A PRACTICAL METHOD FOR PREPARING Ca(OH)2 NANODISPERSIONS FOR THE CONSOLIDATION OF ARCHAEOLOGICAL CALCAREOUS STONES

Abstract

Exposure to atmospheric conditions results in considerable deterioration of calcareous building stones,

lime mortars and plasters in archaeological monuments, requiring several conservation treatments. During

the consolidation treatments of the deteriorated calcareous stones, compatibility can best be achieved by in

troducing a material that would have similar chemical composition and mineralogical structure with the

original stone. In recent years, studies on the preparation of Ca(OH)2 nanodispersions for the consolidation

of limestone and marble have increased but the preparation processes of these nanodispersions are usually

complicated and time consuming. This study aimed to prepare Ca(OH)2 nanodispersions in ethyl alcohol at

sufficient concentration levels with a practical method for the consolidation of calcareous archaeological ma

terials.

The preparation of higher concentrations of Ca(OH)2 nanodispersion in ethyl alcohol was done by using

nano sized CaO and its dispersion in ethyl alcohol.

Deteriorated marble pieces from Roman Marble Quarry near Pessinus Archaeological site (Ballıhisar,

Turkey) were treated with the prepared Ca(OH)2 nanodispersion and kept at high relative humidity (~90%)

at room temperature in the laboratory. Efficient penetration of the nanodispersion, and increase in the physi

comechanical properties of treated marbles were followed by examinations with polarizing microscope,

SEM, XRD and ultrasonic pulse velocity measurements. Carbonation of the dispersion was followed by ti

trimetric analysis. Calcite was the main polymorph observed after carbonation.

The results showed that consolidation treatments with Ca(OH)2 nanodispersions similar to the one pre

pared in this study can be used for all calcareous archaeological materials that need improvements in their

physical and mechanical properties.