Geo-polymer Mortar as Retrofitting Material for R.C. Element

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Geopolymer has been subject of research in recent years. There are many studies which are carried out to examine viability of geopolymer mortar as an alternative material to Ordinary Portland Cement. Geopolymer material mainly consist of replacement of cementitious material by industrial waste like fly ash, blast furnace slag, bottom ash, metakaolin, Silica fumes etc. so in such way industrial waste will be used judiciously and there will be low emission of CO2. The present investigation aims to develop geopolymer mortar as a repair material using metakaolin, fly ash, blast furnace slag as source materials. For the purpose of evaluation of the performance of geopolymer mortar as repair material, reinforced concrete beams were casted, and damaged in two different patterns i.e. wide and hairline cracked and tested under two-point load flexure testing machine. Geopolymer mortar (GPM) comprises of supplementary cementitious material as a primary binder material and mixing it with alkali activators. Sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) were used as Alkali activators. Their different concentrations were prepared to study the most suitable mixture and its properties. Alkali activators with 10 M, and 12 M with 1:2 and 1:2.5 concentration ratio was prepared and tested for checking compressive strength gain of geopolymer mortar cubes. After casting and compressive testing of geopolymer mortar cubes it was observed that among all different trial mix with varying binder ratio, the cubes with GGBS (Ground Granulated blast furnace slag) to Fly ash ratio of (80:20) showed relatively higher strength at 7 days. Hence that proportion of binder to fine aggregate was used in preparation of geopolymer paste (GPP) and that paste was used for repairing beams which were damaged by applying two-point flexure load to obtain its gain in load carrying capacity at 7 and 28 days respectively.