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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 89 Abstracts search results
Document:
CI4412Klinger
Date:
December 1, 2022
Author(s):
James Klinger, Oscar R. Antommattei, Aron Csont, Trevor Prater, Michael Damme, and Bruce A. Suprenant
Publication:
Concrete International
Volume:
44
Issue:
12
Abstract:
Although the Code requires the engineer to design for adequate concrete placement, it offers very little guidance for congested reinforcement. This article provides information on design and detailing prerequisites, reinforcement congestion economics, allowance recommendations related to congestion of reinforcement, and proposed Code and Commentary language with respect to constructability.
SP356_02
October 1, 2022
Nafiseh Kiani, Steven Nolan, and Antonio Nanni
Symposium Papers
356
A common challenge in reinforced concrete construction is the need to connect bars of finite length to provide reinforcement continuity. Lap and mechanical splices are common methods that have been used to make continuous reinforcement. Lap splicing may cause additional congestion making concrete consolidation difficult. Mechanical splices are used when lap splicing is not practical. Different types of mechanical splices are commercially available for steel bars. For the case of GFRP reinforcement, mechanical splices are very useful in staged construction because the reinforcement cannot either be bent at the site or there is insufficient space for lap splicing. Mechanical splices for GFRP bars, however, must account for the low transverse stiffness and strength of the bars. For these reasons, only certain mechanical splices are practical for GFRP bars and careful consideration must be given to their installation and effectiveness. In this study, a commercially available swaged coupler was selected to investigate the behavior of spliced GFRP bars. Expected performance was numerically evaluated using a Finite Element (FE) model to develop a framework for test validation. The FE model was calibrated with a laboratory test to compare the results. The coupler’s length, the bar’s tensile strength, and the slip between the coupler and the bar were investigated. The outcome of this study allows for the definition of an efficient test campaign.
DOI:
10.14359/51737244
SP-336_07
December 11, 2019
David Darwin, Rouzbeh Khajehdehi, Muzai Feng, James Lafikes, Eman Ibrahim, Matthew O’Reilly
336
The goal of this study was to implement cost-effective techniques for improving bridge deck service life through the reduction of cracking. Work was performed both in the laboratory and in the field, resulting in the creation of Low-Cracking High-Performance Concrete (LC-HPC) specifications that minimize cracking through the use of low slump, low paste content, moderate compressive strength, concrete temperature control, good consolidation, minimum finishing, and extended curing. This paper documents the performance of 17 decks constructed with LC-HPC specifications and 13 matching control bridge decks based on crack surveys. The LCHPC bridge decks exhibit less cracking than the matching control decks in the vast majority of cases. Only two LCHPC bridge decks have higher overall crack densities than their control decks, which are the two best performing control decks in the program, and the differences are small. The majority of the cracks are transverse and run parallel to the top layer of the deck reinforcement. The results of this study demonstrate the positive effects of reduced cement paste contents, concrete temperature control, limitations on or de-emphasis of maximum concrete compressive strength, limitations on maximum slump, the use of good consolidation, minimizing finishing operations, and application of curing shortly after finishing and for an extended time on minimizing cracking in bridge decks.
10.14359/51722459
SP-332_08
July 1, 2019
Ashok Kakade
332
When preparing ready-mix concrete for private applications, it is typically recommended that owners and contractors collaborate with suppliers and concrete specialists to understand the possibilities and limitations of concrete in their applications. Here, we describe a situation in which a homeowner took direct control over the exact specifications of concrete and admixtures, and ultimately resulted in an unsatisfactory concrete slab. The owner subsequently sued and settled with the concrete supplier outside of the court, which raises important questions regarding who maintains responsibility for concrete mixtures, their installation, and the final slab results. Suggestions are provided to help mitigate this problem.
10.14359/51719127
CI4004Saldua
April 1, 2018
Benjamin P. Saldua, Ethan C. Dodge, Peter R. Kolf, and Carlton A. Olson
40
4
Nondestructive testing was used to evaluate concrete consolidation in an antenna pedestal recently constructed at the Canberra Deep Space Communications Complex in Australia. Evaluations were based on impulse-response tests, ultrasonic shear-wave tomography, core tests, and visual observations. The work showed that impulse-response testing allows rapid, reliable identification of significant defects. The consequent repair program is summarized.
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