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International Concrete Abstracts Portal

Showing 1-5 of 8 Abstracts search results

Document: 

SP269-01

Date: 

April 30, 2010

Author(s):

K. H. Obla

Publication:

Symposium Papers

Volume:

269

Abstract:

This article makes a strong case that prescriptive specifications are an impediment to sustainability. Some of the least sustainable prescriptive requirements are the use of minimum cementitious contents, restrictions on types and dosages of SCMs, and the overuse of maximum w/cm. It is not feasible to adopt an optimized prescriptive specification. On the other hand, performance-based specifications allow for mixture optimization, which requires producers and contractors to be more knowledgeable about their materials. Performance-based specifications reward attaining lower variability, which promotes investment in better quality and improved technology practices. Optimized mixtures with a lower variability will result in mixtures that are more cost-effective and sustainable. The article concludes by making a case that sustainability is more than CO2 emissions from cement and concrete production only.

DOI:

10.14359/51663718


Document: 

SP269-03

Date: 

March 31, 2010

Author(s):

B. Blair

Publication:

Symposium Papers

Volume:

269

Abstract:

Today, the demand for high-performance building materials continues to grow along with the demand for "green" product manufacturing and sustainable building practices. Supplementary cementitious materials (SCMs) and blended cements offer sustainable and performance advantages for those who build and occupy structures of all kinds. The growing use of these environmentally friendly materials is due to several performance factors, including low permeability, resistance to chlorides and sulfates, mitigation of alkali silica reaction, greater strength, lower temperatures for mass concrete, and improved workability. The use of cementitious blends not only results in stronger, more durable, high-performance concretes but also helps reduce global climate impact by lowering energy consumption and greenhouse gas emissions. In fact, each ton of portland cement that is replaced by SCMs reduces CO2 emissions by approximately 0.8 ton (0.7 metric ton). Using cementitious blends also reduces solid waste disposal because SCMs are by-products from other industries. These environmental benefits are increasingly important to project developers and owners.

DOI:

10.14359/51663720


Document: 

SP269-07

Date: 

March 31, 2010

Author(s):

E. Lorenz

Publication:

Symposium Papers

Volume:

269

Abstract:

The transportation industry is viewed by some as less sustainable due to its lack of a green rating system similar to the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) system. However, many long-standing design considerations of the transportation market segment have embraced sustainable design criteria. This paper relates current bridge design and construction terminology to sustainable design concepts and the sustainable benefits of precast concrete. A case study of the Otay River Bridge illustrates some of these concepts in practice. Sustainable concepts discussed in the case study include material choices, minimizing site disturbance, community involvement, and wildlife preservation.

DOI:

10.14359/51663724


Document: 

SP269-02

Date: 

March 1, 2010

Author(s):

S. Ratchye

Publication:

Symposium Papers

Volume:

269

Abstract:

Supplementary cementitious materials (SCMs), such as fly ash or blast-furnace slag, can achieve broad sustainable aims, including the mitigation of global warming and easing pressure on landfills. Specifically, SCMs reduce the use of portland cement, increase the recycled content of concrete, and can increase concrete’s durability.

DOI:

10.14359/51663719


Document: 

SP269-05

Date: 

March 1, 2010

Author(s):

C. Ozyildirim

Publication:

Symposium Papers

Volume:

269

Abstract:

Slag cement was introduced to the Virginia Department of Transportation (VDOT) in the early 1980s. Early laboratory studies indicated that slag cement provides resistance to alkali-silica reaction and reduces the permeability of concrete. Since the mid-1980s, slag cement has been successfully used by VDOT in bridge structures and pavements to reduce permeability and improve the durability of concrete. The bridge structures with concrete containing slag cement (slag concrete) included normalweight concrete in beams and decks, and lightweight concrete or self-consolidating concrete in beams. In large footings, slag cement has been used at a high replacement rate of 75% to control thermal cracking from temperature rise and reduce permeability. Testing of slag concrete obtained during the construction of field projects has indicated the low permeability of these concretes. Evaluations and tests on cores from bridge decks with some field exposure have confirmed the benefit of slag concrete in reducing permeability, thus increasing the durability of these concretes.

DOI:

10.14359/51663722


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