are 1.48g/cc, 1.46 g/cc and 1.43g/cc respectively for 5%, 10%, 15% silica admixed with 10%
lime. The OMC values are in the range of 27.01% to 29.81%.
The optimum moisture content did not vary much for varying % silica unlike γ dmax. The
reduction in γ dmax is expected because of the low specific gravity silica replaces soil and
thereby the γ dmax decreases, Sridharan and Prakash [4] and James K. Mitchel [5].
The γ dmax is always lower in soil for any % of silica and lime. Compare to the effect of
lime, the role of silica is significant in reducing γ dmax values. The OMC value increases
steeply with % of lime. This is due to enhanced water holding capacity of soil-silica-lime mix
due to the formation of flocculated structure.
4.1.3. Effect of Silica + Lime Mix on UCC Strength of Soil
From the stress-strain curves for soil with increasing % of silica with 2% to 10% lime, the
UCC peak strength is determined and presented in this section with reference to silica
independently for varying lime. All the UCC strength values are corresponding to 7 days
cured UCC specimens.
Figure 7 Effect of lime on the UCC strength of soil+ silica mix
As seen from figure 9 and 10, the UCC strength is always higher in soil + 10% silica for
2% and 6% of lime compared to soil + 5% silica and soil + 15% silica with varying % lime.
The optimum % for effective utilization of soil + silica + lime mix seems to be 5% silica +
10% lime.
Figure 8 Effect of silica on the UCC strength of soil+ lime mix
UC
C S
tren
gth
, k
N/m
2
% of Lime
5%
Sil…
UC
C
Str
ength
, k
N/m
2
% Silica
2 % lime
6% lime
10% lime
Influence of Nanosized Silica and Lime Particles on the Behaviour Of Soil
http://www.iaeme.com/IJCIET/index.asp 359 [email protected]
4.2. Influence of Nano Sized Additives on the Index, Compaction and UCC
Strength Properties of Soil
Table 3 compares the influence of nano particles and non-nano particles on the index
properties of soil. The liquid limit, plastic limit and plasticity index non-nano particles of 5%
silica+10% lime in soil are 49%, 36% and 13% respectively. In the case of 5% nano
silica+10% nano lime in soil, the values are 58%, 37% and 21% respectively. The nano
particles produced higher plasticity characteristics compared to non-nano particles. This
mainly because of enhanced surface area of nano particles which eventually give raise to
more water holding capacity resulting in high plasticity characteristics.
The γ dmax and OMC of soil+5% nano silica+10% nano lime are 1.42g/cc and 32.03%
and whereas for the same combination, non-nano particles admixed soil produce the γ dmax
value of 1.45g/cc and OMC of 27%. The lesser value of γ dmax and higher value of OMC of
nano particles admixed soil are mainly because of enhanced specific surface area because of
particle fineness.
The UCC strength of soil alone is 254kN/m2, and that of soil+non nano particles of 5%
silica+10% lime is 493 kN/m2. In the case of soil+5% nanosilica + 10% nano lime, the peak
strength 589 kN/m2.
Compare to non-nano particles in soil, the nano admixed soil yielded UCC strength of 589
kN/m2 which is 1.2 times higher than non-nano particles. The higher strength of nano
particles admixed soil is mainly due to higher reactivity of silica and lime with the soil
because of the enhanced specific surface area.
Table 3 Effect of Nano sized silica and lime on the Index, Compaction and UCC strength properties
Description LL% PL % PI % ϒd max g/cc OMC % UCC Strength
kN/m2
Soil alone 80 32 48 1.52 25.74 254
5% Silica + 10%
Lime 49 36 13 1.45 27.01 493
5% Nano Silica +
10% Nano Lime 58 37 21 1.42 32.03 589
5. HYDRAULIC CONDUCTIVITY OF NANO PARTICLES ADMIXED
SOIL
The co-efficient of permeability (k) of soil was determined using falling head permeability
test with a mould diameter of 7.5cm and effective height 6cm. The permeability test was
conducted on compacted soil+ additive mix corresponding to the ϒdmax and OMC of the mix
constituents.
