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International Concrete Abstracts Portal

Showing 1-5 of 12 Abstracts search results

Document: 

SP185-07

Date: 

February 1, 2000

Author(s):

D. R. Morgan, A. Lobo, and L. Rich

Publication:

Symposium Papers

Volume:

185

Abstract:

Concrete berth faces in the St. Lawrence river at the Port of Montreal constructed in the early 1900's are undergoing continuing deterioration from the combined effects of frost damage, alkali aggregate reactivity and in some areas attack from deicing chemicals stored on the adjacent wharves. In some places the concrete is turning to rubble, and a major retrofit program is required to restore the berth faces to a serviceable condition. Both cast-in-place reinforced concrete and anchored and tied-back fiber reinforced shotcrete remedial potions are being evaluated to establish the most technically sound and cost-effective remedial alternatives for this work. This paper describes a prototype construction project in which about two thirds of a berth face, 122m long and 7.1m. High, was repaired with a synthetic fiber reinforced shotcrete and the remaining third with a steel fiber reinforced 25mm long by .38mm diameter added at an addition rate of 1.25 percent by volume of the shotcrete. The deformed steel fiber 38mm long was added at an addition rate of .75 percent by volume of the shortcrete. The shotcrete used was air entrained, silica fume modified, supplied by transit mixers from a central-mix plant and applied by the wet-mix plant and applied by the wet-mix shotcrete process. This paper describes the remedial design, shotcrete mixture designs, preconstruction mock-up production and quality control testing and provides a summary of construction quality control test results. Test results reported include plastic shotcrete properties such as as-batched and as-shot slump and air-content, compressive strength, boiled absorption and volume of permeable voids and toughness. The behavior of the shotcrete repairs is being monitored service is described. Comparative data is provided regarding the relative costs of the cast-in-place reinforced concrete and fiber reinforced shotcrete alternatives.

DOI:

10.14359/5713


Document: 

SP185-05

Date: 

February 1, 2000

Author(s):

N. Banthia and C. Yan

Publication:

Symposium Papers

Volume:

185

Abstract:

In most industrialized countries of the world, bulk of the future activity in the construction sector will be related to repair and rehabilitation of the existing structures. Given the general inadequacy of our present repair materials, much future research is needed towards developing high performance repair materials especially for executing durable thin repairs and patching. In this paper, polymer modified micro-fiber reinforced concrete composites are evaluated as repair materials by conducting CMOD controlled repair bond tests in uniaxial tension. A significant improvement in the bond strength and bond fracture energy due to both fiber reinforcement and polymer modification is noted. In addition, surface preparation emerges as one of the most important variables controlling the strength and fracture energy of the bond.

DOI:

10.14359/5711


Document: 

SP185-01

Date: 

February 1, 2000

Author(s):

A. E. Naaman

Publication:

Symposium Papers

Volume:

185

Abstract:

Following a brief introduction on the definition of high-performance fiber reinforced cement composites (HPFRCCs), this paper suggests that HPFRCCs are very well suited for repair and rehabilitation applications. It describes the range of tensile properties currently achievable using HPFRCCs, focusing in particular on the trade-off between strength and strain capacity and the importance of large strains, as evidenced by quasi-strain hardening behavior and multiple cracking. Particular attention is given to describing the tensile stress-strain response of slurry infiltrated fiber concrete (SIFCON), and the parameters influencing that response such as type of fiber, type of matrix, fiber orientation, fiber length, and fiber bond. Also a brief summary of three representative applications involving the use of HPFRCCs in repair and rehabilitation is given, namely: the use of fibers in the tensile zone area of reinforced concrete beams to control cracking and improve durability; the use of SIMCON for repair and rehabilitation of reinforced concrete beams and columns to satisfy seismic requirements; and the use of SIMCON as a jacket in reinforced concrete columns, also to improve seismic resistance. It is concluded that exceptional structural performance such as strength and ductility, particularly in reinforced and prestressed concrete structures, can be achieved if the matrix material is an HPFRC composite.

DOI:

10.14359/5707


Document: 

SP185

Date: 

February 1, 2000

Author(s):

Editors: Neven Krstulovic-Opara and Ziad Bayasi

Publication:

Symposium Papers

Volume:

185

Abstract:

SP-185 Up until now there has been very little information on the use of high-performance fiber-reinforced concrete (HPFRC). But recent laboratory studies and field applications show that HPFRC improves performance of civil engineering infrastructure in a cost-effective manner. This publication includes 11 papers on the mechanical properties of HPFRC for infrastructural repair and retrofit.

DOI:

10.14359/14226


Document: 

SP185-09

Date: 

February 1, 2000

Author(s):

N. Krstulovic-Opara, J. M. LaFave, E. Dogan, and C.-M. Uang

Publication:

Symposium Papers

Volume:

185

Abstract:

Older reinforced concrete structures constructed in seismically active areas of the United States are usually non-ductile and are thus identified as hazardous. Extensive efforts have been devoted to the development of adequate retrofitting techniques for these buildings. While laboratory studies have shown that the use of "conventional" Fiber Reinforced Concretes (FRCs) and High Performance FRCs (HPFRCs) in new construction leads to substantially improved seismic response, seismic retrofit techniques have not yet taken advantage of these advanced composites. The advantages of conventional FRCs is a significant increase in ductility over that of reinforced concrete. The advantage of HPFRCs is that, when loaded beyond the elastic limit, they exhibit significant increases in structure to dissipate energy--a feature particularly desirable for earthquake resistant design. The goal of the presented research was to develop a novel seismic retrofit technique, using recently developed HPFRCs, to solve the following common problems of non-seismically designed reinforced concrete frames: 1) inadequate anchorage of the discontinuous bottom beam reinforcement, 2) inadequate confinement of the column lap splices, and 3) inadequate confinement of the joint. HPFRCs used in the presented research include Slurry Infiltrated Fiber Concrete (SIFCON) and Slurry Infiltrated Mat Concrete (SIMCON). The presented research was conducted in collaboration with a project Advisory Panel consisting of consulting structural engineer from Wiss, Janney, Elstner Associates, Inc.

DOI:

10.14359/5715


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