International Concrete Abstracts Portal

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International Concrete Abstracts Portal

Showing 1-5 of 286 Abstracts search results

Document:

17-275

Author(s):

Haider M. Al-Jelawy, Kevin R. Mackie, and Zachary B. Haber

Publication:

Structural Journal

Volume:

115

Issue:

4

Abstract:

Accelerated bridge construction (ABC) is being increasingly used in new bridge construction and repair. For bridge substructure elements, ABC typically requires connections, such as mechanical couplers, between prefabricated elements where moment demands are largest. Grouted sleeves (GSs) offer good construction tolerances and load transfer between precast concrete elements. Therefore, they have gained interest for use in ABC in seismic regions. Large-scale precast column models using GS splices were designed and tested using a shifted plastic hinge (SPH) concept to minimize the damage in the footing and retain the column ductility. The testing matrix considered aspect ratio, moment gradient, and splicing details. Results showed that SPH can be used for flexural and flexural-shear columns; plastic hinging formed above the sleeve region and footing dowels remained elastic to minimize footing damage. Each precast column exhibited good ductility and energy dissipation, and formed slightly shorter SPH length compared with conventional columns.

Date:

July 1, 2018

DOI:

10.14359/51702233


Document:

16-440

Author(s):

Mostfa Al Azzawi, Philip Hopkins, Joseph Ross, Gray Mullins, and Rajan Sen

Publication:

Structural Journal

Volume:

115

Issue:

4

Abstract:

Two full-scale concrete masonry walls were repaired with three horizontally aligned 20 in. (508 mm) wide unidirectional carbon fiber sheets using different commercially available epoxies. Twenty years later, the carbon fiber-reinforced polymer concrete masonry unit (CFRP-CMU) bond was determined through selective pulloff tests that were preceded by detailed nondestructive evaluation. Results showed that despite superficial damage to the top epoxy coating and debonding along masonry joints, the residual CFRP-CMU bond for the wall surface was largely unaffected by prolonged exposure to Florida’s harsh environment. Therein, over 90% of the failures were in the concrete substrate. Although bond was poorer at mortar joints because the CFRP was well bonded to the masonry surface, its impact on structural performance of the repair was expected to be minimal. Overall, the repairs proved to be durable with both epoxy systems performing well.

Date:

July 1, 2018

DOI:

10.14359/51702226


Document:

17-246

Author(s):

P. Kathirvel, S.-J. Kwon, H.-S. Lee, S. Karthick, and V. Saraswathy

Publication:

Materials Journal

Volume:

115

Issue:

3

Abstract:

In the present investigation, a feasibility study was made for the first time by using graphite ore tailings (GOTS) as a replacement material for river sand in making mortar and concrete. As-received GOTS and treated GOTS (T-GOTS) at 1000°C (1832°F) were replaced with river sand and various percentages of replacement ranging from 10 to 100%, and their strength evaluation, were done by conducting compression and split tensile tests in mortar and concrete. Bond strength was evaluated using a pullout test and the permeability characteristic was assessed by water absorption and effective porosity tests. The quality of the concrete was assessed by electrical resistivity and ultrasonic pulse velocity measurements. The corrosion resistance evaluation was done by half-cell potential measurement, alternating current impedance or electrochemical impedance spectra, and potentio-dynamic polarization studies. From the studies, it is observed that river sand may be replaced with 40% T-GOTS and be effectively used for structural repair applications.

Date:

May 1, 2018

DOI:

10.14359/51702191


Document:

16-284

Author(s):

Satish Sharma, V. V. Arora, Suresh Kumar, Y. N. Daniel, and Ankit Sharma

Publication:

Materials Journal

Volume:

115

Issue:

2

Abstract:

One of the main causes of damage in dam structures is the high-velocity action of water containing solid particles such as silts and boulders, causing abrasion-erosion and cavitation losses during floods at the downstream side, which reduces the stability of the dam. India has more than 5100 large dams and many of them face the challenges of deferred maintenance. At present, highperformance concrete used for repair and restoration of structures at the downstream side is not found to be sustainable. With the objective of providing a suitable solution to this problem, research using high-strength steel fiber-reinforced concrete (HSSFRC) to resist abrasion-erosion and cavitation attack has been undertaken. This paper highlights the performance characteristics of 90 MPa (13.05 ksi) plain concrete and its corresponding steel fiber reinforced concrete (SFRC) by incorporating 1, 1.25, and 1.5% hooked-end steel fibers of 0.55 mm (0.021 in.) diameter with an aspect ratio of 63. Based on the findings, substantial improvement is observed on impact resistance, toughness, and energy absorption capacity of SFRC incorporating 1.25 to 1.5% steel fibers.

Date:

March 1, 2018

DOI:

10.14359/51701122


Document:

16-140

Author(s):

Shi-ping Yin, Yao Li, Zhe-yu Jin, and Peng-hao Li

Publication:

Materials Journal

Volume:

115

Issue:

2

Abstract:

Textile-reinforced concrete (TRC), which has superior crack- and corrosion-resistance capacity, is a type of available inorganic repairing material. However, TRC is still undefined in terms of its interfacial performance between it and existing concrete under marine erosion environments. In this paper, a double-side shear test was used to study the effect of TRC precracking, concrete strength, interface form, short-cut fiber, and freezing-and-thawing cycle number on the interfacial bond properties between TRC and existing concrete under chloride salt erosion and freezing-and-thawing cycles. The results indicate that the shear capacity can be improved by increasing the concrete strength, roughening the reinforced interface, and adding short-cut fibers into the TRC. In addition to that, proper precracking in TRC can also improve the interfacial properties; however, increasing the precracking of TRC to a certain extent will decrease the interfacial properties. In addition, as freezing-and-thawing cycles increase, interfacial properties between TRC and existing concrete will decrease, obviously without serious deterioration in the TRC layer. Therefore, TRC has the potential application of repairing and enhancing existing concrete structures under a harsh freezing-and-thawing environment.

Date:

March 1, 2018

DOI:

10.14359/51701919


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