Compositional variability of natural hydraulic limes (NHL) in Europe. Part 1: comparative analysis of raw materials and manufacturing processes across eight European producers

This research aims to highlight the different manufacturing factors that influence the compositional variability of natural hydraulic limes (NHL). For this purpose, the main production stages of eight commercial NHL factories have been studied, in order to understand how the raw materials selection, calcination and slaking influence the final properties of NHLs available on the European market today. Beyond geological variability in carbonate-clay raw materials, the results obtained in this study can be interpreted as the direct outcome of manufacturer-specific production routes, where extraction, kiln operation, fuel selection, and slaking/grinding strategies act as coupled variables controlling the final chemical and mineralogical composition and performance of natural hydraulic limes. This research demonstrates that accounting for manufacturing-related aspects is essential for achieving more accurate standardisation of NHL.