Hydraulic limes

Lime is a material known and used since Antiquity, obtained by calcining limestone rock, generally followed by a phase of slaking with water before use. An article in this collection tells the story [C 922] .

But it's a misnomer to speak of lime in the singular, as this material has many facets. In particular, we need to distinguish between air lime and hydraulic lime. While air lime hardens only in air, hydraulic lime, like cement, sets in contact with water, before also reacting in contact with air.

Hydraulic limes are therefore binders, since they ensure the cohesion of the materials with which they are mixed, as soon as water is added. This article deals solely with hydraulic limes. For air lime, readers are invited to consult the corresponding article published in this same document base [C 923] .

The hydraulic nature of lime was only truly mastered following Louis Vicat's work on hydraulic properties (as early as 1820). The industrial boom in hydraulic lime reached its peak in the first decades of the 20th century: by 1925, France was producing more hydraulic lime than cement (3.2 million tonnes versus 2.3 million). The trend then sharply reversed with the boom in cement production (introduction of the rotary kiln in 1910). Directly correlated with the raw materials available, notably limestone deposits of varying silica content, the hydraulic character of cement production varies greatly.

This article summarizes the properties of hydraulic lime, its manufacturing process and its applications, mainly in the construction sector.

Finally, given the many analogies with the properties of cements, we also recommend reading an article on cements in this collection [C 920] .