Rusty Rebar

We have all heard our customers say it. They don’t want rusty rebar. The inspectors will hate it and it won’t be accepted.

And we have all heard the opposite, there is nothing in the ASTM manual of standards that suggests we cannot use rusty rebar, so long as the deformations (the ridges) are intact.

The truth is that both are right.

There is nothing in the ASTM manual of standards, which are the standards that 99.8% of inspectors use for their work, that prohibits using rusty rebar.

But when we are doing flat work, or concrete tilt-up, or concrete construction that will be seen artistically, we may want to specify that the rebar be “bright.” And sometimes different cities or counties have different building inspection requirements for foundations.

Some mills have rebar that rusts more quickly than others. Mills with extra “mill scale”, a very light flaky surface produced in the hot roll process, can actually keep the bar looking nicer for longer. On the other hand, sometimes bar that is “quenched” creates an outer crust that results in a more even cooling and stronger tensile properties.

In short: consider the needs of your project and your inspector. There is nothing wrong with rusty bar, except that it may possibly leave a rust stain in the slabs during the pouring process.