Abstract

Geopolymer cements were prepared using a bioactive waste like Egg Shell Powder (ESP) and Commercial Calcium Carbonate (CCC). These geopolymer cements were prepared by adding 6M phosphoric acid as a chemical hardener to siliceous clay containing 0, 3, 6, 9, 12 and 15wt. % from ESP and CCC. Results showed that Toshka clay (T-C) which is siliceous material, and it is mainly composed of kaolinite, illite and quartz phases. This was confirmed by the XRD patterns, and other trace minerals have also been found. The ESP is composed of calcium carbonate, CaCO₃. Results showed that the bulk density of the prepared geopolymer cements improved and increased with the gradual replacement with ESP or CCC at the expense of the T-C only up till 12wt. %, while the water absorption and apparent porosity decreased, whereas the flexural and compressive strengths improved and enhanced. However, all the characteristics of geopolymer cements based on ESP are higher than those based on CCC. The optimum geopolymer cement was that incorporated 12wt. % ESP waste because it achieved the best results. It was also concluded that the low-grade calcium carbonate-rich wastes of the egg shells could be used as a pore-forming agent to produce porous geopolymer cements. This could be successfully utilized as thermal insulation units if the geopolymer cement incorporated high amounts of it.

Keywords: Geopolymer; Clay; Egg shell; Hardener; Density; Porosity; Strength