LAUSR

Abstract Nowadays, there has been a growing interest in using recycled aggregate which is locally available from the devastating buildings damaged by the war in Iraq’s Mosul City (2017) as a replacement with coarse natural aggregate in concrete. In the present study, the coarse Normal Aggregate (NA) in high strength concrete (HSC) mixes containing silica fume was replaced by 0%, 50% and 100% of coarse Recycled Aggregate (RA) with the addition of different proportions of polypropylene fiber (PP) of 0%, 0.15%, 0.3%, 0.45%, 0.6%, 0.75% and 0.9%. An experimental program was performed to scout their effects on concrete mechanical properties. The results showed that the addition of PP fiber intensifies the mechanical properties of the RA concrete up to 0.6%, where the increases in compressive strength of the 0%, 50% and 100% RA were 20.8%, 15.2%, and 11.6% respectively. Furthermore, an optimum solution for designing parameters was done by employing the response surface method (RSM), which attained maximum mechanical properties and recycled aggregate, as well as minimum fiber percentage.