Mixing was done in an air conditioned room at approximately
25 ◦C. The proportion of each mix was stoichiometrically weighed
according to Table 2. The mixing procedure started with mixing of
NaOH(orKOH) solution, sodiumsilicate (Na2SiO3) and DE for 5 min.
Water was then added and mixed for a further 5 min. The mixtures
were castin50 mm × 50 mm × 50 mmacrylic cubemould. The
specimens were then wrapped with plastic film to prevent moisture
lost during curing. After delayed time of 1 h, the specimens
were cured in an electric oven. The specimens were cooled down
in the oven and then demoulded and kept at 23 ◦C room under
ambient conditions until the scheduled testing. The compressive
strength tests were performed at 7 days in accordance with ASTM
C109; density measurements were also conducted at 7 days. The
reported strength and density values were the mean of three tests.