The Synergetic Compressive Strength and Microstructure of Fly Ash and Metakaolin Blend Geopolymer Pastes

The present work deals with the effect of the interaction between fly ash (FA) and metakaolin (MK) geopolymer blend on the development of compressive strength and microstructure. The blended geopolymers were prepared using different solid- to- liquid (S/L) ratios (0.6, 0.8, 1.0, 1.2 and 1.4) and sodium silicate- to- sodium hydroxide (SS/NaOH) ratios (2.4, 2.6, 2.8, 3.0, 3.2). The blended geopolymers were subjected to ambient curing. The aim of this study to measure the performance of the blended geopolymers (two precursors). The differences in microstructure have been correlated to the compressive strength properties. The results indicated that these ratios were optimized at S/L ratio of 1.2 and SS/NaOH ratio of 2.6 which leads to a significant improvement in strength and supported with microstructural study. The association of FA and MK as binary precursors also proved very interesting regarding the compressive strength.