The Compatibility of Earth-Based Repair Mortars with Rammed Earth Substrates



Earth constructions are susceptible to degradation due to natural or human causes. The degradation of the exterior surface of earth walls is very common, either due to lack of maintenance or to the use of incompatible materials, and often requires the application of a repair mortar. This work experimentally analyses the performance of earth-based repair mortars applied on rammed earth surfaces. The mortars are based on earths collected from rammed earth buildings in south Portugal or on a commercial earth. Eight repair mortars were formulated, with the unstabilized earths or including low binder content. For the stabilized mortars four types of binder were tested: hydrated air-lime, hydraulic lime, Portland cement and natural cement. The repair mortars were applied on two types of standard defects purposely made on rammed earth blocks, representing the most current common defects found on exterior rammed earth surfaces: a standard superficial defect and a standard deep defect. The performance of the mortars, their compatibility with the substrates and the visual effectiveness of the intervention were evaluated. It was concluded that the same mortars behaved differently when applied on different rammed earth supports. However, the best performances occurred always for the mortars made from unstabilized earth identical to that of the rammed earth substrate. Indeed, the use of stabilizers systematically worsened the behavior of the repair mortars, regardless of the type of binder used for that purpose.


Rammed earth substrate Wall defect Earth repair mortar Compatibility between materials 



M. I. Gomes was supported by a doctoral grant from the Fundação para a Ciência e a Tecnologia (FCT). This work was carried out at the National Laboratory for Civil Engineering (LNEC), in Lisbon. The authors are grateful to the people who collaborated in the experimental work, in particular LNEC technicians José Costa, João Junior, Luis Nunes, and Bento Sabala. We wish to thank the following companies for their aid: Sorgila company, Lusical and Secil, Georg Hilbert and Aubiose.


