Abstract:
Concrete is a mixture of aggregate, cement, and water, of these materials the most
expensive and polluting element is cement. The production process of cement affects the
environment by means of release of CO2 gas into the atmosphere and affects ecology due
to the exploitation of virgin materials. Therefore, searching for other inexpensive
cementing materials is of great attention to deal with such circumstances. The primary
aim of this research is to obtain the capability of using coffee husk ash and bamboo leaf
ash as a ternary blended material in concrete production. The coffee husk and bamboo
leaves that have been used for this research investigation were obtained from the Gamo
zone, which were calcined at a controlled temperature of 550°C and 600°C for two and
three hours respectively. To understand the effect of these materials on the fresh
properties such as workability, mechanical property experiments such as tensile,
compressive, and flexural have been conducted and, for a durability property test acid
attack and water absorption tests have been conducted and for a micro-structural
characterization XRD and SEM have been conducted concerning the designed dosage
replacement content of 0%, 7.5%, 15% and 20% by weight of cement. The result observed
from the experimental studies demonstrated that the workability of mixtures showed a
decreasing trend with an increase in the proportion of the CHA and BLA content, in
which the measured slump values ranged between 42 and 25 mm. On the other hand, the
setting time of concrete mixtures showed an increasing trend with an increase in CHA
and BLA content. The initial and final setting times of the concrete mixtures were within
the range of 81-198 minutes and 298-538 minutes, respectively, which meets the criteria
set by the standards. The compressive strength of the concrete mixtures C7.5B7.5 and
C7.5B10 exhibited an increase of (+0.83%) and (+0.56%) respectively, compared to the
control mix (C0B0), which has a mean strength of 37.04 MPa on the 28th day of testing.
On the 56th day of testing, the replacements of C7.5B7.5 and C7.5B10 further increased
the concrete strength by 2.31% and 1.49% respectively. The water absorption and sulfate
attack resistance of the CHA and BLA-blended concrete showed significant improvements
in the C7.5B7.5 and C7.5B10 dosage contents. Based on these findings, it can be
concluded that the blended mixes of CHA and BLA have the potential to replace cement
up to 17.5% without compromising the quality of the concrete.
