Durmeková T., Adamcová R., Maľa M. & Grand P., 2021: Efficiency of protective coating applied on a highly porous decorative tuff. Acta Geologica Slovaca, 13, 1, 85–94.

Efficiency of protective coating applied on a highly porous decorative tuff

Tatiana Durmeková, Renáta Adamcová, Martin Maľa & Petra Grand

Department of Engineering Geology, Hydrogeology and Applied Geophysics, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, 842 15 Bratislava, Slovak Republic; tatiana.durmekova@uniba.sk

Abstract

The application of protective coatings can significantly influence the essential physical properties of rocks used in building and decorative industries. This paper presents the results of laboratory tests demonstrating the positive effect of the protective coating Antipluviol S applied on a tuff from Tuscany in Italy, which is a weak volcanic rock of a very low strength and very high porosity. The efficiency of the coating was measured by absorption tests, standard uniaxial compressive strength tests and cyclic frost resistance tests. After the coating application, the water absorption decreased from 39.1% to 31.3% by total rock immersion at atmospheric pressure conditions. The water absorption only by capillary suction showed much higher efficiency of the coating. The change in the rock strength, resulting from the coating application, was less pronounced; the mean values rose from 5.8 to 6.8 MPa (17.2% increase). For all strength values are quite similar in both treated and untreated groups, as well as scattered within the groups, no relevance to the coating impact could be confirmed. But, even such a slight improvement of the monitored physical parameters has the effect of slowing down the rock's weathering. This was proven by the results of the frost resistance test. Coated samples withstood all the standard 25 freeze-thaw cycles, whereas untreated samples began to disintegrate after the 17th test cycle. These findings can help the maintenance of the famous historic architecture of picturesque tuff towns of Tuscany suffering from weathering, and contribute to the preservation of the cultural heritage. On the other hand, they showed how important such tests are when considering building stone import.

Key words: uscany tuff, weathering, protective coating, water absorption, UCS, frost resistance

Manuscript received: 2021-04-14

Revised version accepted: 2021-05-07