Biomimetically-engineered FRP composites: integration of nanostructured resin matrix with hybrid fiber networks towards ultrahigh chemical stability and mechanical strengthening

Axial compressive behavior of polyethylene terephthalate/carbon FRP-confined seawater sea-sand concrete in circular columns

Advancements in fiber-reinforced polymer composite materials damage detection methods: Towards achieving energy-efficient SHM systems

The application of fiber-reinforced polymer (FRP) composites has achieved significant attention in the industry of transportation, specifically as metal substitutes due to a need for fabricating stable and fuel-efficient airplanes, vehicles, and ships. Excellent strength, resistance to corrosion, lightweight, and suitable fatigue endurance are some of the desirable properties that would encourage the use of FRP composites in the transportation sector. Polymer-based composite materials, combining the favorable properties of both polymer matrix and reinforcing fibers, can contribute to several excellent behaviors of the obtained material. Epoxy, polyethylene, and polypropylene are the primary polymer matrices used in FRP composites. The main reinforcing fibers incorporated in fiber-reinforced composites are made out of glass, carbon, basalt, hemp, or natural resources (e.g., sisal and jute). Due to high cost, low Young's modulus, low durability, and linear stress?strain behavior to failure of the FRP materials, which are used in transportation infrastructure, the objective of this review article is to study the recent aspect of reinforced polymers with a close focus on their mechanical properties in order to evaluate their application in maritime, automotive, and aerospace.

Application of fibre-reinforced polymer composites has increased over the last two decades as compared to conventional materials. This improvement in the application of fibre-reinforced polymer composites is attributed to their unique material properties, such as high strength and stiffness-to-weight ratio, specific modulus and internal vibration damping. However, in most of the industrial applications, composite materials encounter tribological complications. Economic indicators and market dynamics suggested that the market for composite materials is booming and the dominant materials are carbon fibres, glass fibres and thermoset polymer (polyester resin) in resin segments. That is why tribological characteristics are crucial in designing carbon and glass-based fibre-reinforced polymer components. Owing to this importance, the study of tribological behaviour of fibre-reinforced polymer composite materials has expanded significantly. The present study has made an attempt to review the fundamental tribological applications and critical aspects of fibre-reinforced polymers, based on research work, which has been carried out over the past couple of decades. This work has primarily focused on the fibre-reinforced polymer composites, based on carbon and glass fibres with thermosets as the matrix material for probing into tribological behaviours. In the process, the focus has largely been on the most commonly occurring erosive and abrasive mode of wear process.

Durability assessment of PEN/PET FRP composites based on accelerated aging in alkaline solution/seawater with different temperatures

In recent years, fiber‐reinforced polymer (FRP) composites have been widely used as a new type of high‐performance material in concrete structures. FRP composites have the advantages of high strength, light weight, and corrosion resistance. Based on existing studies in the literature, this paper reviews the development and applications of FRP materials for the strengthening and rehabilitation of bridge structures. The types and properties of FRP composites are summarized, and the applications and development of FRP sheets, FRP bars, FRP grids, and prestressed FRP tendons for bridge structures are discussed. Different types of FRP composites result in different failure characteristics and bearing capacities. Moreover, this paper covers the FRP strengthening methods and the response properties of the flexural performance, bonding performance, and ductility. Significant conclusions regarding the strengthening/repair of bridge structures with FRP composites are presented. The review details the current state of knowledge and research on strengthening bridge structures with FRP composites and is helpful for better understanding and establishing design criteria.

The application of fiber-reinforced polymer (FRP) composites is gaining increasing popularity in impact-resistant devices, automotives, biomedical devices and aircraft structures due to their high strength-to-weight ratios and their potential for impact energy absorption. Impact-induced high loading rates can result in significant changes of mechanical properties (e.g., elastic modulus and strength) before strain softening occurs and failure characteristics inside the strain localization zone (e.g., failure mechanisms and fracture energy) for fiber-reinforced polymer composites. In general, these phenomena are called the strain rate effects. The underlying mechanisms of the observed rate-dependent deformation and failure of composites take place among multiple length and time scales. The contributing mechanisms can be roughly classified as: the viscosity of composite constituents (polymer, fiber and interfaces), the rate-dependency of the fracture mechanisms, the inertia effects, the thermomechanical dissipation and the characteristic fracture time. Numerical models, including the viscosity type of constitutive models, rate-dependent cohesive zone models, enriched equation of motion and thermomechanical numerical models, are useful for a better understanding of these contributing factors of strain rate effects of FRP composites.

