A new type of concrete was made stronger by adding a mix of steel and ultra-high molecular weight polyethylene (UHMWPE) fibers. The researchers tested 16 types of this hybrid fiber reinforced concrete (HFRC) to see how the mix of fibers affected its strength and ability to resist cracking. They found that adding UHMWPE fibers on top of steel fibers made the concrete even stronger. When 0.3% more UHMWPE fibers were added, the tensile strength increased by 13.64%, 49.49%, or 8.08%, and the compressive strength increased by 13.51%, 15.49%, or 14.57% compared to concrete with only steel fibers. UHMWPE fibers were more effective at increasing strength than polypropylene fibers when mixed with steel fibers.