Experimental investigation of the combined effects of TiO2 Nanoparticles (TNP) and WasternPlastic Fiber (WPF) for the modifications of concrete materials has been conducted. The TNPrnpartially substituted cement by the wt. % of (0, 0.5, 1.0, and 1.5) and WPF partiallyrnsubstituted sand by the wt. % of (0, 0.2 and 0.4) in C-25 grade concrete. The strength forrnmodified and unmodified concrete after 3, 7, and 28 days of curing has been tested. Thernresults showed that the maximum strength and durability were achieved by combined effectsrnin comparison to all other concretes for all the curing days. The SEM analysis of concreternmodified with both WPF and TNP showed a densified and well-compacted microstructurernthan unmodified and also only TNP modified concrete. The XRD analysis of concrete rnmodified with both WPF and TNP showed the existence of more phases, which are rnresponsible for strength modification than only TNP modified and unmodified concrete.rnFurthermore, the thermal analysis of the samples was conducted with DSC-TGA (DifferentialrnScanning Calorimetry-Thermo-Gravimetric Analysis). The maximum weight loss wasrnrecorded for unmodified concrete at lower temperatures than modified concrete. The problemsrnassociated with conventional concrete materials with respect to a maximum load resistance,rncompressive strength and splitting tensile strength, and crack-resistant behavior has beenrnmodified. Achieving high strength, gaining high quality, and long term serviceability wererncritical issues to Ethiopian construction sectors and in other countries as well. In this study,rnthe combined effects of TNP and WPF addressed the challenges of concrete cracking andrndurability properties.