Preparation and characterization of a hybrid alkaline binder based on a fly ash with no commercial value

Johanna M. Mejía; Erich Rodríguez; Ruby Mejía De Gutiérrez; Nidia Gallego

doi:10.1016/j.jclepro.2015.05.044

Preparation and characterization of a hybrid alkaline binder based on a fly ash with no commercial value

Johanna M. Mejía, Erich Rodríguez, Ruby Mejía De Gutiérrez, Nidia Gallego

Nanomaterials Chemistry Group

Research output: Contribution to journal › Article › peer-review

57 Scopus citations

Abstract

Alkali-activated Portland fly ash cement (FA/OPC) and alkali activated blast furnace slag-fly ash cement (FA/GBFS) were prepared using 70% of a low quality fly ash (FA). The low quality is associated with a high content of unburned material (loss of ignition of 14.6%). The hybrid cements were activated by the alkaline solution in order to obtain an overall SiO₂/Al₂O₃ molar ratio of 5.0 and 6.0 and unique overall Na₂O/SiO₂ molar ratio of 0.21. The microstructural characterization of the blended pastes generated in the systems showed the coexistence of amorphous gels C-A-S-H and N-A-S-H gels in the hybrid systems. The addition of OPC or GBFS increases the compressive strength (at 28 days of curing) up to 127% compared with the geopolymer systems based only on FA used in this study. The content of silicates soluble also plays an important role in the reaction products and higher SiO₂/Al₂O₃ lead to obtain higher mechanical performance and denser structure. The results obtained show that these hybrid cements are an effective way for valorization the waste used in this study for the production of high strength and low-carbon footprint cement-type material.

Original language	English
Pages (from-to)	346-352
Number of pages	7
Journal	Journal of Cleaner Production
Volume	104
DOIs	https://doi.org/10.1016/j.jclepro.2015.05.044
State	Published - Oct 1 2015

Funding

This study was sponsored by the Instituto Colombiano para el Desarrollo de la Ciencia y Tecnología “Francisco José de Caldas” (COLCIENCIAS) (Research Project: Hybricement, Contract N° 0638-2013), the Center of Excellence of Novel Materials (CENM) and Universidad del Valle (Cali, Colombia). Authors also thank to GENSA Thermo electrical Company for providing the fly ash.

Keywords

Blast furnace slag
Fly ash
Hybrid alkaline cement
Ordinary Portland Cement

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.jclepro.2015.05.044

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title = "Preparation and characterization of a hybrid alkaline binder based on a fly ash with no commercial value",

abstract = "Alkali-activated Portland fly ash cement (FA/OPC) and alkali activated blast furnace slag-fly ash cement (FA/GBFS) were prepared using 70% of a low quality fly ash (FA). The low quality is associated with a high content of unburned material (loss of ignition of 14.6%). The hybrid cements were activated by the alkaline solution in order to obtain an overall SiO2/Al2O3 molar ratio of 5.0 and 6.0 and unique overall Na2O/SiO2 molar ratio of 0.21. The microstructural characterization of the blended pastes generated in the systems showed the coexistence of amorphous gels C-A-S-H and N-A-S-H gels in the hybrid systems. The addition of OPC or GBFS increases the compressive strength (at 28 days of curing) up to 127% compared with the geopolymer systems based only on FA used in this study. The content of silicates soluble also plays an important role in the reaction products and higher SiO2/Al2O3 lead to obtain higher mechanical performance and denser structure. The results obtained show that these hybrid cements are an effective way for valorization the waste used in this study for the production of high strength and low-carbon footprint cement-type material.",

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AU - Mejía, Johanna M.

AU - Rodríguez, Erich

AU - Mejía De Gutiérrez, Ruby

AU - Gallego, Nidia

PY - 2015/10/1

Y1 - 2015/10/1

N2 - Alkali-activated Portland fly ash cement (FA/OPC) and alkali activated blast furnace slag-fly ash cement (FA/GBFS) were prepared using 70% of a low quality fly ash (FA). The low quality is associated with a high content of unburned material (loss of ignition of 14.6%). The hybrid cements were activated by the alkaline solution in order to obtain an overall SiO2/Al2O3 molar ratio of 5.0 and 6.0 and unique overall Na2O/SiO2 molar ratio of 0.21. The microstructural characterization of the blended pastes generated in the systems showed the coexistence of amorphous gels C-A-S-H and N-A-S-H gels in the hybrid systems. The addition of OPC or GBFS increases the compressive strength (at 28 days of curing) up to 127% compared with the geopolymer systems based only on FA used in this study. The content of silicates soluble also plays an important role in the reaction products and higher SiO2/Al2O3 lead to obtain higher mechanical performance and denser structure. The results obtained show that these hybrid cements are an effective way for valorization the waste used in this study for the production of high strength and low-carbon footprint cement-type material.

AB - Alkali-activated Portland fly ash cement (FA/OPC) and alkali activated blast furnace slag-fly ash cement (FA/GBFS) were prepared using 70% of a low quality fly ash (FA). The low quality is associated with a high content of unburned material (loss of ignition of 14.6%). The hybrid cements were activated by the alkaline solution in order to obtain an overall SiO2/Al2O3 molar ratio of 5.0 and 6.0 and unique overall Na2O/SiO2 molar ratio of 0.21. The microstructural characterization of the blended pastes generated in the systems showed the coexistence of amorphous gels C-A-S-H and N-A-S-H gels in the hybrid systems. The addition of OPC or GBFS increases the compressive strength (at 28 days of curing) up to 127% compared with the geopolymer systems based only on FA used in this study. The content of silicates soluble also plays an important role in the reaction products and higher SiO2/Al2O3 lead to obtain higher mechanical performance and denser structure. The results obtained show that these hybrid cements are an effective way for valorization the waste used in this study for the production of high strength and low-carbon footprint cement-type material.

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Preparation and characterization of a hybrid alkaline binder based on a fly ash with no commercial value

Abstract

Funding

Keywords

UN SDGs

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