Factors Influencing the Mechanical Properties of Geopolymer Mortar Made of Fly Ash

Abstract

Geopolymerization is a process where silica and alumina rich source materials turns into excellent binding materials by the aid of alkali solutions. Fly ash class F mainly consists of alumina and silica. Compressive strength of class F fly ash geopolymer mortar is influenced by many factors such as fluid to binder ratio, Na2SiO3/NaOH ratio, curing duration, curing temperatures, age of geopolymer mortar GPM and molarity of the NaOH solution. The present experimental study investigates the effect of these factors on the compressive strength of geopolymer mortar. For each combination, three cubes with dimensions of 50 x 50 x 50 mm were casted. After heat curing in the laboratory oven, the samples were tested on a universal testing machine for the compressive strength. A microstructural study was conducted to observe the internal structure using Scanning electron microscopy, Energy-dispersive X-ray spectroscopy and X-ray diffraction analysis. The results showed very high early compressive strength of 63.9 MPa for samples cured at 80 °C and for a duration of 24 hr. The significance of the present study is that it will allow for establishing methods for production of high strength geopolymer mortar that can be used in civil engineering applications. In addition to the environmental advantages of using such source materials to produce binding materials with good mechanical properties