Optimization of Parameters to Improve the Strength of Concrete Cube Using Bacteria Species
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Date
2018-06
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Publisher
AAU
Abstract
Concrete is the most commonly used building material, but the cracks in concrete create problem
it was main reason for a decreased service life of concrete structures. Most research done used
chemical method which not effective on cost and environmental. So, need of a new technology
to overcome the bottle necking of concrete has led to the development of a very special concrete
known as Bacterial Concrete. The objective of this thesis was optimizing of parameters to
improve the strength of concrete using bacteria bacillus species (Bacillus subitilis, Sporosarcina
pasteurii and Bacillus cibi) self-healing method. Proceed was the bacterial strains were obtained
from Ethiopia Biodiversity Institute and for each bacterial growth in nutrient broth solution for
24-72 hour. Secondly, according to the mixing design twenty seven concrete mixes for each day
and for each bacterial at C25 grades of concrete using water cement ratio 0.58, 0.53 and 0.45 and
cement, fine aggregate and course aggregate contents of 360 kg / m
3,
800 kg / m
3
and 1087.5 kg
/ m
3
were prepared, respectively and tested in 7, 14 and 28 day. Significance of the process
variables were analyzed using analysis of variance (ANOVA). Thus, the influence of all
experimental variables, factors and interaction effects on the response was investigated. Dosage,
time, water/cement ratio and in the case of bacteria Bacillus cibi use interaction between dosage
and water cement ratio have significance effect on the compressive strength. As the result of
RSM optimization, the best compressive strength were found on the 0.45 water cement ratio, 40
ml of dosage and the time after 14day. Also from the three bacterial Sporosarcina pasteurii
selectable or give high compressive strength.
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Keywords
Strength of Concrete Cube, Bacteria Species, Optimization