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 13 Abstracts search results

Document: 

SP136-06

Date: 

January 1, 1993

Author(s):

Mark D. Luther

Publication:

Symposium Papers

Volume:

136

Abstract:

Structural Lightweight Aggregate Concrete

DOI:

10.14359/4265


Document: 

SP136-07

Date: 

January 1, 1993

Author(s):

Alexander M. Vayasburd

Publication:

Symposium Papers

Volume:

136

Abstract:

During the past three decades, lightweight aggregate concrete has emerged as an important sector of the structural concrete industry. It possesses unique properties, similar in some ways to those of normal weight concrete, but differing in significant aspects. Difficulties experienced with lightweight concrete in some projects appears to be caused by a lack of understanding of the differences between normal weight concrete and lightweight concrete as materials and differences in production technologies. It is most wisely used when treated as a material in its own right, with its special properties fully considered in design and construction. A three-phase model of lightweight concrete and its effect on durability are discussed as they relate to selection of materials, concreting and curing technology, control of in-service distress due to freezing and thawing, and corrosion of reinforcing steel. ased on the observed performance of bridge and marine structures built over the past four decades, the author presents a series of generalized observations applying to durability of lightweight concrete that provide a fair cross section of the entire experience. Paper concludes that, with proper selection of materials and design, and good construction practices, lightweight concrete offers an excellent solution to the problem of durability in severe environment.

DOI:

10.14359/4267


Document: 

SP136-09

Date: 

January 1, 1993

Author(s):

T. W. Bremner, T. A. Holm, and J. M. McInerney

Publication:

Symposium Papers

Volume:

136

Abstract:

The effect of stress on the nitrogen gas permeability of structural lightweight concrete was determined using cylindrical hollow concrete specimens loaded in axial compression at the same time that a nitrogen pressure differential was maintained across the cylinder wall. The nitrogen gas flow rate across the cylinder wall was noted and concrete permeability was measuredas the load increased. Flow rates tended to remain constant up to a critical stress corresponding to the onset of unstable crack propagation, at which time the flow rate increased rapidly. Rapid increases in permeability occurred at lower levels of applied stress-to-strength ratio with normal weight concrete than with lightweight concrete.

DOI:

10.14359/4269


Document: 

SP136-08

Date: 

January 1, 1993

Author(s):

Dale E. Berner

Publication:

Symposium Papers

Volume:

136

Abstract:

Presents information regarding highly confined, high-strength lightweight aggregate (LWA) concrete specimens, tested as part of a proprietary research program for which Phase I results have recently been released. The program specifically investigated the ultimate and post-ultimate behavior of members designed to resist high-intensity bending/punching shear loads, such as those imparted by massive ice features against offshore oil/gas platforms. Two special steel confining systems were utilized to confine the high-strength (compressive strengths nominally between 8000 and 9000 psi) LWA concrete; these were T-headed stirrup bars for use in reinforced concrete, and overlapping button-headed studs for use in plate-steel/concrete/plate-steel sandwich composites. These two confining systems both allowed the LWA concrete to exhibit extreme ductility prior to failure. Flexural, deflection, and ductility factors of over 40, and axial compressive strains of over 8 percent, were achieved, while maintaining essentially 100 percent of the ultimate capacity of the test specimens The tests were performed on 1- to 3.5-scale specimens, using a 4 million-lb capacity testing machine. Three approximately 16 x 16 x 42-in. prisms--two of reinforced concrete and one of sandwich composite concrete--were tested in axial compression. Also, four continuous beam specimens (one reinforced concrete and three sandwich composite concrete) were tested in bending/punching shear. These beam specimens were approximately 153 in. long, 36 in. wide, and had effective depths of approximately 13 in. Nonlinear finite element analyses of the beam specimens were also performed as part of the study.

DOI:

10.14359/4128


Document: 

SP136-10

Date: 

January 1, 1993

Author(s):

S. K. Ghosh, D. P. Narielwala, S. W. Shin, and J. Moreno

Publication:

Symposium Papers

Volume:

136

Abstract:

This experimental investigation was aimed at gathering information on flexural properties, including ductility, of high-strength lightweight concrete members (concrete with a dry unit weight of approximately 120 lb/ft 3 and with compressive strength approaching 9 ksi at 56 days) under reversed cyclic loading. Two sets of six specimens each were manufactured using lightweight aggregate concrete having compressive strengths of 5 ksi at 28 days and 9 ksi at 56 days. The test variables were concrete strength, amount of longitudinal reinforcement, and spacing of ties. The test results, including hysteretic load-deflection curves, for specimens representing columns under zero axial load are reported.

DOI:

10.14359/4129


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