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An Innovative and Proven Solution for Repelling Water Ingress into

Concretes Structure

Dr Ian McFeat Smith

Technical Directors, Hydrotech Asia Ltd

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80% of all concrete failures in buildings and structures in Hong Kong are caused by WATER INGRESS.(Chris Stanley, Chairman HKCRA)

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How does Water Ingress Occur ?

• Water penetrates concrete fabric by three primary mechanisms:

. Capillary action.

. Temperature differentials.

. Hydraulic pressure.

• “Water drawn into concrete by capillary action is over 10,000 times more powerful than gravity”. Prof. Andreas B. Fourie (Australian Centre for Geomechanics)

• The smaller the pores the greater the capillary action. 4

Early Stage in Hydration of Portland Cement Cement Hydration after 25 days

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Capillary forces draw water up sides of tubeCohesion and Adhesion

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Capillary Action through Pile Foundations, Floor Slabs and Walls

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Horizontal Capillary Action Through Walls

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Can we find a Cost Effective and

Permanent Solutionto Water Ingress problem?

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MULTI-PULSE SEQUENCING SYSTEM

IS A VIABLE SOLUTION TO STOP WATER INGRESS INTO

CONCRETE STRUCTURES

MPS MPS ®

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What is Multi Pulse Sequencing System and the scientific principle behind it?

Multi-Pulse Sequencing (MPS) System is a highly advanced form of electro-osmotic technology that uses low voltage and low current to ionise water and direct it to a specific area.

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MPSMPS® –– Multi Pulse Sequencing SystemMulti Pulse Sequencing System

• 1807, the German professor Russ, who was living in Russia discovered the theory and principles behind the movement of liquids in capillary structures.

• in 1930. The Ernst brothers in Switzerland discovered how to move fluids in capillary structures through applying an electrical charge between a cathode and electrode

• in 1962. Principles behind the effect was established by E Franke. Subsequent experiments by Prof. Andreas Fourie at Newcastle U/T University over 10 years to move water in concrete failed, because there was no efficient control system.

• In 1987, the Norwegian inventor Kjell Aage Utklev discovered that a pulsating current would continue to transport water in concrete for as long as the current was applied.

• In 1988 this discovery was patented in 1988. Kjell Aage Utklev is a shareholder and consultant to Hydrotech International.

• MPS is new technology, but the principles are universal.

Brief History of the Technology

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The MPS System in action

Underground water source

Reclaimed Land

Negative Electrode

• Using 240 volt transformed down to 40 volts DC • Water molecules are pushed back into the water table.• We can counter up to 60 bar of pressure• The system works continuously however after drying the power usage falls to a minimum level • Normal drying time is ONLY 4 to 8 weeks• The structure stays permanently dry

MPS Control Equipment

Positive Electrode

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DIFFERENCE BETWEEN ELECTRO-OSMOSIS AND CATHODIC PROTECTION

1. CATHODIC PROTECTION HAS SACRIFICIAL ANODE WHILST ELECTRO-OSMOSIS DO NOT.

2. CATHODIC PROTECTION CONNECTS TO THE REBARS WHILST ELECTRO-OSMOSIS DOES NOT.

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MPS System InstallationMPS System Installation

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A marine concrete structure in Chai Wan that started to deteriorate before the construction was complete.

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Alkali - Glass ReactionDeterioration of mosaic clad render

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Spalling of concrete from expansion of rebar leading to secondary corrosion

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Water Ingress is One of the Oldest Problems in Civil Engineering For this Tunnel Singapore spent

millions fixing the cracks but the water ingress problem remained

Water ingress accelerates the degradation of the structure

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Attempts at repair

Flooding

Examples of Asset Degradation caused by Water Ingress

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Water leaking through construction fissures

Large area of water ingress leading to stray current issues.

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Mould, Odour, Airbourne Bacteria

How water ingress can manifest itself

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Chinese Electronic Periodical Services 21/12/07

Results from Testing Air Quality and Odour Problems in Shenzhen Metro

99.2% of 9460 samples yielded bacteria

100% yielded Mycete

11 Hemolytic Streptococcus

CONCLUSION: The contamination in the air of Shenzhen Metro is very serious.

