Fresh, microstructural and mechanical properties of the GGBFS/bamboo leaf ash based geopolymer paste

Ground Granulated Blast furnace slag (the GGBFS) is known as a potential by-product that can be used as a source of alumina-silicate in production of the geopolymers. The GGBFS based geopolymers possess disadvantages such as high shrinkage, low workability and short setting time. It has been proven that these defects can be reduced by partial replacement of the GGBFS by the other low calcium alumina-silicate materials. The bamboo leaf ash (BLA), which contains high content of SiO2 and low content of CaO, can be one of these materials. In this article, the effects of bamboo leaf ash on fresh, microstructural and mechanical properties of the GGBFS and the GGBFS/natural zeolite powder based geopolymer pastes have been investigated. Moreover, effect of the NaOH solution concentration( i.e. 8, 12 and 16 mole/liter) and the Al/Bi ratio (i.e. 0.5, 0.6 and 0.7) on properties of the geopolymer pastes have been evaluated. The results show that replacing 10% wt. of the base materials by the BLA in the studied geopolymer pastes leads to an increase in the workability and setting time. While, this substitution results a reduction in the amount of crystalline phases produced and consequently a decrease in the mechanical characteristics. Based on the results, as the NaOH solution concentration increases from 8 to 16 mole/liter, the workability, setting time and mechanical characteristics of the GGBFS/BLA based geopolymer paste have been reduced. Moreover,