How Interlayers Build Roads That Put the Romans to Shame

We owe a great deal to the Romans. Not only did they leave us with the basis for our legal system in the U.S. and much of Europe, but they also (literally) paved the foundation for our modern roads. Roman roads were some of the best in the world, but today, through technologies such as interlayers, we’ve learned how to greatly improve on their legacy and build stronger roads that can last for decades.

Everyone knows America’s transportation infrastructure could use a little help, to say the least. Our highways and interstates that once captured the envy of the developed world are now fading into disrepair in many places, and it’s becoming increasingly expensive to maintain road quality. When cracks and potholes form, contractors are often hired to repave afflicted roads with a fresh overlay of either Portland Cement or Hot Mix Asphalt, but merely applying a new overlay seems somewhat like applying a Band-Aid to a deep wound, especially when reflective cracking can cause serious damage to new repaved roads in a short amount of time. On pavements repaired with merely a new overlay, cracks can return at a rate of one inch per year, requiring yet more repair work and long-term maintenance to be done.

That’s why engineers are working to improve interlayer technology that can arrest the spread of reflective cracking, lengthening the overall lifespan of a road while reducing routine maintenance work on fixing potholes and cracks. Two kinds of interlayers from the Tensar Corporation, for example, the GlasGrid pavement reinforcement system and the GlasPave waterproofing paving mat, do just that.

GlasGrid is an interlayer comprised of a grid structure made from fiberglass strands coated with an elastomeric polymer. This design makes for greatly increased tensile strength and a higher modulus of elasticity that works to prevent the spread of reflective cracking in pavement. The interlayer has proven to be effective in a diverse array of geographic regions, from hot, dry deserts to cold, wet subarctic areas, and it’s demonstrated a real ability to reduce the rate of return cracking.

Waterproofing roads adds an extra layer of durability, and Tensar’s GlasPave interlayer uses this technique to make for maximum road lifespan elongation. Like GlasGrid, GlasPave also uses fiberglass fibers for improved tensile strength, but instead of forming a grid, the fiberglass strands in GlasPave are formed into a mesh and embedded into high performance polyester mats. This creates a matrix system that allows an asphalt binder to penetrate through the mat, sealing the pavement off from moisture that likes to seep into the road, eating away at pavement and exacerbating reflective cracks, sometimes damaging pavements down to the subgrade.

Geosynthetic reinforcement has seen significant strides in recent years. The Romans may have given us a solid foundation for building modern roads, but we’ve come a long way from a technological standpoint from merely milling old pavement surfaces and adding new overlays. The use of interlayers can do wonders for our infrastructure problem, building roads that will last for the next generation of Americans.