mineralogical evaluation of lateritic soil of …minerals present in lateritic soil and in section...

http://www.iaeme.com/IJCIET/index.asp 836 [email protected]

International Journal of Civil Engineering and Technology (IJCIET)

Volume 10, Issue 02, February 2019, pp. 836-853, Article ID: IJCIET_10_02_081

Available online at http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=10&IType=02

ISSN Print: 0976-6308 and ISSN Online: 0976-6316

© IAEME Publication Scopus Indexed

MINERALOGICAL EVALUATION OF

LATERITIC SOIL OF SELECTED ZONES IN

UDUPI DISTRICT, KARNATAKA, INDIA

Bhagyashree

Assistant Professor, Department of Civil Engineering, MIT, MAHE, Manipal

Udayashankar H N

Professor, Department of Civil Engineering, MIT, MAHE, Manipal

Purushotham Sarvade

Professor, Department of Civil Engineering, MIT, MAHE, Manipal

ABSTRACT

Lateritic soil is one of the main soil types in the tropical countries like India for

basic construction works. Since lateritic soils are the main underlying soil structure

in coastal Karnataka, its detailed study of mineralogical properties is of utmost

importance. The study area chosen is Udupi district and samples were procured from

coastal plains and hinterland regions. The samples taken from each places (three

layers-top, middle and bottom at around 2.5-3 m depth) were collected in zip locked

polythene bags and were oven dried at 1050 Celsius for 24 hours and then passed

through 75 µm IS sieve size. For clear images of the soil structure and for

identification of elements, samples were coated with gold sputtering. These samples

were tested by Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray

Spectroscopy (EDAX/EDS) and analyzed. SEM results show various minerals present

in the samples. EDAX results show the percentage of each element (like C, O, Si, K,

Cu, Ti, Mg etc) present in the sample. Therefore it can be concluded that laterites

change their composition from iron to aluminium resulting in bauxite ore as one

moves towards north in the coastal belt of Karnataka.

Keywords: EDAX, Laterite soil, Mineralogy, SEM, Sputtering.

Cite this Article: Bhagyashree, Udayashankar H N and Purushotham Sarvade,

Mineralogical Evaluation of Lateritic Soil of Selected Zones in Udupi District,

Karnataka, India, International Journal of Civil Engineering and Technology, 10(2),

2019, pp. 836-853.

http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=10&IType=02

Mineralogical Evaluation of Lateritic Soil of Selected Zones in Udupi District, Karnataka, India


1. INTRODUCTION

The word “laterite” is procured from a Latin language from the phrase ‘later’, which means a

brick. It is a red colored material, which is rich in iron content that originates mostly in South

India. The basic character of the lateritic clay soils allows them to absorb water easily into

their inter-granular pore spaces. Due to their inherent nature of poor permeability, they

prevent them from discharging the excess water held in the pore-spaces [1]. Coastal area of

Karnataka, which includes three districts namely Dakshina Kannada, Udupi and Uttara

Kannada, is an area, which is highly stressed due to lots of developmental activities taking

place. It is very crucial activity center of Karnataka owing to its location.

The SEM is routinely used to generate high-resolution images of shapes of objects and to

show spatial variations in chemical compositions: 1) acquiring elemental maps or spot

chemical analyses using EDS, 2)discrimination of phases based on mean atomic number

(commonly related to relative density) using BSE, and 3) compositional maps based on

differences in trace element "activator’s" (typically transition metal and Rare Earth elements).

The SEM is also widely used to identify phases based on qualitative chemical analysis and/or

crystalline structure. Precise measurement of very small features and objects down to 50 nm

in size is also accomplished using the SEM [2][3]. Energy-dispersive X-ray spectroscopy

(EDS, EDAX), is an analytical technique used for the elemental analysis or chemical

characterization of a sample. It relies on an interaction of some source of X-ray excitation and

a sample. Its characterization capabilities are due in large part to the fundamental principle

that each element has a unique atomic structure allowing a unique set of peaks on its

electromagnetic emission spectrum (which is the main principle of spectroscopy)[4][5].

