Tailoring fiber dispersion and mechanical properties in strain-hardening alkali-activated composite through viscosity adjustment and casting methodologies

Abstract

This paper aims at enhancing tensile properties of strain-hardening alkali-activated composite (SHAAC) by using a flow-induced casting approach. Ca(OH)₂-activated ground granulated blast-furnace slag (GGBS) was used as binder material and viscosity modifying admixture (VMA) was applied to adjust the rheology. Combined X-ray computed tomography (X-CT) scanning and image analysis were proposed to obtain the spatial distribution of polyvinyl alcohol (PVA) fibers in hardened SHAAC prepared with various VMA dosages using different (i.e. conventional and flow-induced) casting approaches. The results revealed optimal rheological properties (yield stress of 192 Pa, plastic viscosity of 17.6 Pa·s) of paste for fiber distribution and alignment. The SHAAC with fiber distribution and orientation factors of 0.91 and 0.83 was prepared using the flow-induced casting approach with a WMA dosage of 1.0 %. Its ultimate tensile stress and tensile strain capacity reached 6.1 MPa and 5.5 %, respectively, which was 37 % and 36 %, more than the conventionally cast SHAAC. In the end, an empirical equation for ultimate tensile strength and strain capacity prediction with high determination coefficient was proposed based on fiber distribution, orientation, and porosity.