Thermographic Evaluation of Concrete Masonry Walls: Have They Been

Properly Reinforced?

Gregory R. Stockton

Stockton Infrared Thermographic Services, Inc., Randleman, NC

ABSTRACT

Infrared thermographers literally walk by more work than they can do. The world is one big radiator, and new, non-

traditional applications for infrared thermography are being found every day.

This paper discusses one of these non-traditional applications; specifically, the use of infrared thermography to find whether

or not concrete reinforcing (grouting) has been properly placed in Concrete Masonry Unit (CMU) or 'block' walls. These

walls are being erected everywhere. They are used to build discount stores and shopping centers, schools and buildings of

every size and shape. They are almost never built exactly to specifications, and by using infrared th ermography it is possible

to see and report the faults in the walls, so that timely repairs can be accomplished.

This paper discusses the development of the technique that we use to image and evaluate these building walls successfully,

and to make usable reports of our findings. I also discuss some market factors for infrared on buildings in general.

Keywords: infrared, thermography, concrete, masonry, CMU, walls, grouting, reinforcing, construction

1. INTRODUCTION

The infrared inspection of buildings for heat loss was one of the first commercial uses for infrared thermography. Annually, I

get at least thirty inquires, mostly from our website, from people who are interested in going into the infrared business with

the idea of checking buildings for heat loss. I tell them the following:

There are four types of buildings by use: residential, commercial, industrial and institutional. Because energy prices in the

United States are held low relative to the rest of the world, heat loss surveys are not performed often on buildings.

Residential owners move frequently and since IR and blower-door testing is not itself remedial, they are not willing to spend

very much to find out what is wrong, unless they are uncomfortable. Commercial buildings are often leased to a tenant who

does not want to make repairs to a building not owned by him. The commercial building owner sees no need in repairing the

building because he is not paying the utility bills. Industrial building owners will not fix the building unless the operation is

being affected. Heating and cooling the building is a small part of his utility bills anyway. They also have more important

issues to deal with, like making the widget machines run faster. Institutional buildings, like schools and government

buildings are usually built under a rigid set of guidelines. These designs are perceived to be sound, as are the buildings.

So until the occupants are miserable, damage is occurring or the operation is affected, and as long as energy prices remain

relatively low, heat loss is not perceived to be a problem by building owners. That is why performing heat loss surveys for a

living does make the basis of a very good infrared business. Below, I will deal with the structural inspection of the walls of

one type of building: CMU or concrete masonry unit. Fig. 1 is a photograph illustrating typical CMU construction.