Compositions of geopolymer in mole ratios of samples No.
1–10 investigated are shown in Table 2. The concentrations of
NaOH andKOH of 4, 6, 8, 10 and 12 Mand Na2SiO3/NaOH ratio of
1.23 were used. In this respect, starting Na2O/Al2O3 ratios were
varied from 0.66 to 1.09 with the constant starting SiO2/Al2O3
of 13.0 as shown in Table 2. After delayed time of 1 h, specimens
were cured at 60 ◦C for a period of 3 days.