Seminar on Concrete Damage Assessments, Concrete Repair and Concrete Mix Technology

Organiser: Hong Kong Concrete Institute

Co-organisers:The Hong Kong Institution of Engineers (Building Division)Hong Kong Concrete Repair AssociationDepartment of Civil and Structural Engineering, The Hong Kong Polytechnic University

Use of Vapour Phase Corrosion Inhibitor Capsules for Long Term Protection of Repaired Reinforced Concrete Structures

Mr. Brian Davies, XQ International, Bristol, UK

Seminar on Concrete Damage Assesments, Concrete Repair and Concrete Mix Technology, HK Concrete Institute, HK PolyU 5 Feb 2010

Use to protect steel for over 50 years Widely used in reinforced concrete since 1980s

Types:

Integral or cast in corrosion inhibitors (ICI) Surface applied migratory corrosion inhibitors (MCI) Vapour phase corrosion inhibitor capsules (VPCI)

Corrosion InhibitorsHistory and Types

Integral or cast in corrosion inhibitors (ICI) Yes, but dosage is critical

Surface applied migratory corrosion inhibitors (MCI) Yes ?, but highly dependent on porosity and correct

application rate and method

Vapour phase corrosion inhibitor capsules (VPCI) Yes, but spacing must be controlled

Seminar on Concrete Damage Assesments, Concrete Repair and Concrete Mix Technology, HK Concrete Institute, HK PolyU 5 Feb 2010

Corrosion InhibitorsDo they work?

VPCI capsule is inserted into 25mm holes which are drilled in the structure to be protected.

Seminar on Concrete Damage Assesments, Concrete Repair and Concrete Mix Technology, HK Concrete Institute, HK PolyU 5 Feb 2010

Vapour Phase Corrosion InhibitorsHow they work

Three separate inhibitors are released over time as a vapour that saturates a given airspace, this vapour forms a mono-molecular coating on embedded steel. The product travels easily through concrete to coat embedded reinforcement at a rate of around 1m per week.

Seminar on Concrete Damage Assesments, Concrete Repair and Concrete Mix Technology, HK Concrete Institute, HK PolyU 5 Feb 2010

Vapour Phase Corrosion InhibitorsHow they work

2 nails were sealed in test tubes in 1995, these pictures were taken in 2007, the example on the left had no VPCI and the one on the right had VPCI added.

The corrosion to the nail on the left is significant, the nail on the right shows very little corrosion and the tip of the nail is still shiny.

Seminar on Concrete Damage Assesments, Concrete Repair and Concrete Mix Technology, HK Concrete Institute, HK PolyU 5 Feb 2010

Do Vapour Phase Corrosion Inhibitors Protect Steel?Simple Nail Test

Seminar on Concrete Damage Assesments, Concrete Repair and Concrete Mix Technology, HK Concrete Institute, HK PolyU 5 Feb 2010

Do Vapour Phase Corrosion Inhibitors Protect Steel?Further Evidence

May 17, 2007May 17, 2007

May 22, 2008May 22, 2008

Seminar on Concrete Damage Assesments, Concrete Repair and Concrete Mix Technology, HK Concrete Institute, HK PolyU 5 Feb 2010

Do Vapour Phase Corrosion Inhibitors Protect Steel?Laboratory Tests Steel in Concrete2% calcium chloride, 6 months duration

Future Testing

Measurement of VPCI travel in large scale laboratory prepared samples and adsorption measures using gas chromatography

Intertek

Testing to NACE TM 0294-2001, Testing of embedded current anodes for use in cathodic protection of reinforced concrete, modified for use with VPCI

The Technology Centre (Taywood Engineering)

Seminar on Concrete Damage Assesments, Concrete Repair and Concrete Mix Technology, HK Concrete Institute, HK PolyU 5 Feb 2010