International Concrete Abstracts Portal

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International Concrete Abstracts Portal

Showing 1-10 of 929 Abstracts search results

Document: 

SP331-08

Date: 

February 1, 2019

Author(s):

Hayder Alghazali, Zuhair Al-Jaberi, Zena Aljazaeri, John J. Myers

Publication:

Special Publication

Volume:

331

Abstract:

Structures may need to be repaired for different reasons, such as, construction or design defects, or service stage changing which include, ageing of structures or deterioration due to exposure to aggressive environmental conditions. New materials are emerging, such as steel reinforced Polymer (SRP) composite, which can be used to strengthen and repair structures with greater durability and less maintenance over the life of the structure. An experimental test program was carried out to investigate the performance of repaired damaged concrete beams with (SRP) repair technique. Six full-scale reinforced concrete (RC) beams were designed and tested using 4-point load test setup to be failed in lap splice in the middle region of the beam. The damaged concrete was repaired, and SRP sheet (longitudinal soffit laminates and transverse U-wrapping strips) was applied to restore the original flexural capacity. All beams were 10 ft (3.0 m) in length, 18 in. (457 mm) in depth, and 12 in. (305 mm) in width. Different repairing configurations were investigated. The studied variables were the number of plies and the amount and distribution of U-wrapping strips. Ultimate load capacity, deflection, and mode of failure were recorded during testing. The test results were compared to beam results with continuous reinforcement. It was concluded that repairing beams with SRP plies and U-wrapping strips can restore the beam to a capacity similar to that of reinforced concrete (RC) beam with continuous reinforcement.


Document: 

SP331-06

Date: 

February 1, 2019

Author(s):

Abheetha Peiris and Issam Harik

Publication:

Special Publication

Volume:

331

Abstract:

An exterior girder of a prestressed concrete bridge over Interstate 65 in Kentucky was damaged due to an over-height truck impact. The damaged section spanned two of the three northbound lanes of the highway. Two prestressing strands were severed and two additional strands were damaged by the impact. In addition, shear reinforcing bars in the vicinity of the impact were cut-off. CFRP Rod Panels (CRPs) were deployed to restore some of the load carrying capacity lost due to the severed prestressing tendons. CRP 195, with CFRP rods of 3.96 mm (0.156 in) diameter, having a capacity of 867 kN (195,000 lbs.) per 305 mm (1 ft.) width of panel, was selected for the flexural strengthening. A triaxial braided quasi-isotropic CFRP fabric was selected for shear strengthening and served as containment of crushed concrete in the event of future over-height impacts. Since the ACI and AASHTO Codes or Guides do not directly address the design with CRPs, strain limits based on debonding of the rods similar to externally bonded CFRP (EB-CFRP) are imposed when determining the retrofitted beam capacity. The load rating evaluation of the impacted beam, the retrofit analysis and design, and the field repair stages are presented and discussed.


Document: 

SP331-02

Date: 

February 1, 2019

Author(s):

Ian Shaw, Hang Zhao and Bassem Andrawes

Publication:

Special Publication

Volume:

331

Abstract:

Fiber reinforced polymer (FRP) composites have emerged as a lightweight and efficient repair and retrofit material for many concrete infrastructure applications. FRP can be applied to concrete using many techniques, but primarily as either externally bonded laminates or near-surface mounted bars or plates. This paper presents the results of direct shear pull-out tests performed on aged concrete specimens reinforced with glass FRP (GFRP) and carbon FRP (CFRP) externally bonded laminates and near surface mounted (NSM) bars. An accelerated aging scheme consisting of freeze/thaw cycling in the presence of a deicing salt solution is implemented to determine the effect of long-term environmental exposure on the FRP/concrete interface in regions that experience aggressive winter environments. The results show that the NSM bar technique is superior to externally bonded laminates in terms of efficiency in the use of FRP material and the effects of accelerated aging. Generally, the performance of GFRP is affected less than CFRP after freeze/thaw cycling for both externally bonded laminates and NSM bars. For high strength NSM FRP bar applications, a spalled or cracked concrete surface caused by freeze/thaw cycling may drastically reduce the capacity of the FRP/concrete interface by inducing failure at the concrete/epoxy filler interface.


Document: 

SP331-01

Date: 

February 1, 2019

Author(s):

Tarek Omar and Moncef L. Nehdi

Publication:

Special Publication

Volume:

331

Abstract:

Bridge deck condition assessment is commonly conducted through visual inspection by bridge inspectors. Considering the colossal backlog of aging bridge structures, there is a need to develop cost-effective and innovative solutions to evaluate bridge deck conditions on regular time intervals, without interrupting traffic. This makes remote sensing technologies viable options in the field of bridge inspection. This paper explores the potential for applying infrared thermography (IRT) using unmanned aerial vehicle (UAV) to detect and quantify subsurface delaminations in concrete bridge decks. The UAV-borne thermal sensing system focuses on acquiring thermal imagery using a UAV and extracting information from the image data. Two in-service concrete bridge decks were inspected using a high resolution thermal camera mounted on a UAV. The captured images were then enhanced and stitched together using a tailored procedure to produce a mosaic view of the entire bridge deck, indicating the size and geometry of the detected delaminated areas. The results were validated by conducting hammer sounding and half-cell potential testing on the same bridge decks. The findings reveal the capability of the technology to provide measurements comparable to those derived from traditional hands-on inspection methods. Thus, it can be an excellent aid in efficient bridge maintenance and repair decision-making.


