Damp Roofing

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WATERPROOFINGBELOW GROUND LEVEL

PRESENTATION BY GEETHIKA SUSAN

ROLL NO: 16

UNDER GUIDANCEOF

BINDHU B.K.


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CONTENTS

IntroductionImportance of waterproofing

Design Requirements

Design Approach

Methods of Positive Side Waterproofing

Steps of Application

Negative Side Waterproofing

Modern Methods of Waterproofing

Case Study


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INTRODUCTION

q Use of underground structures has beenincreased

q Damp proofing and water proofing-diff andsimilarity.

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IMPORTANCE OF WATERPROOFING

q Effects of water seepage are:

-aggressive chemical exposure

-Corrosion of metals-Chemical reactions of aggregates

-Cracking

-Rust stains

q Overall durability of structure affected.

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DESIGN REQUIREMENTS

q 3 types of water penetration:

Uncracked concrete

Cracked concrete Leaking joints

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Water flow through cracked concreteWater flow at leaking joints

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q Penetration of water through uncracked

concrete.eg:cut and cover tunnel.

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DESIGN APPROACHES

q 2 Approaches of design:

Positivewaterproofing :

Applied to same sideas applied hydrostatic

pressure.

Negative

waterproofing :Applied to opposite

side as appliedhydrostatic pressure.

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Continued

Negative waterproofing doesnt provide anyprotection to concrete if soils containcorrosive chemicals.

Extreme care taken at joints .

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SYSTEMS OF POSITIVE SIDE

WATERPRROFING2 Methods: 1)Water tight concrete

2) Surface barrier

1) Watertight concrete

Use of pozzolanic nanoparticles in concrete.It crystallises,overall

porositydecreases,cracks are

sealed

Use of additives whichcauses contraction of

capillaries.It converts water

absorbing capillary forces

into water repellant.

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Continued .

2) Surface Barrier Materials

Function is to arrest the passage of water

through concrete.Eg: Built up bituminous membrane.

These are bonded by heat welding or cold

application.Liquid applied membranes more suitable :

1)Ease of application

2)Can suit to any geometry

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STEPS OF APPLICATION

Excavation of slopes

Surface preparation

Application of primer

Application of 1st layer of bituminouspolymer membrane forming coating.

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Continued

Insertion of fabric mesh into 1st layer.

Application of 2nd layer of bituminouspolymer membrane

Curing and application of protection boards

Backfilling

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FACTORS AFFECTING DRYING TIME

FACTORS EFFECTS ON DRYINGTIME

LOW HUMIDITY ACCELERATES DRYING

RAIN STOPS DRYING AND MARS THE SURFACE

SUNSHINE ACCELERATES DRYING

WIND OR BREEZE ACCELERATES DRYING

HIGH ABSORBENCY REDUCES DRYING TIME

THIN COATING REDUCES DRYING TIME

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NEGATIVE SIDE WATERPROOFING

Used only at unavoidable situations.

Main requirement-low permeable concrete,nohoneycombs,no cracks.

Sealing of cracks is the main operation.

Material injected to cracks through injectionpackers.

Grid injection system used.Acrylic gels can be also used.

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MODERN WATERPROOFING PRODUCTS

1)Waterstop RX-101

-Flexible strip concrete constructon joint waterstop

-Expands upon contact with water

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2)Voltex and Voltex DS 2- Both uses the

waterproofing property of bentonite.

-Voltex DS is mainly used intunnels.

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Case study-pedestrian subway,

sealdah station

Observed water leakages at horizontal const. joints, honeycomb areas , point leakages.

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Continued.

q Surface treatment:

2 layer plaster

q Unnecessary expansion joints should beavoided

1st layer:6 mm thick plaster

Water proofingcompound +

cement(3:5)

2nd layer:8 to 12 mm thick

plasterCement :sand (1:2to

1:3)

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CONCLUSIONS

Success of waterproofing depends onapplication and understanding limitations of materials.

QA systems should be installed.

Positive side water proofing is preferred.

If negative side waterproofing, then go foracrylic gel technology.

Proper water proofing methods improve thedurability of structure.

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REFERENCES

Civil Engineering and Construction Review,March 2011

NBM CW journal, April 2011

NBM-CW journal, Feb 2011Facilities Engineering Journal, May 2010

Civil Engineering and Construction Review,

Nov 2010Concrete technology, MS.Shetty

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THANK YOU!!!

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