Paving our way to green

Segmental paving dates back to the Roman Empire. Treating a road surface like a wall buried in the earth, they created a series of primary and secondary roads that together covered almost 200,000 miles (321,900 km). Built to last for a century, these roads shared the characteristics of a straight path, gradual gradients, curved surfaces for water run-off, curbs, and gutters. Often 6 feet (1.8 m) thick, the primary roads consisted of a series of rock, stone, and gravel layers covered with paving stones.

Today, asphalt covers more than 94 percent of the paved roads in the United States; it’s the popular choice for driveways, parking lots, airport runways, racetracks, tennis courts, and other applications where a smooth, durable driving surface is required.

Interlocking concrete pavement (ICP) or permeable interlocking concrete pavement (PICP) consists of manufactured concrete units that reduce stormwater runoff volume, rate, and pollutants. Placed in segmental paving much like the Roman’s did, today’s version is made of precast, high-strength concrete paving units. They are designed with small openings that create permeable joints. The openings typically comprise 5% to 15% of the paver surface area and are filled with highly permeable, small-sized aggregates. The joints allow stormwater to enter a crushed stone aggregate bedding layer and base that supports the pavers while providing storage and runoff treatment.

The physical properties of pavers provide longer pavement life, reduced maintenance costs and extend the replacement cycle while conserving the use of raw materials. It can use local materials and recycled content that reduces energy requirements and carbon footprint. Segmental concrete pavements withstand freezing temperatures, snow plows and deicing materials.

For more information about this sustainable approach to roads and paved surfaces, visit Interlocking Concrete Pavement Institute.

For more information about urban naturalization and how it relates to you, visit