International Concrete Abstracts Portal

This two volume set contains 95 papers from the 7th International Symposium and includes chapters devoted to materials characterization, masonry, bond, external strengthening, serviceability, design and behavior of members internally reinforced with FRP composites, FRP used for confinement, field applications, extreme events, and durability. The technical papers not only emphasize the experimental, analytical, and numerical validations of using FRP composites for externally strengthening or internally reinforcing concrete structures, but most are aimed at providing the insight needed for improving existing design guidelines. Several papers discuss the proposed design guidelines for deflections, shear strength, and reinforcing masonry, which practitioners should find useful. New applications are also featured, including studies and design equations for the use of near-surface-mounted FRP products, use of steel-reinforced polymer for reinforcing concrete, and the use of FRP to retrofit structures for blast mitigation. FRP composites performance is presented in chapters on durability and extreme events. Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP230

The Mechanically Fastened-FRP (MF-FRP) strengthening system consists ofpre-cured FRP laminates having high longitudinal bearing strength attached to theconcrete surface using closely spaced steel fasteners in the form of nails or concretewedge anchors. The connection depends on several parameters such as, the intrinsiclaminates properties (tensile and bearing strength), diameter and effective embedmentlength of the fasteners, clamping force, presence and type of washer, presence andtype of filler in the gaps between the FRP material, the fastener and accessories, andthe concrete. This paper focuses on the material characterization of pultruded pre-cured laminate which was used as MF-FRP strengthening to retrofit and rehabilitate off-system bridges in Missouri, USA. Tensile tests, in the longitudinal and transversedirection of the laminate, were performed on full section and open hole coupons inorder to characterize the material. Bearing tests, in the longitudinal and transversedirection of the laminate, were performed to determine the capacity of the unrestrainedfastener-FRP-concrete connection.

A method for screening the durability of FRP bars under bending stress andimmersion in high pH solution at elevated temperature is described. Discussion of theneed for such a test, process variables affecting durability, determination of theappropriate bending radius and a description of the test method are shown. Testresults from a series of eight production runs varying only one of the processes relatedvariables, glass fiber supplier, are shown. Fiber sizing chemistry for the fiber/resin/production system is key to better durability of GFRP rebar. The bending stressdurability test method helps reveal FRP bar system performance for differentconstituent materials and offers a more practical method for evaluating alkalinedurability of GFRP bars. The method is intended as an indicator of durabilityperformance and not a definitive evaluation.

This paper focuses on the behavior of Glass Fiber Reinforced Polymer (GFRP)bars manufactured with nanoclay. Benefits of nanoclay in the resin for manufacturingFRP composites include reduced moisture ingress, better fire resistance, and enhancedresin stiffness. Several molds were developed at CFC-WVU laboratory to produce glassFRP bars with smooth surface, and crescent shaped or circular lugs. Bars weremanufactured at room temperature by manual pultrusion process with varying fibervolume content and percentage of nanoclay. Vinyl ester resin exfoliated with nanoclaywas used to manufacture GFRP bars with a fiber volume fraction of 44.7% and tested fortensile, bond and shear strength.Bars manufactured in this research and tested in tension had typical ultimate stress of108.76 ksi (749.87 MPa) –133.43 ksi (919.96 MPa) and stiffness of 4.18 msi (28.8 GPa) -4.67 msi (32.2 GPa). Pullout tests conducted on a bar with crescent-shaped lugs andcircular lugs embedded in concrete provided a maximum bond stress value of 2385 psi(16.44 MPa) and 1762.77 psi (12.15 MPa), respectively. Bars with nanoclay showed8.3% less shear strength than those without nanoclay (24.10 ksi (166.16 MPa) vs. 26.27ksi (181.13 MPa)). Bars with nanoclay absorbed more moisture initially than barswithout nanoclay, and the moisture absorption decreased with time.

Fiber reinforced polymers (FRP) are investigated in this study in comparisonwith a new class of materials, textile reinforced mortars (TRM), for shear strengtheningand/or seismic retrofitting of concrete structures. Textiles comprise fabric meshesmade of long woven, knitted or even unwoven fiber rovings in at least two (typicallyorthogonal) directions. Mortars – serving as binders – contain polymeric additives inorder to have improved strength properties. In this study, experimental investigationswere carried out in order to provide a better understanding on the effectiveness of TRMversus FRP jackets as a means of increasing: (i) the axial capacity of concrete throughconfinement; and (ii) the load-carrying capacity of shear-critical reinforced concreteflexural members. From the results obtained it is strongly believed that the proposedTRM strengthening technique is a viable alternative to the already successful FRPstrengthening technique.