Concrete sustainability with very high amount of fly ash and slag

Sustentabilidade do concreto com altos teores de escória e cinzas volantes

Abstracts

This article approaches concrete mix designs where cement is replaced by high amounts of slag and fly ash, with the purpose of turning it into a more sustainable construction material, that is, an authentic green concrete. Mix proportions with fly ash, ground-blasted furnace slag, and Portland cement were studied in binary and ternary mixtures for compressive strength levels of 40 MPa and 55 MPa. The replacement of cement with mineral additions ranged from 50% to 90% in mass. Mean decreases of 55% in the energy consumption, 78% in the CO² emissions, and 5% in the cost of the concrete m³, plus an increase of 40% in the mean index of durability were obtained, all ofwhich compared to the 40-MPa reference concrete. This study attests the technical, economical and environmental potentialities for theuse of concrete mixtures with until 90% of fly ash.

sustainability; slag; fly ash; durability; energy consumption; CO2 emission; cost

Este artigo versa sobre traços de concreto com substituição de cimento por altos teores de escória e cinza volante, com o objetivo detorná-lo um material de construção mais sustentável, ou seja, um autêntico concreto verde. Foram estudados traços de cinza volante, escória de alto forno e de cimento Portland em misturas binárias e ternárias para níveis de resistência à compressão de 40 MPa e 55MPa. A subsituição de cimento por adições minerais, em massa, variou entre 50% e 90%. Foram obtidos, em média, decréscimos no consumo de energia de 55%, nas emissões de CO² de 78% e no custo do m³ de concreto de 5%, e o índice médio de durabilidade aumentou40%, todos comparados com o concreto de referência de 40 MPa. Este estudo atesta as potencialidades técnicas, econômicas e ambientais do uso de misturas de concreto com até 90% de cinza volante e escória.

sustentabilidade; escória; cinza volante; durabilidade; consumo de energia; emissão de CO2; custo

Concrete sustainability with very high amount of fly ash and slag

Sustentabilidade do concreto com altos teores de escória e cinzas volantes

G. C. Isaia^I ; A. L. G. Gastaldini^II

^IStructures and Civil Construction Department Technology Center of the Federal University of Santa Maria (UFSM) - Corresponding author : Rua Camélias, 175, Santa Maria, RS, Brazil, 97020-120, Tel. [phone] fax [phone] E-mail: [e-mail] ^IIAssociated Professor, Dr. - Structures and civil Construction Department Technology Center of Federal University of Santa Maria (UFSM) [e-mail]

ABSTRACT

This article approaches concrete mix designs where cement is replaced by high amounts of slag and fly ash, with the purpose of turning it into a more sustainable construction material, that is, an authentic green concrete. Mix proportions with fly ash, ground-blasted furnace slag, and Portland cement were studied in binary and ternary mixtures for compressive strength levels of 40 MPa and 55 MPa. The replacement of cement with mineral additions ranged from 50% to 90% in mass. Mean decreases of 55% in the energy consumption, 78% in the CO² emissions, and 5% in the cost of the concrete m³, plus an increase of 40% in the mean index of durability were obtained, all ofwhich compared to the 40-MPa reference concrete. This study attests the technical, economical and environmental potentialities for theuse of concrete mixtures with until 90% of fly ash.

Keywords: sustainability, slag, fly ash, durability, energy consumption, CO₂ emission, cost.

RESUMO

Este artigo versa sobre traços de concreto com substituição de cimento por altos teores de escória e cinza volante, com o objetivo detorná-lo um material de construção mais sustentável, ou seja, um autêntico concreto verde. Foram estudados traços de cinza volante, escória de alto forno e de cimento Portland em misturas binárias e ternárias para níveis de resistência à compressão de 40 MPa e 55MPa. A subsituição de cimento por adições minerais, em massa, variou entre 50% e 90%. Foram obtidos, em média, decréscimos no consumo de energia de 55%, nas emissões de CO² de 78% e no custo do m³ de concreto de 5%, e o índice médio de durabilidade aumentou40%, todos comparados com o concreto de referência de 40 MPa. Este estudo atesta as potencialidades técnicas, econômicas e ambientais do uso de misturas de concreto com até 90% de cinza volante e escória.

Palavras-chave: sustentabilidade, escória, cinza volante, durabilidade, consumo de energia, emissão de CO₂, custo.

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Full text avaliable only in PDF.

REFERENCES

[01] Klee, H. Summary of International Cement Industry Structure and Practice. Draft, 2003. http://www.wbcsd.org/DocRoot/9LEp5LbjBYH9HjCQqbcn/ cement-best-practices.pdf , January, 2009.

[02] Feuerborn, H. J. Coal ash utilization over the world and in Europe. 2005. www.coal-ash.co.il/sadna/Abstract_Feuerborn.pdf , January, 2009.

[03] Malhotra, V. M. Making concrete ‘greener' with fly ash. Concrete International. Farmington Hills, v. 21, n. 5, p. 61-66, 1999.

[04] Mehta, P. K. Bringing the concrete industry into a new era of sustainable development. In: Mario Collepardi Symposium on Advances in Concrete Science and Technology. Proceedings. Rome, 1997, p. 49-68.

[05] Galbraith's Limited. World crude steel and pig iron production. 2008. http://74.125.47.132/search?q=cache:JGhI1nWwRSUJ:www.galbraiths.ltd.uk/content_manager/document.php%3Fdbc%3Ded7dee7145d2390c49ac4f52c489ac8f%26ID%3D7074%26ext%3D.pdf+Galbraith%E2%80%99s+Limi ted+World+crude+steel+and+pig+iron+production&hl =pt-BR&ct=clnk&cd=1&gl=br, January, 2009.

[06] Isaia, G., Gastaldini, A., Moraes, R. Physical and pozzolanic action of mineral additions on the mechanical strength of high-performance concrete. Cement Concrete and Composites, v. 25, n. 1, p. 69-76, 2003.

[07] NTC - Associação Nacional de Transporte de Cargas. Transport National Guide. 2003. http://www.ntc.org.br/pesquisa_frota_nacional.htm, January, 2009 (in Portuguese).

[08] Bucher, H. R. E. Aggregates for concrete. In: I National Symposium of Aggregates, São Paulo, 1986. Proceedings. Escola Politécnica da USP, São Paulo 1986 (in portuguese).

[09] Worrell, E., Galitsky, C. Energy efficiency improvement opportunities for cement making. An Energy Star guide for energy and plant managers. 2004. http://www.climatevision.gov/sectors/cement/pdfs/final_lbnl.pdf , January, 2009.

[10] CEMBUREAU. Cement industry's efforts to reduce CO2 emissions. 2005. http://www.cembureau.be/default.asp?p=Key_09.asp, January, 2009.

[11] Carvalho, J. Environmental lifecycle analysis applied to civil construction - Case study: comparison between Portland cement and by-products addition. 2002. M.Sc. Dissertation. Polytechnic School of São Paulo University, São Paulo.

[12] EPA - Environmental Protection Agency. Greenhouse gases and global warming potential values. 2002, 16 p. http://yosemite.epa.gov/oar/GlobalWarming.nsf/UniqueKeyLookup/ SHSU5BUM9T/$File/ghg_gwp.pdf, January 2009.

Received 21 Jan 2009

Accepted 28 May 2009

Available Online 30 Sep 2009

Publication Dates

• Publication in this collection
  18 Sept 2014
• Date of issue
  Sept 2009

History

• Accepted
  28 May 2009
• Received
  21 Jan 2009