Tell it to the Romans, who used concrete to build The Colosseum, which is still standing.
From E&E newswire – h/t to Marc Morano
Concrete’s life span is shortened by climate change — study
Published: Wednesday, October 15, 2014
Climate change may reduce concrete’s durability, with long-term consequences for buildings, roads and bridges constructed with the common material, according to a recent study.
Matthew Eckelman and Mithun Saha of Northeastern University focused their research on how infrastructure in Boston will be affected by the most extreme climate change scenarios.
They predict about 60 percent of Boston’s buildings will have some structural deterioration by 2050. Eckelman and Saha published their study results in the journal Urban Climate.
“Starting in 2025 is when [we expect] to see the concrete cover on buildings start to fail, assuming they were built to code,” Eckelman said.
Concrete is considered one of the most solid structures humans have engineered. Modern concrete structures and roads are further reinforced with steel bars to make the material less brittle. However, over time both carbon dioxide and chloride ions seep into the concrete and corrode the steel bars, called rebar. This corrosion expands the concrete, destabilizing it. Eventually, the damage becomes visible when the facade of a building cracks or chunks of concrete break off.
The amount of carbon dioxide in the atmosphere is expected to increase with climate change, and Boston in particular is vulnerable to chloride because of its proximity to salt water.
Under current building codes in the United States, buildings’ concrete coverings have to be about an inch and a half thick for the structures to last three-quarters of a century. However, the researchers noted that these building codes don’t take into account how climate is likely to change over that amount of time. When climate change is considered, buildings built today will likely last between 50 and 60 years, roughly 25 years less than if temperatures remained the same, the researchers said.
Eckelman and Saha said the biggest effect will likely be higher construction costs to reduce corrosion, like adding 3 to 12 millimeters of thickness to buildings’ concrete cover. This could increase building costs by between 2 and 4 percent.
The buildings most at risk in the near term are those built in the 1950s and ’60s because they are built with weaker concrete.
The American Concrete Institute, which provides guidelines for setting building codes, is going over its standards while taking into account global warming (Kevin Hartnett, Boston Globe, Oct. 12). — NH