 Or you could use caulks that are specifically designed for concrete that are latex-based. Quikrete makes products like that. And as to the color, if you're concerned about the color, I'll give you a trick of the trade. But it's a little bit above the average DIYers. But what I've done is I've found areas in the concrete that weren't that visible, like on the side or the bottom of the step or slightly below grade.