Two-way linked multiscale method integrated with nanomechanical tests and cohesive zone fracture to model highly heterogeneous binding materials

This paper presents a two-way linked multiscale method that is integrated with nanomechanical tests and a cohesive zone fracture model to investigate highly heterogeneous cementitious materials such as alkali-activated geopolymer. To this end, geopolymer paste, which is known to have multiphase heterogeneous media, was fabricated and tested to identify (1) local-scale microstructures and nanomechanical properties of individual components within the paste, and (2) global-scale fracture through a three-point bending beam test. Local-global results were then integrated with the two-way linked finite-element modeling. Global and local scales were systemically represented in the model with a homogeneous bending beam structure where the elements of the potential crack zone are linked to a heterogeneous geopolymer microstructure representative volume element (RVE) in the two-way coupled multiscale modeling framework. This integrated experimental- computational multiscale approach can provide the material properties, such as micrometer-length-scale cohesive zone fracture properties, which are considered core properties but not usually feasible to identify using conventional test methods. Test-modeling results imply that the two-way linked multiscale method integrated with nanomechanical tests can be used as a method for characterization and design of various multiphase media, including materials used for critical civil infrastructure.