Geopolymer synthesis by the alkali-activation of blastfurnace steel slag and its fire-resistance

Geopolymer has been synthesized by the activation of blastfurnace steel slag (GGBFS) using 6% (NaOH) or 3% NaOH + 3% Na2SiO3. The geopolymer obtained in both cases exhibits an amorphous homogeneous and tightly-packed structure as well as a high compressive strength exceeding, that obtained by conventional mortar. In testing the response toward elevated temperatures it has been found that the geopolymer formed using 3% NH + % NS as activator reveals high stability and fire resistance where it retains high strength values even upon exposure to temperatures up to 500 °C. The results clarify, also, that the geopolymer possesses stability and fire resistance higher than those exerted by normal concrete. The current study indicated the feasibility of the alkali - activated BFS geopolymer as a fire resistant coat substituting the reinforced concrete coat to lightweight polystyrene panels used for walls, roofs and partitions in construction work. Such introduced coat offers the following merits relative to the reinforced concrete coat: lower density, higher strength, higher fire-resistance, free of steel mesh reinforcement and reduced cost. The results of the present investigation clarify that geopolymerization could be considered as a viable technology for the conversion of industrial by-products having an aluminosilicate composition into attractive construction materials.