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Review of some options for WATERPROOFING CONCRETE

• Concrete can be made waterproof using admixturesthat are mainly pore-blockers

• Concrete structures can be made waterproof by means of sheet or spray membranes

• Grouting using Jetting methods can be applied to adjacent ground

• Multiple Pulse Sequencing (MPS) using electro-osmosis can be installed on walls and slabs of existing and new build structures.

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THE MULTIPLE INSTALLATION PROCESS FOR MEMBRANES IS COMPLEX, TIME CONSUMING, INVOLVES THE USE OF EXPENSIVE MATERIALS AND IS

THEREFORE HIGHLY EXPENSIVE

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BUCKLING AND WRINKLING OF MEMBRANES COMMONLY OCCUR. DAMAGE RESULTS FROM INSTALLING ANCHORS,

CUTTING MEMBRANE TO SUIT SHAPES

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• This had to be grouted as shown.

• Supplier advises that membrane can only be applied to dry surfaces ?

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REPAIRS TO EXISTING STRUCTURES

OBJECTIVES CRACK REPAIRS - SPRAY ON RESINS COATINGS

CRACK INJECTION

Preventing capillary actionSealing large cracks >0.2mmMinimise cracking from corroding steelWater exclusion

Long term humidity, mold and odor controlCost - Installation

Savings Heating/Ventilation/A/CPerformance Monitoring

-Effective -Partially effective - Marginal n/a - not applicable34

REPAIRS TO EXISTING STRUCTURES

OBJECTIVES CRACK REPAIRS - SPRAY ON RESINS COATINGS

CRACK INJECTION

Preventing capillary action

n/a n/a

Sealing large cracks >0.2mmMinimise cracking from corroding steelWater exclusion

Long term humidity, mould and odour controlCost - Installation High – does not stop water ingress High – does not stop water ingress

Savings Heating/Ventilation/A/C

n/a n/a

Performance Monitoring

n/a n/a

-Effective -Partially effective - Marginal n/a - not applicable

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WATER INGRESS PROTECTION FOR NEW CONCRETE STRUCTURES

OBJECTIVES

ADMIXTURES MEMBRANESGROUTING

OF GROUNDSHRINKAGE REDUCTION

CAPILLARY ABSORPTION REDUCTION

SHEET(OUTSIDE

CONCRETE)

SPRAY - ON(INSIDE AT AIR

INTERFACE)

Reducing / preventing capillary absorption

Minimise ingress through cracking*

Long term water exclusion

Prevent corrosion of rebar

Long term humidity,odourand mould control

Heating/Vent/A-C Savings

Performance Monitoring

*Thermal and shrinkage cracking

- Effective - Partially effective - Marginal n/a - not applicable

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WATER INGRESS PROTECTION FOR NEW CONCRETE STRUCTURES

AIMS

ADMIXTURES MEMBRANESGROUTING

OF GROUNDSHRINKAGE REDUCTION

CAPILLARY ABSORPTION REDUCTION

SHEET(OUTSIDE

CONCRETE)

SPRAY - ON(INSIDE AT AIR

INTERFACE)

Reducing / preventing capillary absorption n/a n/a n/a n/a

Minimise ingress through cracking* n/a n/a n/a n/a

Long term water exclusion

Prevent corrosion of rebar

Long term humidity,odorand mold control

Heating/Vent/A-C Savings n/a n/a n/a n/a n/a

Performance Monitoring n/a n/a n/a n/a n/a

*Thermal and shrinkage cracking

- Effective - Partially effective - Marginal n/a - not applicable

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MPS Scope of Application

• Underground projects such as railway stations, car parks and all other basement structures

• Tunnels such as road and rail, pedestrian tunnels, cable and gas and other tunnels.

• Hydroelectric and dam projects etc

• Marine structures, underwater foundation projects and embankments

• Bridges and viaducts.