  1. Angulo-Ibáñez, Q., Mas-Tomás, Á., Galvañ-LLopis, V., & Sántolaria-Montesinos, J. L. (2012). Traditional braces of earth constructions. Construction and Building Materials, 30, 389–399.CrossRefGoogle Scholar
  2. Ashurst, J., & Ashurst, N. (1995). Practical building conservation: Brick, terracotta & earth (Vol. 2). Hampshire, England: English Heritage Technical Handbook. Gower technical press.Google Scholar
  3. Boussalh, M., Jlok, M., Guillaud, H., & Moiset, S. (2004). Manuel de conservation du patrimoine architectural en terre des vallés présahariennes du Maroc. Noûs. CERKAS-Centre du Patrimoine Mondial de l’UNESCO-CRATerre—Centre de Recherché et d´Application.Google Scholar
  4. EN 196-1, (2005). Methods of testing the cement—Part 1: Determination of mechanical strength. Brussels: CEN—European Committee for Standardization.Google Scholar
  5. EN 1015-3. (1999). Methods of test for mortar for masonry. Part 3: Determination of consistence of fresh mortar (by flow table). Brussels\ A1: 2004\ A2: 2006: Brussels: CEN—European Committee for Standardization.Google Scholar
  6. Faria, P. (2005). Rendering of earth walls. In Earth Architecture in Portugal. 1st Edição. Lisboa, Argumentum. 68–73.Google Scholar
  7. Gomes, M. I., & Faria, P. (2011). Repair mortars for rammed earth constructions. In V. P. Freitas, H. Corvacho, & Lacasse (Eds.), Proceedings of the 12th International Conference on Durability of Building Materials and Components (Vol. 2, pp. 689–696). Faculdade de Engenharia da Universidade do Porto, Portugal, 12–15 April.Google Scholar
  8. Gomes, M. I., Gonçalves, T. D., & Faria, P. (2012a). Análise experimental de argamassas de terra com cais e fibras naturais. Proceedings of the 4th Congresso Português de argamassas e ETICS - APFAC. Coimbra, Cd Proceddings.Google Scholar
  9. Gomes, M. I., Gonçalves, T. D., & Faria, P. (2012b). Earth-based repair mortars : Experimental analysis with different binders and natural fibers. In C. Mileto, F. Vegas, & V. Cristini (Eds.), Proceedings of the 1st International Conference on Rammed Earth Conservation (pp. 21–23). Valencia, Spain.Google Scholar
  10. Gomes, M. I., Gonçalves, T. D., & Faria, P. (2012c). Evaluación de la influencia del contenido de agua en la trabajabilidad del mortero de tierra. APUNTES, 25(2), 8–27.Google Scholar
  11. Gomes, M. I., Gonçalves, T. D., & Faria, P. (2012d). Unstabilised rammed earth: characterization of the material collected from old constructions in south Portugal and comparison to normative requirements. International Journal of Architectural Heritage, Taylor & Francis, 8(2), 185–212.CrossRefGoogle Scholar
  12. Guelberth, C. R., & Chiras, D. (2003). The natural plaster book: Earth, lime and gypsum renders for natural homes. Gabriola Island, Canada: New Society Publishers.Google Scholar
  13. Hamard, E., Morel, J.-C., Salgado, F., Marcom, A., & Meunier, N. (2013). A procedure to assess the suitability of plaster to protect vernacular earthen architecture. Journal of Cultural Heritage, 14(2), 109–115.CrossRefGoogle Scholar
  14. Houben, H., & Guillaud, H., (2006). Earth construction: A comprehensive guide Technology. London: Technology Intermediate Publications (1st edition 1994), ITDG Publishing.Google Scholar
  15. Houben, H., & Guillaud, H. (1996). Earthen architecture: Materials, techniques and knowledge at the service of new architectural applications. The Courier. No. 159, Dossier Investing in People Country Reports: Mali.Google Scholar
  16. Jiménez Delgado, M. C., & Guerrero, I. C. (2006). Earth building in Spain. Construction and Building Materials, 20(9), 679–690.CrossRefGoogle Scholar
  17. Keable, J. (1996). Rammed earth structure: A code of pratice. London: Intermediate Technology Publications Ltd.CrossRefGoogle Scholar
  18. Le Tiec, J.-M., & Paccoud, G. (2006). Pisé H2O. De l’eau et des grains pour un renouveau du pisé en Rhône-Alpes (CRATerre.). Villefontaine, France.Google Scholar
  19. Maniatidis, V., & Walker, P., (2003). A Review of Rammed Earth Construction. Review Literature and Arts of the Americas DTi Partne (May).Google Scholar
  20. McHenry, P. (1984). Adobe and rammed earth buildings: Design and construction. Arizona: The university of Arizona Press. Wiley-Interscience.Google Scholar
  21. Miccoli, L., Müller, U., & Fontana, P. (2014). Mechanical behaviour of earthen materials: A comparison between earth block masonry, rammed earth and cob. Construction and Building Materials, 61, 327–339.CrossRefGoogle Scholar
  22. Morton, T. (2004). Earth structures, renders and plasters: Experiments in historical techniques and weathering. In Dachverband Lehm e.V. (Eds.), 4th International Conference on Building with Earth, LEHM (pp. 272–275). Weimar, Germany, 29–30 October 2004. ISBN: 3000148647.Google Scholar
  23. New Mexico Code. (2006). New México Earthen Building Materials Code 14.7.4, New Mexico: Santa Fé, NM: Construction Industries Division (CID) of the Regulation and Licensing Department. Available at:
  24. Norton, J. (1997). Building with earth (2nd ed.). Warwickshire: Pratical Action.CrossRefGoogle Scholar
  25. SAZS 724. (2001). Standards Association Zimbabwe. Standard Code of Practice for Rammed Earth Structures, Harare: Standards Association of Zimbabwe.Google Scholar
  26. SNZ, 4298. (1998). Materials and workmanship for earth buildings. Standards New Zealand. New Zealand.Google Scholar
  27. Toumbakari, E.-E., Ntziouni, A., & Rigopoulou, V. K. (2010). Cement-stabilized earth mortars for application in archaeological sites and prehistoric momuments. In J. Válek, C. Groot, & J. J. Hughes, (Eds.), 2nd Historic Mortars Conference and RILEM TC 203-RHM Final Workshop (pp. 1209–1217). Prague, Czech Republic, 22–24 September: RILEM Publications SARL.Google Scholar
  28. Veiga, R. (1998). Behavior of mortar coating walls. Contribution to the study of its resistance to cracking (in Portuguese). Ph.D. thesis, Faculty of Engineering of University of Porto.Google Scholar
  29. Walker, P., Keable, R., Martin, J., & Maniatidis, V. (2005). Rammed earth: Design and construction guidelines. Watford: BRE Bookshop. ISBN 1 86081 734 3, 146.Google Scholar
  30. Walker, P., & Australia, S. (2001). HB 195: The Australian earth building handbook. Sydney, Australia: Standards Australia International Ltd. ISBN. 0733740006, 151.Google Scholar
  31. Warren, J. (1999). Conservation of earth structures. British Library: Butterworth Heinemann.Google Scholar
  32. WCED. (1987). Report of the World Commission on environment and development: Our common future, 83.Google Scholar

Copyright information

© Springer International Publishing AG, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Civil EngineeringLisbon Engineering Superior Institute (ISEL), Lisbon Polytechnic Institute (IPL)LisbonPortugal
  2. 2.National Laboratory for Civil Engineering (LNEC)LisbonPortugal
  3. 3.Department of Civil EngineeringNOVA University of Lisbon (FCT NOVA) and CERISLisbonPortugal

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