ICI Update - Aug - Sep 2014 04 ICI Technical Paper ICI Update - Aug - Sep 2014 QUANTITIES OF SODIUM HYDROXIDE SOLIDS AND WATER TO PREPARE SODIUM HYDROXIDE SOLUTION OF GIVEN MOLARITY FOR GEOPOLYMER CONCRETE MIXES (1) (2) Rajamane N. P. , and Jeyalakshmi R. (1) Head, Centre for Advanced Concrete Research, SRM University, (Ex CSIR-SERC) (2) Professor and Head, Dept of Chemistry, Faculty of E&T, SRM University Abstract Geopolymer concretes (GPCs) have been investigated in several academic institutes in India. They are made often from fly ash as Geopolymeric Source Material (GSM) and require Sodium Hydroxide Solution (SHS) of various molarities as part of Alkaline Activator Solution (AAS) used in GPC mixes. A common procedure suggested in chemistry to prepare a SHS of molarity say M is to dissolve (M * 40) gms of sodium hydroxide solids in some amount of water and then make up the solution to 1 liter by adding further the water. This procedure, though correct technically, does not give directly the amount of water required to produce the SHS in large quantities with desired molarity. This topic is considered in this paper and a table is given to estimate the quantities of water and Sodium Hydroxide solids required to produce SHS of given Molarity, based on the data available on SHS in Perry's Handbook for Chemical Engineers. NOTATIONS AAS = Alkaline Activator Solution D= Density of SHS, kg/l GPCs = Geopolymer concretes GSM = Geopolymeric Source Material M = Molarity = Concentration of SHS in moles/litre M = Molarity of SHS SHS p = Concentration of SHS = p gram of Sodium Hydroxide Solids per gram of SHS P% = Percent concentration of SHS = P grams of Sodium Hydroxide Solids per 100 gram of SHS SHf = Sodium Hydroxide Solids i.e., Sodium Hydroxide Solids ws = Weight of Sodium Hydroxide Solids in grams per 1 kg of SHS W = Weight of Sodium Hydroxide Solids in SHf W kg of SHS SHS W = Weight of SHS required, kg SHS W = Weight of water for W kg of SHS water SHS 1.0 INTRODUCTION Geopolymer is the term suggested by Davidovits for the inorganic polymer which is alumino-silicate in nature (Davidovits, 2011). Many investigations have been carried out to get geopolymer from source materials containing silica and alumina (Buchwald 2003; Davidovits , 2011; Provis , 2009; Rajamane 2005, 2011, 2012, 2013, 2014; Rangan, 2005; Sindhunata, 2006; Torgal, 2008). Geopolymer Concrete (GPC) with Geopolymer as binder can be highly eco- friendly since its carbon foot print is very low as compared to conventional Portland cement based concretes since GPCs are made usually from industrial waste (such as fly ash) based and do not contain any Portland cement (Rajamane, 2013). However, GPC mixes require Alkali Hydroxide solution as part of the alkaline activator solution required for geopolymerisation of Geopolymeric Source Material (GSM) used. A common alkali hydroxide is Sodium Hydroxide since this is less costly than the other one, namely, Potassium Hydroxide. Various concentrations of Sodium Hydroxide solution (SHS) have been used and the concentration is generally measured in terms of molarity. However, the present authors have found that many civil