1. Effect OF SOIL SALT INTERACTION
ON GEOTECHNICAL PROPERTIES OF SOIL
By
T.Srikanth et al
Guide
M.Chitranjan Sir (M.Tech)
2. Clays are important constituent of soils, which evolve
mainly from chemical weathering of rock forming minerals, and
regarded as fine-grained soils in geotechnical engineering. Clays
may show considerably different engineering behavior mainly
depending on their mineralogical and chemical compositions. Pore
fluid chemistry may significantly alter the chemical compositions of
clays by means of exchangeable cat ions, which govern the
engineering properties of clays in most cases.
Introduction:--
.
3. Therefore, it is better to start ground monitoring from the
beginning of a project instead of waiting for complete failure of the
ground to support human activities and then start the remedial actions.
Black cotton Soils have high shrinkage and swelling
characteristics. In general, these soils are very much sensitive to
changes in environment. The environment includes the stress system,
the chemistry of pore water in the system, the seasonal variations in
ground water table and temperature variations.
4. Soil for the present investigation is collected from
Appikatla near Bapatla. The soil is of high swelling type
with Differential Free Swell Index of 50%. Its swelling
pressure under no-volume change condition is 338.2
kN/m3, It is classified as CI group as per IS classification
(1970).
Materials used:--
Soil:--
5. Salt water:--
The salt water used for this investigation is obtained from
Suryalanka Beach, Bapatla.
6. Procedure for contamination:--
The soil sample kept for contamination is mixed
with sodium chloride solutions of varying concentrations,
prepared by dissolving sodium chloride powder in distilled
water. The soil from the site is dried and the pebbles and
vegetative matter present, if any, are removed by hand. It
is further dried and pulverized and sieved through a
sieve of 4.75 mm to eliminate gravel fraction, if any.
7. Tests Conducted:--
The following tests are conducted:
I. Sieve anaysis,
II. Liquid limit tests,
III. Plastic limit tests,
IV. Differential Free Swell Index tests,
V. Strength tests.
8. Results and discussion:--
Sieve analysis:--
Weight of soil take = 500gms
Weight of soil passed from 47μ
sieve = 439gms
% of clay particles = 87.8
Weight of soil passed from 4.75m
sieve = 57gms
% of sand particles = 11.4
Weight of soil retained from 4.75m
sieve = 4gms
% of gravel = 0.8
9. Specific gravity:--
Weight of density bottle (w1) = 33gm
Weight of density bottle + oven
dried soil(w2) = 60gm
Weight of density bottle + soil +
water (w3) = 99gm
Weight of density bottle + full of
water (w4) = 82gm
Specific gravity = 2.7
10. Liquid limit:--
Tap water:-- % of water No. of blows
40 30
45 27
50 22
Sea water:--
% of water No. of blows
40 35
45 28
50 25
11. Plastic limit:--
Tap water:-- weight of soil = 200gm
water added = 50ml
% of water used = 25
Sea water:--
weight of soil = 200gm
water added = 54ml
% of water used = 27
12. Differential free swell:--
Initial reading = 16mm
Final reading after 24hr. = 17mm
% of swell = 6.25
Tap water:--
Sea water:--
Initial reading = 15mm
Final reading after 24hr. = 16mm
% of swell = 6.67
13. Compaction Test:-- Volume of mould (v) 943.89cc
Weignt of mould (a) 3561gm
Tap water:--
S.
No
% Water
Wt. of mould +
compacted soil
(b) gm
Weight of
compacted soil
(b-a) gm
Bulk density
(ɣ) gm/cc
1 10 6351 2790 2.956
2 12 6843 3282 3.477
3 14 6870 3309 3.506
4 16 6895 3334 3.532
5 18 6920 3359 3.559
6 20 6929 3368 3.568
7 22 6915 3354 3.553
8 24 6908 3347 3.546
9 26 6894 3333 3.531
17. Conclusion:--
We can say that there is decrement as well as increment in a
few cases in the experiment that we have done. The experiments like CBR,
consolidation etc……… have a decrease in the results. This decrement varies
between 30 – 40%. The experiments like LL, PL, etc……… have a decrement
in the results. This decrement varies between 5 – 10%. Since, the decrement is
very less hence we can say that the decrement can be neglected. The
increment (or) decrement of results depends upon the percentage(%) of
chemical ions like NaCl, MgCl2, KCl, CaCl2 and Ions Na+ and Cl- etc…… are
present in the water which we have chosen to take for the purpose of
experiment.
18. References:--
•M. Reza Emami Azadi (2007) “The Effects of Urmieh Lake Salt Water on the
Proctor Compaction and CBR Test Results of Well Graded Gravel-Sand Mixed
With Clay (GSCW) Soil Sample.”
•Abidin Kaya et al (2008) “Seawater effect on consistency limits and
compressibility characteristics of clays. ”
•Imad H. Alainachi et al (2010) “The Effects of Basra Gulf Salt Water on the
Proctor Compaction and CBR Test Results of Soil Samples at Baniyas City,Abu
Dhabi, UAE.”
•O.A. Agbede et al (2009) “Influence of Sodium Chloride on Subgrade Soil
California Bearing Ratio.”
•Anil Kulnar MISHRA et al (2005) “Effect of Salt Concentrations on the
Permeability and Compressibility of Soil-Bentonite Mixtures.”
•Matthew Ayininuola et al (2009) “Influence of Calcium Sulphate on Subsoil
Cohesion and Angle of Friction.”
•S. ROSENBAUM (1976) “Effect Of Compaction On The Pore Fluid Chemistry Of
Montmorillonite.”
•Seracettin ARASAN et al (2008) “Effect of Inorganic Salt Solutions on the
Consistency Limits of Two Clays.”
