Porosity Optimization in Cement Composites with Waste Plastic Additives Using the Taguchi Method

In this study, the effects of using PET and ABS waste plastics as fine aggregate substitutes on the porosity of cement composites were optimized using the Taguchi L8(2³) experimental design. Currently, the depletion of environmental and natural aggregate resources of plastic waste is increasing the need for sustainable building materials. The parameters determined were the plastic type (PET, ABS), the plastic substitution ratio (0.5%, 1.5%), and the fly ash ratio (5%, 10%). The water/binder ratio was kept constant at 0.35 in all mixtures. Porosity values were determined experimentally according to the ASTM C642 standard. Signal-to-noise (S/N) ratios were calculated according to the “smaller is better” quality characteristic, and optimum mixture parameters were determined by ANOVA analysis. The results showed that the porosity values ranged from 8.44% to 14.02%, and the optimum mixture was PET (0.5%) + fly ash (10%). Plastic type was identified as the most dominant factor with a 43% contribution rate, while plastic content contributed 31.5% and fly ash content 22.5%. PET-modified samples exhibited significantly lower porosity values compared to ABS. The Taguchi method was found to be an effective and reliable method for optimizing porosity in cement composites with waste plastic additives.