Impact of Calcium Hydroxide Based Impregnation on Characteristics of Porous Mort

Impact of Calcium Hydroxide Based Impregnation on Characteristics of Porous Mortar and Stone

Datum | 10.06.2010, 16.00 h
Ort | Akademie der bildenden Künste Wien, Schillerplatz 3, 1010 Wien, Vortragssaal EA1 (Erdgeschoss)

Lecture by Prof. Dr. Milos Drdacky (Director, Professor of the Czech Technical University in Prague, Dipl.Ing., DrSc., dr.h.c.) and Dr. Zuzana Slizkova (Head of Department of Particulate Materials, Dipl.Ing., Ph.D.) from the Institute of Theoretical and Applied Mechanics of the Academy of Sciences of the Czech Republic (Lecture in English).

Development of compatible consolidation methods of degraded historic materials combines traditional approach with modern technologies. This calls for designing specific experimental procedures and testing different from usual standard methods. First part of the lecture will present some innovative techniques and achievements concerning the non-standard approach and investigation methods able to follow subtle change of material characteristics of degraded historic lime mortars or stones. Their application is demonstrated on examples of study of consolidation effects on lime mortars based on repeated applications of a water solution of calcium hydroxide. This technology requires tens or hundreds of application cycles in order to achieve observable strengthening effects, due to the very low solubility of these hydroxides in water. Therefore, new agents using calcium hydroxide nano-particles suspended in alcohols have now been developed and their effectiveness will be shown in the second part of the lecture. Here the lime particles are suspended in a stable manner in various alcohols and during application after the alcohol evaporates, the calcium hydroxide that is formed converts into limestone by reacting with atmospheric carbon dioxide. Thus, consolidation is achieved using a material originally present in the mortar and in many natural stones. The lecture presents the results of treatment with nano-materials in various modes of application, i.e. different numbers of repeated penetration treatments of the modeled degraded mortar or with the consolidating products. The measured strengths are compared to the effects attained with other present-day and historical consolidation methods. The structural change in the treated mortar is illustrated and compared to the effects of older techniques.