Table 4 Co-efficient of permeability of nano particles admixed soil
Description Permeability ‘k’
cm/sec
Soil Alone 4.95 X 10-6
5% Silica + 10% Lime 2.92 X 10-6
5% Nano Silica + 10% Nano Lime 1.97 X 10-7
The co-efficient of permeability of soil alone is 4.95 X 10-6
cm/sec. This value has
reduced to 2.92 X 10-6
for soil+5% silica+ 10% lime. The ‘k’ value reduced to almost a fold.
The ‘k’ value of for soil + 5%silica + 10% lime is 1.97 X 10-7
cm/sec.
Dr. P. Eswaramoorthi, V. Senthil Kumar, P. Sachin Prabhu, T. Prabu and S. Lavanya
http://www.iaeme.com/IJCIET/index.asp 360 [email protected]
This result clearly indicates that of the soil particles could effectively fill the void of the
soil particles and thereby soil-additives matrix becomes less permeable nature. In this case,
compared to non-nano particles, nano particles could effectively fills the pores of soil
particles owing to its fineness and hence results in lower permeability values.
6. CONCLUSIONS
Based on the analysis of results, the following conclusions may be drawn.
1. Addition of Nano sized silica and lime additives on soil decreases the liquid limit and
plasticity Index values and increases the plastic limit values. Decrease in liquid limit
and plasticity index was more than non-Nano sized additive mixtures with soil.
2. The maximum dry density of soil with addition of 5% Nano Silica + 10% Nano Lime
decreases the dry density to 1.42 gm/cm3 with increase in OMC of 32%.
3. For addition of 5% Silica and 10% lime the UCC strength increased to 493 kN/m2
with 7 days curing. Upon adding Nano sized particles of Silica and Lime the same
value increased up to 589kN/m2 with 7days curing.
4. The Nano particles admixed soil yielded the co-efficient of permeability; 10 times
lower than that of non-nano sized additives silica and lime.
REFERENCES
[1] Taha.,(2009), A review of stabilization of Soils by using Nano materials Australian
Journal of Basic and Applied Sciences, 7(2) ISSN 1991-8178, pp.576-581
[2] Zaid Hameed Majeed and Mohd Raihan Taha, (2010), Effect of Nano material treatment
on geotechnical properties of a penang soft Soil, Journal of Asian Scientific Research,
pp.587-592
[3] Noll M.R., Bartlett C, and Dochat T.M. (1992), In situ Permeability Reduction and
Chemical Fixing Using Colloidal Silica, Proceedings of the 6th National Outdoor Action
Conference, National Ground Water Association, Las Vegas, NV, pp 443-457.
[4] Sridharan. A and K.Prakash, (2007), Geotechnical engineering characterisation of coal
ashes, 3rd
Ed, CBS publishers, New Delhi, India.
[5] James K. Mitchel and Kenichi Soga, (2005), Fundamentals of Soil Behaviour, 3rd
Ed, John
Wiley & Sons, New York, USA.
[6] E Balaji, Dr. S Senthil Selvan and Vishnu Prasad P R, An Experimental Study on the
Effect of Nano Silica on Strength and Durability of Concrete. International Journal of
Civil Engineering and Technology, 8(4), 2017, pp. 1182–1188.
[7] S. Prasath, Dr. S. Senthil Selvan and E. Balaji, Experimental Study of Nano Silica and
Silica Fume Concrete Column Subjected To Corrosion. International Journal of Civil
Engineering and Technology, 8(3), 2017, pp. 708–719
[8] V. Nagendra, C. Sashidhar, S. M. Prasanna Kumar and N. Venkata Ramana GGBS and
Nano Silica (NS) Effect on Concrete. International Journal of Civil Engineering and
Technology, 7(5), 2016, pp.477 – 484.