Optimising hybrid fibre and nanocellulose reinforced engineered cementitious composites using Taguchi-TOPSIS analysis

A structured approach to optimising the constituents of engineered cementitious composites (ECC) is crucial for reducing resource intensity and improving design efficiency. This study presents the design of a novel sustainable ECC that simultaneously achieves high strength and ductility, incorporating hybrid fibres, nanocellulose (NC), and high volumes of fly ash and silica fume. A novel approach utilising the hybrid application of Taguchi- Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) methods is adopted for the design, enabling systematic and precise adjustment of mix constituents and leading to optimized performance. The standard Taguchi orthogonal array, consisting of four factors, i.e. fly ash to silica fume ratio, water-to-binder ratio, fibre proportions, and nanocellulose dosage, was used to design the mix. The optimum combination of these constituents was determined to maximize five key response parameters: compressive strength, elastic modulus, flexural strength, tensile strength, and ultimate tensile strain. Results indicated that fly ash to silica fume ratio of 1:0.2, a water to binder ratio of 0.22, 1.5 % polyethylene +0.75 % steel fibre by volume, and 0.25 % NC by weight represent the optimal mix design. This mix achieved a compressive strength of 71 MPa, an elastic modulus of 30 GPa, a flexural strength of 17 MPa, an ultimate tensile strength of 4 MPa, and an ultimate tensile strain of 3 %. The optimal design was further validated by experimental results, which showed that the optimized mix outperformed all other mixes in all indices. This further demonstrates the effectiveness of the design method and the potential for successfully incorporating nanocellulose in ECC designs.