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Sika CarboDur CFRP Plates Strengthen 18th Century National Trust Property

28 June 2005

Buscot House, an 18th Century Manor in Oxfordshire, UK, has undergone recent structural renovation using modern CFRP materials to strengthen a concrete ornate stairwell.

Sika, international specialists in structural strengthening using CFRP, hired the UK contractors, Concrete Repairs Ltd, to apply Sika's patented CarboDur CFRP plates. The plates were used to strengthen the stone landings of an ornate stairwell at Buscot House, bequeathed to the National trust in 1956, and home to the Farringdon Collection of works by contemporary artists.

The house is a popular tourist site that has become the victim of its own popularity. With the weight of visitor numbers over the years, the landings are beginning to show signs of structural degradation, and a solution was required to strengthen the structure, but causing minimal visual impact on the stairwell.

Following thorough evaluation, consulting engineers Gifford and Partners, in consultation with the National trust, chose the Sika CarboDur system as the ideal solution to add the required strength, and be virtually invisible on completion.

The Sika CarboDur CFRP structural strengthening system comprises pultruded carbon fibre plates of various width, thickness and strength, bonded in place with SikaDur 30, a specially formulated cold-cure, two component epoxy structural adhesive. SikaDur 30 is suitable for damp and dry substrates, and is used widely for the upgrading of all types of structures. The company add that the high quality and quantity of T700 carbon fibres used in the epoxy bound matrix provides 70 percent of the pultruded plate cross section giving precise performance properties.

Buscot House – courtesy of the National Trust

Work commenced by first channelling out the undersides of the landings to accept the 50mm wide Sika CarboDur plates, which were then bonded in place with SikaDur 30 adhesive. The adhesive holds the plates in place with no additional support required.

After curing, the plates were coated with a layer of the SikaDur 30 with sand fill to form a bonding bridge for Sika MonoTop 620 levelling mortar, bringing the repairs back to the level of the surrounding substrate.

A spokesman for the company said that this is a great example of how modern materials and techniques, properly applied, can be utilised to maintain old and listed buildings with the minimum of visual impact.

The image shows a close up of the CarboDur material with 70 percent carbon fibre content which contributes to the increase in performance properties.