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Examples of Significant Projects

LondonLondon Underground Railway StationWalthamstow Central Subway

Hong Kong International Finance CentreHong Kong Central Station, Airport ExpressHong Kong Hang Seng Bank HeadquartersCity Plaza Taikoo Shing CentreHong Kong XinHua Agency

China Projects

Norway ProjectsTafjord DamSira Kvina Power StationDrammen Central Railway StationSkien Central Railway StationOslo Housing Society (OBOS)Norway National Museum

Zheng Zhou High-tension Electric Cable Tunnel

Projects under investigationWarehouse Basement, Kowloon Tong (completed)Zhongliang Highway Tunnels, ChongqingFengman Dam, Jilin ProvinceGuangzhou Metro Railway tunnels, Chonqing, Metro Station

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MTRC Central Station, Artwork Area

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No MPS installation at theRight behind of the Artwork

MPS System was installed at the Left behind the Artwork

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Before MPS Installation

After MPS Installation

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International Finance Centre One, Hong Kong

Year: 2000 Location: Hong KongProject: Lift Machine RoomClient: Hendersonland

Background:

• Severe saline water ingress through the walls resulted in a lift machine room being extensively flooded

• All the plant was submerged.

• Following installation of MPS in 2000, water ingress has been completely ceased.

MPS System Control Unit Installation

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• IFC below Car park Area• Machine Room flooded out• Completely dried out after

MPS Installation

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• CITY PLAZA 4 Loading Area• Diaphragm wall was saturated

due to flooding from ground water ingress

• Frustrated, Swire Properties tested several methods for preventing water ingress

• MPS selected as the only successful method

• Wall remains bone dry after 10 years of monitoring

• Maintenance costs are negligible

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Electrode Placement in City Plaza 4

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Walthamstow London Underground Station Central Subway. MPS Works

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Walthamstow Station - Central subway. MPS Circuits in Subway

48MPS Layout at Walthamstow

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Electro-Magnetic ComplianceCertificate

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Water ingress problem at the Underground Railway in Singapore

7th May 2008

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Oslo Central Railway Station

Year: 1990 Location: NorwayProject: Central Railway StationClient: NSB AS

Background:• Water ingress had occurred in block work located 100 meters from the sea and below ground water level.

• The wall had been constructed with an external membrane and back filled.

• In 1990, anode lines were installed in the inside wall with an external ground spear.

•The problem has been completely solved

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TAFJORD Dam Norway

Year: 1997 Location: NorwayProject: Dam StructureClient: S.N. Electric Company

Background:• The concrete dam in Tafjord is Europe’s second highest at 96meters.

• The structure is 12 meters thick at the top and 40meters thick at its base.

• By early 1990’s, a number of cracks were appearing that resulted in significant leakage. On the assumption that nothing could be done to remedy the situation, the structure was eventually condemned and schedule for demolition.

• Electro-osmotic technology was employed to address the defects and the leakage was stopped.

• Following on from the drying process, the physical cracks could be repaired by conventional sealing methods.

•The problem did not reoccur54

Sira-Kvina Power Station

Year: 1992

Location: Norway

Project: Power Station

Client: S.N. Electric Company

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MPS INTELLIGENT SYSTEMControl and Performance Monitoring

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FACT MPS Removes the Need to

Waterproof Concrete

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MPS System Permanently Protects your structure from Water Ingress

Cost BenefitThe cost of MPS is less than

HK$ 150/m2

The cost of repairing concrete damaged by water ingress is more than

HK$4,000/m2

Enormous savings in life-cycle costs

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WATER INGRESS PROTECTION BY MPS

OBJECTIVES SYSTEM PERFORMANCE

Reducing / preventing capillary absorptionMinimise ingress through cracking* <0.2mmMinimise ingress through cracking* >0.2mm

n/a

Prevention of Corrosion of steel rebar

Prevention of cracking from expansion of corroding steelLong Term Humidity, Mould and Bacterial ControlHeating/Vent/A-C Savings

Performance Monitoring

*Thermal and shrinkage cracking - Effective n/a - not applicable

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TESTIMONIAL LETTERS

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CONCLUSIONS

• MPS provides a viable, easily installed and cost – effective solution to STOP WATER INGRESS

• Long term humidity, mould and odour control

• MPS provides a unique long term control and performance monitoring system.

• Operational costs using MPS are negligible and savings in life cycle costs are considerable.

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THANK YOU

ANY QUESTIONS?