IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308 _______________________________________________________________________________________ Volume: 04 Special Issue: 01 | NCRTCE-2014 | Feb-2015, Available @ http://www.ijret.org 30 EFFECT OF ALKALINE LIQUID RATIO ON THE COMPRESSIVE STRENGTH OF GEOPOLYMER CONCRETE (A THEORETICAL APPROACH) D. Annapurna 1 , Ravande Kishore 2 , G.Vikas 3 1 Assistant Professor, Civil Engineering Department, UCE (A), Osmania University 2 Professor of Civil Engineering Department, UCE (A), Osmania University 3 M.E scholar, Civil Engineering Department, University College of Engineering, Osmania University, Hyderabad- 07 Abstract Carbon dioxide (CO 2 ) emission into the atmosphere is a factor for the cement industries, as the green house effect created by emission is considered to produce an increase in global temperature that may result in climate change. The use of concrete is increasing worldwide in a fast track and therefore the development of suitable concrete is expected for environmental reasons and for strength parameter. Replacement of cement with Geopolymer is one of the efforts to produce more environmentally friendly concrete. No cement is used in Geopolymer concrete, but fly ash and alkaline solutions, i.e, sodium hydroxide (Na OH) and sodium silicate (Na 2 O, SiO2) are used to make the binder necessary to manufacture the concrete. To produce 2.5 cubic meter of high quality Geopolymer concrete, One tone of fly ash can be utilized. In this study investigations are made to see the effect of Alkaline liquid to fly ash ratio on compressive strength of Geopolymer concrete in ambient conditions as well as oven dry conditions at 90 0 for 4 hours. Alkaline liquid ratio is varied from 0.5 to 0.3 and compressive strengths are detected after 7 and 28 days. A mathematical model is prepared by using the Fuzzy logic to predict the compressive strength of Geopolymer concrete for different chemical ratios using the experimental results. The alkaline liquid ratio is used as input and 7 days, 28 days and oven dried samples compressive strengths are used as output while developing Fuzzy logic model. Compressive strength of Geopolymer concrete depends on proportioning of ingredient of mix design. Fuzzy logic model can be effectively used to replace the experimental work. To develop the model, part of the experimental data is used for Training & Testing and remaining part for validating the results. Keywords: Geopolymer Concrete, Fuzzy Logic model, Compressive strength. --------------------------------------------------------------------***---------------------------------------------------------------------- 1. INTRODUCTION The most widely used construction material is concrete. By partially replacing cement with fly ash the unit cost of concrete can be reduced. The fly ash disposal is one of the major issues for environmentalists, because dumping of fly ash as waste material causes severe environmental problems. Instead of dumping fly ash as a waste material , partly it can be used on economic grounds as pozzuolana for partial replacement of cement and partly because of its useful effects of lower water demand for workability, reduction in bleeding and lower heat evolution. It will be used particularly in mass concrete applications and large volume placement to control expansion due to heat of hydration and also helps in reducing cracking at early ages. Because of improved qualities, Fly ash based Geopolymer concrete can be used widely for any construction purpose. If Geopolymer concrete is used in constructing floors and walls, then it gives a glossy surface that can give a good appearance. Flyash based Geopolymer concrete fire resistance properties and resistance against abrasion with alkali activation when compared to that of Ordinary Portland Cement. As fly ash is only a by product material found from industrial wastes cost of such Geopolymer concrete is less than or at most equal to OPC concrete which uses expensive cement as binder material. Davidovits from France first used the term Geopolymer concrete and proposed that an alkaline liquid could be used to react with the silica and the Alumina in the geological source material or in by-product materials like fly ash, rice husk ash to produce binders. The geopolymer materials chemical composition is similar to natural Zeolitic materials, but this has amorphous microstructure. Based on the Silica to alumina atomic ratio present in the polymers, the geopolymers are widely used in Bricks, fire protection works ,ceramics, in low CO 2 cements manufacturing, concretes radioactive and toxic waste encapsulations, and fire protection fiber glass composites etc. The application of Mat lab is high level language that includes matrix based data structures, its own internal data an extensive function catalog , an environment in which to develop your own functions and scripts, import ability and export to many data files. In Mat lab, Fuzzy logic tool box we have member function, which play an important role for output parameter. The Mathematical model using Fuzzy logic is developed in Mat lab to replace the experimental work. The obtained results with Fuzzy logic model were compared with the experimental results and found remarkably close to each other.