A review of the present and future utilisation of FRP composites in the civil infrastructure with reference to their important in-service properties

The author details the reactions of various concretes on steel reinforcement. Although portland cements, slag cements and high alumina cements are all hydraulic binders, each possess special properties which are examined. The discussion of causes and methods of preventing the corrosion of steel reinforcement covers such aspects as galvanised steel reinforcement, effects of concrete composition, corrosion of steel reinforcments in concrete and prestressed reinforcement. It is concluded that the most significant influences on the corrosion of prestressing wire in concrete are: the presence of chloride; the presence of nitrates; the composition of the concrete; the degree of carbonation of the concrete; concrete compaction and, chlorides and sulphates should be used as far as possible when steel is embedded. (TRRL)

Corrosion of steel by concrete

Composites have been found to be the most promising and discerning material available in this century. Presently, composites reinforced with fibers of synthetic or natural materials are gaining more importance as demands for lightweight materials with high strength for specific applications are growing in the market. Fiber-reinforced polymer composite offers not only high strength to weight ratio, but also reveals exceptional properties such as high durability; stiffness; damping property; flexural strength; and resistance to corrosion, wear, impact, and fire. These wide ranges of diverse features have led composite materials to find applications in mechanical, construction, aerospace, automobile, biomedical, marine, and many other manufacturing industries. Performance of composite materials predominantly depends on their constituent elements and manufacturing techniques, therefore, functional properties of various fibers available worldwide, their classifications, and the manufacturing techniques used to fabricate the composite materials need to be studied in order to figure out the optimized characteristic of the material for the desired application. An overview of a diverse range of fibers, their properties, functionality, classification, and various fiber composite manufacturing techniques is presented to discover the optimized fiber-reinforced composite material for significant applications. Their exceptional performance in the numerous fields of applications have made fiber-reinforced composite materials a promising alternative over solitary metals or alloys.

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Fiber-Reinforced Polymer Composites: Manufacturing, Properties, and Applications.

Strengthening of steel structures with fiber-reinforced polymer composites

https://www.quakewrap.com/frp%20papers/Progress-On-Understanding-Debonding-Problems-In-Reinforced-Concrete-And-Steel-Members-Strengthened-Using-FRP-Composites.pdf

Progress on understanding debonding problems in reinforced concrete and steel members strengthened using FRP composites

This paper presents results from an experimental investigation to determine the feasibility of using carbon fiber reinforced polymer (CFRP) epoxy laminates to repair steel composite bridge members. Six specimens, each consisting of a 6.1 m long W8×24 wide flange A36 steel beam acting compositely with a 0.114 m thick by 0.71 m wide reinforced concrete slab, were first loaded past yield of the tension flange to simulate severe service distress. The damaged specimens were then repaired using 3.65 m lengths of 2 or 5 mm thick CFRP laminates bonded to the tension flange and tested to failure. The results indicated significant ultimate strength gains but more modest improvement in the elastic response. Non-linear finite element analyses were in good agreement with the experimental results. The study suggests that it is feasible to strengthen steel composite members using CFRP laminates.

Strengthening steel bridge sections using CFRP laminates

The lightweight, high strength and corrosion resistance of fiber reinforced polymers (FRP) make them ideally suited for quick and effective structural repairs. As a result, they have been favoured for conducting emergency bridge repairs where speed is of essence. The availability of resins that can cure under water has made it possible to similarly extend its application to substructure elements such as partially submerged damaged piles. Such repairs can be carried out using the same strategies that were successfully used in recent demonstration projects in which FRP was used to repair and rehabilitate corrosion-damaged piles. In the projects two disparate FRP systems – a pre-preg and a wet layup – were used and both carbon and glass evaluated. Access to the piles in the deep waters was provided by a custom-designed, lightweight modular scaffolding system that was assembled around the piles. An overview of the project is provided with particular emphasis on changes that would allow its adoption for emergency repairs. � 2006 Elsevier Ltd. All rights reserved.

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Application of FRP composites for underwater piles repair

Although pressure grouting beneath the tips of drilled shafts had been used successfully worldwide for close to 4 decades, it has remained relatively unused in the United States in part due to the absence of a rational design procedure. Previous international usage relied predominantly upon experience and unpublished proprietary approaches. More recently, research aimed at quantifying the improvement that could be derived from postgrouting drilled shaft tips has resulted in a design methodology. This paper briefly discusses the postgrouting process and outlines the full scale test programs used to identify parameters affecting postgrouting performance. Correlations developed between applied grout pressure and end bearing improvement are presented along with a numerical example illustrating the design procedure.

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Predicting End Bearing Capacity of Post-Grouted Drilled Shaft in Cohesionless Soils

This paper presents results from a 9-month experimental study to evaluate the durability of E-glass/vinylester reinforcement used by the U.S. Navy in the construction of the MRI Pier in San Diego, California. A total of 36 specimens were tested. These were split into 4 groups of 9 specimens each exposed to simulated pore solution with a pH ranging from 13.3 to 13.5 for periods of 1, 3, 6, and 9 months. Of the 9 specimens in each group, 33% were unstressed, 33% were stressed to 10%, and the remaining 33% were stressed to either 15 or 25% of their ultimate short-term tensile strength. At the end of the exposure periods, surviving specimens were tested to failure to determine their residual tensile strength. Results showed that the E-glass/vinylester bars tested had very limited durability in this environment, especially at stress levels of 15% or higher. Overall, findings indicate that first-generation glass fiber-reinforced polymer bars are unsuitable as structural reinforcement in concrete members.

Durability of E-Glass/Vinylester Reinforcement in Alkaline Solution

In this paper, results are presented from a long-term exposure study to assess the role of fiber-reinforced polymer (FRP) in mitigating corrosion in a marine environment. Twenty-two 1/3-scale models of prestressed piles cast with built-in chloride were exposed to simulated tidal cycles under outdoor ambient conditions for nearly 3 years. These included 8 carbon FRP (CFRP)-wrapped specimens, 8 glass FRP (GFRP)-wrapped specimens, and 6 controls. Embedded titanium reference electrodes and thermocouples were used to monitor the corrosion performance inside the wrapped region throughout the exposure period. The performance of the FRP was evaluated on the basis of bond and gravimetric tests conducted at the end of the exposure period. The results showed that the FRP-concrete bond was largely unaffected by exposure and both CFRP- and GFRP-repaired specimens significantly outperformed the controls. The underlying trend in corrosion rate measurements showed increases for the controls and reductions for the wrapped specimens. This was reflected by much lower metal losses in wrapped specimens compared with controls. These findings indicate that FRP is effective in reducing the corrosion rate in heavily chloride-contaminated prestressed concrete elements such as those exposed to a marine environment.

Gray Mullins

Papers

Strengthening steel bridge sections using CFRP laminates

Application of FRP composites for underwater piles repair

Predicting End Bearing Capacity of Post-Grouted Drilled Shaft in Cohesionless Soils

Durability of E-Glass/Vinylester Reinforcement in Alkaline Solution

Effectiveness of fiber-reinforced polymer in reducing corrosion in marine environment