What is a capping layer?
The SuDS Manual published by CIRIA in 2015 defines a capping layer as: ‘A layer of unbound aggregate of lower quality than sub-base, that is used to improve the performance of the foundation soils before laying the sub-base, and to protect the subgrade from damage by construction traffic. ‘
What is pavement layer?
A highway pavement is a structure consisting of superimposed layers of processed materials above the natural soil sub-grade, whose primary function is to distribute the applied vehicle loads to the sub-grade.
What are the three layers of a flexible pavement?
A typical flexible pavement structure (see Figure 2) consists of:
- Surface Course. The layer in contact with traffic loads.
- Base Course. The layer immediately beneath the surface course.
- Subbase Course. The layer between the base course and subgrade.
What is a subgrade layer?
The sub-grade layer of a pavement is, essentially, the underlying ground. It is also known as the “Formation Level”, which can be defined as the level at which excavation ceases and construction starts.
What materials do capping layers use?
crushed rock
The materials most commonly used in a capping layer are crushed rock, hardcore or a hydraulically bound mixture. Because the grading of the material in a capping layer doesn’t need to be particularly tightly controlled, the material can usually be sourced locally.
What is capping a road?
Capping, or highway deck parks are a way to create new acreage and/or provide green space that can spur downtown development. Capping a highway to create a park also can reconnect urban neighborhoods sliced apart by the expressway building boom of the 1960s and ’70s.
How do you design a road pavement?
Pavement Design in Road Construction – Design Parameters
- Introduction.
- General:
- Traffic:
- As per the IRC:37 design traffic should be 0.1 msa to 2 msa (million standard axles). Weight of commercial vehicle (laden) is considered as 3 tonnes or more.
- Computation of design traffic:
- Subgrade:
- CBR:
- Sub-base course:
Why is pavement design important?
The most important function of the pavement is to withstand the load applied from a vehicle such as a truck or an aircraft, without deforming excessively. Since water can be detrimental to a pavement, a basic necessity of designing a proper pavement is to provide adequate drainage for both surface and subsurface water.
How many layers are in flexible pavement?
Lastly, it is important to protect the lower pavement layers and subgrade from any of the weakening effects of water. There are actually typically five or six layers in a flexible pavement, divided into two overlapping sections: the pavement section and the foundation section.
Why subgrade is a important part in a road pavement?
The subgrade must be able to support loads transmitted from the pavement structure. This load bearing capacity is often affected by degree of compaction, moisture content, and soil type. A subgrade that can support a high amount of loading without excessive deformation is considered good.
What is the use of capping material?
Capping layer materials help to reduce costs and to protect the subgrade from rainfall and weathering.