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Applied Composite Materials: An International Journal for the Science and Application of Composite Materials (v.7, #2-3)
Composite Materials in Bridge Repair by Urs Meier (pp. 75-94).
This paper seeks to demonstrate how advanced polymer matrix composite materials developed for high-performance aircraft can offer major advantages for repairing ageing infrastructures. It focuses on the development and first applications of advanced rehabilitation, retrofitting, strengthening, and field monitoring technologies for civil engineering structures based on unique combinations of corrosion-resistant fibre-reinforced polymers and integrated fibre optic structural sensing.
Keywords: post-strengthening with CFRP; adhesively bonded external reinforcement; CFRP cables; external post-tensioning; anchorage systems; non-laminated FRP straps
Fiber Reinforced Composites – Advanced Materials for the Renewal of Civil Infrastructure by Vistasp M. Karbhari; Frieder Seible (pp. 95-124).
Fiber reinforced polymer matrix composite materials hitherto used predominantly in aerospace and marine applications are increasingly being considered for use in the renewal of civil infrastructure ranging from the seismic retrofit of bridge columns and the strengthening of parking garage floor slabs to their use in replacement bridge decks and in new bridge structures. Their corrosion resistance, potentially high overall durability, light weight, tailorability and high specific performance attributes enable their use in areas in which the use of conventional materials might be constrained due to durability, weight or lack of design flexibility. This paper provides an overview of the use of composites in the renewal of civil structures with particular emphasis on bridges and pipelines. Examples of large scale testing for the validation of structural effectiveness are given and future design and research advances are presented.
Keywords: rehabilitation; repair; renewal; concrete; civil infrastructure; bridge decks; columns; superstructure; pipes
A Study on Polymer Composite Strengthening Systems for Concrete Columns by Shi Zhang; Lin Ye; Yiu-Wing Mai (pp. 125-138).
An experimental study was conducted to investigate the effects of various composite wrapping systems with different fibres (E-glass and carbon), resins (vinyl-ester and epoxy) and architectures on the strengthening efficiency for wrapped concrete columns. Raw material costs were evaluated to identify the cost-efficiency of each individual system. The results indicated that the use of E-glass fibres with vinyl-ester resin to reinforce concrete columns externally is effective with a low cost of raw materials. The epoxy resin-based system does not show much improvement in the load carrying capacity. The small R/T ratio (thickness of wrap/radius of concrete column) may cause a low strengthening efficiency. Glass fibre mats were hybridised with carbon fibre layers to obtain better mechanical properties and an increased thickness of the composite wraps. Reinforcing efficiency is also highly dependent on the composite architecture. The fibre reinforcement in the hoop direction gives a high confining efficiency to the concrete columns. However, a certain amount of fibres in the axial direction are still needed in designing composite wraps, especially for long, slender columns.
Keywords: concrete columns; wrapping technique; polymer composite; strengthening efficiency; infrastructure
Carbon Fibre Composites as Stay Cables for Bridges by Johannes Fritz Noisternig (pp. 139-150).
High tensile strength and stiffness as well as high fatigue life, low weight and excellent chemical resistance are material properties of carbon fibre composites (CFRP) which make these materials interesting for stay cable systems. The key problem to which the application of stay cables as well as tendons is faced is the anchoring. This paper describes the properties of CFRP-wires, the requirements to stay cables or tendons and the development of such a system through calculations and experiments along with a successful field stress test of a CFRP based stay cable.
Keywords: carbon fibre composite; stay cable; construction industry; requirements; properties; anchorage; static tests; fatigue tests; field test
Structural Characterization of Fiber-Reinforced Composite Short- and Medium-Span Bridge Systems by V. M. Karbhari; F. Seible; R. Burgueño; A. Davol; M. Wernli; L. Zhao (pp. 151-182).
The paper describes the development of a new structural system for short and medium span bridges wherein use is made of both advanced composites and conventional materials such as concrete. The concept uses prefabricated composite tubes as girders which are then filled with concrete, after which a conventional precast or cast-in-place, or advanced composite, deck system is integrated to form the bridge superstructure. The paper presents experimental results of large-scale tests aimed towards the structural characterization of the girders, anchorages, and girder-deck assemblies for both serviceability and ultimate limit states.
Keywords: composites; concrete filled tubes; bridge systems; decks; fatigue; joints
Influence of Aggregate Structure on Mode-III Interfacial Fracture between Concrete and CFRP by Christian Weimer; Frank Haupert (pp. 183-193).
One of the crucial issues in the use of fiber reinforced polymers for civil engineering applications is the interfacial bonding between the different materials used. As a load transfer from the concrete to the composite components occurs via shear stresses in the interfacial region, studies of the interfacial bond quality should concentrate on load situations in which primarily shear stresses are induced. In this study, a 3-Point Bending Test was modified to initiate shear failure under Mode-III conditions in the interface between a composite and a concrete component. In particular it was the objective to study the interfacial shear strength between three different concretes and an unidirectional carbon fiber reinforced epoxy matrix system. The three concretes had the same compressive strength (B35 KP, German Standard), but differed in the type of filler material: (a) “heavy” concrete, filled with granite (Diorit) particles, (b) “normal” concrete, filled with gravel grains (Pyrite), and (c) “light weight” concrete, filled with vopourtone (Liapur). The mechanical test results showed that both the type of filler exposed to the joint surface as well as the type of adhesive used clearly influence the interfacial shear strength. Best values were achieved with Diorit-fillers, and the Sikadur-adhesive was in all cases superior to the Dywipox-adhesive. Reasons for these differences were demonstrated by light optical and scanning electron micrographs of the fractured surfaces.
Keywords: rehabilitation; bonding; repair; mode-III-fracture; aggregate; infrastructure; concrete
Applications of High-Performance Fiber-Reinforced Cement-Based Composites by G. L. Guerrini (pp. 195-207).
Advanced composites and the fundamental understanding of their behaviour is a rapidly expanding branch within the field of civil engineering materials. In particular, fiber-reinforced cement-based materials have had a great evolution in these years, so that they are more and more utilized in the building sector. Besides, large efforts have been made to develop high-performance cements and concretes showing further performance improvements. High-performance fiber-reinforced cement composites include, for example, materials such as SIFCON (Slurry Infiltrated Fiber CONcrete), fiber-reinforced DSP (Densified with Small Particles), and fiber-reinforced MDF (Macro-Defect-Free) cements. Developments of these materials were possible due to: (a) the introduction of new reinforcement systems; (b) the development of high-performance cement-based matrices, which present greatly improved microstructural properties in terms of strength and durability; (c) the development of adequate processing techniques (including controlling chemical reactions) which allow us to obtain composite materials with surprising toughness properties. After a brief description of high-performance cement-based matrices and relative composites, two different examples among the above-cited products will be deeply presented.
Keywords: applications; CRC; DSP; fiber-reinforced concrete; MDF; mechanical properties; RPC; SIFCON; very high performance