Polymer Matrix and Stone Powder Based Composite Mortar for the Restoration of Sille Stone Structures

Abstract

Excavated in the Sille region of Konya (Turkey) province, Sille stone (SS) is a building material used during the Roman, Seljuk, and Ottoman periods. The presence of SS in cultural assets is due to its robustness, nevertheless different environmental factors have caused the deterioration of SS based structures. Among the restoration strategies developed in order to prevent the destruction of cultural heritage, repairing mortars are the most common. These mortars can either mechanically reinforce the building or create a barrier against humidity or pollution that cause destruction. Furthermore, according to the Venice charter, mortar properties like color, freeze/thaw, etc. must match with those of the structure. In this study, for the first time composite mortar has been prepared from Sille stone powder (SSP) with polymer (epoxy, phenolic, polyurethane, and polyester) matrix. The mechanical and hydrophilic properties of the composite mortar prepared with different compositions and grain size distributions were investigated. The most suitable mortar is prepared with 30 wt.% polyester matrix and 70 wt.% SSP with grain size between 63-150 mu m. The composite color fits well with the SS while its compression strength is more than 62% higher than the original SS. Moreover, the contact angle of the composite mortar is 62.15(o) which is higher than the 24.53(o) of the SS showing an increase in hydrophobicity of the structure after restoration. For this reason, polyester matrix mortar is compatible with SS-based cultural heritage and contributes to its preservation over time.