Micromechanics-based investigation of a sustainable ambient temperature cured one-part strain hardening geopolymer composite

Geopolymer composite research is aimed to make sustainable alternatives to Portland cement-based composites. However, the two main obstacles for commercialization are the use of large quantities of user-hostile liquid activators and heat curing. This study is aimed to overcome these obstacles by developing an ambient temperature cured “one-part” strain hardening geopolymer composite (SHGC). The developed composite as a “dry mix” uses a small amount of solid activator and eliminates the necessity for heat curing. The quantitative influences of curing condition and type of slag on the composite tensile performance were evaluated. The developed composite demonstrated strong strain hardening behavior comparable to typical strain hardening cementitious composite (SHCC) with high tensile strength of 4.6 MPa and very high tensile strain capacity of 4.2%. A micromechanics-based investigation was performed to explain the experimentally observed macroscopic high tensile ductility of the developed composite. The investigation involved determination of the matrix fracture properties and the fiber-matrix interface properties using fracture toughness tests and single-fiber pullout tests, respectively. The crack-bridging relation of the developed composite, computed via a micromechanics-based model, satisfied the necessary strength and energy-based conditions of steady-state flat crack propagation, which result in sequential development of multiple cracking. The material sustainability evaluation verified that the developed ambient temperature cured one-part SHGC is a promising sustainable alternative to typical SHCC offering 76% less carbon emissions and 36% less energy consumption. This research presents the rational basis for design of such cement-less composites with both high tensile ductility and high material sustainability.