Development of fly ash based geopolymer precast concrete elements

In view of the serious impact of carbon dioxide on the environment and the continued anticipated growth of industrialization and urbanization, there is a need to redirect the building industry away from its overwhelming reliance on Portland cement by developing alternative binder systems like geopolymer binders. It is proposed that an alkaline liquid could be used to react with the silicon (Si) and the aluminum (Al) in a source material of geological origin or in by-product materials such as fly ash to produce cementitious binders. Experiments have been conducted at Annamalai University, India on the behaviour of fly ash based geopolymer concrete and structural elements such as beams. The mechanical properties of geopolymer concrete such as compressive strength, split tensile strength and flexural strength have been found out and compared with that of ordinary cement concrete. Five beams of size 125 × 250 × 3200 mm were cast and tested. Out of this five beams,one beam is control beam with normal cement concrete and the remaining four are geopolymer concrete beams with Alkali-Activator Solution / Fly ash ratio 0.40, 0.45, 0.50, 0.55 and comparable compressive strength. The alkaline Alkali-Activator Solution used in this study is a combination of sodium hydroxide and sodium silicate. The load-deflection and moment-curvature behaviours obtained from the experimental results are compared with analytical solutions.