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 isattracting attention nowadays. In relation to that, this study focuses on determining the effects of combiningtwo 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) wasused to model the relationship between the response and the factors considered. Using central compositedesign (CCD) to establish the design of experiment, the researchers was able to reduce the required numberof experimental runs to 20 from a total of 27 runs for 3 level full factorial experimental program that iscommon for responses with nonlinear behavior. Optimization was conducted to determine the optimumamount of PHF and GMS in concrete that could yield maximum compressive strength while keeping theworkability at an acceptable level. As for the results, an increase in compressive strength of concrete wasrecorded with the incorporation of PHF and GMS to concrete. However, decrease in workability wasexperienced due to the amount of fiber reinforcement present in the mix. Results of RSM suggested anoptimum combination of 0.70% PHF content and 7.81% GMS partial cement substitute at 0.47 water-cementratio (w/c) to achieve 27.40 MPa and 2.78 MPa compressive and tensile strength respectively with aminimum 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 theuse of GMS as a partial cement substitute, it could reduce the overall cement requirement for a project thusincurring savings and most importantly promotes the use of environment friendly materials.