Determining the Allowed Fiber Content for WHBR (Water Hyacinth and Bio-Resin) FRP Composite as the Future Environmentally Friendly External Concrete Retrofit Material

The effect of water hyacinth fiber produced through a treatment process such as boiling and natural alkali on the volume fraction of fiber in the hand lay-up manufactured WHBR FRP composite has been investigated. Based on the investigations, the content of water hyacinth fiber and tensile properties are linearly related. The higher the fraction of fiber volume in WHBR FRP is, the tensile strength of the composite will increase. However, WHBR with water hyacinth fiber content that exceeds the maximum limit causes a tendency in the form of inter-rope voids. Therefore, by using existing equations and models, a value is obtained to approximate the fraction of the maximum water hyacinth fiber volume of 39.38%. The lowest fraction of fiber volume in WHBR FRP will cause matrix control failure and tensile strength to be lower than the tensile strength of the matrix. Therefore, the minimum and critical water hyacinth fiber volume fractions for each treatment of boiling and natural alkali are found to be 13.6% & 15.5%, and 14.0 & 15.5% respectively. Based on the value of critical and maximum fiber volume fraction, it is determined that the allowed volume fraction of water hyacinth fiber used for WHBR FRP composite is around 18-39%, generally.