Abstract:
This research aimed to study the effect of fly ash type on properties of paste, mortar and
concrete that could be applied as a guideline in using different types of fly ash in paste, mortar and
concrete.
The normal consistency of paste, the setting time of paste, the autoclave expansion of paste,
the autogenous and drying shrinkages of mortar, and the slump and compressive strength (fc ') of
concrete were studied. Four types of fly ash were used in ordinary Portland cement (OPC) three
were from Mae Moh power plant and one was from BLCP power plant.
The results indicated that the normal consistency of the paste with fly ash from Mae Moh
power plant (FAM) was less than that of OPC paste while the normal consistency of the paste with
fly ash from BLCP power plant (FAR) was greater than that of OPC paste. Moreover, the setting
time of the fly ash paste was shorter than that of OPC paste. The setting time of the paste with fly
ash containing high free lime (fCaO) showed a faster setting time than one with less fCaO content.
Furthermore, the autoclave expansion of the paste with fly ash containing high fCaO content gave
higher values while the autoclave expansion of paste with low fCaO fly ash was similar to that of
OPC paste. In addition, the autogenous and drying shrinkages of the fly ash mortar were very small
compared to that of OPC mortar. Besides, the autogenous and drying shrinkages of FAR mortar
were greater than those of FAM mortar. Finally, the slump of FAM concrete was higher, while the
slump of FAR concrete was less comparing to the OPC concrete. The f[SubscriptC]' of fly ash concrete was less than that of OPC concrete. When small quantities of fly ash were used, the f[SubscriptC] of each fly ash
concrete was not different. However, when large quantities of fly ash were used, the concrete with
fly ash containing a great amount of SiO[Subscript2] and Al[Subscript2]O[Subscript3] resulted in more f[SubscriptC]'.