TY - JOUR
T1 - Novel synthesis of lightweight geopolymer matrices from fly ash through carbonate-based activation
AU - Alghamdi, Hussam
AU - Neithalath, Narayanan
N1 - Funding Information:
The authors gratefully acknowledge partial support from the National Science Foundation (NSF) (CMMI: 1463646) towards the conduct of this work. The materials were supplied by Headwaters and PQ Corporation. This work was carried out in the Laboratory for the Science and Sustainable Infrastructural Materials (LS-SIM) and the LeRoy Eyring Center for Solid State Sciences (LE-CSSS) at Arizona State University. The support that has made the establishment and operation of these laboratories are also acknowledged.
Funding Information:
The authors gratefully acknowledge partial support from the National Science Foundation (NSF) ( CMMI: 1463646 ) towards the conduct of this work. The materials were supplied by Headwaters and PQ Corporation. This work was carried out in the Laboratory for the Science and Sustainable Infrastructural Materials (LS-SIM) and the LeRoy Eyring Center for Solid State Sciences (LE-CSSS) at Arizona State University. The support that has made the establishment and operation of these laboratories are also acknowledged.
Publisher Copyright:
© 2018 Elsevier Ltd
PY - 2018/12
Y1 - 2018/12
N2 - This paper describes a novel synthesis route for porous geopolymers based on carbonate-based activation of fly ash as the primary source material. The aqueous dissolution of sodium carbonate supplies NaOH which provides the alkaline medium for fly ash geopolymerization (along with externally supplied sodium silicate also, if needed). The CO2 released from the low temperature (∼100 °C) decomposition of carbonates formed as reaction products, acts as the pore-forming agent. The dosage of the alkaline agents is tailored to obtain a porous material with large enough porosity (∼50%), and sufficient mechanical strength (∼15 MPa) and thermal conductivity (∼0.3 W/m-K) so as to be used as structural/insulating elements in buildings. Detailed analysis of microstructure and reaction products reveals the presence of sodium carbonate crystals in the matrix, recrystallized from the initial carbonates added. Determination of CO2-equivalent emissions shows that these matrices, despite releasing some amount of CO2 in the pore-forming process, are more sustainable than similar matrices synthesized from portland cement or geopolymerized using same starting materials and other activating agents.
AB - This paper describes a novel synthesis route for porous geopolymers based on carbonate-based activation of fly ash as the primary source material. The aqueous dissolution of sodium carbonate supplies NaOH which provides the alkaline medium for fly ash geopolymerization (along with externally supplied sodium silicate also, if needed). The CO2 released from the low temperature (∼100 °C) decomposition of carbonates formed as reaction products, acts as the pore-forming agent. The dosage of the alkaline agents is tailored to obtain a porous material with large enough porosity (∼50%), and sufficient mechanical strength (∼15 MPa) and thermal conductivity (∼0.3 W/m-K) so as to be used as structural/insulating elements in buildings. Detailed analysis of microstructure and reaction products reveals the presence of sodium carbonate crystals in the matrix, recrystallized from the initial carbonates added. Determination of CO2-equivalent emissions shows that these matrices, despite releasing some amount of CO2 in the pore-forming process, are more sustainable than similar matrices synthesized from portland cement or geopolymerized using same starting materials and other activating agents.
KW - Carbonate activation
KW - Fly ash
KW - Foamed geopolymer
KW - Microstructure
KW - Thermal conductivity
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U2 - 10.1016/j.mtcomm.2018.09.014
DO - 10.1016/j.mtcomm.2018.09.014
M3 - Article
AN - SCOPUS:85054158307
SN - 2352-4928
VL - 17
SP - 266
EP - 277
JO - Materials Today Communications
JF - Materials Today Communications
ER -