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International Concrete Abstracts Portal

Showing 1-5 of 283 Abstracts search results

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


Document:

17-077

Author(s):

Edward G. Moffatt and Michael D. A. Thomas

Publication:

Materials Journal

Volume:

115

Issue:

1

Abstract:

Rapid-strength concretes are currently used to repair structures such as bridge decks, substructure elements on bridges (for example, piers and columns), pavements, and components of buildings. Although these products gain a high strength in a short period of time (for example, ≥ 20 MPa [3000 psi] in 3 hours), it is usually intended that they not only provide a temporary fix but can also provide a permanent repair for the remaining service life of the structure. One approach for delivering high early-age strength is through the rapid formation of ettringite using a binder that contains a calcium aluminate or calcium sulfoaluminate phase with calcium sulfate. Although it has been proven that such binders gain high early strength and acceptable working time, limited information exists concerning the long-term durability of concrete produced with these binders in the aggressive conditions often encountered in service. This paper presents durability data on the chloride resistance, corrosion protection properties, deicer salt scaling and carbonation resistance. These concretes include: portland cement (PC) and high-early-strength portland cement (HEPC) as references; a newly developed ternary cement (PC-CAC-CS) consisting of a blend of PC, calcium aluminate cement (CAC), and calcium sulfate (CS); and two commercially available calcium-sulfoaluminate (CSA) cement systems.

Date:

January 1, 2018

DOI:

10.14359/51701006


Document:

16-245

Author(s):

A. Ghazy and M. T. Bassuoni

Publication:

Materials Journal

Volume:

114

Issue:

6

Abstract:

The overall performance of cementitious repair systems depends greatly on the compatibility between the repair materials and existing concrete, which is a major issue for many rapid-setting repair materials for concrete pavements. Current state-of-the-art research on the use of nanoparticles in concrete, including repair applications, is growing due to its promising potential. However, with the advent of nanomaterials in concrete, it is imperative to understand its shrinkage behavior due to the very rapid hydration and pozzolanic reactions at early age, which warrants a focused investigation. Thus, in the present study, a series of volume stability (shrinkage) tests were conducted to evaluate the performance of nanomodified fly ash concrete as a repair material for concrete pavements. The results indicate that, despite their higher autogenous shrinkage, most nanomodified fly ash concrete mixtures exhibited low total shrinkage (free and restrained) when adequate curing was provided.

Date:

November 1, 2017

DOI:

10.14359/51700891


Document:

16-429

Author(s):

Ruo-Yang Wu and Chris P. Pantelides

Publication:

Structural Journal

Volume:

114

Issue:

5

Abstract:

Experimental results are presented regarding the seismic repair of reinforced concrete bridge columns using a carbon fiber-reinforced polymer (CFRP) shell and epoxy-anchored headed steel bars. The CFRP shell, consisting of unidirectional laminates in the hoop and vertical direction, encloses the headed bars and is filled with non-shrink concrete to relocate the column plastic hinge. Two columns designed to current standards—one in a cap beam-to-column connection and the other in a footing-to-column connection—were damaged under cyclic forces. Damage included longitudinal bar fracture and buckling across multiple spiral hoops; concrete damage in the plastic hinge region included cracking and spalling of the column core concrete. Finite element analysis was used to design the CFRP shell and the headed bars were designed for the increased flexural demand on the repaired section. The seismic repair was rapid, required minimal intervention, and successfully relocated the plastic hinge and restored strength and displacement capacity.

Date:

September 1, 2017

DOI:

10.14359/51700789


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