Synthesis of binary blends using phosphate with Ash/Slag in the production of ambient cured geopolymer mortar

Abstract

Utilizing industrial by-products in the construction industry has significantly developed the sustainable technology. In the past few decades, Geopolymer concrete has been a compromising technology as an alternative for conventional concrete. This paper is a report on the geopolymer concrete synthesized from the combination of pulverized rock phosphate (RP) with slag/ash at 10 M, 12 M and 14 M of sodium hydroxide as an alkaline activator. Nine mix proportions with varying the binder content with flyash and GGBS were prepared. Other constituents like alkaline to binder ratio were fixed to 0.35, and phosphate was kept constant of 30% binder irrespective of the reference samples. These samples were tested to determine the compression and spilt tensile strength after 28 days of ambient curing regime. The highest compressive stress of mortar samples was 38 MPa, achieved in the 70%GGBS and 30%RP combination with the binder content of 408 kg/m3. Further increasing the RP content beyond 30% of the binder leads to reduced compressive stress and affects the setting time of the geopolymer mortars. The pore structure of the proposed research was determined from the water absorption, sorptivity and rapid chloride diffusivity test. The mix GM6 was affirmed with lower permeability when compared to all other mixes.