The document discusses compaction of soils. It defines compaction as artificially rearranging and packing soil particles into a closer state through mechanical means to decrease porosity and increase dry density. Compaction is done for purposes like increasing density, strength, load bearing capacity, and stability while decreasing compressibility, permeability, and erosion damage. It reviews literature on field permeability tests being more accurate than lab tests, correlating compaction characteristics like optimum moisture content with thermal behavior, and stabilizing compacted clay through admixtures or compactive effort. The conclusion discusses the importance of field tests, avoiding thin clay liners, compacting wet of optimum, relationships between density, moisture content and thermal properties, not rejecting high saturation tests,

1. BY
ROHAN RAJ DAS
CLASS : BCE – III
ROLL : 001210401026
SECTION: A2
GUIDED BY
PROF. SUDIPTA GHOSH

2. INTRODUCTION
 Compaction is a process by which the soil particles are artificially
rearranged and packed together into a closer state of contact by
mechanical means in order to decrease the porosity or void ratio and
thus increase its dry density.
 Compaction is done to Increase Density, Increase Shear Strength,
Increase Load Bearing Capacity, Reduce Compressibility, Increase
Stability of Slopes and Embankments, Reduce Permeability, Reduce
Water Seepage, Reduce Swelling and Shrinkage, Reduce Frost Damage,
Reduce Erosion Damage.
 The Optimum Moisture Content and Maximum Dry Density for a
particular Compactive Effort are the Compaction Characteristics.
 Determination of Compaction Characteristics is of importance for the
sake of Quality Control during actual Compaction in the field.
 Compacted fine-grained soils are used for embankments, clay liners etc.

3. REVIEW OF LITERATURE
 David Daniel (1984) presented data from four projects in which rates of
leakage from pond lined with clay significantly exceeded the rates that
would have been predicted on the basis of laboratory tests. The actual
hydraulic conductivities of the clay liner were generally found to be 10 to
1000 times larger than values obtained from laboratory tests on either
undisturbed or re-compacted samples of the clay liner. He concluded
that the source of difficulty with laboratory permeability tests is the
problem of obtaining a representative sample of soil for testing and that
field permeability tests are more likely to yield accurate estimates of
hydraulic conductivity than laboratory tests.
 Lawrence Salomone, William Kovacs and Tamami Kusuda (1984) worked
on the thermal performance of fine grained soil by employing thermal
probe tests on an AASHTO standard reference material (a silty clay)
showing that the thermal behaviour correlated with the limit states of
fine-grained soils. Results indicated that the optimum moisture content
and the plastic limit could be correlated with the thermal behaviour of
fine-grained soils and it was found that the minimum thermal resistivity
and the critical moisture content occurred at the optimum moisture
content when the soils were compacted using various compactive efforts.

4. REVIEW OF LITERATURE
 John Schmertmann (1989) had studied whether one should or should
not consider density tests above the zero air voids line. To compute the
degree of saturation, S, one must have the results from tests for water
content, wet unit weight, and specific gravity each having an inherent
variability, which results in a variability in S which results in a
percentage of S plotting above the zero air voids line. His studies
revealed that one should not reject tests simply because they compute
above the zero air voids line as it not only destroys a possible quality
assurance tool, but one might force the contractor to produce a fill
having a higher mean degree of saturation than intended by the
specifications which could trigger extra cost and also a higher S could
also produce a fill that was weaker, more compressible and more
susceptible to developing high pore pressures during construction.

5. REVIEW OF LITERATURE
 Gregory Broderick and David Daniel (1990) worked on stabilizing
compacted clay against chemical attack using admixtures like Lime,
Portland cement and Sodium Silicate, mechanical stabilization using a
large compactive effort and using special clay minerals like Attapulgite,
a non-expandable clay with a low negative surface charge. They found
that addition of approximately 7% by weight of Lime, Portland Cement,
or Lime plus Sodium Silicate greatly improved the ability of compacted
clay to resist attack by concentrated organic chemicals and also
mechanical stabilization using a large compactive effort i.e. modified
Proctor compaction or application of a compressive stress a 70
kilopascal rendered a compacted clay invulnerable to attack by
concentrated organic chemicals under laboratory-test conditions as it
provided resistance to alteration of soil fabric through mechanical
means. They also found Attapulgite to be relatively unaffected as
compared to more common clay minerals such as Kaolinite, Illite etc. by
concentrated organic chemicals.

