Civil Engineering

PERVIOUS CONCRETE RESEARCH CREATES ALTERNATIVES TO TRADITIONAL PAVEMENT

pervious concrete experiment with water flowing through the concreteA better understanding of the behavior of pervious concrete subjected to severe weather conditions is essential for industry to design and install concrete that will outlast current maintenance practices. Dr. Liv Haselbach’s research investigates potential strengths of using pervious concretes over traditional, impermeable concrete used for pavement in urban settings.

“Pervious concrete is a special type of concrete made with few or no fine aggregates making it a permeable material,” says Haselbach. “In an urban setting where roads, buildings, parking lots and sidewalks are almost 100% impermeable, the use of pervious concrete as a pavement surface course allows water to seep through, reduce runoff, alleviate flooding and brings many other benefits, such as recharging groundwater and reducing urban heat islands.” Because of these benefits, it is considered a Best Management Practice by the Environmental Protection Agency, and its application can contribute to a Leadership in Energy and Environmental Design certification.

When pervious concrete pavements are installed in cold climate areas, they are subjected to deicing chemicals and freeze-thaw cycles, as with any other kind of pavement. However, during severe winters, there is evidence this material can be more heavily affected than traditional concrete pavement. This is due to the porous structure of the pervious concrete that allows deicing chemicals to accumulate and infiltrate precipitation to freeze-thaw within its structure. It is not clear whether the deicing chemicals, the freeze-thaw cycles or both are responsible for the failure of pervious concrete in cold climates.

Dr. Haselbach’s research intends to further investigate the behavior of the pervious concrete when subjected to the above conditions. To better understand how deicers can chemically and physically affect the cement paste matrix, aggregate bonding, pavement durability and strength, a series of laboratory experiments must be conducted using various deicing chemicals including, but not limited to: sodium chloride, magnesium chloride and calcium chloride.

“A better understanding of the behavior of pervious concrete when subjected to severe winters is crucial in order for the industry to design and install pervious concrete that is more resistant to wintertime maintenance practices,” says Haselbach. Her research will suggest a testing procedure comparing various mix designs and their resistance to deicing degradation. This will enable the industry to more efficiently and economically implement the installation of this alternative pavement, promoting low-impact, sustainable development.

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