Masonry Magazine February 2006 Page. 33
By Gerald A. Dalrymple, P.E.
Principal, Whitlock Dalrymple Poston & Associates Inc.
Gerald Dalrymple, P.E., is providing two educational sessions during the MCAA Masonry Showcase, being held in Las Vegas, March 29-31. "Non-Destructive Test Methods for Masonry" is Thursday, March 30, from 9-10:30 a.m., and "Commercial Masonry Problems & Solutions will be held on the same day from 10:45 a.m.-12:15 p.m. For more information or to register for this industry event, visit www.masonryshowcase.com.
HAVE YOU EVER HAD TO CONVINCE AN INSPECTOR THAT A MASONRY WALL WAS GROUTED?
Have you ever cut an opening in a wall that was supposed to have been grouted only to find that it was not? Have you ever wondered if the reinforcing specified for a masonry wall or footing was actually installed? If so, how did you answer all of these questions in the past? Banging on face shells with a hammer? Making Swiss cheese out of wall sections with hammer drills and core rigs? There are better ways to address these issues today with better accuracy and less destruction of completed work.
Surface-penetrating radar (SPR) and infrared thermography (IRT) are powerful, nondestructive test methods that aid in the assessment of masonry structures. The testing techniques permit rapid "on-the-spot" evaluation of existing construction conditions and document existing conditions in a portable electronic format.
Masonry Evaluation
SPR AND IRT ARE TWO METHODS that have demonstrated advantages in assessing grout placement and can be used to verify reinforcing steel placement and filling of the grout spaces in reinforced masonry construction. SPR has the added advantage of identifying reinforcement embedded in grouted cells.
Each of these methods permits survey of a section with access to only one face and, as such, has an advantage over pulse velocity or x-ray methods, which require access to both faces of the component being surveyed. However, SPR and IRT are only useful after grouting operations are complete and grout curing has progressed to a point where no free water is in or on the grouted section. Therefore, nondestructive testing must usually be started approximately one to two weeks after grout placement.