Physico-Chemical, Petrographic, and Mechanical Characteristics of Lime Mortars in Historic Yoros Castle (Turkey)

Abstract

This study examines the physicochemical, petrographic, and mechanical properties of lime mortars used in construction of Yoros Castle in the Byzantine period (13th–14th centuries ad ). The study of mortar samples has been performed through polarizing and stereomicroscope observations, x-ray diffraction (XRD) analyses, chemical (inductively coupled plasma emission spectroscopy [ICP-ES] and (high performance liquid chromatography [HPLC]), physical, and mechanical analyses. The hydraulic character of the mortars was mostly provided by pozzolanic brick dust and tuff additives. The results of spot tests indicate that the mortars contain protein and organic additives, which were used in their production. Albumin was detected during HPLC analysis, which was performed in order to determine the nature of the ingredients. The presence of albumin and vaterite, of which the latter was determined by XRD analysis, was considered to be the result of egg white content. The ignition loss and acid treatment analyses show that the binder/aggregate ratio varies between 1:2 and 1:3. The porosity ratio of mortars is approximately 30% on the average. According to the results of mechanical tests, average compressive strength of mortars is approximately 9.4 N/mm2, flexural strength is approximately 2.4 N/mm2. Despite their age of approximately 800 years, absence of extensive disintegration in the mortars may well indicate proper techniques of production.