Dissertação
Estudo da microestrutura do concreto com adição de cinza de casca de arroz residual sem beneficiamento
Fecha
2008-05-07Registro en:
DUART, Marcelo Adriano. Concrete microestruture study with addition of unground residual rice husk ash without burn control. 2008. 134 f. Dissertação (Mestrado em Engenharia Civil) - Universidade Federal de Santa Maria, Santa Maria, 2008.
Autor
Duart, Marcelo Adriano
Institución
Resumen
The use of mineral adition in concrete is a widely studied theme for several researchers that looking for features
like: save cement for reducing costs, durability improvement to increase mechanical strenght and use of
industrial wastes for reducing environmental pollution.
This study intend to analize the microstructure of concretes mixtures with ungrounded residual rice husk ash
addition without burn control unground (RHAN), like a partial cement substitute in conventional concrete for
reducing costs, since cement is the most expensive component, and the use RHAN avoiding dumping on
environment like a ground and water pollutant. Five different concrete mixtures proportions: 2 mixes of RHAN,
with 15% and 25% of partial cement substitution, 2 mixes of ground RHA (RHAM), with 15% and 25% of partial cement substitution, for comparison, and a control design, withouth adition. All concrete disigns were developed for 3 water/binder relationships (0,45, 0,55 e 0,65), 15 differents concrete design in total, for ages 28
and 91 days, were done. Tests like: axial compressive strenght, percentual of chemically combined water, mercury intrusion porosimetry,X-ray difraction and image analysis by scanning eletronic microscope (SEM) combined energy
dispersive spectroscopy (EDS) were done. Tests results proved that RHA use is feasible for 15% of substitution
of cement by RHAN, since concretes had values of compressive strenght few smaller than control concrete
values, at 28 days, however higher than it at 91 days.
Because of pozolanic reaction and filler efect combination, of RHAN and RHAM particles, concrete with RHA
adition had microstructural changes like: size pore refinement, total porosity reduction and calcium silicate
hydrate (C-S-H) formation through pozolanic reaction. RHA Inert particles created nucleation sites improving
hydrate crystals formation.