Synergetic effect of fibers on geopolymers: Cost-effective and sustainable perspective

The aim of this research is to investigate the change of physico-mechanical properties of geopolymer mortar (GPM) depending on fiber addition and different curing temperatures. In addition, in this study, total cost and CO2 emission analysis of GPM mixtures were made. Glass and carbon fiber with a length of 14 mm were added to the mixtures, and two different curing methods were applied to the samples as air curing and 75 degrees C heat curing. Both the addition of fibers and curing at 75 degrees C had positive effects on the physical and mechanical properties of GPM mixtures in different ways. The most dominant effect of the fibers was on flexural strength and deflection values. The bridging effect of the fibers increased the flexural strengths up to 397% (from 3.49 MPa to 17.38 MPa) and the deflection values up to 657% (from 0.07 mm to 0.53 mm). While the fibers added to the GPM mixture increased the specific fracture energy up to 10.4 times, the specific fracture energy of the samples cured at 75 degrees C increased between 94% and 242% compared to air cured. Also in this study, three different high temperatures (150, 450 and 750 degrees C) were applied to the samples to observe the effect of high temperature on GPM mixtures. Although there was a slight increase in compressive strength when the samples were exposed to 150 degrees C, there was a significant loss of strength when the applied temperature exceeded 450 degrees C. After 450 degrees C and 750 degrees C, the mass loss increased to a large extent and the elastic modulus values decreased significantly. Finally, the total cost of GPM mixes is slightly higher than the reference studies produced with Ordinary Portland Cement, while GPM samples CO2 emissions were lower, up to 29%, than references.