The massive harbor project not only referenced Augustus; it was built using Roman construction techniques, including the use of hydraulic mortar
that required the importation of massive amounts of volcanic pozzolana from Italy.
The word "concrete" means a mixture of hydraulic mortar, pebbles and sand.
In all of the cited works from the 19th century, we have found a wide range of materials and different techniques used (burning in airy conditions, burning in closed vessels, diverse types and techniques of slaking, various types of mixtures) but all of the tests and essays follow one target: to obtain stabile hydraulic mortar despite the materials on the construction site being different.
Badly eroded masonry was replaced by new quarried sandstone and a hydraulic mortar
lime similar to the original medieval mix was used to fill gaps.
Most useful is the contribution of Sha'er in which the constituent components of hydraulic mortar
are gone into in great detail.
On the contrary, in hydraulic mortars
, where the paste is dense, salt crystals may be also formed in small cracks .
Cantini et al., "Archaeometric study of natural hydraulic mortars
: the case of the Late Roman Villa dell'Oratorio (Florence, Italy)," Archaeological and Anthropological Science, vol.
They created hydraulic mortars
that contained lime and pouzzolane such as clay brick dust and volcanic ash.