International Concrete Abstracts Portal

Fiber-reinforced polymer (FRP) composite materials been widely used in civil engineering new construction and repair of structures due to their superior properties. FRP provides options and benefits not available using traditional materials. The promise of FRP materials lies in their high-strength, lightweight, noncorrosive, nonconducting, and nonmagnetic properties. ACI Committee 440 has published reports, guides, and specifications on the use of FRP materials for may reinforcement applications based on available test data, technical reports, and field applications. The aim of these document is to help practitioners implement FRP technology while providing testimony that design and construction with FRP materials systems is rapidly moving from emerging to mainstream technology.

This volume represents the thirteen in the symposium series and could not have been put together without the help, dedication, cooperation, and assistance of many volunteers and ACI staff members. First, we would like to thank the authors for meeting our various deadlines for submission, providing an opportunity for FRPRCS-13 to showcase the most current work possible at the symposium. Second, the International Scientific Steering Committee, consisting of many distinguished international researchers, including chairs of past FRPRCS symposia, many distinguished reviewers and members of the ACI Committee 440 who volunteered their time and carefully evaluated and thoroughly reviewed the technical papers, and whose input and advice have been a contributing factor to the success of this volume.

This paper presents an extensive experimental study of the effect that the surface profile has on the bond behavior of FRP bars in concrete. Studied parameters include: concrete strength (~35 MPa (5075 psi) and ~66 MPa (9570 psi)), test type (pull-out, direct tension pull-out and beam pull-out) and surface profile of the FRP bar (helically wrapped, indented, two types of sand coated and two types of helically wrapped and sand coated. For comparison, ribbed steel bars were also used). It was found that the bond strength can vary considerably when different finishing of the same surface profile type are used (e.g., fine and rough sand coating) and that the concrete strength does influence the bond strength even if it is higher than the limit (~30 MPa (4350 psi)) stated in literature. Furthermore, the bond strength results of all FRP bars were consistently higher than those of steel bars. The highest slip value to reach the bond strength was observed for helically wrapped FRP bars, and the lowest for sand coated bars. Finally, the test setup was found to affect the bond strength, while no significant effect of bar diameter was observed in the results.

This paper presents partial results of an international collaborative project named ‘SEACON’ that aims at demonstrating the safe and durable utilization of seawater and salt-contaminated aggregates (natural or recycled) for a sustainable concrete production when combined with noncorrosive reinforcement. Seawater and salt-contaminated aggregates use in reinforced concrete (RC) is currently prohibited by building codes due to corrosion of the steel reinforcement. In response to this challenge, concrete made with seawater and salt-contaminated aggregate is combined with noncorrosive reinforcement (i.e. Glass-Fiber-Reinforced-Polymer (GFRP) or stainless steel). The initial results presented herein evaluate the durability of GFRP bars embedded in concrete mixed with seawater and exposed to seawater at 60 °C (140 °F) as accelerated aging. The residual mechanical properties of the embedded GFRP bars after one-year exposure to accelerated conditioning were compared to pristine bars. The experimental results showed comparable performance between GFRP bars embedded in seawater concrete and pristine bars. In addition, the bond strength of GFRP bars in seawater and conventional concrete was measured by pull out testing after being aged for six months in the same accelerated conditioning. The bond strength of the GFRP bars embedded in seawater concrete was comparable to the ones in conventional concrete.

This paper presents the seismic behavior of two large-scale hollow-core fiber-reinforced polymer-concrete-steel (HC-FCS) precast columns having two different footing connections. The precast HC-FCS column consists of a concrete shell sandwiched between an outer fiber-reinforced polymer (FRP) tube and an inner steel tube. The steel tube was embedded 635 mm (25 inches) into a reinforced concrete footing, while the outer FRP tube confined the concrete shell only i.e. it was truncated at the top surface of the footing. One connection included embedding the steel tube into the footing. The other one included using a corrugated steel pipe (CSP) embedded into the concrete footing outside the steel tube to achieve better confinement. This study showed that the connection including the CSP is deemed satisfactory and was able to develop the plastic flexural capacity of the HC-FCS column providing good ductility and energy dissipation compared with the other connection type.

Fiber reinforced polymers (FRP) are used for short-span bridge construction due to their special features. However, it was found that the resin matrix in the FRP materials become soften at the glass transition temperature (Tg). Some FRP materials have relatively low Tg values and hence, the flexural behavior of FRP composite beams can be affected by moderately high temperatures. In this study, the influence of moderately high temperature on the flexural behavior of glass FRP (GFRP) and ultra-high strength fiber reinforced concrete (UFC) composite beams was investigated. Large-scale beam bending tests were conducted at temperatures between 20°C (68℉) and 90°C (194℉). The experiment results revealed that the flexural capacity and stiffness of the GFRP I-beams are highly influenced by the glass transition temperature of the vinylester resin. The use of UFC segments significantly improves both the flexural capacity and stiffness of the GFRP I-beams within 20°C (68℉) and 90°C (194℉). The fiber model analysis showed that the stiffness of the GFRP-UFC composite beams is not significantly affected by the temperature gradient in the real situations. However, the flexural capacity of the GFRP-UFC composite beams at the slipping of the UFC segments is greatly influenced by the temperature at beam top.