OPTIMIZATION OF COMPRESSIVE STRENGTH OF CONCRETE WITH PIG-HAIR FIBERS AS FIBER REINFORCEMENT AND GREEN MUSSEL SHELLS AS PARTIAL CEMENT SUBSTITUTE

Abstract

The feasibility of different waste materials as substitute to the main components of concrete is
attracting attention nowadays. In relation to that, this study focuses on determining the effects of combining
two waste materials namely, pig-hair fibers (PHF) as fiber reinforcement and crushed green mussel shells
(GMS) as partial cement substitute to the properties of concrete. Response Surface Methodology (RSM) was
used to model the relationship between the response and the factors considered. Using central composite
design (CCD) to establish the design of experiment, the researchers was able to reduce the required number
of experimental runs to 20 from a total of 27 runs for 3 level full factorial experimental program that is
common for responses with nonlinear behavior. Optimization was conducted to determine the optimum
amount of PHF and GMS in concrete that could yield maximum compressive strength while keeping the
workability at an acceptable level. As for the results, an increase in compressive strength of concrete was
recorded with the incorporation of PHF and GMS to concrete. However, decrease in workability was
experienced due to the amount of fiber reinforcement present in the mix. Results of RSM suggested an
optimum combination of 0.70% PHF content and 7.81% GMS partial cement substitute at 0.47 water-cement
ratio (w/c) to achieve 27.40 MPa and 2.78 MPa compressive and tensile strength respectively with a
minimum recommended slump of 25 mm for concrete beams and columns as per ACI. Based on these results,
PHF-GMS concrete could be used in structures not requiring compressive strength above 28 MPa. With the
use of GMS as a partial cement substitute, it could reduce the overall cement requirement for a project thus
incurring savings and most importantly promotes the use of environment friendly materials.