Fibre glass a serious alternative for bridge reinforcement, UC expert says

September 6, 2013

A fibre glass alternative to steel reinforcement in concrete structures could be a potential answer to problems caused by corrosion of steel bars, a University of Canterbury (UC) expert says.

Bridges along New Zealand’s coastline are more susceptible to problems caused by corrosion of steel reinforcement than inland bridges due to greater exposure to chlorides in salty sea winds.

``We are testing full scale bridge slabs on campus using fibre glass bars instead of steel,’’ civil and natural resources engineer Dr Alessandro Palermo says.

``The use of steel as bridge reinforcement historically in New Zealand means that many coastline bridges, especially those built in the 1940s and 1950s, are beginning to show signs of deterioration.
Large maintenance costs and traffic delays can be involved in repairing this damage.

``As part of our civil engineering research, we are testing and comparing the performance of concrete bridge deck slabs reinforced with both steel bars and bars made of fibre glass.

``Glass fibre reinforced polymer (GFRP) bars are a potential alternative to traditional steel reinforcing for some civil engineering structures exposed to harsh environment. The GFRP bars will not corrode, making the structure last longer and require less maintenance than a steel reinforced structure. Other benefits include non-conductivity and being a third of the weight by volume of steel.

``There are some obstacles in designing with GFRP as it behaves quite differently to steel. Many practising engineers are very used to using steel in their reinforced concrete design, so a shift in thinking is required when using GFRP bars. It’s certainly not like comparing apples with apples.

``The GFRP product used in this experimental testing is Mateen-bar, which is manufactured by Pultron Composites in Gisborne. The cost of using GFRP is at least twice the price of steel but GFRP bars can be economic where a long life span of a structure is taken into account.

``Reduced maintenance costs lower the overall life cycle costs of a GFRP reinforced concrete structure design and may make it a cost-competitive alternative to using steel reinforcement.’’

The fibre glass testing at UC this week is part of a project by masters student Victoria Worner, who is being supervised by Dr Palermo.

Findings of the project will include a set of design recommendations for using GFRP bars as bridge deck reinforcement in a New Zealand bridge design context.

The Ministry of Science and Innovation has granted, in collaboration with Pultron, a $40,000 scholarship for the project.

UC postgraduate student Victoria Worner and Dr Alessandro Palermo.

ENDS

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