ISSN 1392–1320 MATERIALS SCIENCE (MEDŽIAGOTYRA). Vol. 9, No. 2. 2003 Properties of Dimension (Facing) Stone from Estonian Dolostone M. Pyldme, U. Kallavus ∗ , J. Schvede, R. Traksmaa Centre for Materials Research, Tallinn Technical University, Ehitajate tee 5, 19086, Tallinn, Estonia Received 03 March 2003; accepted 07 May 2003 In this work the hydrophobization of dimension (facing) stone from Estonian dolostone was investigated. Due to the diversity of the structure and properties of the stone from one source and the differences of dolostone mined from different areas of Estonia – Kaarma, Selgase and Orgita, certain properties of stone were investigated by chemical analysis, X-ray diffraction and scanning electron microscopy. Water absorption by DIN 52103 and frost resistance by DIN 52104 were carried out. XRD measurements showed that the composition of Estonian dolomite was nonstoichiometric for samples from all three deposits. For Selgase and Orgita dolostone, in comparison to Kaarma dolostone, typical absence of relatively large pores and smaller interval of absorption times of a water drop occurred. Comparing the ratio of water absorption time to the stated by producer norm of hydrophobic liquid (R/N) it could be concluded that commonly coating once is sufficiently suitable. After 100 freezing-thawing cycles no signs of damages on any specimen cubes or plates were discovered. Keywords: carbonate rock, weathering of stone, degradation, prevention against deterioration. 1. INTRODUCTION∗ Dolostone together with limestone and marble is one of basic forms of carbonate rocks [1, 2]. Carbonate rocks have been and continue to be the major source of architectural and statuary stone. The pyramids, Sphinx, and most other Egyptian monuments were built from limestone; most Greek and Roman architecture, including the many temples at Acropolis, were built from marble. Famous pieces of statuary in dolostone are also well known, but the primary importance of dolostone has been in common construction. Finishing stone from dolostone stem from Estonia were used continually in architecture in Baltic countries and also in St. Petersburg [3, 4]. Due to sedimental formation of carbonate rocks and chemical properties of main constituent minerals durability of dolostone to weathering is much lower than of granite stones. Weathering includes processes, such as chemical influence of air and rainwater and the mechanical action of water, whereby rocks, when exposed to atmosphere, decay into products or disintegrate into fragments. Weathering includes also disintegration by mechanical forces generated within the rock. As carbonate rocks contain a network of pores and cracks, aqueous solutions penetrate into rock and damage it in variety of ways. The loss of cohesiveness between grains by wetting and bursting pressure from freezing, salt crystallization and swelling clay minerals may occur. Deterioration of carbonate stone was noticed rather soon after beginning its usage. The problems hade rapidly became more alarming as the world became industrialized and polluted. Greek and Roman writers indicated the necessitate of treatments to forestall deterioration of stone already centuries ago. So-called scientific approaches began to appear in the 19 th century. Prevention against deteriorating of stone was primarily carried out by applying different waxes, paint, or other coating what was available and might work. After about 1960, polymeric chemicals with more suitable properties became commercially available. It is essential, before applying certain chemicals to carbonate stone against deterioration, to study properties of stone. The composition and texture of carbonate stone from different deposits may vary in a big extend. Therefore treatment effect of each chemical on stone may occur very different. The aim of present study was to investigate some properties of Estonian dolostone and the coating effect with hydrophobic liquid chemicals of dimension (facing) stone. 2. EXPERIMENTAL DETAILS Dolostones from Kaarma, Selgase and Orgita deposit were studied using chemical analysis, microscopic and X- ray diffraction methods. X-ray analysis on D5005 Bruker AXS diffractometer and microscopic observations in the scanning electron microscope JEOL JSM 840A were carried out. Commercial dimension (facing) stones with size 150×150×10 mm with ground upper side, and cubic form specimens with size 40×40×40 mm were used for the experiments. For coating commercial hydrofobization liquids HIDROFOBS and FUNCOSIL SNL were used. Water absorption by DIN 52103 and frost resistance by DIN 52104, using freezing-thawing cycles with water saturated cubes and plates in atmosphere with 100 % relative humidity were performed. For characterization of water absorption speed the time of complete absorption of 1 water drop was measured [5]. Eight plates were choosen from each deposit. To reveal the possible discrepancy in the absorption over the whole area of one sample, 35 separate areas were marked on ground surface of every plate and the absorption time of 1 drop was measured on each area separately. As a whole, in one series, 280 drops of water were dipped onto the marked areas of 8 samples ∗ Corresponding author. Tel.: + 372-620-3152; fax.: + 372-620-3153. E-mail address: urka@staff.ttu.ee (U. Kallavus) 213