Desert and swampy road construction

1. Desert And
Swampy Road
Construction
Presented by:
Bhavya Jaiswal
20MCT006

2. 1. Desert Areas
• Deserts are those locales on Earth which are arranged as having parched
environments.
• Because of blowing of wind, sand ridges are shaped in deserts.
• Every ridge type is the consequence of various breeze designs, and the presence or
absence of vegetation on the ground.
• Subsequently, the development in desert area is troublesome when contrasted with
the typical areas.

3. Desert Areas
• Due to blowing of wind, sand dunes are shaped in deserts.
Sand Dunes
1. Longitudinal sand dunes
 Parallel to flow
 Winds do not have
much change in
direction
2.Transverse sand dunes
 Perpendicular to flow
 Winds have a change in
direction

4. Sand dunes

5. AASHTO Classification
System
AASHTO M-145 Classification System for Soils and Soil-Aggregate Mixtures (M145)

6. 1. Desk study
2. Plan survey
3. Find and Mapping of resources
4. Source evaluation
5. Data capture and feedback of that
captured data/ Source evaluation

7. Subgrade
• Many roads constructed in the sand region will have predominantly sandy subgrades.
• Most sands when compacted to the appropriate density will easily comply with the specified
requirements.
• Provided sand subgrades are compacted to the required standard, their chance of failure is
relatively low.
• Where subgrade compaction problems are encountered, particularly with the more uniform
sized sands and manifested as a tendency for shearing of the material during compaction.
• Particularly when excessive vibration is used, a method specification based on controlled
compaction trials should be considered.

8. Subbase
• For the roads in the sandy soil specifically in the desert region are checked and analysed
for the DN values. The DN value is the outcome from the Dynamic cone penetration
which is a penetration Rate.
• Many sands will provide the specified DN values for subbase when compacted to an
appropriate density.
• Such sands have been successfully used on a number of projects in the region.

9. Base
 It is not uncommon for certain untreated sands
to exhibit relatively high DN values at the
equilibrium moisture content that typically
prevails under paved roads and these
materials when adequately compacted in the
field are likely to perform satisfactorily.
 Figure illustrates the variation in laboratory CBR strength with moisture content for a red
Kalahari sand that was used successfully as neat base on an experimental section of a low
volume road pavement in Botswana.
 The sand sample was compacted at OMC and dried back to various moisture content ratios
before its strength was determined.

10. Surfacing
• Sand is generally too fine and uniform for chip seals and is unsuitable for use, even for
conventional sand seals.
• Typically a 60 % Emulsion or an MC3000 binder is sprayed at between 0.7 and 1.0 ℓ/m2
and immediately covered with Kalahari Sand at a spread rate of about 0.014 m3/m2.
• This must be rolled with a pneumatic tyred roller, ensuring that the sand is evenly spread
and rolled. A light drag must be used to remove any unevenness.
• Sand dislodged by traffic should be broomed back onto the road until the balance between
binder and sand is correct and no further sand is lost or bleeding occurs.

11. Wearing courses for unsealed
Roads
• Sands are not generally suitable as wearing courses for unsealed roads. Although the fines
of some sands, particularly the red ones which contain iron oxide, also have some
cohesion, it is generally insufficient to resist the abrasive forces of moving wheels.
• The sands are, however, very effective for sand cushioning.
• Sand cushioning: In this process, a well compacted gravel wearing course is covered with a
thin layer (about 40 mm) of relatively single-sized sand. This upper sand layer is maintained
on a regular basis, using a towed grader and drag, such that vehicles do not traffic the base
material.

12. Stabilization of
Sands
The choice of stabilizer is influenced by the
properties of the material to be stabilized and the
cost of stabilization.
• Granular materials Mechanical stabilization
• Portland cement
• Lime (quicklime and hydrated lime)
• Pozzolans (fly ash)
• Bitumen and tar
• Chemical stabilization
Mechanical stabilisation: Mechanical stabilization is
one of the cheaper means of improving the quality of
sands. Such stabilization can be achieved by
blending sand with other materials with the following
beneficial results..
• improved CBR
• lowering of PI
• lowering of OMC
• improved workability
• lowering of soluble salt content where salts
are present
Lime stabilization, Cement stabilisation, Bitumen
stabilization

13. 2. Swampy Roads
• Building roads in challenging terrain and swamps or bogs requires special attention
compared to construction in ordinary soil. Reason behind that is Swampy lands are
periodically or permanently inundated by water.
• This type of soil contains large quantities of vegetable matter, clay and mud.
• Swamps are classified into brackish or fresh water depending on the salt content of the
water. The depth of this particular layer may vary from shallow to deep.
• For construction of roads, shallow deposits can be removed, and deeper deposits
strengthened by suitable means.

14. Surveys and investigations
• There are certain basic design controls and criteria which govern the geometric features of a
highway such as topography, traffic, speed, capacity, vehicle and control access.
• The different surveys to be conducted in connection with the construction of roads are:
1. Transport planning
• Traffic surveys
• Highway inventory
• Pavement
deterioration
• Accident studies
2. Alignment and route
location
• Desk study
• Reconnaissance
survey
• Preliminary survey
• Final location survey
3. Drainage studies
• Hydraulic studies
• Subsurface drains
• Cross drainage
4. Soil survey
• Desk study
• Site reconnaissance
• Soil exploration and
sampling

15. Design Approaches for
Swamps
• Compared with ordinary soil, for construction of roads in swamps, special treatment
and techniques are to be adopted depending on the characteristics of the underlying
soil. Such as..
 Partial or total removal of undesirable material
 Stage construction and surcharge fill
 Use of sand drains
 Use of light weight material

16. Soil stabilization
• The soil properties can be changed either by addition or by mechanical blending of
different soil types. The additives normally used are lime, cement, sodium silicate, calcium
chloride and bituminous materials. In mechanical stabilization, the stability of the soil is
improved by blending the available soil with imported soil or aggregate.

17. Use of geo textiles
• Geo textiles are synthetic fabric made out of Nylon,
Polyester, and Poly Propylene.
• They are non- decomposable.
• They are used for the following purposes:
• Ensuring physical separation of layers,
• Acting as a filtering medium,
• Working as a reinforcing layer permitting heavy
loads on weak soils.
Woven Geotextiles
Non-Woven Geotextiles
Knitted Geotextiles

18. Use of geo grids
• Geo grids are high strength plastic grids
which are interposed either at the bottom of
a layer or in a layer itself to increase the
strength.
• When geo grids are used at the bottom of a
granular layer and above the sub grade,
the grid increases the load bearing
capacity of the soil.

19.  References
1. Desert Areas
• AASHTO: American Association of State Highway
and Transportation Officials
• AFCAP (2013). Design Manual for Low Volume
Sealed Roads Using the DCP Design Method.
Ministry of Transport and Public Works, Lilongwe,
Malawi.
• Baart D., 1961. Road Construction in Kalahari
Sands and Associated Formations. Proc. Constr.
Engrs. Conf. Ministry of Roads & Road Traffic,
Rhodesia, August 1961.
• Botswana Roads Department, 1992. Roads in
Botswana. Gaborone: Botswana Roads Department.
2. Swampy Roads
• IRC: 34-1970,The Indian Roads Congress, New
Delhi,1970 Recommendations for road construction
in water-logged areas
• Terzaghi K & R B Peck, Asia Publishing House,
New Delhi,1962 Soil Mechanics in Engineering
Practice
• Handbook of quality control for construction of
roads and runways
• Special Publication 11,The Indian Roads
congress, New Delhi,1970