Hostname: page-component-848d4c4894-2pzkn Total loading time: 0 Render date: 2024-04-30T14:18:14.172Z Has data issue: false hasContentIssue false
  • English
  • Français

Simulated Standards for the Characterization of Dolomitic Mortars

Published online by Cambridge University Press:  21 March 2011

C. Montoya ,
J. Lanas ,
M. Arandigoyen ,
I. Navarro ,
P.J. García Casado  and
J.I. Alvarez
C. Montoya
Affiliation:
Dept. of Chemistry and Soil Science, University of Navarra, 31080 Pamplona, Spain.
J. Lanas
Affiliation:
Dept. of Chemistry and Soil Science, University of Navarra, 31080 Pamplona, Spain.
M. Arandigoyen
Affiliation:
Dept. of Chemistry and Soil Science, University of Navarra, 31080 Pamplona, Spain.
I. Navarro
Affiliation:
Dept. of Chemistry and Soil Science, University of Navarra, 31080 Pamplona, Spain.
P.J. García Casado
Affiliation:
Dept. of Chemistry and Soil Science, University of Navarra, 31080 Pamplona, Spain.
J.I. Alvarez
Affiliation:
Dept. of Chemistry and Soil Science, University of Navarra, 31080 Pamplona, Spain.
Get access

Abstract

In order to clarify the structure underlying the appearance of several compounds in dolomitic mortars (specifically hydromagnesite, Mg5(CO3)4(OH)2.4H2O), as well as the suitability of the X-ray diffraction (XRD) and thermogravimetric and thermodifferential simultaneous analysis (TGA-DTA) in their determination, different patterns from phases that could be present in mortars of these characteristics have been prepared and studied by these techniques. The standards were prepared from: hydromagnesite (HY) with calcite in weight/weight proportions 1:1 to 1:5; HY with calcite and quartz in proportions 1:1:1 and 1:6:12; HY with quartz, 1:1 and 1:2; HY with portlandite (calcium hydroxide), 1:1 and 1:2; HY with portlandite and quartz, in 1:6:12, and HY with magnesium oxide in 1:1, 1:2 and 2:1.

The XRD results have shown that it is possible to detect HY and the other compounds (dolomite, calcite, magnesite, quartz, …), but when the HY is mixed, the intensity of its diffraction peaks is very weak, even not detectable in some cases. The poor crystallinity of the HY could be the reason of this drop in intensity. Therefore thermal studies were necessary to find HY phases in low weight percentages.

TGA-DTA led us to establish the experimental conditions most suitable for thermal studies. A high CO2 pressure around the sample was required for the occurrence of an exothermic peak at 500°C. This high pressure was guaranteed in the present work as follows: static air atmosphere, packed sample, high heating rate (20°C.min-1), and alumina crucibles with holed lids in order to establish a selfgenerated atmosphere. The thermal behavior of hydromagnesite phases has been clearly established in contradiction to some references of the literature; specifically, the exothermic peak at 500°C has been observed repeatedly. This result invalidates reports of the crystallization of magnesium carbonate from the amorphous phase.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 712: Symposium II – Materials Issues in Art and Archaeology VI , 2002 , II3.1
Copyright
Copyright © Materials Research Society 2002

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Bruni, S. Cariati, F. Fermo, P. Pozzi, A. and Toniolo, L, Thermochim. Acta. 321, 161–165 (1998).Google Scholar
2. Dheilly, R.M., Bouguerra, A. Beaudoin, B. Tudo, J. and Queneudec, M. Mat. Sci. Eng. A —; Struct. 268, 127–131 (1999).Google Scholar
3. Vecchio, S. Laginestra, A. Frezza, A. and Ferragina, C. Thermochim. Acta. 227, 215–223 (1993).Google Scholar
4. Fiori, C. and Macchiarola, M. in III Congreso Internacional de Rehabilitación del Patrimonio Arquitectónico y Edificación, Granada (España), edited by Pardo, E.M. Sebastián, Espinosa, I. Valverde and Zezza, U. 1996, pp. 223–237.Google Scholar
5. Newton, R.G. and Sharp, J.H. Stud. Conserv. 32, 163–175 (1987).Google Scholar
6. Montoya, C. Lanas, J. Arandigoyen, M. Navarro, I. Casado, P.J. García and Alvarez, J.I. presented at the 2001 Fall Meeting, Boston, 2001 (in press).Google Scholar
7. Bruni, S. Cariati, F. Fermo, P. Cairati, P. Alessandrini, G. and Toniolo, L. Archaeometry 39 (1), 1–7 (1997).Google Scholar
8. Webb, T.L. and Krüger, J.E., in Differential Thermal Analysis, edited by Mackenzie, R.C. (Academic Press Inc., London, 1970) pp. 303–341.Google Scholar
9. Sawada, Y. Uematsu, K. Mizutani, N. and Kato, M. Thermochim. Acta. 27, 45–49 (1978).Google Scholar
10. Beck, C. W., Am. Miner. 35, 985–1013 (1950).Google Scholar