Mechanical Performance of Geopolymer Mortar Incorporating Fly Ash Based Sand as an Alternate Construction Material

The construction industry for a long time looking a substitute for fine aggregates (i.e., sand) because of ever depleting river sand deposits and implementing stringent sand mining regulations. Development of such alternate fine aggregate using an affluently available industrial by-product is commendable. This study endeavors to develop geopolymer mortar (GPM) using fly ash based sand (FAB sand) as an alternate fine aggregate, demonstrates its performance by comparing with river sand and proposes a suitable mix design methodology for the same. The novelty of the study lies in replacing river sand (100%) with FAB sand to manufacture GPM and thus, propose FAB sand as a potential novel construction material. Two sets of GPM cubes, one with 100% FAB sand while the other with 100% river sand, are made, considering NaOH molarity of 10, Na2SiO3/NaOH ratio of 1.5, curing temperature of 60 & 80°C, and curing period of 7, 14, and 28 days. Flowability, compressive strength, water absorption, morphological, and mineralogical properties of GPM cubes are further assessed. The results evidently show a high compressive strength of GPM cubes made with FAB sand. The findings of the study elucidate that FAB sand is a doable and practicable alternative to river sand in construction applications.