Papers by Author: Miloš Drdácký

Abstract: The paper presents a novel concept and a prototype of a diagnostic tool for in-situ assessment of timber in existing structures and buildings. The device enables direct determination of conventional compressive strength and modulus of deformation in arbitrary depth along timber profile. The measurement of the stress-deformation relationship is performed in a prepared hole of a very small diameter by means of a special small size symmetrical loading jack. Testing and verification of the new device behaviour during loading of wood along the fibres has been carried out on fir which is the most frequent wood species in European buildings. The comparison of stress-strain diagrams acquired by means of the new device with those measured in compliance with the European standard for testing of wood shows a very good correlation including the determination of the compressive strength values. This semi-destructive method causes a very gentle damage and can be also used for the assessment of historic timber structures.

Abstract: This paper presents a comparative study of the effects of calcium hydroxide based agents on consolidating a lean lime mortar. In the first part, it describes the properties and characteristics of CaLoSiL® – a new stone strengthener based on colloidal suspensions of lime nanoparticles in various solvents. It further summarizes the results of recent tests on the influence of applying nano-agents based on colloidal calcium hydroxide dispersed in ethanol or isopropyl alcohol (CaLoSiL®), and compares them with the effects of lime water and with a traditional barium hydroxide treatment. The tests were carried out on non-standard test specimens fabricated from a lean mortar (1:9) and developed specially for the purpose of testing the relatively low strengthening effects that are typical for lime water consolidation. The comparison presented in this paper is based on the mechanical characteristics of consolidated lime mortar.