Paving roads with glass: an American experiment from half a century ago that has been replicated over the decades

14/11/2026 12:00

Updated to

14/11/2026 12:00

What to do with millions of glass bottles that end up in trash and cannot be reused? In the early 1970s, the United States found an unexpected but effective solution: crushing them and using them to build roads. This idea, known as glassphalt (a combination of the English words glass and asphalt), turned a common waste into a material for paving streets.

One of the earliest documented experiments took place on October 26, 1970, in Fullerton, California. There, a section of a road in the Fullerton Air Industrial Park was paved with a mixture that included glass from crushed bottles. Additionally, for the test, one part of the road was covered with the new material while another part was covered with conventional asphalt, in order to compare the performance of the two formulations.

The recipe wasn’t simply mixing crystals with tar; rather, according to the technical report from the U.S. Environmental Protection Agency (EPA), the mixture used contained 63% crushed glass, 36% rock dust, and 1% hydrated lime, in addition to the asphalt binder. The goal was to determine whether glass waste could replace some of the conventional materials used in pavement construction.

Tests at over thirty locations

But Fullerton’s experience was not the only one nor the first; a few months earlier, in July 1970, the University of Missouri-Rolla paved an access road using a mixture that contained recycled glass. Two years later, the pavement was in generally satisfactory condition, with slip resistance deemed adequate, and any visible defects were attributed to problems with the road’s foundation.

However, California’s results were less encouraging, as an inspection conducted in March 1972 revealed significant deterioration in the driving surfaces, including material loss, loose glass particles, and the appearance of potholes. Researchers attributed much of this damage to the heavy traffic of vehicles equipped with studded tires during an especially harsh winter, though they also noted possible deficiencies in compaction and the amount of asphalt used.

Despite these challenges, the idea did not disappear. Instead, tests were conducted in approximately 33 locations across the United States and Canada during those years, according to the U.S. Federal Highway Administration (FHWA). Omaha, Nebraska, was another notable site: in August 1971, an entire block in the city center was paved using glass collected through a community bottle-recycling campaign.

This initiative continued throughout the following decades, with examples appearing across the United States over time. Baltimore incorporated recycled glass into the pavement of at least 17 streets between the mid-1970s and the mid-1980s. In New York, approximately 225,000 tons of glass were used in resurfacing projects between 1990 and 1995.

A mixture with some drawbacks

The problem arose when moving to larger-scale projects, which required solving several issues. One of the main ones was adhesion, as water could cause separation between the asphalt and glass particles. Wear and tear on the surface, slip resistance, and the reflections the surface might produce when exposed to sunlight or streetlights were also concerns.

A 1990 report by the Virginia Transportation Research Council concluded that it was possible to incorporate small amounts of glass, between 5% and 15%, into asphalt mixtures under controlled conditions. However, it warned that using it in other layers of infrastructure, such as fill materials or granular bases, might be more practical. The cost of crushing and transporting the material also influenced its feasibility.