The compressive strength of the cement paste containing palm oil fuel ash size high fineness cement is
contributed by hydration reaction, packing effect and pozzolanic reaction as shown in Figure 3. At 7 days,
the compressive strength of 10G2POA cement paste was higher than that of OPC cement paste. It was
packing effect plus pozzolanic reaction. For example, at the age of 90 days, Percentage hydration reaction,
packing effect and pozzolanic reaction of the 30G2POA cement paste were 71%, 5%, and 29%,
respectively, while the compressive strength was higher than that of the control cement paste OPC. This
indicated that high fineness of palm oil fuel ash had excellent pozzolanic reaction and the small particles
could also in the voids of cement paste. Therefore, the G2POA cement paste more homogeneous and denser.
This resulted in an increase in the compressive strength (Chindaprasirt et al. 2005; Isaia et al. 2003).