Hot lime technology imparting high strength to historic mortars

摘要

In previous works the mineralogical and physico-chemical properties of crushed brick-lime mortars in response to stresses, simulating earthquakes or dynamic soil structure interactions, were studied. It was proved that the effective mechanical properties of the mortars could be attributed to the alkali-silicate reactions occurring at the brick fragment-lime interface. Since the category of the pozzolanic mortars presents a wide spectrum, spanning from the crushed brick to various cemen-titious mortars, the idea was to study the effectiveness of other hydraulic mortars as well. The Symonos Petra Monastery at Mount Athos was selected for investigation as pilot monument, because in our previous works it was found to be scientifically sound. The mortars were analysed following a procedure correlating chemical and instrumental analysis to determine CaCo_3/CaOsil. TA, IR, SEM and EDX were performed and tensile strength and adhesion was measured. The amounts of Ca~(++) and Mg~(++) were determined by AAS. Old mortars, from the Arsenal tower (16th c.) present higher tensile strengths than traditional hydraulic lime mortars and are effective against dynamic stresses exerted onto the greater Serbomacedonian mass as well as against the intense marine environment. Fine ground magnesium-alumino-silicate dust of the montmorillonitic clays in the area could have been mixed in a ratio of 2/(1/5) of lime/'pozzolanic' or active clay admixtures/inert aggregates reacted with the in situ slaked lime, their hydraulic components augmenting considerably with Mg~(++). Hence Arsenal mortars present an intermediary between Roman and modern concrete for marine structures produced by hot lime technology.