Effect of Carbon Fibers on Thermal and Mechanical Properties of Metakaolin-Fly Ash-Based Geopolymers

Abstract

This paper presents results from a set of experiments carried out to evaluate the effect of carbon fibers on thermal and mechanical properties of metakaolin fly-ash-based geopolymers. Bending and compression tests were conducted at ambient temperature and after exposure to elevated temperatures on fiber-reinforced geopolymers with varying proportions of carbon fibers, metakaolin, and fly ash. Also, crack propagation, dimensional changes, and temperature gradients in geopolymers with different carbon fiber content were recorded during and after heating. Data from these tests show that the addition of short carbon fibers in geopolymers provides an effective mechanism for controlling temperature-induced cracking and thermal deformation, and this in turn enhances bending strength under high temperatures. The enhancement in bending strength under high temperatures, due to the presence of carbon fibers, is higher in geopolymers with higher fly ash content than that with lower fly ash content. Further, the addition of carbon fibers has no significant effect on compressive strength of geopolymers both at ambient temperature and after exposure to high temperatures.