Effect of Addition of GGBS & Glass Powder on the Properties of Geopolymer Concrete

Abstract

There is a growing interest in the development of new concrete type known as geopolymer in the recent years due to its lower global warming potential, higher durability, better serviceability and overall economy. Geopolymer concrete represents a class of alkaline activation systems in which activation of the aluminosilicate source such as flyash is carried out by alkaline activators such as sodium silicate & sodium hydroxide respectively. The final end product of this whole reaction process is a three dimensional polymeric chain & ring structure containing Si – O – Al – O bonds. The system used in our dissertation work is a calcium-alumino-silicate system comprising of a combination of Flyash, GGBS & Glass Powder & activated using sodium hydroxide. The present study aims at adopting ambient curing for developing geopolymer concrete so as to make this concrete feasible for mass applications. Keeping up with ambient curing the addition of GGBS in percentages of 15%,20%,25% & Glass Powder in percentages of 5%,10%,15% has been done so as to bypass the need for carrying out oven curing. In addition to this the study aims at gauging the effect of different molarities i.e 4M, 8M & 12M on the mixes prepared & in turn deciding the optimum molar concentration for preparation of the mixes. To develop this geopolymer concrete according to our objectives some of the past literature has been reviewed to understand its reaction mechanism and accordingly select the proportion of materials for carrying out experimental work. To study the effectiveness of ambient curing over oven curing a total of 150 no samples have been prepared out of which 15 no comprise the control mix. The mix proportions of the geopolymer concrete samples prepared in this study have been adopted on a trial and error basis due to non availability of IS codes for design mix. To carry out the dissertation work as per proposed objectives cubical specimens of size 150mm x 150mm x 150 mm, cylindrical specimens of size 300mm height x 150mm dia. & beam specimens of size 150mm x 150mm x 700mm have been prepared for finding out compressive, split tensile & flexural strength of concrete. Testing of these specimens have also been carried out according to IS 516-1959 & IS 5816-1999 respectively.

On testing the specimens for the properties mentioned above it has been found that the control mix containing only flyash has developed lesser strength as compared to all the other blended mixes. In addition to this it has been observed that samples with highest percentage of GGBS have developed highest strength. From the strength point of view the noticeable variation have been non observance of above mentioned pattern in 12M category samples & lesser flexural strength obtained for 28 days as compared to 7 days in the 12M category samples. On the molarity front it has been seen that the maximum strength has been obtained for 4M category samples which is in variance with the trend observed in flyash based mixes.To study the effect of these variations comparison charts & tables have been made for each property studied. The possible reasons for each of these variations have been assigned on the basis of SEM-EDS test results and recommendations regarding further scope of work have been suggested.