Pervious Pervades

Waldorf, Md.-based Chaney Enterprises emphasizes that its Drain-Crete pervious concrete marks the company's latest iteration of a time-tested product

Waldorf, Md.-based Chaney Enterprises emphasizes that its Drain-Crete pervious concrete marks the company's latest iteration of a time-tested product to meet 21st century challenges. The constituent material of Roman viaducts that are still standing, as well as highway networks covering entire continents, concrete has spanned the ages, the producer notes.

Yet, the advent of petroleum-based asphalt binder, spurred by an oil boom during early decades of the 20th century, occasioned a setback for ready mixed concrete, which for pavements proved more expensive than asphalt and required longer placing and setting times. Throughout the 1950s, faster and cheaper asphalt pavement methods met the skyrocketing demand for roads to accommodate a burgeoning fleet of automobiles. Today, however, environmental concerns, plus escalating crude oil costs and the increasing scarcity of petroleum by-product due to greater oil-refining efficiency, favor concrete pavement options that offer unparalleled ÎgreenÌ construction benefits at stable prices.

MEETING ÎGREENÌ IMPERATIVES

In view of climate change concerns, concrete provides an attractive alternative to asphalt, which absorbs light and creates a heat island effect. By nature reflective, concrete pavements minimize surface heat under sunlight glare; and, less overhead lighting is required at night due to more effective light spill. Accordingly, energy savings tied to a concrete pavement can reach 30 percent compared to an asphalt alternative.

Further recommending the use of concrete is its longer lifespan, reducing maintenance costs over time. The use of recycled content, e.g., fly ash (a by-product of coal-fired power plants), blast-furnace slag, and concrete aggregate, in ready mixed also enhances its value as a sustainable construction material.

Adding to conventional concrete's environmental benefits the potential for stormwater pollution control, Chaney's Drain-Crete signature mix comprises largely the same materials minus sand, creating a dense, durable, yet porous surface that allows water penetration to prevent ponding. Stormwater management is thereby achieved, as groundwater is replenished, runoff into local watersheds virtually eliminated, and EPA regulations satisfied. Moreover, the product filters out water-borne pollutants (e.g., heavy metals, suspended solids, even petroleum products) and helps provide more air and water to tree and plant roots. To ensure quality and long-term pavement performance, Chaney Enterprises requires certification of Drain-Crete installers, hosting National Ready Mixed Association-modeled training sessions as needed for construction teams.

MAINSTREAM MOMENTUM

Recognizing its valuable properties, engineers and government officials more commonly are taking note of pervious concrete and revisiting planning ordinances to incorporate the mix in planning and construction codes. In 2006, the City of Chicago Department of Transportation initiated a Green Alleys pilot program, placing permeable pavement in five alleyways, followed by 30 to 45 such installations every year since. A late-2009 Chicago Tribune report cited a total of 98 green alleys, concentrated primarily in neighborhoods closer to Lake Michigan where sandier soils are conducive to drainage.

In the southern Maryland region, Chaney's Drain-Crete has been used for residential driveways to waterfront homes, a pathway for the Smithsonian Environmental Research Center in Edgewater, a parking lot in Lexington Park, and a portion of the golf cart path at Queenstown Harbor Golf Course on the Eastern Shore. Additionally, Queen Anne's County is installing 225 yards of Drain-Crete at an historic site where the county is incorporating green rehabilitation and construction practices to protect the grounds from runoff and pollution.

Another environmentally proactive project owner, Peninsula Regional Medical Center in Salisbury, Md., recently constructed a two-acre Drain-Crete parking lot, reportedly the Eastern Shore's largest pervious concrete installation. The lot was designed by Becker Morgan Group as part of a major renovation project. Its pervious concrete specification, which includes fly ash, complements the Center's Go Green recycling program that aims to reduce or eliminate landfill use. Drain-Crete for the project was supplied by C&D Concrete's Salisbury plant.

With specification changes implemented by Maryland Department of the Environment, we are moving in the right direction to control storm water runoff, affirms Chaney Enterprises Marketing Manager Steve Tripp. We'll see a lot more pervious concrete in years to come.