Although we don't actually want concrete to crack, we certainly expect it to, and all good designs plan for it. Indeed, the reinforcement in concrete doesn't even begin to work until it cracks. We even put in lines of weakness and beg the cracks to follow, which of course they sometimes don't.
But there is not always agreement on just which cracks should be repaired and how they should be repaired. Several years ago, in the pages of the International Concrete Repair Institute's Concrete Repair Bulletin (May/June, July/August, and September/October 1993), James Warner and John Trout "agreed to disagree" on this topic. We asked them if they had changed their minds (definitely not) and excerpted much of what follows from that exchange. James Warner is a concrete repair consultant in Mariposa, Calif., and a regular contributor to ICRI's Concrete Repair Bulletin. John Trout is with the Lily Corporation, Aurora, Ill.; he speaks on epoxy injection at the World of Concrete and has published a book on the subject (Epoxy Injection in Construction) that is available from the Hanley-Wood Bookstore (800-323-3550 or www.worldofconcrete.com).