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International Concrete Abstracts Portal

Showing 1-5 of 278 Abstracts search results

Document: 

20-207

Date: 

May 1, 2021

Author(s):

Lihe Zhang, Dudley R. Morgan, Iain Kirk, Anastasia Rolland, and Robert Karchewski

Publication:

Materials Journal

Volume:

118

Issue:

3

Abstract:

Wet-mix shotcrete has been used more and more for structural applications in the past few decades. Recently, wet-mix shotcrete was successfully used to construct a mass structural wall with congested reinforcement and minimum dimensions of 1.0 m in a sewage treatment plant. A low-heat shotcrete mixture that included up to 40% slag was proposed for shotcrete application. A preconstruction mockup was shot to established proper work procedures for shotcrete application and qualify the shotcrete mixture and shotcrete nozzlemen. Extraction of cores and cut windows from the mockup confirmed proper consolidation around the congested reinforcement. A thermal control plan was developed, which included laboratory and field testing requirements, thermal analysis modeling with a three-dimensional (3-D) finite element program, and thermal control requirements, including installation of cooling pipes and thermal blankets. Shotcrete proved to be an efficient means for mass concrete structural construction. Thermal control for mass shotcrete construction was studied, and the proposed thermal control plan was proved to function properly. The general guidance for mass shotcrete construction is provided.

DOI:

10.14359/51730423


Document: 

20-246

Date: 

May 1, 2021

Author(s):

Fulvio Tonon

Publication:

Materials Journal

Volume:

118

Issue:

3

Abstract:

Although several JSCE-SF6 tests have established the strength improvements caused by fiber reinforcement, it is unknown whether the measured strength improvements are caused by shear strength improvements (that is, Mode II), or by tensile or flexural strength improvement (Mode I). This paper provides a basic understanding of the state of stress: 1) in a JSCE-SF6 test; and 2) in an ASTM D5607 direct shear test, which has never been used earlier to investigate the shear strength of fiber-reinforced concrete (FRC). It was found that the JSCE-SF6 standard does not test the shear strength of a material, and it cannot be used to obtain shear characteristics of FRC. On the other hand, the ASTM D5607 standard can be used effectively to obtain shear characteristics of FRC because it creates a stress field very close to pure shear. The addition of steel fibers to concrete does not increase the peak shear strength of concrete.

DOI:

10.14359/51732599


Document: 

18-315

Date: 

March 1, 2021

Author(s):

John S. Lawler, Jonah C. Kurth, Stephen M. Garrett, and Paul D. Krauss

Publication:

Materials Journal

Volume:

118

Issue:

2

Abstract:

Reliability-based durability design of reinforced concrete structures requires a probabilistic service life modeling approach. Probabilistic service life modeling of chloride-induced corrosion should consider the statistical distributions of key parameters that influence corrosion initiation and subsequent damage. For typical reinforced concrete structures (such as bridge decks), these are chloride exposure, chloride penetration resistance of the concrete, chloride-induced corrosion threshold, depth of concrete cover, and corrosion propagation time. Assessing the impact of the use of corrosion-resistant reinforcement, such as epoxy-coated reinforcing bars (ECR), is typically performed through a selection of the chloride threshold and/or propagation time. This paper provides recommendations for statistical distributions for the chloride threshold to be used in service life modeling for structures containing carbon steel and ECR based on both experimental work reported in the literature and field investigations of existing structures conducted by the authors.

DOI:

10.14359/51730411


Document: 

20-253

Date: 

March 1, 2021

Author(s):

Goran Adil, Ceki Halmen, George Seegebrecht, and John T. Kevern

Publication:

Materials Journal

Volume:

118

Issue:

2

Abstract:

Corrosion performance of reinforced pervious concrete was evaluated through field and laboratory evaluations. Two reinforced pervious cemetery walls in Chicago, IL, were visually evaluated, and samples were investigated through petrographic examination. Corrosion performance of two-layered concrete samples, with an outer layer of conventional concrete and an inner layer of pervious concrete, was evaluated in the laboratory. Results indicated that pervious concrete around the reinforcement can significantly delay the cracking and spalling of samples compared to conventional concrete. Chloride profiles of samples and instantaneous corrosion rate measurements showed that corrosion of reinforcement embedded in two-layered samples was similar to conventional concrete although two-layered samples provided a longer time to cracking. Laboratory results are in agreement with long service life performance observed in the field and with prior pervious concrete corrosion studies.

DOI:

10.14359/51730514


Document: 

20-040

Date: 

January 1, 2021

Author(s):

R. Kampmann, S. Telikapalli, A. Ruiz Emparanza, A. Schmidt, and M. A. Dulebenets

Publication:

Materials Journal

Volume:

118

Issue:

1

Abstract:

Concrete infrastructure is deteriorating at a fast pace because of corrosion issues inherent to traditional black steel reinforcing bars. Alternative non-corrosive reinforcement materials for concrete structures have been developed and reinforcing bars made from fiber-reinforced polymers (FRP) are one of the most predominantly used non-corrosive materials for internal reinforcement. This research focused on basalt FRP reinforcing bars as this technology is still in development for the U.S. market and no standard specifications are available yet. In an effort to develop basalt specific acceptance criteria, two commonly available BFRP reinforcing bar sizes from five different sources and two different production lots were tested to quantify the tensile strength and stress-strain behavior of this emerging reinforcing bar technology. The obtained results were used to evaluate the performance of each reinforcing bar type in a relativistic comparison to existing benchmark values for glass FRP reinforcing bars given in AC454. The tensile strengths were consistent for all reinforcing bar types and the recorded values surpassed the strength measurements generally reported for comparable GFRP reinforcing bars. It was found that No. 3 reinforcing bars measured guaranteed tensile strengths between 760 and 1266 MPa (110 and 184 ksi), while No. 5 reinforcing bars ranged between 836 Pa and 1074 MPa (129 and 131 ksi). Though the fiber-to-resin ratio of all tested reinforcing bar types was similar, the tensile strength of these reinforcing bars varied due to differences in the raw materials and production. The elastic moduli were calculated according to AC454 and it was noted that this property varied significantly between the different reinforcing bar types because of irregular cross-sectional dimensions and the various proprietary (not standardized) manufacturing processes. It was determined that acceptance criteria for BFRP reinforcing bars can be conservatively defined according to the currently available GFRP values, but more specific criteria can be developed through further research to take advantage of the additional load capacity and potential improved stiffness of BFRP reinforcing bars.

DOI:

10.14359/51729288


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