Hydraulic Lime

Hydraulic lime sets and hardens through a chemical reaction with water — including underwater — making it fundamentally different from non-hydraulic slaked lime and a preferred binder in historic masonry restoration, marine construction, and specialty mortars. Classified under tariff line 2522300000, it is produced from limestone with a higher silica and clay content than standard calcitic stone. France is the leading US supplier, reflecting that country's long tradition of natural hydraulic lime production for heritage conservation projects. Mexico and Spain also supply the US market, with Germany and Belgium contributing smaller volumes.