Mineral content can be considered as the crucial feature that controls the shape, size, and

various characteristics. Fine particle percentage (particles passing IS sieve size of 75 µm) will

have very important efficacy related to rendering the soil to be used as underlying foundation

material. More amounts of finer particles may lead to the depletion of possible highest

density and bearing capacity of the soil which in-turn leads to enhancement in the

vulnerability to immobilization due to infiltration of water [6]. The metals present in the

lateritic soils are crystalline oxides of Fe and their residues, which will be altered towards

interchangeable structure on the top layer of the soil. Special absorbing capability is observed

in the minerals towards few heavy metals, thus they exert a straight impact on geochemistry

and reversible nature of heavy metals in the lateritic soils [7].

Changes in size and shape of clay soils can be observed owing to changes in water

content that will lead to damages to structures erected on them. In lots of research works, it

has been strived to describe the couplings owing to moisture variations and its succeeding

volume change alterations. Research related to the durability of the clay soils unmasked to

external atmospheric pressures like alternate dry and wet cyclic variations need to be found

out. [8].

The other type of soil found in coastal Karnataka and along the Konkan belt is

Lithomargic clay. Whenever the top laterite soil (2.5-3 m thick) is removed, the underlying

shedi soil gets exposed. Construction activities are done very often on this exposed shedi soil

or in many cases, construction activities are done on lateritic soil filled-up grounds. Such

shedi ground will have very low bearing capacities. Such grounds need to be improved to

achieve higher bearing capacities. [9].

2. METHODOLOGY

For any research work, it is necessary to clearly define the fieldwork so as to get intended

opportune results. Hence, it is imperative to regulate the position of each sampling location.

https://serc.carleton.edu/research_education/geochemsheets/elementmapping.html

https://serc.carleton.edu/research_education/geochemsheets/eds.html

https://serc.carleton.edu/research_education/geochemsheets/bse.html

https://en.wikipedia.org/wiki/Elemental_analysis

https://en.wikipedia.org/wiki/Characterization_(materials_science)

https://en.wikipedia.org/wiki/Characterization_(materials_science)

https://en.wikipedia.org/wiki/X-ray_generator

https://en.wikipedia.org/wiki/X-ray

https://en.wikipedia.org/wiki/Sample_(material)

https://en.wikipedia.org/wiki/Atom

https://en.wikipedia.org/wiki/Emission_spectrum

https://en.wikipedia.org/wiki/Spectroscopy

Bhagyashree, Udayashankar H N and Purushotham Sarvade


Each sampling location should provide a distinct representative result with good number of

samples and minimize errors. The samples will be collected from the lateritic mesa which are

situated right after the coastal plains which are usually constituted by flat hilltops. This region

is rich in lateritic soil and this lateritic soil is stressed due to various infrastructural

development taking place on this soil. Lateritic quarries are also situated in these places.

Some samples are collected from hinterland consisting of rolling topography which contains

small plateaus that contains lateritic soil in high concentrations. 10 sampling locations are

selected from the coastal plains and hinterlands (where lateritic profile is exposed).

2.1. Sample Collection and Preparation

For mineralogical test, the samples taken from each places (three layers-top, middle and

bottom at around 2.5-3m height) were collected in zip locked polythene bags and were oven

dried at 1050 Celsius for 24 hours and then passed through 75 µm IS sieve size. Sputter

coverings done for the specimen with a thin layer of conducting material, typically a metal,

such as a gold (Au) alloy. It helps in providing deposition of a thin-film on the samples. This

will help in samples to be more conductive in the present study (coating of gold sputtering is

provided on the soil samples). Then it will undergo SEM/EDS analysis

3. RESULTS

The images of Scanning Electron Microscope and EDAX results are discussed below in the

form of images and tables. In the figures, (a) represents top layer, (b) represents middle layer

and (c) represents bottom layer of soil respectively. In section 3.1, the images show various

minerals present in lateritic soil and in section 3.2 EDAX results show percentage variation

of weights of different elements present in lateritic soil.

3.1. SEM Images of Udupi Region

Figure 1 Scanning electron micrographs of Kapu (a) magnetite (b) arrows points towards Diaspora

(c) Clay is pointed using arrows and hematite grains in the oval shape.



