engleski

A new approach on data extrapolation for mortar dating in the Zagreb Radiocarbon Laboratory

There is no unique way of mortar sample preparation that would always provide the true date. We propose a procedure of 14C age extrapolation from CO2 fractions obtained by sequential dissolution of mortar grain size 32 – 63 μm by phosphoric acid. The collection of CO2 fractions is deduced from kinetics of mortar- hydrolysis curve. The procedure was designed from data obtained from mortars prepared in laboratory and tested on mortar/plaster from three archaeological cases, with confirmed ages. The first fractions gave true result for historical mortars, but for laboratory ones only extrapolated values were true. When certain conditions regarding CO2 fraction collection were met, extrapolated values agreed with the first fractions for the historical mortars. Although the extrapolation procedure seems to eliminate the effect of dead carbon contamination, it is not effective against influence of delayed hardening or restoration.

Mortar radiocarbon dating ; Sequential dissolution ; Data extrapolation ; Carbonate hydrolysis kinetics ; Dubrovnik Cathedral ; Radošević Palace – Hvar ; Croatia

nije evidentirano