Special natural hydraulic limes

Special natural hydraulic limes, as defined in [16.60] are produced by intimately blending powdered natural hydraulic limes with powdered pozzolanic or hydraulic materials. 

Hydraulic limes have the property of setting and hardening under water — see natural hydraulic limes, special natural hydraulic limes and artificial hydraulic limes. The term is also used to describe eminently hydraulic and Roman limes. 

Special natural hydraulic limes are produced by blending natural hydraulic limes with up to 20 % of suitable pozzolanic products (e.g., pulverised fuel ash, volcanic ash and trass), or hydraulic materials (e.g., ordinary Portland cement and blast furnace slag). 

In this framework, in the specially designed mortars consisting of binders of either lime and metakaolin or natural hydraulic lime and fine aggregates of carbonate nature, nano-titania of anatase (90 per cent) and rutile (10 per cent) form has been added (4.5-6% w/w of binder). The aim was to study the effect of nano-titania in the hydration and carbonation of the above binders and to compare the physico-chemical properties of the nano-titania mortars with those mortars without nano-titania, used as reference. Thermal analysis (DTA-TG), infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were performed to investigate the evolution of carbonation, hydration and hydraulic compound formation during a six-month curing period. Furthermore, the stone-mortar interfaces, the adhesion resistance to external mechanical stress, relative to the physicochemical characteristics of the stone-mortar system and the role of the nano-titania as additive, were reported and are discussed in this chapter. 

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