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FRP construction materials have longer life
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FRP construction materials have longer life CONSTRUCTION PRODUCTS made of fibre reinforced plastic (FRP) have a better long term performance than previously thought, according to a report from UK construction research consultant Building Research Establishment Ltd (BRE). Because FRP is a relatively new material, it has not been possible until recently to measure the long term effects of using reinfored plastic in construction, beyond the usual product service life of 30-60 years. In the past it was assumed that, because FRP is polymer-based, it would not last long – an assumption which has limited its use in some construction sectors. However, the report, which was commissioned by the UK’s Department of Trade and Industry (DTI), has shown that not only have some FRP construction materials lasted longer than predicted, but that when failures in the material
have occurred, they are often a result of a lack of understanding of FRP’s properties at the design stage. As well as this, any deterioration which took place did not usually affect the structural performance of the component or building, according to BRE. The study entailed numerous site visits and focused on the weathering of various glass/ carbon reinforced polyester or epoxy laminates in use. This weathering included cosmetic effects, such as fading or darkening, yellowing, blooming, loss of gloss or chalking. BRE showed that in many cases these effects can be avoided by correct use of pigments, resins additives and gel-coats. For example, fading and darkening of material can be a result of using unstable pigments, while yellowing can be prevented by using a more ultraviolet (UV) resistant resin. Blooming can be caused by the
migration of an incompatible pigment or additive to the surface of a gel-coat and avoiding certain organic pigments can stop this happening. BRE’s study also showed that the service life of some FRP construction material can be reduced when a FRP structure is incorrectly maintained. For example, using inappropriate cleaning agents based on strong alkali solvents or abrasives can damage surfaces. In conclusion, BRE reported factors that could help increase the service life of FRP products even longer – for example, using a protective coating or incorporating light stabilisers and anti-oxidants. It added that improvements in resin and FRP manufacturing over the last ten years will produce material with ever increasing durability – and that design lives of up to 100 years could be achieved.
BRE added that the findings of the study should contribute to the development of standards and design codes in the UK, and should lead to a wider range of applications using FRP. It maintains that continuing measurement of FRP durability is vital. “This project has been significant in gathering data on the performance of FRPs, but ongoing monitoring of structures is needed to gather comprehensive data,” says Dr Sue Halliwell, project manager of BRE’s durability project. “Work is also needed on predicting the service lives of the newer composites such as those based on natural fibres,” she adds. BRE report 416: Long-term performance in service of FRPs in construction is available from www.brebookshop.com. Building Research Establishment Ltd; website: www.bre. co.uk.
NCC wins $1m composite bridge project THE NATIONAL Composite Center (NCC), Dayton, Ohio, USA, has been awarded US$1 million in federal funds to build composite bridge decks for pedestrian and bicycle traffic along the Anacostia River waterfront in Washington, DC. NCC’s Lou Luedtke expects this project to reduce the lifetime cost of the DC bridges by as much as 30%, one of composites’ key advantages. “A recent conference attended by groups like NCC, the Federal Highway Administration (FHWA), the State Department of Transportations (DOT), suppliers and universities
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REINFORCEDplastics
examined public perception and found that the focus tended to target short term issues like faster bridge deck replacement rather than longer term benefits like life cycle cost,” according to Luedtke. “While composite material does offer quicker installation, we feel projects like this one will help shift more attention to composites’ long term advantages.” US Senator Mike DeWine, who is chairman of the District of Columbia Appropriations Committee, secured funding for the project as part of the Fiscal Year 2005 DC Appropriations Bill. Washington, DC is providing matching funding.
November 2004
The project is the latest in NCC’s Composites for Infrastructure (C4I) programme, an initiative designed to help infrastructure customers harness the advantages of fibre reinforced plastic (FRP) materials. The programme is also developing techniques to reduce material costs and provide monitoring and inspection support for composite bridge structures. While the actual bridge installation will be done by DC construction companies, contracts for materials are expected to be awarded through a competitive process involving Ohio businesses and
companies from surrounding states. “The infrastructure market continues to be a key growth area for composites, and a dynamic solution to address the significant problem the US faces with deteriorating bridge decks,” says Luedtke. “Over 50% of the bridge inventory in the US is load rated. That means maximum design loads are no longer allowed. This condition is especially prevalent in the Northern states where road salt is used to combat winter icing conditions.” NCC; tel: +1-937-297-9450; website: www.compositecenter. org.
