Fracture behaviour of sustainable activators-based fibrous alkali -activated concrete under mode I, I/III & III loading

Fracture behaviour of sustainable activators-based fibrous alkali -activated concrete under mode I, I/III & III loading

The construction industry is confronted with substantial challenges due to the ecological consequences of traditional concrete production, a substantial role player in carbon emissions. In light of these issues, there is increasing interest in sustainable alternatives, such as geopolymer concrete, which can be enhanced with steel fibres to improve mechanical properties. This study aims to examine the critical aspect of fracture toughness in steel fibrous one-part alkali-activated concrete (OAAC). The one-part clinker-free binder for geopolymer concrete used in the study has been developed utilizing activators synthesized from agricultural and industrial waste, specifically waste glass powder (WGP) and rice husk ash (RHA). Thirty-nine mixing combinations were prepared using varying WGP/RHA to sodium hydroxide (NaOH) ratios from 1:0.50 to 1:1.75 in 0.25 intervals, alongside 0%, 0.5%, and 1% steel fibre. The parameters investigated in this study included compressive strength and fracture toughness against Mode I, Mode III, and mixed-mode (I/III) loading conditions using edge-notched disc bend specimens. The obtained results indicate that under mode I loading, 1.0% steel fibres yielded a maximum fracture toughness improvement of 18.1% at an RHA-NaOH ratio of 1:1.00. In OAAC mixes with steel fibres, a WGP-NaOH ratio of 1:1.25 resulted in notable improvements in fracture toughness, with increases of 8.1% for 0.5% steel fibres and 16.3% for 1.0% steel fibres. The formation of amorphous aluminosilicate gel and semi-crystalline phases identified in the SEM and XRD analyses show that RHA and WGP-derived activators enhance bonding and reactions with the aluminosilicate precursor in OAAC, resulting in a strong microstructure with reduced porosity and improved compressive strength.

The construction industry is confronted with substantial challenges due to the ecological consequences of traditional concrete production, a substantial role player in carbon emissions. In light of these issues, there is increasing interest in sustainable alternatives, such as geopolymer concrete, which can be enhanced with steel fibres to improve mechanical properties. This study aims to examine the critical aspect of fracture toughness in steel fibrous one-part alkali-activated concrete (OAAC). The one-part clinker-free binder for geopolymer concrete used in the study has been developed utilizing activators synthesized from agricultural and industrial waste, specifically waste glass powder (WGP) and rice husk ash (RHA). Thirty-nine mixing combinations were prepared using varying WGP/RHA to sodium hydroxide (NaOH) ratios from 1:0.50 to 1:1.75 in 0.25 intervals, alongside 0%, 0.5%, and 1% steel fibre. The parameters investigated in this study included compressive strength and fracture toughness against Mode I, Mode III, and mixed-mode (I/III) loading conditions using edge-notched disc bend specimens. The obtained results indicate that under mode I loading, 1.0% steel fibres yielded a maximum fracture toughness improvement of 18.1% at an RHA-NaOH ratio of 1:1.00. In OAAC mixes with steel fibres, a WGP-NaOH ratio of 1:1.25 resulted in notable improvements in fracture toughness, with increases of 8.1% for 0.5% steel fibres and 16.3% for 1.0% steel fibres. The formation of amorphous aluminosilicate gel and semi-crystalline phases identified in the SEM and XRD analyses show that RHA and WGP-derived activators enhance bonding and reactions with the aluminosilicate precursor in OAAC, resulting in a strong microstructure with reduced porosity and improved compressive strength.