Mix proportioning of geopolymer concrete

The method for designing of geopolimer concrete mix proportioning was presented and experimentally verified. The binder was composed of siliceous fly ash and ground granulated blastfumace slag (GGBS). The best relations of the following ratios was establish: alkaline solution/binder, binder/aggregate, fine aggregate/coarse aggregate. Siliceous fly ash GGBS in the binder was varied as : 70-30, 60-40 and 50-50 and it was shown that the addition of GGBS in geopolymer concrete significantly reduces the setting time and helps in attaining strength. The strength of geopolymer concrete was increased with increase in percentage of GGBS in a mix. Geopolymer concrete gives satisfactory result at outdoor temperature by the replacement of fly ash with GGBS. When the alkaline liquid to binder ratio is increased up to a certain point, instead of the compressive strength increasing it actually decreases. The ratio of this maximum has been found to be above 0.45 and below 0.55.