Multicriteria performance assessment of sustainable recycled concrete produced via hybrid usage of basalt, polypropylene and glass fiber

Fiber hybridization is a new and effective way of altering the inherent low mechanical properties and durability issues of recycled concrete by using a multi-fiber approach. Research conducted thus far is majorly focused on studying the effects of hybrid fibers on the basic mechanical properties of recycled concrete and no attention is given to the multicriteria-based performance assessment, which is highly important from the perspective of practical applications. The current study is an effort in this regard that intends to evaluate, compare, and rate the multicriteria-based performance of a total of eleven mix formulations prepared with a single and hybrid usage of basalt fiber (BF), polypropylene fiber (PPF) and glass fiber (GF). In addition, two mineral admixtures namely pulverized flyash (PFA) and ground granulated blast furnace slag (GGBFS) were used. From the results of mechanical properties, it is determined that mix formulations comprising hybrid 0.75 %BF-0.25 %PPF and 0.5 %BF-0.5 %GF had the highest strength improvement of 16–21% in compressive strength, 36–49% in splitting tensile strength, and 54–71% in flexural strength. The freeze–thaw assessment revealed that the use of hybrid fibers together with PFA and GGBFS resulted in superior durability performance of recycled concrete specifically in terms of lower length variation (0.055%), lower mass loss (0.39%) and higher UPV (4137 m/s) after 300 cycles. From the cost analysis, it is observed that MRC-1BF had the highest net cost increase of 121.7% of all mixes. Lastly, the multicriteria analysis revealed that the hybrid BF-GF and BF-PPF based MRC had the best performance score and ranking of all formulations, thus implying that their practical use would be highly beneficial in terms of mechanical performance as well as cost-effectiveness.