STRUCTURAL REINFORCEMENT OF PIŃCZÓW LIMESTONE
The aim of the research was to examine the possibilities and ways of application of S. Z. Lewin’s method in limestone reinforcement. The method constists in limestone impregnation with the solution of carbamide and barium hydroxide. As a result of the chemical reaction in limestone pores the insoluble barium carbonate is precipitated; it is to play the function of the reinforcement. ' At the first stage of the research work the experiments, as described by S. Z. Lewin, were carried out. They dealt with the cementation of powdered chalk in reinforcing solution. Results of these experiments, however, proved to be a failure: after the six-month period of impregnation the cementation of limestone powder did not occur. The second stage consisted in extending the scope of the research. It included the influence of temperature and duration upon the processes of barium carbonate precipitation and limestone powder cementation as well as the effects of the duration of impregnating solution action on mechanical and physical properties of limestone. Moreover, derivatographic and X-ray structural analyses of impregnated limestone were made. As a consequence of the above experiments it was stated that the efficiency of the process of barium carbonate precipitation in room temperature was very small ((about 26 per cent after 30 days). It increases proportionally to the growth of temperature, being sufficient at 95°C. The increase of limestone strength was not stated on the grounds of influence of duration of the solution action (up to 3 months) in room temperature. Absorbing and capillary capacities of limestone, however, decreased and this proved the partial seal of limestone pores caused by barium carbonate. The application of barium hydroxide solution (free of carbamide) brought similar results. In the latter case the chemical reaction of barium hydroxide with calcium carbonate took place. The above-mentioned results were confirmed by X-ray structural investigations. It should be stressed that the cementation of limestone powder and chalk did not occur although hardening solutions of raised temperature (up to 95°C) were being used. Because of negative results of the tests carried out we cannot apply S. Z. Lewin’s method in limestone hardening. This method seems to be sufficient only for protecting the stone against the destructive components of atmosphere (chiefly S 0 2). There are two possible explanations of this situation: in his publications S. Z. Lewin did not make the conditions of limestone hardening clear enough or he might have used some additional substances which caused crystalline barium carbonate to emerge. Crystalline barium carbonate is capable of making crystalline concretions with calcite. In this case both the cementation of limestone powder and thereby reinforcing of limestone should occur.
prof. dr hab., Laboratorium Naukowo-Badawcze Konserwacji Kamienia PP PKZ Oddział w Toruniu
mgr, Laboratorium Naukowo-Badawcze Konserwacji Kamienia PP PKZ Oddział w Toruniu
J. Ri e d e r e r , „Maltechnik” (Restaure), nr 3, 1973
J. J e l i k a n , Ć. Sediwy, „Pamatkova Pece”, nr 3, 1970.
J. G a ł e c k i , Preparatyka nieorganiczna. Wydawnictwa Naukowo-Techniczne, Warszawa 1964, s. 158.
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