Construction of Pavement Layers
CHAPTER-1
INTRODUCTION
1.1 PAVEMENT DEFINITION
Surface or pavement is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway. In the past gravel road surfaces, cobblestones and granite settles were extensively used, but these surfaces have mostly been replaced by asphalt or concrete. Such surfaces are frequently marked to guide traffic. Today, permeable paving methods are beginning to be used for low-impact roadways and walkways.
1.2 REQUREMENTS OF PAVEMENT
An ideal pavement should meet the following requirements:
1. Sufficient thickness to distribute the wheel load stresses to a safe value on the sub-grade soil.
2. Structurally strong to withstand all types of stresses imposed upon it.
3. Adequate coefficient of friction to prevent skidding of vehicles.
4. Smooth surface to provide comfort to road users even at high speed.
5. Produce least noise from moving vehicles.
6. Dust proof surface so that track safety is not impaired by reducing visibility.
7. Impervious surface, so that sub-grade soil is well protected, and
8. Long design life with low maintenance cost.
1.3 TYPES OF PAVEMENTS
The pavements can be classified based on the structural performance into two,
1. Flexible pavements
2. Rigid pavements.
In flexible pavements, wheel loads are transferred by grain-to-grain contact of the aggregate through the granular structure. The flexible pavement, having less strength, acts like a flexible sheet On the contrary, in rigid pavements, wheel loads are transferred to sub-grade soil by textural Strength of the pavement and the pavement acts like a rigid plate (e.g. cement concrete roads). In addition to these, composite pavements are also available. A thin layer of flexible pavement over rigid pavement is an ideal pavement with most desirable characteristics. However, such pavements are rarely used in new
INTRODUCTION
1.1 PAVEMENT DEFINITION
Surface or pavement is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway. In the past gravel road surfaces, cobblestones and granite settles were extensively used, but these surfaces have mostly been replaced by asphalt or concrete. Such surfaces are frequently marked to guide traffic. Today, permeable paving methods are beginning to be used for low-impact roadways and walkways.
1.2 REQUREMENTS OF PAVEMENT
An ideal pavement should meet the following requirements:
1. Sufficient thickness to distribute the wheel load stresses to a safe value on the sub-grade soil.
2. Structurally strong to withstand all types of stresses imposed upon it.
3. Adequate coefficient of friction to prevent skidding of vehicles.
4. Smooth surface to provide comfort to road users even at high speed.
5. Produce least noise from moving vehicles.
6. Dust proof surface so that track safety is not impaired by reducing visibility.
7. Impervious surface, so that sub-grade soil is well protected, and
8. Long design life with low maintenance cost.
1.3 TYPES OF PAVEMENTS
The pavements can be classified based on the structural performance into two,
1. Flexible pavements
2. Rigid pavements.
In flexible pavements, wheel loads are transferred by grain-to-grain contact of the aggregate through the granular structure. The flexible pavement, having less strength, acts like a flexible sheet On the contrary, in rigid pavements, wheel loads are transferred to sub-grade soil by textural Strength of the pavement and the pavement acts like a rigid plate (e.g. cement concrete roads). In addition to these, composite pavements are also available. A thin layer of flexible pavement over rigid pavement is an ideal pavement with most desirable characteristics. However, such pavements are rarely used in new