N.º 7 2008 pp. 21-28

Article
Development of lime based mortars for repairing glazed tile coatings of historic buildings in the city of Ovar, Portugal

B. Teixeira^1,*, C. Valente¹, A. L. Velosa², M. R. Veiga³, I. M. Ferreira⁴

¹ Civil Engineer, University of Aveiro, Aveiro, Portugal

² PhD/Auxiliar Professor, University of Aveiro, GeoBioTech, Aveiro, Portugal

³ PhD/Main Investigator, National Laboratory of Civil Engineering, Lisboa, Portugal

⁴ Msc/Archeologist, Atelier de Conservação e Restauro do Azulejo (ACRA), Porto, Portugal

* miguelteixeira@ua.pt

Abstract

Portugal is one of the European countries in which built heritage is a testimony of its history. In this context, the legacy of the decorative glazed tile coatings of facades must be preserved and restored. This research is dedicated to the conservation of such facades in the city of Ovar, considered an example due to its rich heritage in glazed tiles, a high percentage of which requires a deep intervention. Therefore, this work is focused on the study of lime renders serving as a support for this type of tile facades. For this, samples were collected from several buildings in the city, targeting their mechanical and physical study with the aim of producing compatible mortars to be used for application of detached tiles in these buildings and generally for the repair of the facades with glazed tile coatings. For this purpose, four lime mortar formulations with different volumetric ratios were composed. The aggregates used were: ordinary river sand and local gravel. In three of the mixtures, metakaolin was added, with the intention of acting as an artificial pozzolan and thus improving the performance of these mortars. The use of a pozzolanic addition promotes hardening of lime mortars in cases when the ingression of carbon dioxide is low as is the case of mortars placed below glazed tile coatings. These mortars were also tested in the laboratory taking into account their physical and mechanical characteristics. The mechanical characteristics determined were: modulus of elasticity by two different methods, compressive strength and flexural strength. In turn, the physical characteristics determined were: water vapour permeability and water absorption by total immersion and capillary action. The best mechanical behaviour (compressive and flexural) was observed in the mortar with pozzolanic additions. Similarly, the value of the modulus of elasticity was better in mortars with pozzolanic additions. The performance of these mortars was also adequate in terms of water behaviour. The mortars revealed suitable characteristics for application in building conservation situations concerning coating with glazed tiles.

Keywords

Conservation
Glazed tiles
Lime mortars
Pozzolanic additions

Language

English

DOI

10.14568/cp7_3

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History

Online: 2017-10-3
Publication: 2009-6-2

References

1 Veiga, M. R.; Aguiar, J.; Santos Silva, A., Carvalho, F, Conservação e Renovação de Revestimentos de Paredes de Edifícios Antigos, LNEC, Lisboa (2004).

2 Ferreira, M. I., 'Revestimentos Azulejares Oitocentistas de Fachada em Ovar. Contributos para uma metodologia de conservação e restauro', MSc dissertation, Universidade de Évora (2007).

3 Moropoulou, A.; Bakolas, A.; Moundoulas, P.; Kopoulou, E.; Anagnostopolou, S., 'Strength development and lime reaction in mortars for repairing historic masonries', Cement & Concrete Composites 27 (2005) 289-294.

4 CEN, EN 1015-19, Methods of test for mortar for masonry, Part 19: Determination of water vapour permeability of hardened rendering and plastering mortars, CEN, Brussels (1998).

5 Veiga, M., 'Comportamento de argamassas de revestimento de paredes. Contribuição para o estudo da sua resistência à fendilhação', PhD dissertation, Faculdade de Engenharia da Universidade do Porto (1998).

6 Veiga, M.; Velosa, A.; Magalhães, A., 'Evaluation of mechanical compatibility of renders to apply on old walls based on a restrained shrinkage test', Materials and Structures 40(10) (2006) 1115-1126.

Stable url: https://doi.org/10.14568/cp7_3