This research work presents an experimental investigation to applications of recycled aggregate from demolition wastes. The recycled aggregate collected from different demolition sites. Then, the physical and the mechanical properties of the recycled aggregate were measured. The recycled aggregate was used as a replacement to the fresh coarse aggregate with ratios of 5%, 10%, 20% and 30%. The mechanical properties for the different mixes showed that, a replacement of 20% reduces the compressive strength of about 19.3% compared with the control mix. Thus the mix was modified with CdO nanoparticles to compensate the reduction in strength. The used nanomaterial was produced in lab-scale and its activity with cement was measured. Finally, the behavior of 3 reinforced concrete slab specimens with different concrete mixes using fresh, recycled and recycled aggregate in addition with nanoparticles were investigated under three-point loading. The adding of CdO nanoparticles showed a significant improvement in behavior of the reinforced concrete slab specimens.