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ROAD STRUCTUREABDULLAH NAEEM

BGLF06M017

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ANATOMY OF A

ROAD

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CROSS-

SECTION

OF A ROAD

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MATERIA

LABC-- 2 DOWN

SUB-BASE-- 2.5

DOWN

SUB-GRADE --

LOCAL SOIL

ASPHALTICCONCRETE--1

DOWN

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Sub-grade:The part of the soil, natural or constructed, which supports the loads transmitted by theoverlying pavement. It is generally the in-situ soil. In transport engineering, subgradeis the native material underneath a constructed road,[pavement or railway track. Preparation of the subgrade for construction usually involves digging, remove surfacevegetation, topsoil and other unwanted material, and create space for the upper layer ofthe pavement. This process is known as subgrade formation . Compaction required is95%.

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Subbase (pavement)

In highway engineering, subbase is the layer of aggregate material laid on thesubgrade, on which the basecourse layer is located. It may be omitted when there will beonly foot traffic on the pavement, but it is necessary for surfaces used by vehicles.

The thickness of subbase can range from 75-100 mm for garden paths through 100-150

mm for driveways and public footpaths, to 150-225 mm for heavy used roads, and morefor highways. Compaction required is 98%.

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Base Course

In pavements refers to the sub-layer material of an asphalt roadways and is placeddirectly on top of the undisturbed soil so as to provide a foundation to support the toplayer(s) of the pavement.

Generally consisting of a specific type of construction aggregate provides a stable

foundation to support additional layers of aggregates or the placement of asphaltconcrete ,all resulting in a roadway pavement.

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Aggregate basecourse

is typically composed of crushed rock capable of passing through a 3/4 in (19.05 mm)rock screen.

The component particles will vary in size from 3/4 inch down to dust. The material can bemade of newly mined rock, or of recycled asphalt and concrete.

Compaction of 100% is required.

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Asphalt

It is a sticky, black and highly viscous liquid or semi-solid

The primary use of asphalt is in road construction, where it is used as the glue or binderfor the aggregate particles. The road surfacing material is usually called asphalticconcrete.

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RELATED TERMINOLOGY

Sieves

PTR (pneumatic tyre rollers)

Grader

Paver

Asphalt plant

Aggregate plant

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