Lime, the secret of the Roman buildings´ durability

31/07/2023

Researchers from the renowned Massachusetts Institute of Technology (MIT), a team from Harvard University and Italian and Swiss researchers have been able to confirm ancient concrete manufacturing strategies in ancient Rome, where lime is the main protagonist and the responsible of the long life of these constructions.

The study of samples from Roman concrete by US researchers determined that the white inclusions were made up of various forms of calcium carbonate. And spectroscopic examination provided indications that they had formed at extreme temperatures, as would be expected from the exothermic reaction produced by the use of quicklime (calcium oxide) rather than slaked lime (calcium hydroxide) in the mix. In fact, hot mixing was the key to the superdurable nature of the concrete.

Lime has been a product widely used in construction long time ago. In fact, lime mortar is the only material used in architecture that has demonstrated a permanence of centuries, and even millennia, exemplified in medieval cathedrals and Roman constructions.

Today, hydrated lime (calcium hydroxide) is still an ingredient of building materials such as mortars, premixes for plastering, improved floors, paints, asphalts, etc.

Quicklime (Calcium Oxide) is used in the stabilization and improvement of clay soils during the construction of roads, railways, airports, etc. In this field of civil engineering, it has also been shown that the addition of hydrated lime (Calcium Hydroxide) to asphalt mixtures for road construction improves the quality of roads and reduces maintenance costs.

Precipitated calcium carbonate (PCC) is also used in building materials such as PVC window profiles, building sealants, architectural paints or different types of synthetic flooring, thanks to the combination of the properties it confers and the quality of the finishes provided.