Harnessing waste for sustainable construction: A novel synthesizing activators from waste for one-part geopolymer concrete and evaluating its fracture toughness

Abstract

Geopolymer concrete garners significant attention due to its potential to mitigate pressing global challenges, such as CO₂ emissions and waste management for disposal. However, using more expensive commercial activators has posed a significant obstacle to practical implementation. Therefore, scientists want to develop methods to extract powdered activators from agricultural and industrial waste materials. To this end, the study has sought to create innovative activators derived from waste glass powder (WGP) and silica-rich rice husk ash (RHA) to create one-part geopolymer concrete (OPGC). Ground granulated blast-furnace slag is utilized as a precursor material for preparing binder, with varying ratios of WGP/RHA to sodium hydroxide (NaOH) from 0.50 to 1.75 at 0.25 intervals. Twenty-four distinct mixtures of OPGC were prepared using the materials mentioned above and evaluated for their compressive strength and fracture toughness. The primary objective of this research is to evaluate the mode I, III, and I/III fracture toughness of OPGC using edge-notched disc bend specimens. Additionally, a 1 % steel fiber dosage was introduced into the OPGC to reduce brittleness. The microstructural characteristics were examined through X-ray diffraction and scanning electron microscopy. Findings reveal that the fracture toughness of OPGC improves with the RHA to NaOH ratio up to 1.0, peaking at 1.09 MPa·m^0.5. Likewise, the fracture toughness increases with the WGP to NaOH ratio up to 0.75, reaching a peak value of 1.20 MPa·m^0.5. Beyond these respective ratios, a decrease in fracture toughness was observed. Nonetheless, incorporating fibers into OPGC consistently improved the fracture toughness across all mixtures. Mode I fracture toughness is greater than I/III and III, emphasizing the significance of Mode III compared to other fracture modes.