Experimental investigations on hybrid fibre reinforced alkali activated concrete mixes

Abstract

The present study attempts a detailed evaluation of the strength performance of Fiber reinforced Alkali Activated Concrete mixes containing fly ash and ground granulated blast furnace slag (GGBS) as a sole binder. Fly ash and GGBS, a by-product obtained from industries, is incorporated in the AASC mixes as a full replacement to ordinary Portland cement (OPC). Initially OPC and AASC mixes are designed to obtain M30 grade. This experiment investigates the effect of the addition of hooked end steel fiber and polypropylene fiber on the physical and mechanical properties of high ductile Alkali Activated Concrete. Geo-polymer is called one of the best substitutes for ordinary Portland cement (OPC) because of its benefits over OPC. Hooked end steel fiber of length 35 mm and diameter 0.5 mm with aspect ratio of 70, polypropylene fiber of 12 mm length is used in hybrid manner, with five different fiber volume fractions of 0.25 & 1.25%, 0.50 & 1%, 0.75 & 0.75%, 1 & 0.50% and 1.25 & 0.25% respectively. All mixes of fiber reinforced Alkali Activated Concrete includes 50% of GGBS and 50% of fly ash from total binder content. Alkali activators used are, sodium hydroxide pellets and sodium silicate liquid. The experimental result indicated that, the addition of fibers affects the workability by 20–30% down. In the mechanical property wise, fibers variation doesn’t affect the compressive strength much. Flexure and tensile strength increase by about 20–40%, compared to other mixes without any fiber’s addition. This increment of strength is due to addition of both the fibers in hybrid way. Using Alkali Activated Concrete helps to reduce emission of carbon dioxide, which happens from manufacturing of cement. Geo polymer concrete make the environment very much sustainable by maintaining global warming in a limit.