6. REVIEW OF LITERATURE
 Paul Gilbert (1991) had worked on the field of computer controlled
microwave drying for rapid determination of water content. Gilbert is of
the opinion that equipment for determining water content rapidly,
accurately and reliably is required to properly monitor the compaction
of earth fills which conventional techniques requiring time of 24 hours
cannot fulfil. Gilbert thus experimented on and found computer
controlled microwave drying system to be essential for determining
water content accurately in real time for all soils apart from gypsum-rich
soils which are dehydrated by the microwave oven system and do not
converge to the correct water content.

7. CONCLUSION
 Laboratory tests do not always show the true characteristics of the soil
due to unavailability of representative soil.
 Field Tests are extremely necessary for compacted clay liners to
determine its serviceability and laboratory tests are required for design
purposes.
 Thin clay liners are to be avoided due to formation of cracks.
 To reduce permeability of soil, it should always be compacted wet of
optimum.
 Optimum moisture content is extremely important in terms of thermal
resistivity as the critical moisture content, the moisture content where
thermal bridge mechanisms break down coincides with it.
 Critical moisture content is found to decrease with the increase in the
dry density of the soil. So thermal conductivity is found to be high at
higher dry density. This is also indicative of the fact that for higher dry
densities optimum moisture content is lower.

8. CONCLUSION
 Though physically speaking >100% saturation is not possible,
statistically it is imperative that such values should not be rejected as it
results in discrepancies in the averages of the various properties of the
soil leading to unnecessary excess expenditure in soil improvement.
 Compacted soil when attacked by chemicals results in higher hydraulic
conductivity and so stabilisation by the use of admixtures or by
mechanical means is necessary.
 The electrically neutral clay mineral Attapulgite is highly effective in
resisting the action of chemicals.
 Conventional water content determination methods are not entirely
suitable for fast determination and lack accuracy as well.
 Computer controlled microwave drying helps to give fast and accurate
results for water content.
 For water content determination of soils containing gypsum, microwave
drying is to be avoided as the soils get dehydrated and do not yield the
correct water content

9. REFERENCES
 Broderick, Gregory P., and Daniel, David E., "Stabilizing Compacted Clay
Against Chemical Attack," Journal of Geotechnical and
Geoenvironmental Engineering, ASCE, Vol.116, No. 10, 1990, pp 1549-1567
 Daniel, David E., "Predicting Hydraulic Conductivity Of Clay Liners,"
Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol.
110, No. 2, 1984, pp 285-300
 Gilbert, Paul A., "Rapid Water Content By Computer-Controlled
Microwave Drying," Journal of Geotechnical and Geoenvironmental
Engineering, ASCE, Vol. 117, No. 1, 1991, pp 118-138
 Murthy, V.N.S., "Soil Improvement," Textbook Of Soil Mechanics And
Foundation Engineering, CBS Publishers and Distributors Pvt. Ltd., 1st
Edition, Chapter 13, 2014, pp 389-426
 Punmia, B.C., Jain, Ashok K., and Jain, Arun K., "Compaction," Soil
Mechanics And Foundations, Laxmi Publications (P) Ltd., 16th Edition,
Chapter 17, 2014, pp 407-426
 Salomone, Lawrence A., Kovacs, William D., and Kusuda, Tamami,
"Thermal Performance Of Fine-Grained Soils," Journal of Geotechnical
and Geoenvironmental Engineering, ASCE, Vol. 110, No. 3, pp 359-374

10. REFERENCES
 Schmertmann, John H., "Density Tests Above Zero Air Voids Line,"
Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol.
115, No. 7, pp 1003-1018

11. THANK YOU