The earthen road is the cheapest type of road in which the pavement structure is constructed totally from the soil available at the site. It is also called the earth road.
It is advantageous if we have to construct the road at the limited fund and this road can be improved in the future for an increase in traffic volume.
This type of road is generally found in village areas.
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It is the lowest form of pavement surface used and is considered as the first stage in the development of road pavement construction.
These type of road requires frequent maintenance to make them serviceable (i.e. mainly after monsoon).
1.1. Types of Earthen Road
a)Ordinary Earthen Road
The earthen road whose foundation and the wearing surface consists of one or more compacted layers of natural soil available along its alignment is an ordinary earthen road.
The surface of such a type of road is generally dusty and ruts are formed quickly.
b)Stabilized Earthen Road
The road whose foundation and the wearing surface is constructed from one or more compacted layers of stabilized soil ( Stabilized with physical, chemical or biological agents to increase strength and durability) is Stabilized Earthen Road.
It carries greater traffic, load and also provides better service as compared to ordinary earthen roads.
1.2. Materials Required
The material required for the earthen road is well-graded soil with a liquid limit of less than 35% and a plasticity index of 4-10%.
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1.3. Tools and Equipment Used
It is used to dig or to break soil lumps.
It is used for digging, lifting, and moving of materials like soil, gravel, etc.
It is used to transport materials from one point of the site to another desired point.
It is used for excavation purpose ( i.e. used in cutting and filling works).
It is used for compacting the road surface.
1.4. Construction Procedure of Earthen Road
The construction procedure includes the following steps:
1) Locating Alignment
The centerline of road and road edges are marked with the help of wooden peg. The alignment of the road is selected such that:
a. It is short in length.
b. It is easy to construct.
c. It is safe for users.
d. It is economical.
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2) Soil Survey
Soil Survey is carried out to determine the stability and approximate load-bearing capacity of the soil. The higher load-bearing capacity of soil leads to the higher strength of the road.
3) Preparation of Sub-grades
a)Clearing: It is required to clear the road site from grasses and vegetal covers.
b)Excavation or filling up to the desired grade.
c)Shaping the sub-grade.
d)Compacting the sub-grade.
4) Pavement Construction
The borrowed soil is dump on the prepared sub-grade and is spread so that desired cross slope (i.e camber) is achieved and final compaction is done at OMC(Operation, Maintenace & Construction) to get the required grade of compaction.
Compaction work is carried out with a slight application of water.
5) Opening to Traffic
The compacted earthen road is allowed to dry for 1 to 3 days before opening to traffic.
1.5. Advantages of Earthen Road
1) It is the cheapest type of road and can be constructed in a very low budget.
2) Earthen materials are easily available.
3) Local people and materials are utilized during the construction.
4) Can be blacktopped easily whenever required.
5) Can be constructed in less time ( i.e. Fast Construction).
1.6. Disadvantages of Earthen Road
1) Greater maintenance cost as compared to the other types of road.
2) Closed during the period of monsoon.
3) Dusty in nature.
4) Can’t bear heavy loads.
5) Ruts are formed quickly.
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