3.1.3. Effect of Na2SiO3 concentrations
As shown in Table 4, T7 Tag σf development in all mixtures (different Na2SiO3 concentrations of high (type B) #2, medium (type C) #3, and low (type D) #4) indicated two different patterns. At less than 30 days, the σf reduced with increasing Na2SiO3 concentration. However, the σf values for all mixtures increased after 30 days (up to 120 days).
Lee and Deventer  has previously confirmed the findings reported for mixture #2. Their research indicated greater solid dissolution with high activator concentration. However, it resulted in N–A–S–H gel precipitation at a very early age which was due to the fact that mix-water was not chemically bound to the geopolymer binder (N–A–S–H gels type i.e., NaAlSi2O6). Although, it is an integral component of C–S–H structure constituting the CaO–SiO2–H2O ternary system , the decrease in water loss has least effect on integral binder structure.