Visitors to Italy often take time to visit ancient Roman sites, and marvel at the fact that these structures continue to remain standing today. The extant infrastructure of the Romans is really quite amazing, including aqueducts, temples, public baths, and more.
What visitors don't often think about is what these structures were made out of. At first glance, they appear to be masonry, which some may think explains their longevity -- masonry is famous for its endurance and strength. But what's underneath the masonry is actually what's more interesting, because the Romans built with concrete. Very solid, very strong, and very environmentally-friendly concrete that could provide a few lessons for modern concrete contractors interested in green projects.
Concrete is a fabulous building material because it's strong, highly flexible in terms of the potential for use, and extremely durable. Structures built with concrete can bear tremendous loads and may be built in any shape or form desired, as long as the contractor is ready and willing to put in the work on custom concrete forms or specialized blocks. However, modern concrete production practices are, sadly, not the most environmentally friendly.
This building material is made by heating limestone in a kiln with gypsum or another source of sulfate and grinding it to create a product that can be blended with an aggregate to create concrete. When mixed with water, concrete can be poured, scraped, and pushed into shape before being allowed to cure into a hard, waterproof substance that will continue curing over the years to become even stronger and more durable.
The problem? The "kiln" part. Creating the necessary cement requires a huge fuel input, and contributes significantly to fossil fuel production worldwide, which is bad news on a planet where climate change is a concern, and where some nations are starting to think about installing emissions caps and limiting industry-associated emissions. For green design, emissions standards are also an increasingly common sight, which means that while concrete might be a great building material, it's not always a good choice for ecologically-friendly construction.
Analysis of Roman concrete, however, provides a clue that it doesn't have to be that way. The Romans used lime, volcanic ash, and seawater, which required a much lower heating point than modern cement materials. It's possible that we could go back in time to find the recipe for environmentally-friendly concrete, and that might make a big difference in both global emissions and construction standards. Especially in areas where volcanic ash deposits are substantial, like Hawaii, concrete production could be much less expensive and less damaging.
Lest you question whether Roman concrete is up to the job, consider the number of Roman structures that are still standing, including massive unsupported and unreinforced buildings like the Roman Pantheon. More than 2,000 years ago, the Romans were making stronger, more durable concrete with a smaller environmental footprint than we are -- maybe it's time to take a leaf out of their book and reconsider the way we look at concrete in architecture and design.
Could we be on the way to seeing Roman-style concrete replace Portland cement and other attempts at reducing the environmental impact of concrete construction? That stained concrete floor in Cleveland could be pretty, ecologically sound, and cost effective if Roman technology can be widely adopted for today.