State of the practice of FRP composites in highway bridges

The International Institute for FRP in Construction (IIFC) was formed in 2003 with a mission to advance the understanding and application of fiber–reinforced polymer (FRP) composites in civil infrastructure. Since 2005, IIFC has enjoyed a fruitful association with ASCE via co-sponsorship of the Journal of Composites for Construction (JCC). Therefore, it is fitting that this present JCC issue commemorates the 10th anniversary of IIFC. This is the third special IIFC issue published by JCC; the first two issues were in April 2007 (“Recent International Advancements in FRP Research and Application in Construction”) and April 2011 (“In Honor of Professor Urs Meier”). The flagship events of IIFC are undoubtedly its biannual worldwide and Asia-Pacific regional conference series, which are known as FRP Composites in Civil Engineering (CICE) and Asia-Pacific Conference on FRP in Structures (APFIS), respectively. These conferences are held in alternating years at differing locations around the world: CICE in 2001 (Hong Kong), 2004 (Adelaide), 2006 (Miami), 2008 (Zurich), 2010 (Beijing), and 2012 (Rome); and APFIS in 2007 (Hong Kong), 2009 (Seoul), 2012 (Sapporo), and 2013 (Melbourne). CICE 2014 will be held in Vancouver and CICE 2016 in Hong Kong.This special issue of JCC has been timed for release prior to CICE 2014. IIFC also co-sponsors other international conference series and workshops. To better disseminate knowledge to the wider community, IIFC makes the proceedings of most IIFC official and supported events available on its website (http://www.iifc-hq.org) for free download. IIFC publishes a newsletter and all copies are also held on the IIFC website. The newsletter commenced in 1993, and for its first 10 years, was known as FRP International. IIFC also runs several working groups that offer tangible benefits such as educational resources, state-of-the-art reports, conference special sessions, and journal special issues. IIFC recognizes excellence in the form of several awards, namely, IIFC Medal, Distinguished Young Researcher Award, President’s Award, Lifetime Achievement Award, conference best paper awards, and IIFC fellowships. The IIFC website contains lists of all award recipients over the years, in addition to far more information than can be contained in this editorial. IIFC is a dynamic organization that has been positively influenced by numerous individuals over the years. It is governed by an Executive Committee, which is overseen by an Advisory Committee. The Council is populated by up to 40 elected leading figures in the field from around the world, plus members of the Advisory Committee. At present, 21 countries are represented on these three committees and several of these leading figures also serve on the Editorial Board of JCC. This special issue contains 18 invited papers contributed by members of these committees and their collaborators, addressing a diverse range of topics that are representative of the breadth of activity in the field. More specifically, the papers are of an experimental, analytical, and numerical nature and address: • FRP for strengthening concrete; namely, prestressed FRP plates, strips, and rods (two papers), confinement (one paper), FRP patch anchors (one paper), limits to the application of FRP for repair (one paper), near-surface mounted FRP (one paper), cementitious bonding agents (three papers), and large strain capacity FRP (one paper); • FRP for strengthening timber (one paper), steel (one paper), and masonry (one paper) construction materials; and • FRP for new construction; namely, hybrid FRP tendons (one paper), FRP bars (two papers), FRP beams (one paper), and stay-in-place structural forms (one paper). There is plenty of work still to be done in the field. In particular, more systematic and in-depth research is required on the long-term behavior of both FRP structures and FRP strengthened structures to substantiate the common claim that such structures have superior durability over other structures. Innovative combinations of FRP with either traditional construction materials or new materials to produce new structural members and forms will have an important role in designing the next generation of high-performance and sustainable structures. There is no doubt that the conversion of research findings into workable design guidelines and standards for use by design engineers is critical in widening the applications of FRP in civil construction. The contributions of numerous individuals are acknowledged in the preparation of this special issue. The authors of the papers in this issue are thanked for preparing high-quality manuscripts. Professor Charles E. Bakis, Editor-in-Chief of JCC, is thanked for handling the paper review process and ensuring maintenance of the high JCC standard. Professor Bakis is also supported by Ms. Renee Lindenberg and a large team of reviewers; their contributions are all acknowledged. The idea of an IIFC 10th anniversary special issue was positively received by Professor Lawrence C. Bank, IIFC President, and by the members of the Executive Committee following discussions after CICE 2012. For that, they are all thanked for their support. Finally, all members of IIFC, past and present, are thanked for their various contributions over the years, which have enabled IIFC to move into its second decade on a sound and positive footing.

