To the best of our knowledge, there are no detailed data regarding
the effect of RHA grinding fineness on hydration reaction of
RHA blended cement matrix at early and later age. The objective
of this paper is to expand the existing research and systematically
study the grinding fineness of RHA on hydration reaction at early
and later hydration stage and porosity of cement matrix. In this
study, RHA sample from controlled burning in electronic furnace
was subjected to mechanical grinding in the laboratory ball mill.
The effect of RHA grinding fineness on the hydration reaction
and porosity of RHA paste is investigated. The pastes were made
from raw and ground RHA of different fineness. Cement hydration
degree in RHA pastes was tested at early and late age by calculating
the weight loss of hydration products through TGA. The weight loss
of hydration products corresponds to the amount of hydrated calcium
silicates (CSH) and calcium hydroxide (Ca(OH)2), which can
be evaluated through thermogravimetric analysis (TGA). The
increasement of the content of CSH and the reduction of the concentration
of lime in cement paste contribute to evaluating the role
of grinding fineness on the pozzolanic action of RHA in the cement
matrix. The porosity of paste incorporating RHA of different grinding
fineness was also determined at selected curing ages using an
environmental scanning electronic microscope (ESEM) and calculated
using image analysis software. The pore size distribution
helped to explain the difference in strength between various RHA
pastes, because a denser matrix tends to produce high strength
performance and good durability.