Figure 2 Scanning electron micrographs of Katapadi(a) Hematite, (b) and (c) oval shape represents

aluminum, box represents ferro-nickel particles and arrow showing quartz in the second and third

layer of Katpadi.



Figure 3 Scanning electron micrographs of Jantra (a) White oval shapes represents silica and white

arrows represent magnetite spicules and yellow arrows show clay particles (b) Iron particles are

showed in oval shape (c) Nickel is showed in oval shape



Figure 4 Scanning electron micrographs of Kolalagiri (a) nickel (b) Aluminum (c) clay



Figure 5 Scanning electron micrographs of Shirva (a) Oval shape showing aluminum particles and

arrow representing iron contents (b) Arrows shows hematite particles (c) goethite



Figure 6 Scanning electron micrographs of Ucchila (a) magnetic spicules (b) quartz contents and (c)

nickel



Figure 7 Scanning electron micrographs of Udupi (a)aluminum (b)arrow showing quartz and oval

shape indicating clay (c) the circle is representing trigonal hematite grains.



Figure 8 Scanning electron micrographs of Hejamadi (a) Iron is marked in oval shape and arrows

represents clay content (b) Gibbsite and arrows show diaspora (c) Trigonal structures of hematite is

seen



Figure 9 Scanning electron micrographs of Manipal (a) The Right Arrow represent the Hematite,

Diamond shape represents the Magnetite Stipules, Box represent the Al in top Profile.(b) Box

represent the Al, Right Arrow represent the Hematite in Middle Profile. (c) Diamond shape represents

the Magnetite Stipules, Box shape represents Aluminum, arrow represent the Hematite.



Figure 10 Scanning electron micrographs of Palli (a) The Yellow Arrow represent the silica, White

Arrow represent the Hematite, Box shape represents Aluminium.(B) White Arrow represent the silica,

Box represent the Aluminium (C) Yellow Arrow represent the Hematite, Box shape represents

Aluminum.



