It turns out that replacing the conventional aggregates of concrete--sand, gravel, crushed stone, even volcanic ash--with glass is not really a stretch of the imagination.
The Romans might have no trouble building their roads, buildings and dams with glass-aggregated concrete. But MODERN concrete is still problematic for two reasons:
- It's not as tightly packed as ancestral concrete, meaning it's more porous
- It's fitted with steel reinforcement bars for better durability, higher relative strength and higher tolerance of tensile stress.
For these two reasons, modern metropolitan areas are estimated to survive only an average of 100 years in a Life After People.
In this alternate scenario, glass has been the aggregate of both Roman and Modern concrete. Hoover Dam is now a vast wall of glass-aggregated concrete. New York City is a concrete jungle of cement, water and glass. Route 66 is now one of many roads made from glassphalt concrete. Special precautions are made to make sure that Hoover Dam is curing at a slow pace, making it stronger.
Now...is it practical to reinforce concrete with a glass aggregate? If yes, then in a New York and Chicago climate, how long would they stand in a Life After People?