– Pozzolanic concrete, a unique construction material used by the ancient Romans, is responsible for the durability and strength of Roman structures.
– The properties of pozzolana concrete are attributed to its mix of volcanic ash and lime, which react with water to produce strong concrete
– An international team of researchers found that the materials and mixing techniques used to mix the concrete are different from what was previously thought
– Lime clasts, small white chunks of lime, were found in well-mixed concrete samples from the archaeological site of Privernum in Italy
– It is believed that the lime clasts were created through hot mixing, specifically by mixing quicklime with slaked lime at high temperature
– Hot mixing allows for high-temperature-associated compounds and reduces curing and setting times, allowing for faster construction
– Limestone clasts give concrete remarkable self-healing abilities, as cracks form in the concrete and the clasts have a higher surface area than other particles in the matrix
– Caustic acid has been observed in concrete from seawalls and can be used as an alternative to calcium carbonate to make it more durable and environmentally friendly.