3.2. EDAX Results

Table 1 Percentage weights of elements present in top layers of soil

PLACES/% WEIGHTS

KOLALAGIRI UDUPI KATPADI KAPU SHIRVA UCHILA JANTRA HEJMADI MANIPAL PALLI

C 21.2 7.63 27.49 26.44 34.49 15.75 14.55 9.08 7.72 8.07

O 43.31 55.63 44.59 43.63 53.28 42.61 42.85 56.69 42.34 47.66

Al 9.25 12.93 8.47 9.53 12.32 10.73 10.35 14.59 13.7 14.4

Si 13.16 12.86 8.63 7.93 13.36 13.36 10.53 15.32 10.32 13.03

Fe 11.41 9.71 5.72 6.33

12.57

3.04 12.65 10.78

Ti 0 0.59 0.39

2.97

Cr 0

0.85 2.8 12.58

K 0 0.65 0.49

Mg 0

0.21

Mn 0

14.07 17.74

Ni 0

0.023 0.22

Figure 11 Figure 12

Figure 13 Figure 14

Figure 15 Figure 16



Figure 17 Figure 18

Figure 19

Table 2 Percentage weights of elements present in middle layers of soil

PLACES/ WEIGHTS


C 10.85 7.41 18.73 28.22 21.82 26.06 19.65 16.17 14.49

O 37.82 56.95 45.87 48.53 45.25 53.74 41.14 51.75 49.41 51.93

Al 11.62 14.54 10.47 9.3 12.02 14.08 19.67 11.13 14.76 18.84

Si 18.16 15.07 10.74 6.41 13.11 15.98 20.13 12.41 12.51 16.02

Fe 0 4.98 8.84 4.11

8.18 14.03 10.79

Ti 0 0.69 0.75 0.465

Cr 0

5.73 26.69

K 0 0.5

0.34

0.51

Mg 0

Nb 31.53

3.9

9.79

Mn 0

14.07 20.45

Ni 0

0.95 1.35

Figure 20 Figure 21



Figure 22 Figure 23

Figure 24 Figure 25

Figure 26 Figure 27

Figure 28



Table 3 Percentage weights of elements present in bottom layers of soil

PLACES/% WEIGHTS


C 19.73 9.27 16.48 31.04 8.25 18.75 9.45 15.22

O 44.72 50.77 44.9 42.51 46.12 50.03 41.04 52.47 46.08 43.51

Al 12.19 14.99 10.54 8.57 13.2 11.87 9.51 14.05 14.46 13.92

Si 13.77 15.29 9.83 5.62 13.31 13.98 9.69 14.06 14.34 13.52

Fe

9.18 11.11 6.78

25.21 3.03 5.74 3.67

Ti

0.65 0.8 0.39

0.72

Cr

1.215 13.18

K

0.73 0.5 0.36

Nb

2.78

Mn

18.25 14.88

Ni

0.09 0.655

Figure 29 Figure 30

Figure 31 Figure 32

Figure 33 Figure 34



Figure 35 Figure 36

Figure 37

5. CONCLUSION

According to the results obtained from SEM-EDAX analysis the following inferences can be

made. The elements such as Aluminum, Silica, and Carbon are predominately are found in all

the 10 places. Except Shriva and Jantra, iron content was seen in 8 places. Nb was absent in

Top layer soil whereas present in bottom, middle layers and found in 3 places only.

Magnesium is absent in middle layer and bottom layers. The samples collected from Kapu

was rich in Carbon and poor in Fe, Al, Si, Ti and K. High content of Mn, Ni, Cr and Al was

found in Palli. Samples collected from Udupi contained high Percentage of K, Si, Al and Low

Percentage of C. Then from Hejamadi, high percentage of elements like Al, Si, K and Low

percentage of Fe and Cr were found.

Therefore it can be concluded that the lateritic soil in Udupi district is rich in aluminium

and silica and the next predominant element being iron. Hence it can be seen that as one

moves from south to north in the coastal belt of Karnataka laterites change their composition

from iron to aluminium resulting in bauxite ore. Their chemistry is controlled by the

weathering of sedimentary rocks.

5.1. Future Scope

XRD analyses can be done for all these samples so that mineral composition can be

found out

Geotechnical tests can be carried out for assessing engineering properties of the soil

samples

Tests can be carried out on laterite blocks to know their strength to be used as

building materials



ACKNOWLEDGEMENTS

Department of Civil Engineering is thanked for laboratory facilities, Vishwas K and

Kavyashree is thanked for helping in sample collection.

REFERENCES

[1] S. W. and C. F. V. and V. I. etc. Et.al, “Lateritisation Processes,” in Proceedings of the

International Seminar on Laterization Processess(Trivandrum,India 11-14

December,1979), 1981, p. 450.

[2] Egerton, R. F. (2005) Physical principles of electron microscopy: an introduction to TEM,

SEM, and AEM. Springer, 202

[3] Reimer, L. (1998) Scanning electron microscopy: physics of image formation and

microanalysis. Springer, 527 p.

[4] John J. Friel. “X-ray and Image Analysis in Electron Microscopy”, Princeton Gamma-

Tech.

[5] Goldstein, J. (2003) Scanning electron microscopy and x-ray microanalysis. Kluwer

Adacemic/Plenum Pulbishers, 689 p.

[6] B. T. Kamtchueng, V. L. Onana, W. Y. Fantong, A. Ueda, R. F. Ntouala, M. H. Wongolo,

G. B. Ndongo, A. N. Ze, V. K. Kamgang, and J. M. Ondoa, “Geotechnical, chemical and

mineralogical evaluation of lateritic soils in humid tropical area (Mfou, Central-

Cameroon): Implications for road construction,” Int. J. Geo-Engineering, vol. 6, no. 1, p.

1, 2015.

[7] Z. H. U. L. J, “Chemical Forms of Heavy Metals in Carbonate- Derived Laterite and

Enrichment of Its Iron Oxide Minerals,” vol. 16, no. 3, 1997.

[8] G. Stoltz, O. Cuisinier, and F. Masrouri, “Multi-scale analysis of the swelling and

shrinkage of a lime-treated expansive clayey soil,” Appl. Clay Sci., vol. 61, pp. 44–51,

2012.

[9] Ravindranath, “Prediction of settlement characteristics of shedi soil of Dakshina kannada

district”, unpublished MTech thesis, NITK, March 1994

mineralogical evaluation of lateritic soil of …minerals present in lateritic soil and in section...

Documents