Internship work on Flexible pavements .pptx

Flexible Pavements

1. Ku college of engineering & technology Internship report Presented By: S. Uday Kiran (225670058L) V. Chandana (225670062L) Y. Mahendar (225670064L) -PANCHAYAT RAJ ENGINEERING DEPARTMENT [Warangal]

2. CONTENTS INTRODUCTION TYPES OF PAVEMENTS FLEXIBLE PAVEMENTS TYPICAL LAYERS OF FLEXIBLE PAVEMENTS MACHINERY AND EQUIPMENT CONSTRUCTION OROCEDURE

3. Introduction What is a road ? A road is a route, or way on land between two places that has been paved or otherwise improved to allow travel by foot or some form of conveyance, including a motor vehicle, cart, bicycle etc.. pavement A structure consisting of superimposed layers of processed materials above the natural soil subgrade, whose primary function is to distribute the applied vehicle loads to the sub-grade.

4. Types of pavements Flexible Pavements: Flexible pavement can be defined as the one consisting of a mixture of asphaltic or bituminous material and aggregates. Rigid Pavements: A rigid pavement is constructed from cement concrete or reinforced slabs. There are two types of pavement as follows:

5. Flexible pavements Flexible Pavements are road structures that distribute loads to the subgrade primarily through a layered system. The layers typically include asphalt concrete on top, followed by base and sub-base layers made of materials like crushed stone or gravel. They are called “flexible” because they can flex and conform to surface imperfections under traffic loads, distributing stress over a boarder area. Load is transferred to the lower layer by “Grain to grain” distribution. The wheel load acting on the pavement will be distributed to a wider area, and the stress decreases with the depth. Flexible pavement layers reflect the deformation of the lower layers on to the surface layer. The initial cost of mixing and applying flexible pavement is low and with excellent regular maintenance, it has a lifespan of about 10-15YEARS.

6. TYPICAL LAYERS OF FLEXIBLE PAVEMENTS Typical layers of a conventional flexible pavement includes seal coat, surface coat, tack coat, binder course, prime coat, base course, sub-base course, compacted sub-grade, natural sub-grade. SEAL COAT is a thin surface treatment used to water proof the surface and to provide skid resistance. TACK COAT is a very light application of asphalt emulsion diluted with water. And it provides bonding between two layers of binder course.

7. PRIME COAT is an application of low viscous cutback bitumen to an absorbent surface like granular bases on which binder layer is placed and provides bonding between two layers. SURFACE COURSE is the layer directly in contact with traffic loads and are constructed with dense graded asphalt concrete. BINDER COURSE purpose is to distribute load to the base course. Binder course requires lesser quantity of mix as compared to course above it. BASE COURSE provides additional load distribution and contributes to the sub-surface drainage. SUB-SURFACE COURSE the primary function are to provide structural support, improve drainage, and reduce the intrusion of fines from the sub-grade in the pavement structure. SUB-GRADE is a layer of natural soil prepared to receive the stresses from the layers above.

8. Machinery and equipment ASPHALT PLANT : Produces hot mix asphalt used in paving. EMULSION SPRAYER : Used to apply a uniform and controlled layer of bitumen emulsion on the pavement surface. PAVERS : Lay the asphalt mix on the road surface. ROLLERS : Compact the asphalt layer to achieve the desired density. Smooth wheeled rollers. Pneumatic-tired rollers. Vibratory rollers. Emulsion sprayer Pavers Roller

9. MILLING MACHINE : Remove the top layer of existing pavement. LOADERS : Transport materials on the construction site. DUMP TRUCK : Haul materials like asphalt, aggregate, and debris. TACK COATERS : Apply a thin layer of asphalt emulsion to improve bonding between the pavement layers. DEPTH GAUGE : Used to measure the thickness of bitumen layer. Loader Dump truck Tack coater Depth gauge

10. Construction procedure NEW ROAD : Preparation of Subgrade. Preparation of Sub-surface course. Preparation of Base course. Applying Prime coat. Laying of Binder course/Surface course. Applying Seal coat. ON EXISTING SURFACE : Removal of existing surface course. Preparation of base course. Applying Prime coat. Laying of Binder course/Surface course. Applying Seal coat.

11. On existing surface : Step-1 : REMOVAL OF EXISTING SURFACE COURSE. Milling – Mill the existing pavement to the required depth to remove damaged layers and ensure a uniform surface. Step-2 : PREPARATION OF BASE COURSE. This layer is directly below the surface course and generally consists of aggregates. Ensure proper drainage to prevent water accumulation. Milling Base course preparation

12. Prime coat Seal coat

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