WARNING: This article discusses the tragedy of the Champlain Tower South in Surfside, FL, and might be an emotional trigger for some readers.
At the time of the writing of this article, the Champlain Tower South tragedy in Surfside, FL, is still a fresh incident receiving almost twenty-four-hour news coverage. Although many factors are responsible for the building’s failure and eventual collapse, we are focusing on the reported issues involving the concrete. Therefore, in this article, based on the information already known as of July 6, 2021, we will discuss the concrete issues and the importance of inspection and maintenance.
What Is Concrete?
Concrete is a composite material created through the bonding of fine and coarse aggregate. A composite material is anything that comes from two or more materials that are chemically different combining. Then the chemical reaction creates a new or composite material. An aggregate for construction purposes is grained materials such as sand, gravel, stone, etc.
What Is The Average Lifespan Of Concrete?
Concrete structures should last 75 to 100 years. However, other factors might change the concrete’s life expectancy. For example, the average lifespan of concrete used in apartment buildings is between 50 to 60 years and a house around 40 years. For buildings closer to the ocean, such as the Champlain Tower South, saltwater, hurricanes/tropical storms, and flooding can deteriorate the concrete, thus decreasing the lifespan. Champlain Tower South was on the ocean in an area known to experience extreme weather and flooding. Builders completed construction on the tower 40 years ago, so the concrete used in its construction was likely at the end of its useful age.
What Are Other Factors That Can Weaken The Concrete?
Although many factors can weaken a concrete structure, below are the five common reasons for concrete failure.
Corrosion of steel reinforcement, such as the metal rebar that construction workers place inside the concrete to reinforce it. Salt causes the metal rebar to corrode. Of course, this is a problem for a building so near to the saltwater spray of the ocean. Builders cannot stop this corrosion, but there are some preventative measures that they can take. To prevent this corrosion, professionals recommend surrounding the rebar with at least 2 inches of concrete. Additionally, contractors should mix the concrete with a low water ratio.
Sulfate can also weaken concrete structures. Issues tied to sulfate are typical in areas where there is hard groundwater, industrial areas, or near seawater. The sulfate attaches to the outside of the concrete and eventually deteriorates the concrete from the outside inwards. Builders can reduce the risks associated with sulfate with the type of aggregate used to mix the concrete.
Finish delamination is when water or air gets trapped right under the surface of the concrete. This water or air takes the place of what would have normally been a solid material, thus making the structure weaker. This can be a problem for concrete that is out in the open, such as in a parking garage structure.
Freeze deterioration occurs when the concrete becomes saturated with moisture while being exposed to freezing temperatures. This is common in areas where there is a water source and temperatures can dip below freezing, such as New York or Chicago.
Alkali-silica occurs when silica aggregates were used to create the concrete and are exposed to humidity. This can cause the silica in the concrete to cause cracks. These cracks usually expand into bigger and deeper cracks that can cause the structure to fail.
How Can We Avoid Catastrophe?
Although there were likely multiple issues that led to the Champlain Tower South tragedy, one thing that needs to be done is that when the concrete of a structure begins to deteriorate, we should not ignore it. In some cases, it is impossible to just repair the damage. Many times, building managers need to get contractors to replace parts of the concrete completely to ensure the stability of the overall structure. Building owners and managers need to schedule regular maintenance and structural checks.
Thoughts And Prayers
Hicks APC would like to extend our thoughts and prayers to those who are suffering due to the tragedy of the Champlain Tower South.