Which of the following is allowed on rebar?

Light rust on rebar is generally considered permissible because, while rust can be an indicator of corrosion, it does not necessarily compromise the structural integrity of the rebar as long as it remains light and does not penetrate deeply into the steel. The presence of light rust indicates that there has been some exposure to moisture, but as long as the rebar remains structurally sound and adheres to the standards set for construction, it can still be used effectively in concrete work.

In construction, clean rebar is preferred, especially in areas where high durability is required, but light rust does not immediately disqualify rebar from being used. Proper inspection and standards allow for certain levels of surface conditions as part of the acceptance criteria for materials used in construction projects. This reflects an understanding that construction materials can be subjected to various environmental conditions during transport and storage without being out of compliance.

The other materials listed—grease, mud, and oil—are generally not acceptable on rebar because they can interfere with the bonding of the concrete to the steel. These substances can create barriers that prevent proper adhesion, potentially leading to compromised structural integrity. Therefore, while light rust may be tolerable within specified limits, contaminants like grease, mud, and oil are not appropriate as