Influence of various factors on properties of geopolymer paste: A comparative study

A comprehensive experimental study was conducted to investigate effect of different production parameters such as activator type, activator concentration and curing temperature on fresh and hardened properties of volcanic tuff based geopolymer paste (GP) samples. Volcanic tuff obtained from Nevşehir (Central Anatolia, Turkey) was ground to particle size less than 45 μm, after that alkali activation process was provided with two type of alkali activators such as NaOH and NaOH+Na2SiO3 (SH and SH + SS) solutions. Produced geopolymer samples were cured at different temperatures ranging from 23 to 150°C. Compressive strength, setting time, hydration heat of GP samples were investigated. Additionally, microstructural investigations were performed with SEM and XRD analyzes. As a result of modification of experimental parameters, compressive strength development reached to 41.43 MPa was obtained from GP samples, which did not harden in laboratory conditions. It was also determined that the alkali activation of volcanic tuff with SH exhibited better mechanical and microstructural properties than alkali activation with SH + SS.