The study of the interaction between reinforcement and concrete is important to ensure the composite action of the two materials. A high bond strength is desirable in the reinforcement–concrete interface to avoid pullout failure. The higher bond of reinforcing bars with concrete provides better performance and increases the capacity and service life of structural elements. Bond tests of smooth titanium alloy bars (TiABs) and 60 kips per square inch (ksi) (414 MPa) steel with concrete are conducted in accordance with the ASTM C234. Based on the experimental results, the bond strength of TiABs is generally found to be higher than that of the steel. The paper also presents some preliminary investigation for identifying appropriate and commercially available mechanical couplers for splicing the TiABs. Since TiABs are more expensive than normal rebars, it is necessary to limit their quantity and use in bridge piers (e.g., plastic hinge zone only). Products from a well-known producer of mechanical couplers in the United States are used in the research. A few mechanical couplers are investigated for splicing of #5 (15.9 mm diameter) and #6 (19.1 mm diameter) pseudo-threaded TiABs. Tensile testing is carried out in accordance with ASTM A1034 to address the 2017 AASHTO Load and Resistance Factor Design (LRFD) requirements and a suitable coupler was identified. The appropriate mechanical coupler was identified to be the coupler that is designed specifically for use with high-strength bars. It uses a cold swaged steel sleeve and is thicker.

Approximately 246 million waste tires are generated annually in the United States. That is roughly three tires per four individuals in the country. Most tires end up in landfills, adversely affecting the environment. In the last two decades, researchers have explored using tire chips in concrete to replace a portion of coarse aggregates. Past studies have indicated that up to 50% of coarse aggregates in concrete can be replaced with tire chips. This research proposes using recycled rubber tires and rubber chips in concrete columns. The tires are used as external transverse reinforcement in plain concrete columns. The tires function as formwork during the pour while providing confinement after curing. The concepts in this research can be used for retrofitting structures with inadequate foundations and constructing new structures. After analyzing the data from this research, the axial compressive test of confined columns was 50% greater on average than unconfined columns. The confinement effectiveness ratio for all confined specimens was greater than one.

This paper presents the novel concept of titanium alloy reinforced ultra-high performance concrete (TARUHPC) that can be utilized in bridges. This research highlights the advantages associated with titanium alloy bars (TiABs) and ultra-high performance concrete (UHPC). To validate the concept, pullout tests were implemented to assess the pullout behavior of TiABs with concrete and UHPC. Twelve beam samples (normal concrete and UHPC) were prepared using #6 (ø 0.75 inch) TiABs with different embedment lengths. TARUHPC specimens performed exceedingly better, with an average ultimate force of about 29 kips and a resulting shear stress of 1.82 ksi.