Physical Properties:
- Expansion : – Once embedded in the concrete, rebar must have a thermal coefficient that is as closely identical to the concrete’s as possible. In other words, they must expand and contract at the same rate. Why? Because concrete has weak tensile strength. Thus, spalling may occur if there is tension between the rebar and the concrete due to differing expansion rates.
- Rusting: – If you notice rust on rebar, then do not be alarmed at first. A certain amount of rust is not only expected by acceptable. The real issue is whether the rust is causing a considerable amount of corrosion in the bar. If so, the rebar may not be usable.
- Low Magnetic Permeability: – For concrete structures that require a low magnetic field, stainless steel rebar reduces magnetism, thus ensuring that machinery or processes within certain buildings will receive little to no disruption.
- Elongation under load – Steel reinforcement has significant elongation under load providing for well-defined cracks in the structure during overload conditions. Such cracking provides suitable warning for occupants regarding the loading of a structure. Materials that do not exhibit non-elastic behavior under load may not provide sufficient ductility to warn of impending failure.
- Fatigue – The fatigue properties of steel reinforced concrete structures are well understood.
- Bond development – The development strength of reinforcing steel in both straight and bent conditions is well researched and understood.
- Yield – At loads less than yield, steel exhibits elastic properties that enable a structure to rebound upon reloading. Steel reinforcement is available with yield strengths from 40 to 100 ksi. The yield strength of steel is not dependent on the bar diameter and substitution of different combinations of bars with the same bar area may be readily provided. This provides flexibility in the methods of obtaining the same properties in a concrete structure.
- Thermal properties – The modulus of thermal expansion of steel reinforcement is very similar to that of concrete. Due to the similarity of concrete and steel thermal properties additional stresses or deflections are not introduced upon heating the concrete structure.
- Strength retention – Under heating from fire, steel is able to withstand high temperatures before strength and ductility properties change. Many concrete structures that have been subjected to fire can be rehabilitated using the existing reinforcing steel.
- Joining – Steel reinforcement can be joined using welding or couplers that have strengths similar to that of the reinforcing steel.