Document: 

CI4012Pultorak

Date: 

December 1, 2018

Author(s):

Andrew S. Pultorak and Frederick R. Rutz

Publication:

Concrete International

Volume:

40

Issue:

12

Abstract:

Concrete repairs frequently involve placing a new concrete surface (overlay) on existing concrete (substrate). In this study, pull-off, direct shear, and jacking tests were used to evaluate the bond of overlays applied to mechanically roughened and cleaned substrates. Test parameters included substrate moisture condition and the use of cement slurry bonding agent.


Document: 

SP327

Date: 

November 20, 2018

Publication:

Special Publication

Volume:

327

Abstract:

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.


Document: 

SP327-43

Date: 

November 1, 2018

Author(s):

Wassim M. Ghannoum, Nawaf K. Alotaibi, Jose Garcia, Chang Hyuk Kim, Yungon Kim, Douglas Pudleiner, Kevin Quinn, Neil Satrom, William Shekarchi, Wei Sun, Helen Wang, and James O. Jirsa

Publication:

Special Publication

Volume:

327

Abstract:

Strengthening using carbon fiber reinforced polymers (CFRP) provides a valuable addition to available structural preservation and life extension techniques. Damaged bridges can be repaired efficiently while structurally deficient bridges can be effectively retrofitted to higher load capacities using CFRP materials. A large research program has been ongoing since 2008 in Texas to demonstrate the effectiveness of using anchored CFRP sheets in shear strengthening of reinforced concrete bridge beams and girders. The research program has encompassed three main thrusts: 1) over 70 large-scale tests of concrete bridge sections strengthened using externally applied anchored CFRP sheets, 2) small-scale tests aimed at developing CFRP anchor design criteria as well as a simple test procedure for quality control of materials and installation, and 3) developing design specifications for CFRP anchors and sheets in shear strengthening applications. An overview of the experimental findings of the program is presented.


Document: 

SP327-38

Date: 

November 1, 2018

Author(s):

Cristian Sabau, Cosmin Popescu, Gabriel Sas, Thomas Blanksvärd and Björn Täljsten

Publication:

Special Publication

Volume:

327

Abstract:

This paper summarizes the state-of-the-art on the topic of structural wall panels strengthened using fabric reinforced cementitious matrix composites (FRCM) composites. A systematic review of the literature is carried out to identify gaps in the available literature. A database of experimental tests, relevant for structural panels, was created and used to assess the influence of parameters such as test method, fiber type and material compressive strength, on the performance of FRCM strengthening. Since experimental investigations on walls strengthened with FRCM composites is still limited and mostly focused on shear, further investigations on walls as compression members can be considered timely, especially walls with openings, which have been overlooked. Experimental tests performed by the authors on reinforced concrete walls with openings are presented and assessed relative to the complete database. It was shown that FRCM composites are suitable repair solutions when new openings need to be created in existing walls.


Document: 

SP327-30

Date: 

November 1, 2018

Author(s):

Trevor N. S. Billows and Ahmad Rteil

Publication:

Special Publication

Volume:

327

Abstract:

The current state of North America’s infrastructure system is in dire straits. The cost of repair is estimated at over $3.6 trillion in the United States alone. As an alternative to the current strengthening methods, fabric reinforced cementitious mortar (FRCM) is proposed to aid the civil engineering industry in removing the infrastructure spending gap. This research initiative set out to determine the flexural strength improvement on RC beams with different textile ratios, different fabric materials and different anchorage methods. Five full-scale (200 x 300 x 4000 mm) (8 in x 12 in x 13 ft) reinforced concrete beams (1 control, 4 strengthened) were cast and tested under monotonic four-point bending conditions. Ultimate flexural capacity, pseudo-ductility, stiffness, and failure mode were taken as performance indicators. The study found that flexural strength was improved by up 81% over the control value.


Document: 

SP327-28

Date: 

November 1, 2018

Author(s):

Salah Altoubat, Abdul Saboor Karzad, Mohamed Maalej

Publication:

Special Publication

Volume:

327

Abstract:

This paper is part of an on-going research project on the behavior of damaged Reinforced Concrete (RC) beams repaired and strengthened with Externally Bonded Fiber Reinforced Polymer (EB-FRP). A total of seven full-scale rectangular beams; fully-damaged in a previous study, were repaired and retested to failure. The repair methodology consists of filling the cracks with epoxy, and then wrapping the beams with FRP discrete strips with two different thicknesses (1 layer and 2 layers). Out of the seven beams, four beams were strengthened using 2 layers of EB-FRP discrete strips; two beams were strengthened with 1 layer of EB-FRP; and the remaining beam was only repaired by crack injection with epoxy without wrapping with FRP. The beams were instrumented and tested to failure in three-points loading setup. The measured test parameters were the beams deflection and the maximum load-carrying capacity. Furthermore, the mode of failure was also observed and reported in this study. The test results revealed that the use of EB-FRP strips along with epoxy injection is an effective repair method that not only recovers the original strength (strength of the beams tested in previous study, considered as the reference beams), but also significantly increases their shear capacity. Comparing the shear capacity of the repaired beams to that of the reference beams, revealed that 2 layers of EB-FRP increased the shear strength by up to 95%, while the use of 1 layer of EB-FRP increased the shear strength by up to 66%. Moreover, comparison of the test results with existing predictive models (ACI 440.2R and fib TG-9.3) showed that both models reasonably predict the EB-FRP contribution to the shear strength of repaired and strengthened damaged beams.


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