International Concrete Abstracts Portal

International Concrete Abstracts Portal

The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

Showing 1-5 of 49 Abstracts search results

Document: 

SP209

Date: 

September 26, 2002

Author(s):

Editor: V.M. Malhotra

Publication:

Symposium Papers

Volume:

209

Abstract:

This Symposiuml Publication includes 48 papers from the ACI Fifth International Confrence on Innovation in Design with Emphasis on Seismic, Wind, and Environmental Loading, Quality Control, and Innovation in Materials/ Hot-Weather Concreting, held in December 2002 in Cancun, Mexico. Topics include the behavior of flared-column bents under seismic loading, marine exposure of high-strength light-weight concrete, and seismic strengthening of a nonductile concrete frame building. Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP209

DOI:

10.14359/14018


Document: 

SP209-44

Date: 

September 26, 2002

Author(s):

R. Hooper, C. McGrath, C. Morrison, and K. Lardner

Publication:

Symposium Papers

Volume:

209

Abstract:

Recent European and UK policies, for example the Landfill Duecave and the UK landfill tax, have set an agenda to promote reuse and recycling by con-trolling and minimising the landlilling of secondary materials. The UK Govern- ment and it’s agencies are actively pursuing policies of sustainable and environ- mentally responsible construction. The changing attitute towards secondary materials has encouraged investigation into the use of ferro-silicate slag from the Imperial Smelting Furnace (ISF) production of zinc in construction processes. The UK Ten Year Transport Plan, including the development of the highway infrastructure, offers opportunities to successfully demonstrate the consumption of small volume streams of secondary materials, including ISF slag, within the local area. Pavement construction offers several opportunities for consumption, the most credible of these being the replacement of the sand fractions by the slag in bound mixtures, cement and bituminous. This paper focuses upon cementitious mixtures alone. The presence of zinc and lead ions in the ISF slag are proven to have an impact on the setting characteristics of concrete mixtures, although there is little difference in the compressive strengths after 28 days. The leaching, characteristics of the slag suggest that the retardation is not linearly related to the quantities of zinc or lead leached. Additiwuilly, leaching tests in combination with pulverised fuel ash (fly ash) and ground granulated blastfurnace slag indicate that it may be possible to minimise retardation of set in by including these materials in the concrete mixture.

DOI:

10.14359/12534


Document: 

SP209-45

Date: 

September 26, 2002

Author(s):

L. H. Taber, A. Belarbi, and D. N. Richardson

Publication:

Symposium Papers

Volume:

209

Abstract:

During concrete construction, form oil, bond breaker, concrete splatter and other types of contaminants often contaminate reinforcement. Current specifications and quality control measures require the removal and clean up of these contaminants before the placement of concrete due to a concern of a reduction in bonding capacity. This is costly, labor intensive, and may not be necessary. Currently, there is limited research on the effect of reinforcing bar contami- nation on the bond between the deformed steel reinforcing bar and concrete. Because of this lack of data, specifications are conservative and require the removal of the contaminant. Inspectors often cite ACI 301-96, Standard Specifications for Structural Concrete, which states, When concrete is placed, all reinforcement shall be free of materials deleterious to bond. If it could be conclusively proven that this level of care is unnecessary, the construction industry would benefit greatly. To address the effects of contaminants on bond characteristics of deformed steel reinforcing bars, a preliminary study was completed at the University of Missouri-Rolla. The research program focused on three contaminants often seen during construction: form oil, bond breaker and concrete splatter. Other variables included size of reinforcing bar, strength of concrete and epoxy versus uncoated reinforcing bar. This paper will provide the experimental program and test procedures as well as the test results and observations. The results weal that in the majority of situations tested, the ultimate bond stress was not significantly affected by the three contaminants tested. In some cases, the bond breaker and form oil affected the smaller epoxy coated bars, while the effect of concrete splatter was insignificant.

DOI:

10.14359/12535


Document: 

SP209-42

Date: 

September 26, 2002

Author(s):

H. S. Lew and S. K. Kunnath

Publication:

Symposium Papers

Volume:

209

Abstract:

This paper examines the effectiveness of nodinear static procedures for seismic response analysis of buildings. Nonbm static procedures are recom- mended in FEMA 273 (Federal Emergency Management Agency-Guidelines for Seismic Rehabilitation of Buildings) for assessing the seismic performance of buildings for a given earthquake hazard representation. Three nonlinear static procedures specified in FEMA 273 are evaluated for their ability to predict defonnation demands ia terms on inter-story drifts and potential failure mechanisms. Two steel and two reinforced concrete buildings were used to evaluate the procedures. Strong-motion data recorded during the Northridge,earthquake are available for these buildings. Tfie study shows that nonlinear static procedures are not effective in predicting inter-story drift demands compared to nonlinear dynamic procedures. Nonlinear static procedures were not able to capture yielding of columns in the upper levels of one of the sekted buildings. This inability can be a sienificant source of concern in identifying local upper story failure mechanisms.

DOI:

10.14359/12532


Document: 

SP209-43

Date: 

September 26, 2002

Author(s):

J. S. Lawler, D. Zampini, and S. P. Shah

Publication:

Symposium Papers

Volume:

209

Abstract:

Cracking in concrete is fundamentally altered by the addition of reinforcing fibers. A combination of microfibers (less than 22 pi [0.0oO9 in.] in diameter) and macrofibers (500 p.m 10.0197 in.] in diameter) that contribute in comple- mentary ways to performance, is presented as a means for controlling cracking and improving the lifecycle behavior of concrete. In previous work, a hybrid blend of these fibers in a mortar matrix demonstrated better mechanical performance and lower cracked permeability than was seen with a single fiber type. The research presented in this paper attempts to realize the potential of such blends in concrete. A mixture proportioning method that achieves good workability and cohesion in concretes containing microfibers was used to produce a cast concrete. The mechanical performance and shrinkage cracking resistance of this material were evaluated. In the hybrid reinforced concrete, the microfibers delayed the development of macrocracks and so the composite demonstrated greater strength and cracking resistance than a similar matrix reinforced with macrofibers only. However, this influence was less pronounced than was observed with a mortar matrix and was confined to smaller crack openings.

DOI:

10.14359/12533


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