Effect of Various Grades of Na 2 SiO 3 on Compressive Strength Development of Eggshells Powder-Based Alkaline Activated Mortar

The effect of various grades of Na2SiO3 on the compressive strength (CS) development of alkaline activated binder mortar (AABM) synthesized from eggshells powder (ESP) with curing time of up to 28 days has been investigated. Three different mixtures of AABM were synthesized from the solid material and alkaline activator solution (AAS). The solid materials consisted of source material and aggregates. ESP was used as the sole source material for the AABM. The AAS was prepared from NaOH and various grades of Na2SiO3 which was characterized by their SiO2/Na2O molar ratio of 2.064 (#1), 2.27 (#2), and 3.3 (#3), respectively. The results showed that the mixture prepared with Na2SiO3 grade #1 has a higher CS than the other two mixtures. The highest CS was 12.31 MPa at 28 days. The CS development was associated with the formation of tilleyite phase as gel binder and it is in good agreement with the XRD analysis.