Sugar cane bagasse ash (SCBA) is generated as a combustion byproduct
of sugar cane bagasse. Composed mainly of silica, this byproduct
can be used as a pozzolan in cement based paste, mortar
and concrete. Several authors [1–6] have found that the use of
SCBA as a partial Portland cement replacement can improve the
mechanical and durability properties of cementitious materials.
The benefits provided by SCBA are due to both physical and chemical
effects. The physical effects are mainly associated with their
influence on the packing characteristics of the solid mixture [3].
On the other hand, the chemical effects (also called pozzolanic effects)
are linked to their capability of providing amorphous silica
that will react with Ca(OH)2 in the presence of water during cement
hydration.
SCBA is usually obtained under uncontrolled burning conditions
in boilers of the cogeneration processes. Thus, the ash may contain
black particles due to the presence of carbon and crystalline silica,
when burning occurs under high temperature (above 800 C) or for
a prolonged time. The quality of the ash can be improved by the
controlling parameters such as temperature, rate of heating, soaking
time and atmosphere, as was reported for rice husk ash (RHA)
[7–10] – a highly pozzolanic material. Considering only the Brazilian
production of sugar cane, approximately 2.5 million tonnes of
sugar cane bagasse ash were generated in 2006. This ash contains
few mineral fertilizers for soils.
In the present work, processing and characterization of highly
reactive SCBA are studied. Initially, different calcination temperatures
were allowed to obtain SCBA with amorphous silica and
low carbon content. Detailed measurements of structural state,
pozzolanic activity and loss on ignition were carried out in order
to compare the performance of the different SCBAs. Subsequently,
one optimal SCBA was characterized according to pozzolan
specifications.