FRP construction materials have longer life CONSTRUCTION PRODUCTS made of fibre reinforced plastic (FRP) have a better long term performance than previously thought, according to a report from UK construction research consultant Building Research Establishment Ltd (BRE). Because FRP is a relatively new material, it has not been possible until recently to measure the long term effects of using reinfored plastic in construction, beyond the usual product service life of 30-60 years. In the past it was assumed that, because FRP is polymer-based, it would not last long – an assumption which has limited its use in some construction sectors. However, the report, which was commissioned by the UK’s Department of Trade and Industry (DTI), has shown that not only have some FRP construction materials lasted longer than predicted, but that when failures in the material
have occurred, they are often a result of a lack of understanding of FRP’s properties at the design stage. As well as this, any deterioration which took place did not usually affect the structural performance of the component or building, according to BRE. The study entailed numerous site visits and focused on the weathering of various glass/ carbon reinforced polyester or epoxy laminates in use. This weathering included cosmetic effects, such as fading or darkening, yellowing, blooming, loss of gloss or chalking. BRE showed that in many cases these effects can be avoided by correct use of pigments, resins additives and gel-coats. For example, fading and darkening of material can be a result of using unstable pigments, while yellowing can be prevented by using a more ultraviolet (UV) resistant resin. Blooming can be caused by the
migration of an incompatible pigment or additive to the surface of a gel-coat and avoiding certain organic pigments can stop this happening. BRE’s study also showed that the service life of some FRP construction material can be reduced when a FRP structure is incorrectly maintained. For example, using inappropriate cleaning agents based on strong alkali solvents or abrasives can damage surfaces. In conclusion, BRE reported factors that could help increase the service life of FRP products even longer – for example, using a protective coating or incorporating light stabilisers and anti-oxidants. It added that improvements in resin and FRP manufacturing over the last ten years will produce material with ever increasing durability – and that design lives of up to 100 years could be achieved.
BRE added that the findings of the study should contribute to the development of standards and design codes in the UK, and should lead to a wider range of applications using FRP. It maintains that continuing measurement of FRP durability is vital. “This project has been significant in gathering data on the performance of FRPs, but ongoing monitoring of structures is needed to gather comprehensive data,” says Dr Sue Halliwell, project manager of BRE’s durability project. “Work is also needed on predicting the service lives of the newer composites such as those based on natural fibres,” she adds. BRE report 416: Long-term performance in service of FRPs in construction is available from www.brebookshop.com. Building Research Establishment Ltd; website: www.bre. co.uk.
NCC wins $1m composite bridge project THE NATIONAL Composite Center (NCC), Dayton, Ohio, USA, has been awarded US$1 million in federal funds to build composite bridge decks for pedestrian and bicycle traffic along the Anacostia River waterfront in Washington, DC. NCC’s Lou Luedtke expects this project to reduce the lifetime cost of the DC bridges by as much as 30%, one of composites’ key advantages. “A recent conference attended by groups like NCC, the Federal Highway Administration (FHWA), the State Department of Transportations (DOT), suppliers and universities
6
REINFORCEDplastics
examined public perception and found that the focus tended to target short term issues like faster bridge deck replacement rather than longer term benefits like life cycle cost,” according to Luedtke. “While composite material does offer quicker installation, we feel projects like this one will help shift more attention to composites’ long term advantages.” US Senator Mike DeWine, who is chairman of the District of Columbia Appropriations Committee, secured funding for the project as part of the Fiscal Year 2005 DC Appropriations Bill. Washington, DC is providing matching funding.
November 2004
The project is the latest in NCC’s Composites for Infrastructure (C4I) programme, an initiative designed to help infrastructure customers harness the advantages of fibre reinforced plastic (FRP) materials. The programme is also developing techniques to reduce material costs and provide monitoring and inspection support for composite bridge structures. While the actual bridge installation will be done by DC construction companies, contracts for materials are expected to be awarded through a competitive process involving Ohio businesses and
companies from surrounding states. “The infrastructure market continues to be a key growth area for composites, and a dynamic solution to address the significant problem the US faces with deteriorating bridge decks,” says Luedtke. “Over 50% of the bridge inventory in the US is load rated. That means maximum design loads are no longer allowed. This condition is especially prevalent in the Northern states where road salt is used to combat winter icing conditions.” NCC; tel: +1-937-297-9450; website: www.compositecenter. org.