USE POTENTIALITY OF BANANA LEAF ASH AS PARTIAL
REPLACEMENT OF THE PORTLAND CEMENT IN CONCRETE
Pozzolanic activity; Residue of biomass; Cement replacement
The use of alternative materials in the composition of concretes is
gaining ground in the construction industry. The possibility of
improvements in the physical, mechanical and durability properties of
this composite, with lower associated environmental impacts, encourages
the incorporation of mineral additions of natural origin due to the
generation of large volumes of these wastes and a concern with their
final destination. In this sense, the present research aims to study the use
of banana leaf ash as partial substitution in the binder in Portland cement
concretes. Therefore, aiming to achieve this purpose, the research
methodology will contemplate the characterization of the materials and
the evaluation of the properties of the concrete produced with variations
of the contents of 0%, 5%, 10% and 15% of cement mass replacement by
the ashes. In the ash characterization, specific mass, Blaine surface area,
organic matter content, pozzolanic activity by modified Chapelle and
electrical conductivity, chemical, mineralogical, thermogravimetric and
microstructural (SEM) tests were performed. For aggregates and cement
the physical properties tests were performed. In the next stage of the
experimental program, the concrete was measured by the ABCP method
and, later, the production and molding of the specimens. Regarding the
properties of the concrete in the fresh state, it was found that the
incorporation of the residue decreased the consistency and increased the
specific mass, with a maximum value of 10%. Regarding the properties
in the hardened state, the composite obtained higher compressive
strengths with advancing ages and increasing substitution content, up to
10%, with a decrease in values for the 15% content. Such fact, also
observed for the specific mass. Regarding the physical indexes, the
replacement of banana leaf ash showed lower water absorption and lower
voids index. Thus, with the aid of scanning electron microscopy, it was
possible to verify the presence of C-S-H, Portlandite and Etringite at all
ages, and the presence of spherical voids, which can be characterized as
incorporated air. Therefore, the technical feasibility of this substitution is
favorable, considering the improvements in properties, aiming at the use
in non-structural elements.