AUTHOR=Lao Jian-Cong , Xu Ling-Yu , Huang Bo-Tao , Zhu Ji-Xiang , Khan Mehran , Dai Jian-Guo 

TITLE=Utilization of sodium carbonate activator in strain-hardening ultra-high-performance geopolymer concrete (SH-UHPGC)

JOURNAL=Frontiers in Materials

VOLUME=10

YEAR=2023

URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2023.1142237

DOI=10.3389/fmats.2023.1142237

ISSN=2296-8016

ABSTRACT=<p>In this study, strain-hardening ultra-high-performance geopolymer concrete (SH-UHPGC) was produced using Na<sub>2</sub>CO<sub>3</sub>, Na<sub>2</sub>SiO<sub>3</sub> and their hybridization (1:1 in mole ratio) as alkaline activators. An ultra-high compressive strength was achieved for all the developed strain-hardening ultra-high-performance geopolymer concrete (i.e., over 130 MPa). Strain-hardening ultra-high-performance geopolymer concrete with hybrid Na<sub>2</sub>CO<sub>3</sub> and Na<sub>2</sub>SiO<sub>3</sub> activators showed the highest compressive strength (186.0 MPa), tensile strain capacity (0.44%), and tensile strength (11.9 MPa). It should be highlighted that very significant multiple cracking can be observed for all the strain-hardening ultra-high-performance geopolymer concrete even at a very low tensile strain level (e.g., 0.1%). According to the reaction heat, microstructures, and chemical composition analyses, strain-hardening ultra-high-performance geopolymer concrete with hybrid activators had the highest reaction degree, while that of Na<sub>2</sub>CO<sub>3</sub>-based strain-hardening ultra-high-performance geopolymer concrete was the lowest. It was found that the Na<sub>2</sub>CO<sub>3</sub>-based strain-hardening ultra-high-performance geopolymer concrete showed the best sustainability, and the strain-hardening ultra-high-performance geopolymer concrete with hybrid Na<sub>2</sub>SiO<sub>3</sub> and Na<sub>2</sub>CO<sub>3</sub> presented the best overall performance (considering the mechanical performance, energy consumption, environmental impact, and economical potential). The findings of this work provide useful knowledge for improving the sustainability and economic potential of strain-hardening ultra-high-performance geopolymer concrete materials.</p>