Martin Richardson – Structural Strengthening Materials Advice

Martin’s experience extents to the following specialist areas of strengthening using composite materials;

Flexural Strengthening using CFRP Plates

Near Surface Mounted Reinforcement (NSM)

Strengthening Cast Iron Using Ultra High Modulus (UHM) Carbon Fibre Plates

Shear Strengthening Using CFRP L Shaped Links

Structural Adhesives

Materials advice can be provided to both designers and contractors who have a structure that needs strengthening.

Structural Strengthening Materials Advice
Structural Strengthening Materials Advice

Development of Structural Strengthening – Steel Plate Bonding

Steel plate bonding has been used in both buildings and civil structures in the UK since 1975 using first generation epoxy adheives. In 1994 the Highways Agency published BA 30/94 ‘Strengthening of Concrete Highway Structures Using Externally Bonded Plates’. This provided information on application, design and specification of the technique. The application of steel plates is still the best solution to some strengthening problems that occur today.

Steel plate bonding provided the basis for the establishment of strengthening using externally bonded reinforcement. The process involves the bonding of a mild steel plate with a minimum thickness of 4mm (for handling purposes) to a prepared concrete surface.

The steel plates are fabricated off site to the required dimensions and specification, including holes for anti-peel bolts.

To prevent any corrosion of the steel plate a primer system needs to be applied to the prepared steel surface during fabrication. This primer also provides the critical function of transferring forces from the structure to the steel plate and is hence a crucial part of the system.

Holes for anti-peel bolts also need to be inserted in the steel plate during fabrication. These bolts are required to provide additional resistance to peel forces applied to the bond line due to any residual force in the end of the plate. The bolts have to be positioned carefully to avoid damage to the existing reinforcement in the concrete surface.

Temporary works are required to support the heavy steel plates while the 2-part epoxy adhesive is curing. The curing period is dependant on ambient conditions but is likely to be a minimum of 3 days.

A fillet of adhesive is generally placed around the edge of the plate, this provides additional protection to the bond line but also allows the application of the final corrosion protection system to the steel plates to be lapped out onto the concrete surface. The corrosion protection system is likely to provide a life to first maintenance of 8 years and to major maintenance of 16 years in an exposed environment. However, the first project carried out in 1975 has only recently come to the end of its service life over 35 years after its first installation.  Whilst the limited exposure conditons that these plates were exposed to may have extended the life span, current understanding of the performance of corrosion primers and adhesives could have possibily extended the life span.

Interestingly the steel plates have been replaced with a Carbon Fibre (CFRP) plate bonding solution.

Structural Strengthening Product Data Sheets

Why is it so difficult to get find all the Product Data Sheets for CFRP Plates and Structural Adhesive materials which are available in the UK Market for Structural Strengthening Systems? Many of the major suppliers dont have them readily available on there websites.

Below is a selection of the key products which are generally available in the UK, from Sika, Weber and Mapei. You will probably notice that not all of them are from a UK website, so I hope they are correct. These products are generally for use on concrete structures for flexural strengthening

Click to access Sikadur%2030%20PDS%20(CE).pdf


Click to access carbodur_structstrength.pdf


Click to access 10.010_weber.tec_force_carbon_plate.pdf


Click to access 02.020_weber.tec_EP_structural_adhesive_04.pdf


Click to access 1001_carboplate_gb.pdf


Click to access 1006_mapewrap_11-12_gb.pdf

Next step is to do a product comparision which will appear on the website.

Concrete Society Technical Report TR55 Design Guidance for strengthening concrete structures using fibre composite materials 2nd edition

TR55 Concrete Society

Concrete Society Technical Report TR55 Design Guidance for Strengthening Concrete Structures using fibre composite materials Third Edition

Concrete Society TR55

M3 Strengthening Hawley Bridge

Concrete Bridge on M3 Strengthened using CFRP Plates

CFRP Strengthening
Structural Strengthening to Bridge

UHM Plate Bonding

The largest strengthening project for a steel bridge using Ultra High Modulus Carbon Fibre Plates