This rock-like aggregate is made from recycled post-consumer glass | Chesapeake Virginia Dump Truck, Aggregate, Excavation Company

• The substance weighs 85% less than stone, has insulating qualities and could be used for green roofs and gardens. Drexel University and Lafayette College researchers are looking to use it as aggregate in concrete to create a lighter alternative for nonstructural uses.
• Europe has been using foamed glass aggregate for decades in road building and bridge abutments. Transportation departments in Maryland, New Jersey, New York, Pennsylvania and Virginia have given an initial OK to use the product, with Pennsylvania's Transportation Department already using the aggregate under a section of a reconstruction project.

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As material shortage concerns grow and material prices continue to rise, more firms are looking at alternative building methods, including what can be made from recycled materials. Engineering firm Arup, for example, suggests that the 60 million tons of food discarded each year could make building materials, helping to reduce the more than 534 million tons of waste the construction industry produces annually.

Building with recycled materials also could reduce buildings' substantial carbon footprint — they account for 70% of power consumed in the country both through their electricity use and through manufacturing high-carbon footprint materials like steel and concrete. Driven by trades such as insulation, roofing, framing, exterior siding and interior finishes, a Research and Markets report forecasts the world market for sustainable construction materials will be $187 billion by 2026.

Not only does foamed glass aggregate provide a lighter alternative to stone and concrete — something much-needed in applications where heavier fill materials would crush underground utilities or soft soils — but it also may become more mainstream as global sand shortages grow, which would adversely impact concrete production.

Europe, where foamed glass aggregate was developed decades ago, has led the way on numerous sustainable actions. It launched the BREEAM green-building standard in 1990, which rates existing buildings on performance criteria rather than focusing on prerequisites for certification like the U.S. Green Building Council's LEED. Last year, BuildingWise and BRE Group introduced BREEAM USA.

The continent also is a leader in 3-D printed buildings. In October, a Netherlands university completed the world's first 3-D printed concrete bridge and a month later, Denmark-based Printhuset completed Europe's first 3-D printed building.