A fairly new rust stain may succumb to the mild acid of white vinegar. Pour the vinegar over the stain, let sit for 10 minutes, then scrub with a stiff nylon brush. Rinse and repeat if the concrete doesn’t come clean. For old or large rust stains, use commercial rust remover.

Make sure the surface is clean, apply the rust remover or acid (following the instructions and safety precautions on the bottle), let it sit for five to 10 minutes, then scrub and rinse. Use a brush that’s appropriate for your concrete to avoid damaging it. For particularly stubborn stains, rinse the acid away with a pressure washer.

For cleaning concrete, pour the lemon juice or vinegar directly onto the rust stain and allow it to sit for ten minutes, so the ingredients can fully penetrate the rust. Using the scrub brush, scrub the stain, using a considerable amount of pressure. Rinse the area off with cold water.

You should find that a warm water/dish soap mix removes rust stains easily from concrete, though you should avoid scrubbing too hard so as not to mark it. Failing that, try lemon juice on the stain, allowing it to soak in before wiping it away and rinsing off. In both cases, allow to air dry.

Apply the lemon juice or vinegar all over the rusted surface and allow it to sit and penetrate the rust for at least ten minutes; then, using a wire brush, scrub the rusted area using enough pressure. Work in small circles to remove as many of the rust stains as possible, then rinse off the area with cool water.