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International Concrete Abstracts Portal

Showing 1-5 of 34 Abstracts search results

Document: 

SP171-05

Date: 

August 1, 1997

Author(s):

Michael P. Gillen

Publication:

Symposium Papers

Volume:

171

Abstract:

Results from a three year experimental study of the behavior of a high-strength (60 MPa) lightweight aggregate (LWA) concrete at elevated temperatures, including simulated hydrocarbon fire exposure, are described. Mechanical properties as a function of temperature (to 800 C) are also presented, as well as a summary of behavior in fire, and a comparison with normal density high performance and ordinary LWA concretes under similar conditions is made. In addition a simple and practical method for limiting the propensity of very low permeability, high performance concretes to explosively spa11 at elevated temperatures is demonstrated. Finally, the first application of this concrete in a major floating oil platform, the quarter-million ton Eeidrun TLP, is highlighted. High performance LWA concrete is shown . to possess all the best physical, mechanical, and durability characteristics of normal density high performance concretes while still retaining the superior high temperature and fire resistance properties of ordinary lightweight concretes--an ideal combination of properties for construction of offshore platforms.

DOI:

10.14359/6094


Document: 

SP171-07

Date: 

August 1, 1997

Author(s):

C. Muller, R. Hardtl and Peter SchieBl

Publication:

Symposium Papers

Volume:

171

Abstract:

Generally, high-performance concretes can be defined as types of concretes that meet one or more performance requirements in a specific way. Usual concretes are concretes with a compressive strength up to 55 Mpa and fly ash contents of around 20 mass.% relative to the total binding components (c + f). In the production of high-strength concretes (compressive strength > 65 Mpa), silica fume has been used usually in order to achieve the expected strengths at low w/c. In the production of mass concretes blast-furnace slag cements with a high percentage of slag are preferred in order to reduce the heat of hydration released by the cement reaction. The objective of the investigations presented in this paper was to produce high-strength and mass concretes with fly ash and to characterize the performance of these concretes. For this purpose, concretes with fly ash contents of 10, 20 and 30 mass.% relative to (c + f) at w/c between 0.33 and 0.43 are investigated. The properties and the performance of these concretes are presented using the parameters compressive strength and their stress-strain behavior. Beyond this, the performance of mass concretes with high fly ash contents is presented by the example of laboratory experiments and field studies at two newly-built power plants in the East German federal states. Concretes with reduced portland cement contents and fly ash contents between 30 and 60 mass.% relative to (c + f) were used in laboratory tests. Fly ash contents of 53 and 42 mass.% relative to (c + f) were used to produce monolithic base slabs with a concrete volume between 17,000 and 22,000 m3 (production in one operation). The performance of these concretes is shown using the parameters compressive strength development, heat of hydration development and their Ca(OH)z-content.

DOI:

10.14359/6096


Document: 

SP171-14

Date: 

August 1, 1997

Author(s):

S. I. Pavlenko

Publication:

Symposium Papers

Volume:

171

Abstract:

The department of civil enginering of the Siberian State Academy for Mining and Metallurgy (SSAMM) together with Tom-Usinsk Precast Works have developed compositions and technology for producing a lightweight concrete based on ash and slag from Tom-Usinsk power plant. The concrete can be used for external wall panels as a replacement for daydite concrete. The ash slag blend from hydrodumps of the power plant contains 33% ash, 52% slag sand with a particle size of 0.14 to 5 mm and 15% slag with a particle size of 5 to 10 mm. The blend meets the requirements of Russia Standard 25592-91 for use in concretes as an aggregate. Compressive strength of the concrete ranged from 5 to 10 MPa depending on the degree of air-entrainment and the function of panels. Average density of the concrete mixture was in the range of 1070 to 1150 kg/m3 before placing and 1100 to 1200 kg/m3 after placing, compacting and heat treatment, the coefficient of heat conductivity of the light-weight concrete was in the range of 180 to 250 W/m oC depending on average density and strength. The thickness of wall panels produced from this concrete could be reduced to 400 mm with out any warm coating. The concrete developed has-been patented and tested at the Tom-Usinsk reinforced concrete works. The cost of 1 m3 of external wall panels produced from the concrete is 30% lower than that of panels made from claydite concrete.

DOI:

10.14359/6103


Document: 

SP171-12

Date: 

August 1, 1997

Author(s):

D.H.Chisholm

Publication:

Symposium Papers

Volume:

171

Abstract:

A natural amorphous silica with a purity of approximately 90% is mined from an extensive geothermal deposit near Rotorua, New Zealand. After refining and processing to remove impurities, the ‘Microsilica 600TM’ has properties which comply with Australian Standard AS 3582 Part 3 ‘Silica Fume’ as a supplementary cementitious material for use with portland cement. The performance characteristics of concrete incorporating the ‘Microsilica 600’ were evaluated at two cement levels of 320 and 400 kg/m 3 and two silica addition levels of 7 and 10%. Properties evaluated were compressive strength, tensile strength, concrete shrinkage, sulfate resistance, resistance against chemical attack, abrasion resistance, and chloride permeability. Performance improvement compared favorably with published data on concretes incorporating processed ‘conventional’ silica fume.

DOI:

10.14359/6101


Document: 

SP171-03

Date: 

August 1, 1997

Author(s):

D. W. S. Ho, G. J. Chirgwin and S. L. Mak

Publication:

Symposium Papers

Volume:

171

Abstract:

Performance-based specifications are increasingly used to complement traditional prescriptive specifications in an effort to improve service life perform-ance of major infrastructure assets such as bridges. The water sorptivity of concrete, which relates to the moisture transport properties of near-surface concrete, has recently been adopted for trial application as a performance specification of concrete for bridge construction. Whilst data on water sorptivity of concretes cured under normal conditions are available, those of concrete subjected to heat curing are not yet widely available. This is particularly pertinent given that heat-cured precast structural elements are frequently used in bridge construction. This paper discusses the water sorptivity concept, its adoption in bridge specifications in New South Wales, and the performance of heat-cured concretes that could potentially be used in bridge construction.

DOI:

10.14359/6092


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