Properties of polyvinyl alcohol fiber reinforced fly ash based Engineered Geopolymer Composites with zeolite replacement

Engineered Geopolymer Composite (EGC), with the typical characteristics of high ductility and low environmental impact, is attracting more and more research interest. The present study focuses on studying a fly ash based EGC system with partial replacement by zeolite. Mechanical properties, i.e. tensile and compressive properties, were tested. Meso-scale studies, including three-point bending test, single crack tensile test and single fiber pullout test, were performed. The purpose was trying to correlate the meso-scale results with the macro-scale (e.g. mechanical) properties. X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) techniques were adopted to study the characteristics of the reaction products of the EGC materials. High tensile strain capacities were observed for all the studied mixes, with the maximum strain capacity up to 8.62%. An optimal zeolite replacement ratio, i.e. 3%, was noted with respect to the tensile properties. A preliminary discussion was conducted on the effect of sample shape and size on the compressive strength of EGC and it was concluded the effect in general can be more significant than that on normal concrete. Further, it was demonstrated that the macro-scale properties of the EGC system can be well explained by the results of a number of parameters derived from the mesoscale studies. The XRD analyses demonstrated that new crystalline phases are insignificant in the reaction products of the studied system. The FT-IR studies revealed that the reaction products are mainly amorphous aluminosilicate phases, i.e. gel-like materials resulted from geopolymerization reactions. (C) 2019 Elsevier Ltd. All rights reserved.