Concrete has been the most widely used construction material for many years. Various synthetic and natural materials, such as polymers, fibers, and other additives, are incorporated into the concrete structure to enhance its compressive, tensile, and flexural strength, durability, and overall physical properties, thereby improving its performance under different environmental conditions. Additionally, the use of these additives in combination with concrete materials helps reduce their environmental impact. In this study, concrete mixtures were modified with microcompound a widely used polymeric material and fibrous strands derived from waste plastic strapping. The effects of these materials on the mechanical properties of concrete were investigated. To this end, compressive and flexural strength tests were conducted on 15×15×15 cm cubic specimens, 15×30 cm cylindrical specimens, and 10×10×50 cm rectangular prism specimens. The results showed that the average compressive strength of concrete containing microcompound and fibrous strands from waste plastic strapping increased by 12.25% compared to the control samples at 7, 28, and 42 days. Furthermore, the average flexural strength of the specimens containing these materials increased by 19% compared to the control sample.