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  • PAVEMENT OVERLAY- SITE VISIT

    Prepared by- Simranjit Singh /Amit Aneja /Aman Pabbi

  • ACKNOWLEDGEMENT

    The authors would like to express special thanks of gratitude to Prof.

    AK Duggal for his immense guidance, and providing a first hand experience of

    working on actual site.

    We are grateful for his cooperation and his zeal to impart knowledge to the

    minds of tomorrow, for a better future.

    2 Authors- Simranjit Singh/ Amit Aneja/ Aman

    Pabbi

  • CONTENTS

    Purpose of Visit

    Introduction

    Need for Overlay

    Slurry Seal Coat

    Equipment used

    Check for thickness of Overlay

    Sampling

    Problems faced on site

    Important Notes

    3 Authors- Simranjit Singh/ Amit Aneja/ Aman

    Pabbi

  • PURPOSE OF VISIT

    The visit aimed at introducing the students to the overlaying process of a

    pavement in practical.

    To familiarize the students with the problems that frequently occur at

    site.

    The equipment used for highway maintenance, overlay.

    To educate the students to measure the thickness of the overlay.

    The procedure for sampling, for quality testing of the mix.

    4 Authors- Simranjit Singh/ Amit Aneja/ Aman

    Pabbi

  • INTRODUCTION

    Overlay is a practice of highway maintenance, by adding a layer to the

    existing pavement surface.

    Various factors to be considered for the design of the overlay are-

    1. Surface conditions of the existing road

    2. Structural conditions

    3. Relative vertical displacement

    4. Surface texture.

    5 Authors- Simranjit Singh/ Amit Aneja/ Aman

    Pabbi

  • NEED FOR OVERLAY

    The strength of the pavement as

    was measured using Benkelman

    beam method was satisfactory.

    Overlay is provided because of the

    problem of slippage.

    Earlier the pavement on the

    opposite carriageway was treated.

    Strength for that was also found to

    be satisfactory using Benkelman

    beam method.

    At some location cracks were

    observed, and hence it was treated

    using a Slurry Seal Patch (Pictures

    2 & 3).

    Picture-1

    6 Authors- Simranjit Singh/ Amit Aneja/ Aman

    Pabbi

  • SLURRY SEAL COAT

    7

    Slurry seal coat/patch

    For reference, here only a small portion is covered with the slurry seal coat

    hence for reference, it is referred to as slurry seal patch.

    As shown in picture-2, marked with red circle, are cracks on the pavement.

    Such cracks have been repaired using stone dust, fine grit and bitumen.

    Bitumen content here is greater than 6%.

    Picture-2 Picture-3

    Authors- Simranjit Singh/ Amit Aneja/ Aman

    Pabbi

  • EQUIPMENTS USED

    8

    1. Paver Finisher

    Equipment as shown in pictures 4 and

    5.

    This is used for laying the mix as a

    loose course.

    Loose laying for the desired 40mm

    compacted thickness was 52mm.

    Tipper is connected to the rear of the

    paver at points marked by a circle in

    picture-5.

    Picture-4

    The paver is moved in reverse

    direction with the connected tipper

    in neutral gear.

    The mix moves through the

    conveyor belts forward to the

    screed which spills it.

    Picture-5

    Conveyor

    Belts

    Authors- Simranjit Singh/ Amit Aneja/ Aman

    Pabbi

  • EQUIPMENTS USED

    9

    2. Tar boilery

    Equipment is as shown in pictures 6 and

    7.

    Normally tractor mounted.

    With heating arrangement to keep

    bitumen in hot/ molten state.

    Picture-6

    Picture-7

    Pressure gauge as shown in

    picture-7.

    This indicates the pressure at

    which bitumen is to be released.

    Authors- Simranjit Singh/ Amit Aneja/ Aman

    Pabbi

  • EQUIPMENTS USED

    10

    3. Nozzles

    As shown in picture-8.

    It should be insulated,

    such that it is easy to

    handle by the labor

    (Picture-9)

    This is used for tack coat.

    4. Tipper

    As shown in picture-10.

    The rear of the tipper is

    mounted to the rear of the

    paver, such that the

    material supply is

    continuous to the conveyor

    belts for spread through

    the screed.

    Picture-9 Picture-8

    Nozzle

    Picture-10

    Authors- Simranjit Singh/ Amit Aneja/ Aman

    Pabbi

  • EQUIPMENTS USED

    11

    5. Compaction Roller

    The rollers used for compaction are

    Vibratory Rollers (Picture-11)

    Smooth Wheel Roller (Picture-

    12)

    Initial compaction is done using

    Vibratory rollers.

    Picture-11

    Picture-12

    In certain cases, where there are

    structures (nearby buildings) on

    soft soils, vibratory rollers are

    not preferred as they can cause

    settlement of those foundations.

    Authors- Simranjit Singh/ Amit Aneja/ Aman

    Pabbi

  • 12

    Check for thickness

    This is done in 2 steps:

    1. Driving a nail through the

    pavement vertically.

    2. Measuring the depth by vernier

    callipers.

    NOTE- Nail should be driven till the

    striking sound of changes, indicating the

    pavement layer beneath.

    Sampling

    Sample for testing the quality of

    mix (like checking of bitumen

    content in mix) is taken from the

    paver itself, i.e. the mix being

    actually laid on site.

    Picture-13

    Picture-14 Nail

    Sample

    CHECK FOR THICKNESS / SAMPLING

    Authors- Simranjit Singh/ Amit Aneja/ Aman

    Pabbi

  • PROBLEMS FACED ON SITE

    13

    1. Loose material along Pavement Edges

    As seen clearly in picture-15 the material along

    the edges in loose state, showing poor

    compaction along the edges.

    2. Camber

    It was observed at the site, the thickness of

    overlay near the edge was 40mm, and that

    reduced to 39mm towards the center.

    Proper camber needs to be maintained to avoid

    accumulation of water on the pavement as it

    could be disastrous.

    Picture-15

    Pavement

    Edge

    Authors- Simranjit Singh/ Amit Aneja/ Aman

    Pabbi

  • IMPORTANT NOTES

    Date of visit 23rd April, 2014.

    Location Road opposite Kalagram, Chandigarh-Panchkula Road.

    NITTTR is the 3rd party for quality control in this project, under leadership

    of Prof. AK Duggal.

    Loose thickness of overlay = 52mm, from paver.

    Overlay consists of a 40mm compacted layer of Bituminous Concrete.

    The slurry seal patch on the other carriageway has a bitumen content

    greater than 6%, designed by NITTTR.

    14 Authors- Simranjit Singh/ Amit Aneja/ Aman

    Pabbi

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