When Hurricane Andrew hit Florida’s east coast in 1992, many of the structures that were destroyed were not properly constructed. This prompted several changes to the Florida Building Code. Many concrete block structures failed during Hurricane Andrew because of inconsistent grouting of the concrete blocks within the wall system.
Concrete Masonry Walls (CMU), commonly referred to as concrete block walls, are not structurally sound without proper rebar and grouting. Grouting is concrete that is pumped into the center of the blocks; this ties the blocks, the rebar, and the entire wall system together. Without proper grouting, concrete walls are dangerous. In fact, after Hurricane Wilma hit southwest Florida in 2005, several homes under construction with concrete block walls toppled over because they had not been grouted. Obviously, this occurred because the homes were still under construction. But what if homes are constructed without proper grouting? How would you know?
There are several ways to ensure proper grouting. Previously, the only way that a residential or commercial building owner could see inside the masonry wall was to hammer a hole in it and install inspection ports. This usually provides a good indication that the cells have been completely grouted; however, inspection holes do not ensure a solid, thorough pour. Inspection holes are only installed in a few locations in each wall. Proper validation would require hundreds of holes in a typical building. How many holes do you want punched into your brand-new concrete home or building?
If voids are present in the grouted cells, they can reduce the structural capacity of the systems, and in the case of reinforced masonry, can limit the effectiveness of the steel reinforcement. These voids often collect water, leading to interior damage and corrosion of the reinforcement. We find that, in most cases, voids are a result of improper supervision at the construction site. Unfortunately, quality control and project supervision are not adequate during most construction projects and are usually one of the first sacrifices of cost cutting measures. You also can’t rely on county building inspectors to catch these deficiencies because they do not have the time or resources to police every aspect of a construction project.
Today, infrared technology is the best tool for surveying a masonry wall to find deficiencies in the structural components. It’s a fast, inexpensive, and accurate method of quality control for grouted masonry and also provides photo documentation of the project. We provide this service for schools, shopping centers, commercial buildings, government buildings, and homes.
The process of performing cell fill verifications usually requires a full day at the project site. We typically follow the sun throughout the inspection. The sun’s heat acts like a radiator and changes the thermal characteristics of the wall system, depending on whether voids are present within the wall. Sometimes we will artificially heat a wall that does not get direct sunlight during the day. BDG has performed hundreds of these cell fill inspections. We have the expertise, knowledge, and experience to accurately document the structural integrity of even the most difficult projects.
Contact us today for more information about all of our non-destructive testing services.