1 - Introduction

1 - Introduction

Ultra-high-performance concrete is typically defined as an advanced cementitious material that has a compressive strength of over 150 MPa and superior durability. This article presents the development of a new type of ultra-high-performance concrete, namely, ultra-high-performance seawater sea-sand concrete. The development of ultra-high-performance seawater sea-sand concrete addresses the challenges associated with the shortage of freshwater, river-sand and coarse aggregate in producing concrete for a marine construction project. When used together with corrosion-resistant fibre-reinforced polymer composites, the durability of the resulting structures (i.e. hybrid fibre-reinforced polymer–ultra-high-performance seawater sea-sand concrete structures) in a harsh environment can be expected to be outstanding. The ultra-high strength of ultra-high-performance seawater sea-sand concrete and the unique characteristics of fibre-reinforced polymer composites also offer tremendous opportunities for optimization towards new forms of high-performance structures. An experimental study is presented in this article to demonstrate the concept and feasibility of ultra-high-performance seawater sea-sand concrete: ultra-high-performance seawater sea-sand concrete samples with a 28-day cube compressive strength of over 180 MPa were successfully produced; the samples were made of seawater and sea-sand, but without steel fibres, and were cured at room temperature. The experimental programme also examined the effects of a number of relevant variables, including the types of sand, mixing water and curing water, among other parameters. The mini-slump spread, compressive strength and stress–strain curve of the specimens were measured to clarify the effects of experimental variables. The test results show that the use of seawater and sea-sand leads to a slight decrease in workability, density and modulus of elasticity; it is also likely to slightly increase the early strength but to slightly decrease the strengths at 7 days and above. Compared with freshwater curing, the seawater curing method results in a slight decrease in elastic modulus and compressive strength.

Dams are currently confronted with severe risks from frequent extreme climates and expanding aging deterioration, with traditional mitigation measures struggling to balance efficient prevention/control and long-term management. As an innovative solution, fiber-reinforced polymer (FRP) composites support improved dam safety governance. To address the lack of systematic integration in existing dam-related studies, this paper promotes the development of an FRP in the dam field by comprehensively analyzing and summarizing the material properties, interfacial bonding properties of the FRP, as well as the flexural and compressive characteristics of FRP bar–concrete members and FRP sheet–concrete members while systematically organizing their practical engineering application cases. It also explores the FRP’s potential in hydraulic structures and suggests its wider application therein based on the FRP’s superior properties.

Fiber-reinforced polymer (FRP) composites are becoming increasingly popular as an alternative to conventional civil engineering materials in existing structures as externally applied systems for strengthening purposes, and in new structures as internal reinforcements in the form of bars, meshes, and strands. The next phase of development in the application of FRPs in concrete structures could culminate in elements possessing both internal and external FRP systems simultaneously. With these advancements in the application of FRP in civil engineering, it is conceivable that traditional steel reinforcements could become obsolete in certain aggressive and hostile environments, such as coastal areas. Although higher durability and performance are associated with FRP materials in some respects when compared to steel, concerns remain regarding the damage and defects in this material, many of them related to their unique features. Regardless, similarly to other structural materials, it is necessary to understand the damage and defects associated with the use of FRP composites, as well as to identify their sources. This knowledge will support the positive prospects for FRP technology, promoting its application in civil infrastructure. Accordingly, this study investigated the types, characteristics, and identification of the observed or expected damage and defects associated with using FRP in reinforced and strengthened concrete elements. The damage was classified according to location and time of initiation. In addition, the sources of these defects and damage were determined, and a damage etiology was established for preventing the occurrence of such damage in future use. The results of this study are intended to provide the background for the development of a guide and training material for the inspection of structures that use FRP materials. The ability to inspect and properly maintain structures containing FRP will result in the enhanced durability and service life of concrete structures reinforced or strengthened with FRP materials.

This study focuses on the tensile behavior of fiber-reinforced polymer (FRP) composites in a concrete-based alkaline environment. Because basalt/glass FRP (BFRP/GFRP) composites exhibit relatively poor alkaline resistance compared with carbon FRP (CFRP) composites, a rubber toughening modification method has been proposed to mitigate microcracking and decrease the diffusion of the alkaline solution in the resin matrix. Different proportions of liquid rubber toughening agents were added into the epoxy resin, on the basis of which different FRP composites were made and then subjected to tensile tests after alkaline exposure. Test results indicated that the rubber toughening modification approach can significantly reduce the tensile strength degradation of the BFRP and GFRP composites in the alkaline solution. Moreover, no degradation of the elastic modulus for the FRP composites was observed. The weight gain and microstructure of the FRP composites were also investigated before and after the alkaline exposure to determine the corrosion mechanisms of the FRP composites in the alkaline environment and interpret the mechanical test results.