Geopolymer Mortar for Retrofitting and Evaluation of its Performance Characteristics as Adhesive

Abstract

Geopolymer has a good potential to be an alternative of ordinary Portland cement for making concrete and mortar. With world moving towards more sustainable material, it is necessary to that each tonne of cement generates equivalent amount of CO2 in the atmosphere. On the other hand, due to huge amount of industrial waste like y ash, blast furnace slag, bottom ash and rice husk ash it is necessary that judicious use of these materials is made in concrete. Lot of research is carried out in understanding mechanical and durability properties of geopolymer mortar and concrete. The objective of this research is to develop geopolymer mixture for the repair purpose by using y ash is a primary binder material and mixing it with additives in form of gran- ulated blast furnace slag and silica fume. A combination of sodium silicate and sodium hydroxide was used as an alkaline activator. Parametric study was carried out by do- ing variation in the concentration of sodium hydroxide, amount of alkaline activator and amount of activating solution in order to achieve requisite performance criteria of the geopolymer mixture. Early age properties of mortar were evaluated by performing ow table test and compression strength test. It was observed that, when y ash is used alone as binder material, it has higher setting time. Inclusion of additives accelerated the reaction and helped in achieving earlier setting time. Inclusion of GGBS as additives also helped in increasing the compressive strength of the mortar. In all the mixtures, it was found that with increasing the concentration of NaOH workability reduced. It was also observed that when sodium hydroxide alone was used as an activator, workability of geopolymer mortar has increased but there was reduction in compressive strength. Plain cement concrete beams of size 100 100 500 mm were cast with the M30 grade of concrete. Ordinary Portland cement (grade 53), Coarse aggregate (20 mm downsize), Fine aggregate, Portable water and superplasticizer are used. Concrete mix design is finalized based on provisions given in IS: 10262(2009). Compressive strength of concrete cubes are evaluated at 7 and 28 days. Bonding behavior of geopolymer mixture with concrete substrate was checked by casting fifteen plain concrete beams. Set of three beams was used to observe behavior of beams. Beams were repaired using y ash as binder material, GGBS as partial replacement of

y ash, silica fume as partial replacement of y ash and with cement mortar. There were three control specimens also and all beams were tested under exural strength test as given in IS : 516(2016). Compared to y ash repaired beams and silica fume repaired beams, exural strength increased in beams repaired with GGBS and y ash. However, its exural strength is lower then cement mortar repaired beams.